CA1203117A - Apparatus for cooking or gelatinizing materials - Google Patents
Apparatus for cooking or gelatinizing materialsInfo
- Publication number
- CA1203117A CA1203117A CA000444888A CA444888A CA1203117A CA 1203117 A CA1203117 A CA 1203117A CA 000444888 A CA000444888 A CA 000444888A CA 444888 A CA444888 A CA 444888A CA 1203117 A CA1203117 A CA 1203117A
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- Prior art keywords
- starch
- nozzle
- chamber
- aperture
- atomization
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
Apparatus is provided for cooking or gelatinizing a material in an atomized state, so that there is obtained an easily dryable, uniform and finely-sized product. The material which is to be cooked is injected through an atomization aperture in a nozzle assembly to form a relatively finely-sized spray.
A heating medium is also injected through an aperture in the nozzle assembly into the spray of atomized material so as to heat the material to a temperature effective to cook or gelatinize the material. An enclosed chamber surrounds the atomization and heating medium injection apertures, and defines a vent aperture positioned to enable the heated spray of material to exit the chamber. The arrangement is such that the elapsed time between passage of the spray of material through the chamber, i.e., from the atomization aperture and through the vent aperture, defines the cooking or gelatinization time of the material. The apparatus disclosed is particularly useful in preparing a novel uniformly gelatinized starch product, but also has utility in connection with cooking protein or other suitable materials.
Apparatus is provided for cooking or gelatinizing a material in an atomized state, so that there is obtained an easily dryable, uniform and finely-sized product. The material which is to be cooked is injected through an atomization aperture in a nozzle assembly to form a relatively finely-sized spray.
A heating medium is also injected through an aperture in the nozzle assembly into the spray of atomized material so as to heat the material to a temperature effective to cook or gelatinize the material. An enclosed chamber surrounds the atomization and heating medium injection apertures, and defines a vent aperture positioned to enable the heated spray of material to exit the chamber. The arrangement is such that the elapsed time between passage of the spray of material through the chamber, i.e., from the atomization aperture and through the vent aperture, defines the cooking or gelatinization time of the material. The apparatus disclosed is particularly useful in preparing a novel uniformly gelatinized starch product, but also has utility in connection with cooking protein or other suitable materials.
Description
APPARATUS FOR COOKING OR GELATINIZING MATERIALS
BACK~RO~ND OF THE INVENTION
This application is a divisional of Application Serial No~ 364,96~, filed November 19, 1980.
The present invention relates to apparatus for uniformly cooking materials, and more particularly, relates to a multi-fluid spray nozzle apparatus for atomizing a mat-erial, such as a suitable starch, and for simultaneously cooking that material. Preferably, a material capable of gelatinizatin, such as a starch, is uinformly gelatinized by the use of the apparatus of this invention.
The present invention is particularly appli-cable to the atomization and cooking or gelatin-ization of materials which are normally difficult to cook or gelatinize and spray dry due to the genera-tion of high viscosities in the materials during cooking or gelatinization.
For many materials, such as starches, it is desirable to perform various chemical or physical modifications of the material when the material is in the form of a slurry, followed by drying the ~7 3~
~2~3~1L7 slurry by, for example, spray drying. When a starch, such as corn starch is in an ungelatinized (uncooked3 state, ~len spray drying the resultant slurry is generally straight forward and may be carried out using conventional atomizers. However, when the starch is in a gelatinized (cooked) state, then spray drying the resultant slurry becomes more difficult and complex due to the increased viscosity of the starch slurry and the shearing to which the gelatini2ed starch granules are subjected to during atomization and spray drying. Gelatinization occurs when an aqueous starch slurry is heated beyond a critical temperature (e.g., above about 65C for corn starch), the starch granules absorbing water and swelling resulting in a slurry with increased viscosities. For example, a slurry with 10% by weight of gelatinized corn starch generally has a viscosity of about 600 centipoises and a slurry with 15% by weight of gelatinized corn starch generally has a viscosity of about 20,000 centipoises, while a slurry with similar amounts of ungelatinized corn starch will have a viscosity similar to water (i.e., about 1 centipoise). When a gelatinized starch slurry having such high viscosities exits the cooker, then drying the starch by use of a rotary atomizer or spray nozzle in a spray dryer is unsuitable. Not only would the gelatinized starch slurry be diffi-cult to pump and atomize due to the high viscosities generated, but the swollen starch granules would be subjected to substantial shearing action during atomization and pumping which would destroy the granule integrity of the starch. Thus, while prior art processes have pumped, atomized and spray dried slurries having up to 10% by weight of gelatinized starch, slurries of about 15% by weight or greater 3~1~
of gelatinized starch could not be effectively pumped, atomized or spray dried by conventional techniques while maintaining whole granule integrity.
Several types of two- and three-fluid nozzles are currently commercially available. With these nozzles, air is commonly used in the atomization process, and steam is occasionally mentioned as being an appropriate fluid for heating (not cooking~
and conveying a material. Nozzles and processes of this type which are in common use or disclosed in the prior art literature may be readily found in the following United S-tates patents:
Patentee U.S. Patent No.
Higgins 1,450,631 Hickey 3,342,607 Knoch 3,314,096 Simmons, et al 3,47~,970 Dindell, et al 3,628,734 Meyer, et al 3,~74,555 Duren 3,689,288 Helmrich 3,684,186 Strommer 3,730,7~9 Tamai 3,887,1~5 ~ildebolt 4,039,691 However, none of these patents disclose or suggest the inventive process or multi-fluid nozzle appar--atus for uniformly cooking or gelatinizing materials as described herein.
SUMMARY OF THE INVENTION
Accordingly, the present invention broadly contemplates providing an improved process and appa~atus for cooking or gelatiniæing a material which is normally difficult to cook and spray dry because of the formation of high viscosities during cooking, so that an easily dryable, uniformly cooked and finely-sized product is obtained thereby. The .~.
lZ~3~L~7 material is initially liguified or mixed in an agueous solvent (e.g. a slurry is formed), then atomized into an enclosed chamber to form a rela-tively fine spray which may be uniformly cooked or gelatinized. A heating medium is interjected into the atomized material in the chamber to cook the material. The chamber contains a vent aperture to allow the heated atomized material to exit the chamber, with the size and shape of the chamber and the vent aperture being effective to maintain the temperature and moisture content of the material for a period of time sufficient to cook or gelatinize the material. In accordance with a preferred embod-iment of ~he invention, atomization of the liquified material is effectuated in a multi-fluid nozzle through which there is conveyed the material, and steam as the heating medium is interjected into the atomized material.
In accordance with a preferred embodiment of the present invention, the material is atomized through an atomization aperture within a nozzle, and steam is interjected into the atomiæed ~aterial through a second aperture in the nozzle. Prefer-ably, the heating medium (e.g. steam) is interjected through a plurality of second apertures surroundin~
the atomization aperture. Furthermore, the chamber which surrollnds the atomization and second apertures defines a vent aperture which is preferably posi--tioned opposite the atomization and second aper-tures. The elapsed time between passage of thematerial from the atomization aperture, through the chamber and exiting thereof from the vent aperture defines the cooking or gelatinization time of the material. The process and apparatus of the present invention not only produces a uniformly cooked or gelatiniæed material with a minimum of shear and heat damage, but it avoids the formation of de-posits, agglomeration or clogging of -the cooked or gelatinized material and provides an apparatus that is easy to maintain and repair. Further, the pres-ent invention ~y subjecting the atomized material to a constant environment is able to gently, guickly, and uniformly cook or gelatinize the atomized mat-erial individually while avoiding overcooking, and even more surprisingly, provide such cooking or gelatinization at relatively high starch content (e.g. 15 to 50%). The present invention is par-ticularly suitable for use in the gelatinization of starches, but is not limited thereto and also has a wide range of applicability to materials such as protein, and other types of cookable or gelatin-izable materials.
When the teachings of the present invention are applied to the processing of starch materials it is desira~le that the resultant gelatinized starch, or products such as instant puddings, have a particle size wherein at least 90% by weight of the particles pass through a 100 mesh U.S. Standard Screen and preferably at least 30% by weight pass through a 400 mesh U.S. Standard Screen. The practice of th~
present invention should result in a uniformly gelatinized starch material having good solubility and dispersibility characteristics, with a minimum of heat damage and granule breakage resulting in a maximum amount of whole precooked granules in a dry useable powder form. The gelatinized starch gran-ules are in the form of indented spheres and upon rehydration of the starch material individual gran-ules swell. `
~Z~3~7 Further, in accordance with the teachings ofthe present invention, the materials may be atomized by methods other than those specifically disclosed herein with regard to the two-fluid or multi-fluid nozzle (pneumatic), such as through centrifugal forces (spinning disc), pressurized atomization, or through the employment of sonic or ultrasonic tech-niques. Ideally, a uniform spray of uniformly-sized, small particles is obtained to thereby ensure uniform cooking or gelatinization, granulation and drying.
Accordingly, it is a primary feature of the present invention to provide a novel method and apparatus for cooking or gelatinizin~ a material in an atomized state such that an easily dryable, finely-sized product is obtained thereby.
Another feature of the present invention is to provide a process and apparatus of the type de-scribed herein which is particularly suitable for uniformly gelatinizing materials, such as starches, with a minimum o heat damage and whole granule breakage.
A more specific feature of the present inven-tion lies in providing a process and apparatus of the type described utilizing a multi-fluid nozzle wherein atomization of the material is effected by the use of at least one atomization aperture and steam as the heating medium is interjected into the atomized material spray, preferably through a plur ality of apertures. More particularly, in accor-dance with the teachings of the present invention, a chamber surrounds the atomization and steam inter-jection apertures and contains a vent aperture positioned preferably opposite relative to the aforementioned apertures, with the si7.e and shape of ~2`~31~7 the chamber and the vent aperture being effective to maintain the temperature and moisture content of the material for a period of time sufficient to cook or gelatinize the material.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features and adv~ntages of the novel method and apparatus for coolcing or gelatinizing a material in accordance with the teachings of the present invention may be more readily understood by one skilled in the art, refer-ence being made to the following detailed descrip-tion of several preferred embodiments thereof, taken in conjunction with the accompanying drawings where-in identical reference numerals are used to refer to identical or similar elements throughout the several views, and in which:
Figure 1 is an elevational sectional view illustrating details of construction of one embodi-ment of a two-fluid nozzle pursuant to the teachings of the present invention;
Figure 2 is an elevational partial sectional view of only the nozzle housing shown in Figure l;
~igure 3 is a horizontal sectional view of the nozzle housing taken along line 3-3 in Figure 2;
Figure 4 is an elevational partial sectional view of only the nozzle cap illustrated in Figure l;
Figure 5 schematically illustrates a top plan view of a drying tower employing an array of two-fluid nozzles;
Figure 6 is an elevational sectional view illustrating a second embodiment of a two-fluid nozzle constructed in accordance with the teachings of the present invention; and Figure 7 is an elevational sectional view of other designs for the nozzle cap.
~2~3~L~7 DETAII.ED DESCRIPTION OF THE INVENTION
Referring now in detail to the drawings, Figure 1 illustrates an elevational sectional view of a two-fluid nozzle 10 having first and second couplings 12 and 14 attached thereto for connecting the nozzle to the fluid sources of, respectively, the slurried material and the heating medium. The first coupling 12 is provided with internal and external threads, with the latter threadedly engag-ing in a threaded vertically-extending bore formed in the top of the nozzle housing 22. The first coupling 12 normally connects the nozzle to a suit-able supply of the liquified material 16 which, during operation, is forced through the nozzle 10 by a positive action pump 18. The second coupling 14 is internally threaded for engagement with a suit-able conduit which is connected to a supply of the heating medium, which i5 preferably steam, but alternatively can be a heating medium such as hot gases (air), super heated steam, heated fluids, etc.
The nozzle housing 22 is shown in detail in Figures 1, 2 and 3, and preferably is constructed as a unitary member from a suitable material, such as steel. The housing has a threaded, vertically-extending bore 24 in its upper end which communi--cates with, for example, four axially-extending atomization apertures 26 sylNnetrically formed about the longitudinal axis of the housing. Each of the four atomization apertures terminates at its lower end in a slightly restricted portion 28 in which a spinner and orifice 20 is inserted. The spinner and orifice 20 atomizes the liquified material being pumped through the atomization aperture 26, forming a hollow cone spray of finely sized particles.
Because the viscosity of materials such as starch is ~2~3~7 g initially low prior to cooking or gelatinization, a pressure atomization ~Ising a spinner and orifice 20 can easily produce the finely sized particles or droplets required to obtain uniform cooking or gelatinization. In other embodiments of this inven-tion, other atomization methods may be employed as is known in the art, such as by centrifugal forces, pressurized atomization (e.~. by steam impinging a stream of liquid), or by employing sonic or ultra-sonic techni~ues, the criteria being that a uniformspray of finely sized particles is produced so that the material may be uniformly cooked or gelatinized.
Preferably, the liquified material is atomized to produce particles within the size range of about 5 to 250 microns.
An annular groove (manifold) 30 is machined around the outer circumference of the housing, approximately midway of its height, to form a mani-fold for the heating medium, e.g., steam, being introduced to the nozzle through coupling 14. A
cylindrical band 32 having an inner diameter match-ing the o~ter diameter of the nozzle housing 22 is positioned around the annular manifold 30 to enelose it and seal it, and the cylindrical band is seeured to the housing by two ring-like fillet welds, one 34 at its top surface and the second 36 at its bottom surface. A hole 38 is drilled through the cylindri-cal band 32 at the location of the second coùpling 14 to allow the heating medium to flow through the coupling into the manifold 30. A plurality of heating medium interjection apertures 40 are drilled axially and concentrieally around the noz~le housing 22, such that the plurality of heating medium inter-jection apertures 40 communicates with the annular manifold 30 and extends to the lower portion of the ~Cl 3~
nozzle housing 22, whereat the heating medium is interjected into and passes in a substantially circular pattern around the atomized material being sprayed from the atomization apertures 26. The interjected heating medium acts to heat the atomized material to the desired cooking or gelatinization temperature, as well as assist in the atomization of the material ~xiting the nozzle vent aperture 52.
In the preferred embodiment, ~wenty-four heat-ing medium (preferably steam) interjection apertures40 surround four atomization apertures 26, all of which are symmetrically placed about the longitu-dinal axis of the nozzle. Obviously, in other embodiments, other arrangements and numbers of atomization and heating medium interjection aper-tures may be utilized.
The lower portion of the nozzle housing 22 has a reduced diameter portion 42 having external threads formed therearound to provide a means of threaded attachment to a nozzle cap 44. A frustoconical surface 46 is provided on the lower edye of the central portion of the nozzle housing to provide for deflection of the heating medium (e.g. steam), in a manner as will be explained in greater detail herein-below.
As illustrated in Figure 1, a small ring 48having interior and exterior frustoconical surfaces is attached, as by a fillet weld 50, to the bottom of the threaded portion 42 of the nozzle housing to thereby deflect the heating medium (e.g., steam), injected through the heating medium interjection apertures 40, radially inwardly into the spray of atomized material. The lower portion of the frusto-conical ring 48 contacts the inner surface of a frustoconical section of the nozzle cap 44, with the ~L~03~7 inner surface of the nozzle cap 44 also assisting in redirecting the annular flow of interjected heatinq medium into the spray of atomized material and toward a nozzle vent aperture 52 formed centrally in the lower end of the nozzle cap.
As best :illustrated in Figure 4, the nozzle cap 44 includes an upper annular portion 54 having internal threads formed therein for attachment with the extexnal threa~s formed on the lower portion 42 of the nozzle housing. The inner frustoconical surface of the nozzle cap extends downwardly and inwardly, terminating in the nozzle vent aperture which has a rounded inner lip at 56. Extending below the upper annular portion 54, the nozzle cap includes an annular lip 53 with a frustoconical surface on the inner portion thereof extending downwardly and outwardly which aids in preventing any substance from dripping down the exterior sur-face of the nozzle cap to clog the nozzle vent aperture 52.
The fillet weld 36 at the bottom of cylindrical band 32 is machined smooth, and a gasket 58 is posi-tioned between the nozzle housing and the nozzle cap to seal the nozzle. The arrangement is such that the nozzle cap may be unscrewed from the nozzle housing to provide access to the interior of the housing for cleaning or servicing thereof.
The enclosed area between the inner surface of the nozzle cap 44 and the lower surface of the nozzle housing 22 forms the enclosed chamber wherein the heating medium is interjected into the atomized material to heat the material to a temperature effective to cook or gelatinize the material. The size and shape of the chamber and the size of the vent aperture is èffective to maintain the tempera-113:~7 ture and moisture content of the material ~or a period of time sufficient to cook or gelatinize the material to the desired degree. Stated another ~7ay, the size and shape of the chamber and the size of the vent aperture is effective to maintain a temp-erature and a moisture content within the chamber and a period of time for passage of the a-tomized material through the chamber sufficient to cook or gelatinize the material. The period of time which it takes for the material to pass from the atomiza-tion aperture 26 and through the vent aperture 52 (i.e., to pass through the chamber) defines the cooking or gelatinization time of the material. The major portion of the cooking or gelatinization of the material occurs within the chamber, however, a minor amount of cooking or gelatinization may occur upon exit of the material from the chamber (from the vent aperture) which is due to the heat and moisture the material is subjected to within the chamber.
Thus, the cooking or gelatini~ation time as herein defined includes the cooking or gelatinization which occurs within the chamber, as well as the cooking or gelatinization which occurs upon exit of the material from the chamber which is due to the maintenance of the material at a temperature and moisture content effective to cook or gelatinize the material.
Accordingly, the nozzle cap 44 (therefore -the chamber size and shape) and the size of the vent aperture 5.~
can be adjusted to control the temperature and moisture content in the chamber and the residence time of the material in the chamber and hence the cooking or gelatinization conditions and time to which the material is subjected.
Figure 5 is a top view of a spray drying tower 60, illustrating schematically an array of two-fluid ~3~7 nozzles 10 provided therein. Figure 5 illustrates one Pmbodiment of how a plurality of nozzles may be combined in one spray drying tower to provide the desired volume throughput of cooked or gelatinized material. A spray drying tower can be approximately twelve feet in dianleter and thirty fee-t in height, and in another embodiment, seven nozzles can be positioned at the top thereof spaced apart at approx-imately two-foot intervals, with a further nozzle being arranged at -the center.
Figure 6 illustrates an elevational sectional view of a second embodimen-t of a two-fluid nozzle 62 constructed pursuant to the teachings of the present invention. In this embodiment of the invention, the liquified material to be processed enters the nozzle through a conduit 64 provided in its right-hand portion (as viewed in Figure 6) and is first direct-ed radially inwardly and then axially downwardly through an atomization aperture 66 formed in the central portion of the nozzle 62 into a spinner and orifice 68 arranged in the lower portion of the atomization aperture 66. The spinner and orifice 68 assists in atomizing `the material so as to convert the material into a fine spray. The viscosity of the liquified material is initially low, and this allows for the atomization of the material b~ the small orifice and spinner, and results in the pro-duction of a relatively fine spray. Steam (or other heating medium3 enters through a conduit 70 in the left-hand portion of the nozzle (as viewed in Figure 6), and enters an annular manifold 72 posi-tioned about the longitudinally-extending atomi-zation aperture 66. The annular manifold is grad-ually reduced in diame-ter towards its lower end forming a heating mediu~ interjection aperture 73.
~Z~ 7 From the hea-ting medium interjection aperture 73 the steam is interjected into the atomized material being sprayed from the atomization aperture 66.
~ nozzle cap 75 encloses the atomization and heating medium interjection apertures (66 and 73 respectively), the nozzle cap 75 containing a vent aperture 74 positioned opposite the atomization and heating medium apertures ~66 and 73 respectively).
The enclosed area between the nozzle cap 75 and the atomization and heating medium apertures (66 and 73 respectively) forms the enclosed chamber wherein the heating medium is interjected into the spray o~
atomized material to cook or gelatinize the material As with the previous nozzle illustrated in Figure 1, the size and shape of the chamber and vent aperture is effective to maintain the temperature and mois-ture content of the material for a period of time sufficient to cook or gelatinize the material. The period of time for the passage of the atomized material through the chamber defines the cooking or ~elatinization time of the material. The enclosed chamber maintains a desired temperature and moisture content enabling the material to be uniformly cooked or gelatinized therein.
While Figures 1, 4 and ~ illustrate preferrecl embodiments for the nozzle cap design and hence the preferred size and shape of the enclosed chamber, other designs are also comprehended by the instant invention, as illustrated in Figure 7. The design of the nozzle cap and the positioning, size and number of vent apertures can be adjusted to obtain the desired cooking or gelatinization conditions (temperature, vapor pressure or moisture co~tent~
and time. Care must be taken in designing the nozzle cap and positioning the vent aperture so that ~Z~:133~7 the atomized material will be uniformly mixed with the heatiny medium and substantial clogging of the vent aperture is avoided.
As previously mentioned with regard to the various embocliments, the nozzle components may be constituted of metal, such as stainless steel, which is suitable for the processing of food products.
Also, in some embodiments, the internal surfaces of the nozzle may be coated with Teflon (registered trademark) to further ensure that the material does not agglomerate therein and form deposits on the interior surfaces of the nozzle, thereby resulting in clogs~ing thereof.
In various designs of a two-fluid nozzle, several parameters may be varied from embodiment to embodiment, such as the number of injection aper-tures, and the degree of atomization. For instance, if the throughput of liguified material i5 constant or unchanged, one relatively large atomization aperture, as opposed to several small atomization apertures, should result in a cooked or gelatinized material having a larger average particle size.
The distance between the atomization aperture and the nozzle vent aperture is important, as that dis~ance determines the time over which the material is cooked or gelatinized. In the illustrated embod iment, the distance between the atomizing aperture and the nozzle vent aperture has optimally been selected to be approximately .875 inches (2~ mm) for a material such as starch, a nominally optimal value when considering other parameters in thé
system and the products processed therein. Prefer-ably, the distance between the atomixing aperture and the nozzle vent aperture is within the range of about .125 inches (13 mm~ to 1~5 inches (38 mm), `" ~2~3~7 however, that dista~ce may be varied from a smaller distance to a larger distance in other operational models. The larger distances result in a greater degree of cooking or gelatinization of the mater-ials, and may conceivably result in overcooking andfouling of the nozzle cap and nozzle vent aperture with caked and agglomerated materials whereas, contrastingly, the shorter distances may not provide for a sufficient cooking or gelatinization time.
However, this is all dependent on the degree of cooking or gelatinization desired for the particular material with the size of the chamber and hence the time the material spends in the chamber being ad-justed accordingly. By cooking, what is meant is that the material is pxepared for subseguent use by subjecting it to the ac-tion of heat and moisture (or other vapor pressure) for a period of time, with gelatinization being a category of cooking in that a suitable material by subjecting it to the action of heat and moisture over time is converted into a gelatinous form ~e.g., by starch granules absorbing water and swelling).
Other apparent variables in the practice of the present invention are the temperature and vapor pressure (moisture content) within the chamber which is controlled, by the size and shape of the chamber and vent aperture, as well as the temperature, ~ressure and flow rates of the heating medium (e.g., steam, super heated steam, heated gases, heated fluids etc.)j concentration and flow rate of the liquified material, etc. In the present invention, steam supplied at a pressure above 50 psig ~3.~
Kg/cm ) would appear to be adeguate to result in cooking or gelatinization of a material such as starch. The nozzle of the disclosed embodiment has ~ o - 17 ~
been utilized with steam pressures varying from 90 to 160 psig (6.~ to 11.3 Kg/cm2), although either higher or lower steam pressures could also be em-ployed. The steam provides temperatures within the 5 chamber in the range of from about 300 to 340~F (150 to 170C), although either higher or lower tempera-tures may also be utilized depending upon other variables (pressure of steam, type of heating medium, size and s~lape of c~l~mber and verlt aperture, solids content, feed rate of liquified material, proportion of heating medium to li~uified material, gelatiniza-tion or cooking temperature, type of material, additives or modifications of material, etc.).
Generally, a temperature of 5QC to 300C within the chamber can be utilized to gelatinize starch, al-though preferably the chamber temperature is main-tained within the range of 120C to 200C.
Another variable which may be changed to con~
trol the temperature and thus the cooking or gela-tinization of the material is the proportion ofheating medium (e.g., steam~ to liquified material with the proportion, for example, for starch being preferably controlled to within the range of .5 to 3 (part by weight steam/part by weight starch slurry).
~5 Operation of the invention is affected by the size of the nozzle vent aperture, with it generally being desirable to maintain a greater area for the heating medium interjection apertures than for the nozzle vent aperture, such that the chamber is maintained at a temperature and moisture content ~vapor pres-sure) which enables the material to be cooked or gelatinized to the desired degree. Preferably the size of the nozzle vent aperture is within the range of about .125 inches (3mmt to .5 inches (13mm), however, this size may be varied from a smaller to a larger size in other operational models depending upon the temperature and moisture content desired as well as the flow rates of the heating medium and atomized material.
Another variable which may be altered in dif-ferent nozzlle designs is the direction in which the heatiny medium is interjected into the spray of atomized material, with it being possible to direct the interjected heating medium directly toward the nozzle vent aperture, or deflect it off the side wall of the nozzle cap towards the vent aperture, or direct the interjected heating medium tangentially to the axis of the chamber. The enclosed chamber should be sufficiently large and the heating medium should be interjected so as to mix the heating medium with the spray of atomized material before the material makes contact with the chamber wall, thus insuring a uniform and desired degree of cook-ing or gelatinization of the material.
Generally, the material must be liquified or mixed with a solvent to enable it to be pumped and atomized. By liquified, what is meant is that the material is reduced to a liquid state (flows freely) by mixing the material with a solvent, which may be carried out by forming a solution or a slurry (in-cludes suspensions, etc.). While water is the preferred solvent other solvents such as alcohol, acetone etc. or combinations thereof may also be employed. When the material is a starch, the starch is liquified or mixed with an aqueous solvent by forming a slurry which may comprise at least 15%
starch, preferably 35 to 45% starch by weight, as compared to prior art spray drying processes which generally have a maximum solids content of about 10%
of gelatinized starch.
3~7 The starch may be derived from any suitable s~urce such as corn, sago, wheat, tapioca, rice, potatoes, sweet potatoes or waxy maize. Further, it may be in a raw unmodified state, or it may have been previously modified in any desired manner, as for example, by hydrolysis, oxidation, dextrini-æation, esterification, etherification, etc. or any combination of these treatments. As well, a material such as a starch may be combined or slur-ried with other ingredients, e.g., emulsifiers (monoand diglycerides, polysorbates, etc.), colors, flavors, carbohydrates (e.g. sugars), proteins, ats, processing aids, etc. followed by atomization and gelatinization or cooking by the process of this invention. In the treatment of starch from whatever source, it is important that the starch is capable of being gelatinized, preferably in an ungelatinized state, and in the form of its original unbroken granules, and that it remain in that form throughout its derivation process prior to being atomized and gelatinized by the present invention. Moreover, the material feed temperature may range from above freezing, to ambient, to 140~ (60C~, and the feed pH may range from 2 to 12 (preferably 5 to 7). The starch may be uniformly ~elatinized by the present invention to any desired degree, but preferably the starch is uniformly substantially completely gela-tinized, as measured under a polari~ed light by the starch losing its birefringent patterns.
The present invention is able to subject the individual particles of the atomized material to a constant environment and gently, quickly and uni!
formly cook or gelatinize the atomized ~aterial while avoiding overcooking. Thus, the gelatinized starch granules obtained are uniformly swelled to the maximum extent, while maintaining whole granule integrity without the need of heavy chemical modi-fication and with a minimum of granule breakage, or heat damage.
The present invention produces a unique spray dried gelatinized starch heretofore unattainable by conventional processes. The dried gelatinized starch contains starch granules in the form of indented spheres. By indented spheres it is meant that the gelatinized spherical starch granules during drying lose moisture causing the partial collapse of the sphere which forms at least one dimple or indentation on the surface of the sphere.
The starch granules are uniformly gelatinized and lS possess at least a majority of granules which are whole and unbroken, and preferably approximately 100% whole and unbroken granules. The starch of the present invention contains a greater degree of whole, unbroken granules than a starch prepared by conventional spray drying processes with similar degrees of modification (chemical or physical) of the starch. Uniquely, the present inveniion enables the control of the pa~ticle size of the dried starch without subsequent grinding obtaining a desired size of agglomerates of starch granules or even individual whole starch granules, without excessive sh~ar and breaking of the granules. The starch agglomerates formed are loosely bound starch yran-ules and upon hydration, the agglomerates break up and disperse into the individual granules which swell. This property is paramount for products such as instant puddings in order to obtain upon hydra-tion a smooth, uniform, homogeneous, continuous and non-grainy texture.
, .
~Z~3~
A comparision with conventional gelatinization and drying processes demonstrates the novelty of the gelatinized spray dried starch prepared b~ the process of the present invention. Drum drying produces sheets of gelatinized starch which are subsequently ground to a desired particle size, The drum dried starch flakes are in agglomerate form and posses a high degree of broken granules and free starch due to the grinding. The drum dried agglom-erates (fractured sheets or flakes) swell and break - up slightly upon hydration. Conventional spray drying of gelatinized starch must be carried out at extremely low concentrations (less than 10%~ to enable the starch slurry to be pumped and atomized, thus ren~ering the process economically unfeasable.
Even lower concentrations must be employed if whole granules are desired, as conventional methods xe-~uire subjecting fragile swollen (gelatinized) granules to the sheer associated with atomization.
The conventional spray dried starch is in the form of tightly bound agglomerates due to the free starch from the sheared granules binding the agglomerates together. Upon hydràtion, in general, the agglom-erates swell and stay bound together, which could result in a grainy texture in products such as instant puddings. As well, in conventional spray drying of gelatinized starch one cannot control the particle size of the dried starch to obtain fine starch particles (small agglomerates or individual whole granules) without excessive shear and breaking of the granules. E`urther, with conventional gela tinization processes the uniformity of gelatiniæa-tion cannot be effectively and consistently con-trolled.
~2g~3~
In comparison, with the same level of ~hemical modification of the starch, the present invention is able to produce a starch wi-th a greater percent of whole granules than that obtained by conventional spxay dryiny of gelatinized starch. Further, the dried starch prepared by the present invention requires a lower level of chemical modification and even no chemical modification to obtain whole gran-ules and a dried starch which upon hydration posses desireable appearance -(high sheen) and textural characteristics (smooth, continuous, homogeneous and non-grainy), which conventionally required higher levels of chemical modification to obtain. The identified differences between conventionally spray dried gelatinized starch and the dried starch pre-pared by the present invention become even more pronounced the lower the level of chemical modifi-cation of the starch.
After the material is cooked or gelatinized by 2n the method of the present invention the material is then preferably dried, preferably in a spray drying tower although other dryiny techniques, such as belt dryers or flash dryers, may also be employed.
The teachings of the present invention also have applicability in the processing of other mat-erials, such as proteins, dextrins or even other non-food materials, with the resultant advantage that the protein or dextrin may receive ~inlmAl shearing or heat treatment, and result in a product having good dispersibility and solubility charac-teristics.
While several embodiments of a process and apparatus have been disclosed for cooking or gelat-inizing a material in an atomized state so that there is obtained thereby an easily dryablP, uniform ~ 3~
and finely-sized product, the teachings of the present invention as set forth herein will sugge~t many alternative embodiments and variations to those of ordinary skill in the art.
EXAMPLE I
Seven two-fluid nozzles constructed as illus-trated in Figure 1 were arranged iIl a spray drying tower as illustrated in Figure 5. The atomization apertures contained a spinner and orifice having a spinner with 4 grooves of .020 inches t.51 mm) wide and .035 inches ~.89 mm) deep and having an orifice size of .016 inches (.41 mm). The distance between the atomization apertures and the nozxle vent aper-ture was .875 inches (22 mm~, with the vent aperture having a diameter of .25 inches (6.4 mm). Ungel~
atinized tapioca starch cross-linked with about .01%
of phosphorus oxychloride (by weight of the starch) was sluxried in water at a pH of 6 and at a level of 35% solids by weight.
The slurry at a temperature of 69F (21C) was pumped into each nozzle at a rate of 1.2 gal/min (4.6 liters/ min) per nozzle, with s~eam as the heating medium at a` pressure of 150 psig (10.5 Kg/cm2) being pumped into each nozzle at an esti-mated flow rate of 380 lbs/hr ~172 Kg/hr) per nozzle.
The temperature within the nozzle ch~mber is esti-mated to be approximately 310F (155C). The spray drying tower had an inlet temperature o~ about 300 to 370~F (about 150 to 195C) and an outlet tempera-ture of a~out 175 to 205F (about 80 to 95C).
As the starch was ungelatinized, the slurry flowed readily and was easily pumped into the nozzle wh~re the starch underwent gentle, quick and uniform gelatinization by being subjected to high tempera-,, 3~7 tures in the presence of moisture for an amount of time suficient to gelatiniz~ the starch granules.
The resultant starch possessed approximately 80 whole granules and was uniformly and substantially completely gelatinized (birefringent patterns lost under polarized light) while avoiding overcooking with a minimum of heat damage or granule breakage.
On exiting the nozzle vent aperture, the resultant gelatinized starch was in a finely-sized atomized state and was easily dried in the spray drying tower. The dried pregelatinized starch had a mesh size wherein about 80% by weight of the starch passed through a 230 mesh U.S. Standard Screen and was readily useable, as is, in products such as instant pudding mixes. When used in an instant pudding mix the resultant prepared pudding had the desireable texture (smooth, continuous, homogeneous, non-grainy), appearance (high sheen), mouthfeel and viscosity as is characteristic of puddings prepared with heavily modified starches (e.g. cross-linked and substituted). The dried pregelatinzed starch granules were in the form of indented spheres and the granules were l`oosly bound as agglomerates, which upon hydration separated into individual granules which swelled.
EXAMPLE II
Seven two-fluid nozzles constructed as illus-trated in Figure 6 were arranged in a spray drying tower as illustrated in Figure 5. The atomization aperture contained a spinner and orifice having a spinner with 4 grooves of .025 inches (.S4 mm3 wide and .048 inches (1.22 mm3 deep and having an orifice size of .042 inches (1.07 mm). The distance between the atomization aperture and the nozzle vent aper-~2~13~7 ture was .875 inches (~2 mm), with the vent aperture having a diameter of .25 inches (6.4 mm~. Ungelat-inized tapioca starch cross-linked wi~h about .01%
of phosphorus oxychloride and hydroxypropylated with about 8% of propylene oxide (by weight of the starch) was slurried :in water at a pH of 6 and at a level of 40% solids by weight.
The slurry at a tempera-ture of 69~F (21C) was pumped into each nozzle at a rate of 1.2 gal/min (4.6 liters/ min) per nozzle, with steam as the heating medium at a pressure of 150 psig (10.
Kg/cm2) being pumped into each nozzle at an esti-mated flow rate of 3ao lbs/hr (172 Kg/hr) per nozzle.
The temperature ~ithin the nozzle chamber is esti-mated to be approximately 310F (155C). The spray drying tower had an inlet temperature of about 300 to 370F (about 150 to 195C) and an outlet temper-ature of about 175 to 205F (about 80 to 95C).
As the starch was ungelatinized, the slurry flowed readily and was easily pumped into the nozzle where the starch underwent gentle, quick and uniform gelatinization by being subjected to high tempera-tures in the presence of moisture for a~ amount of time sufficient to gelatinize the starch granules.
The resultant starch possessed approximately 100 whole granules which were uniformly and substan-tially completely gelatinized while avoiding over cooking with a minimum of heat damage or granule breakage. On exiting the nozzle vent aperture, the res~ultant gelatinized starch was in a finely-sized atomized state and was easily dried in the spray drying tower. The dried pregelatinized starch granules had a mesh size wherein about 80% by weight of the starch passed through a 230 mesh U.S.
Standard Screen and was readily useable, as is, in 3~7 products such as instant pudding mixes. When used in an instant pudding mix the resultant prepared pudding had the desireable texture (smooth, contin~
uous, homogeneous, non-grainy), appearance (high sheen), mouthfeel and viscosity as is characteristic of puddings prepared with heavily modified starches.
The dried pregelatinized starch granules are in the form of indented spheres and the granules were loosly bound as agglomerates, which upon hydration 0 separated into individual granules which swelled.
Example III
The following samples of raw un~elatinized tapioca starch were chemically modified as in Examples I and II, then conventionally gelatinized (cooked~ followed by conventional spray drying to enable a comparison to be made between a conven-tional cooking and spray drying process verses the method of uniformly cooking a starch by the process of the instant invention. Sample I of xaw ungela-tinized tapioca starch was cross-linked with about .01% of phosphorus oxychloride (as in Example I~, then cooked at 188F (87C) for about 4 minutes to gelatinize the starch, followed by cooling to about 125F to 140F (50C to 60C). Sample II of raw ungelatinized tapioca starch was cross-linked with about .01% of phosphorus oxychloride and hydroxy-propylated with about 8% of propylene oxide (as in Example II), then cooked at 170F (75C) for about 4 minutes to gelatinize the starch, followed by cool ing to about 125~F to 140F (50C to 60C~. Each sample was microscopically examined to ensure that all the granules were swollen while maint~;ning 100 whole granules.
Each gelatinized starch sample at a solids level of about 1.5% was then conventionally spray - ~LZ~3~l7 .
BACK~RO~ND OF THE INVENTION
This application is a divisional of Application Serial No~ 364,96~, filed November 19, 1980.
The present invention relates to apparatus for uniformly cooking materials, and more particularly, relates to a multi-fluid spray nozzle apparatus for atomizing a mat-erial, such as a suitable starch, and for simultaneously cooking that material. Preferably, a material capable of gelatinizatin, such as a starch, is uinformly gelatinized by the use of the apparatus of this invention.
The present invention is particularly appli-cable to the atomization and cooking or gelatin-ization of materials which are normally difficult to cook or gelatinize and spray dry due to the genera-tion of high viscosities in the materials during cooking or gelatinization.
For many materials, such as starches, it is desirable to perform various chemical or physical modifications of the material when the material is in the form of a slurry, followed by drying the ~7 3~
~2~3~1L7 slurry by, for example, spray drying. When a starch, such as corn starch is in an ungelatinized (uncooked3 state, ~len spray drying the resultant slurry is generally straight forward and may be carried out using conventional atomizers. However, when the starch is in a gelatinized (cooked) state, then spray drying the resultant slurry becomes more difficult and complex due to the increased viscosity of the starch slurry and the shearing to which the gelatini2ed starch granules are subjected to during atomization and spray drying. Gelatinization occurs when an aqueous starch slurry is heated beyond a critical temperature (e.g., above about 65C for corn starch), the starch granules absorbing water and swelling resulting in a slurry with increased viscosities. For example, a slurry with 10% by weight of gelatinized corn starch generally has a viscosity of about 600 centipoises and a slurry with 15% by weight of gelatinized corn starch generally has a viscosity of about 20,000 centipoises, while a slurry with similar amounts of ungelatinized corn starch will have a viscosity similar to water (i.e., about 1 centipoise). When a gelatinized starch slurry having such high viscosities exits the cooker, then drying the starch by use of a rotary atomizer or spray nozzle in a spray dryer is unsuitable. Not only would the gelatinized starch slurry be diffi-cult to pump and atomize due to the high viscosities generated, but the swollen starch granules would be subjected to substantial shearing action during atomization and pumping which would destroy the granule integrity of the starch. Thus, while prior art processes have pumped, atomized and spray dried slurries having up to 10% by weight of gelatinized starch, slurries of about 15% by weight or greater 3~1~
of gelatinized starch could not be effectively pumped, atomized or spray dried by conventional techniques while maintaining whole granule integrity.
Several types of two- and three-fluid nozzles are currently commercially available. With these nozzles, air is commonly used in the atomization process, and steam is occasionally mentioned as being an appropriate fluid for heating (not cooking~
and conveying a material. Nozzles and processes of this type which are in common use or disclosed in the prior art literature may be readily found in the following United S-tates patents:
Patentee U.S. Patent No.
Higgins 1,450,631 Hickey 3,342,607 Knoch 3,314,096 Simmons, et al 3,47~,970 Dindell, et al 3,628,734 Meyer, et al 3,~74,555 Duren 3,689,288 Helmrich 3,684,186 Strommer 3,730,7~9 Tamai 3,887,1~5 ~ildebolt 4,039,691 However, none of these patents disclose or suggest the inventive process or multi-fluid nozzle appar--atus for uniformly cooking or gelatinizing materials as described herein.
SUMMARY OF THE INVENTION
Accordingly, the present invention broadly contemplates providing an improved process and appa~atus for cooking or gelatiniæing a material which is normally difficult to cook and spray dry because of the formation of high viscosities during cooking, so that an easily dryable, uniformly cooked and finely-sized product is obtained thereby. The .~.
lZ~3~L~7 material is initially liguified or mixed in an agueous solvent (e.g. a slurry is formed), then atomized into an enclosed chamber to form a rela-tively fine spray which may be uniformly cooked or gelatinized. A heating medium is interjected into the atomized material in the chamber to cook the material. The chamber contains a vent aperture to allow the heated atomized material to exit the chamber, with the size and shape of the chamber and the vent aperture being effective to maintain the temperature and moisture content of the material for a period of time sufficient to cook or gelatinize the material. In accordance with a preferred embod-iment of ~he invention, atomization of the liquified material is effectuated in a multi-fluid nozzle through which there is conveyed the material, and steam as the heating medium is interjected into the atomized material.
In accordance with a preferred embodiment of the present invention, the material is atomized through an atomization aperture within a nozzle, and steam is interjected into the atomiæed ~aterial through a second aperture in the nozzle. Prefer-ably, the heating medium (e.g. steam) is interjected through a plurality of second apertures surroundin~
the atomization aperture. Furthermore, the chamber which surrollnds the atomization and second apertures defines a vent aperture which is preferably posi--tioned opposite the atomization and second aper-tures. The elapsed time between passage of thematerial from the atomization aperture, through the chamber and exiting thereof from the vent aperture defines the cooking or gelatinization time of the material. The process and apparatus of the present invention not only produces a uniformly cooked or gelatiniæed material with a minimum of shear and heat damage, but it avoids the formation of de-posits, agglomeration or clogging of -the cooked or gelatinized material and provides an apparatus that is easy to maintain and repair. Further, the pres-ent invention ~y subjecting the atomized material to a constant environment is able to gently, guickly, and uniformly cook or gelatinize the atomized mat-erial individually while avoiding overcooking, and even more surprisingly, provide such cooking or gelatinization at relatively high starch content (e.g. 15 to 50%). The present invention is par-ticularly suitable for use in the gelatinization of starches, but is not limited thereto and also has a wide range of applicability to materials such as protein, and other types of cookable or gelatin-izable materials.
When the teachings of the present invention are applied to the processing of starch materials it is desira~le that the resultant gelatinized starch, or products such as instant puddings, have a particle size wherein at least 90% by weight of the particles pass through a 100 mesh U.S. Standard Screen and preferably at least 30% by weight pass through a 400 mesh U.S. Standard Screen. The practice of th~
present invention should result in a uniformly gelatinized starch material having good solubility and dispersibility characteristics, with a minimum of heat damage and granule breakage resulting in a maximum amount of whole precooked granules in a dry useable powder form. The gelatinized starch gran-ules are in the form of indented spheres and upon rehydration of the starch material individual gran-ules swell. `
~Z~3~7 Further, in accordance with the teachings ofthe present invention, the materials may be atomized by methods other than those specifically disclosed herein with regard to the two-fluid or multi-fluid nozzle (pneumatic), such as through centrifugal forces (spinning disc), pressurized atomization, or through the employment of sonic or ultrasonic tech-niques. Ideally, a uniform spray of uniformly-sized, small particles is obtained to thereby ensure uniform cooking or gelatinization, granulation and drying.
Accordingly, it is a primary feature of the present invention to provide a novel method and apparatus for cooking or gelatinizin~ a material in an atomized state such that an easily dryable, finely-sized product is obtained thereby.
Another feature of the present invention is to provide a process and apparatus of the type de-scribed herein which is particularly suitable for uniformly gelatinizing materials, such as starches, with a minimum o heat damage and whole granule breakage.
A more specific feature of the present inven-tion lies in providing a process and apparatus of the type described utilizing a multi-fluid nozzle wherein atomization of the material is effected by the use of at least one atomization aperture and steam as the heating medium is interjected into the atomized material spray, preferably through a plur ality of apertures. More particularly, in accor-dance with the teachings of the present invention, a chamber surrounds the atomization and steam inter-jection apertures and contains a vent aperture positioned preferably opposite relative to the aforementioned apertures, with the si7.e and shape of ~2`~31~7 the chamber and the vent aperture being effective to maintain the temperature and moisture content of the material for a period of time sufficient to cook or gelatinize the material.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features and adv~ntages of the novel method and apparatus for coolcing or gelatinizing a material in accordance with the teachings of the present invention may be more readily understood by one skilled in the art, refer-ence being made to the following detailed descrip-tion of several preferred embodiments thereof, taken in conjunction with the accompanying drawings where-in identical reference numerals are used to refer to identical or similar elements throughout the several views, and in which:
Figure 1 is an elevational sectional view illustrating details of construction of one embodi-ment of a two-fluid nozzle pursuant to the teachings of the present invention;
Figure 2 is an elevational partial sectional view of only the nozzle housing shown in Figure l;
~igure 3 is a horizontal sectional view of the nozzle housing taken along line 3-3 in Figure 2;
Figure 4 is an elevational partial sectional view of only the nozzle cap illustrated in Figure l;
Figure 5 schematically illustrates a top plan view of a drying tower employing an array of two-fluid nozzles;
Figure 6 is an elevational sectional view illustrating a second embodiment of a two-fluid nozzle constructed in accordance with the teachings of the present invention; and Figure 7 is an elevational sectional view of other designs for the nozzle cap.
~2~3~L~7 DETAII.ED DESCRIPTION OF THE INVENTION
Referring now in detail to the drawings, Figure 1 illustrates an elevational sectional view of a two-fluid nozzle 10 having first and second couplings 12 and 14 attached thereto for connecting the nozzle to the fluid sources of, respectively, the slurried material and the heating medium. The first coupling 12 is provided with internal and external threads, with the latter threadedly engag-ing in a threaded vertically-extending bore formed in the top of the nozzle housing 22. The first coupling 12 normally connects the nozzle to a suit-able supply of the liquified material 16 which, during operation, is forced through the nozzle 10 by a positive action pump 18. The second coupling 14 is internally threaded for engagement with a suit-able conduit which is connected to a supply of the heating medium, which i5 preferably steam, but alternatively can be a heating medium such as hot gases (air), super heated steam, heated fluids, etc.
The nozzle housing 22 is shown in detail in Figures 1, 2 and 3, and preferably is constructed as a unitary member from a suitable material, such as steel. The housing has a threaded, vertically-extending bore 24 in its upper end which communi--cates with, for example, four axially-extending atomization apertures 26 sylNnetrically formed about the longitudinal axis of the housing. Each of the four atomization apertures terminates at its lower end in a slightly restricted portion 28 in which a spinner and orifice 20 is inserted. The spinner and orifice 20 atomizes the liquified material being pumped through the atomization aperture 26, forming a hollow cone spray of finely sized particles.
Because the viscosity of materials such as starch is ~2~3~7 g initially low prior to cooking or gelatinization, a pressure atomization ~Ising a spinner and orifice 20 can easily produce the finely sized particles or droplets required to obtain uniform cooking or gelatinization. In other embodiments of this inven-tion, other atomization methods may be employed as is known in the art, such as by centrifugal forces, pressurized atomization (e.~. by steam impinging a stream of liquid), or by employing sonic or ultra-sonic techni~ues, the criteria being that a uniformspray of finely sized particles is produced so that the material may be uniformly cooked or gelatinized.
Preferably, the liquified material is atomized to produce particles within the size range of about 5 to 250 microns.
An annular groove (manifold) 30 is machined around the outer circumference of the housing, approximately midway of its height, to form a mani-fold for the heating medium, e.g., steam, being introduced to the nozzle through coupling 14. A
cylindrical band 32 having an inner diameter match-ing the o~ter diameter of the nozzle housing 22 is positioned around the annular manifold 30 to enelose it and seal it, and the cylindrical band is seeured to the housing by two ring-like fillet welds, one 34 at its top surface and the second 36 at its bottom surface. A hole 38 is drilled through the cylindri-cal band 32 at the location of the second coùpling 14 to allow the heating medium to flow through the coupling into the manifold 30. A plurality of heating medium interjection apertures 40 are drilled axially and concentrieally around the noz~le housing 22, such that the plurality of heating medium inter-jection apertures 40 communicates with the annular manifold 30 and extends to the lower portion of the ~Cl 3~
nozzle housing 22, whereat the heating medium is interjected into and passes in a substantially circular pattern around the atomized material being sprayed from the atomization apertures 26. The interjected heating medium acts to heat the atomized material to the desired cooking or gelatinization temperature, as well as assist in the atomization of the material ~xiting the nozzle vent aperture 52.
In the preferred embodiment, ~wenty-four heat-ing medium (preferably steam) interjection apertures40 surround four atomization apertures 26, all of which are symmetrically placed about the longitu-dinal axis of the nozzle. Obviously, in other embodiments, other arrangements and numbers of atomization and heating medium interjection aper-tures may be utilized.
The lower portion of the nozzle housing 22 has a reduced diameter portion 42 having external threads formed therearound to provide a means of threaded attachment to a nozzle cap 44. A frustoconical surface 46 is provided on the lower edye of the central portion of the nozzle housing to provide for deflection of the heating medium (e.g. steam), in a manner as will be explained in greater detail herein-below.
As illustrated in Figure 1, a small ring 48having interior and exterior frustoconical surfaces is attached, as by a fillet weld 50, to the bottom of the threaded portion 42 of the nozzle housing to thereby deflect the heating medium (e.g., steam), injected through the heating medium interjection apertures 40, radially inwardly into the spray of atomized material. The lower portion of the frusto-conical ring 48 contacts the inner surface of a frustoconical section of the nozzle cap 44, with the ~L~03~7 inner surface of the nozzle cap 44 also assisting in redirecting the annular flow of interjected heatinq medium into the spray of atomized material and toward a nozzle vent aperture 52 formed centrally in the lower end of the nozzle cap.
As best :illustrated in Figure 4, the nozzle cap 44 includes an upper annular portion 54 having internal threads formed therein for attachment with the extexnal threa~s formed on the lower portion 42 of the nozzle housing. The inner frustoconical surface of the nozzle cap extends downwardly and inwardly, terminating in the nozzle vent aperture which has a rounded inner lip at 56. Extending below the upper annular portion 54, the nozzle cap includes an annular lip 53 with a frustoconical surface on the inner portion thereof extending downwardly and outwardly which aids in preventing any substance from dripping down the exterior sur-face of the nozzle cap to clog the nozzle vent aperture 52.
The fillet weld 36 at the bottom of cylindrical band 32 is machined smooth, and a gasket 58 is posi-tioned between the nozzle housing and the nozzle cap to seal the nozzle. The arrangement is such that the nozzle cap may be unscrewed from the nozzle housing to provide access to the interior of the housing for cleaning or servicing thereof.
The enclosed area between the inner surface of the nozzle cap 44 and the lower surface of the nozzle housing 22 forms the enclosed chamber wherein the heating medium is interjected into the atomized material to heat the material to a temperature effective to cook or gelatinize the material. The size and shape of the chamber and the size of the vent aperture is èffective to maintain the tempera-113:~7 ture and moisture content of the material ~or a period of time sufficient to cook or gelatinize the material to the desired degree. Stated another ~7ay, the size and shape of the chamber and the size of the vent aperture is effective to maintain a temp-erature and a moisture content within the chamber and a period of time for passage of the a-tomized material through the chamber sufficient to cook or gelatinize the material. The period of time which it takes for the material to pass from the atomiza-tion aperture 26 and through the vent aperture 52 (i.e., to pass through the chamber) defines the cooking or gelatinization time of the material. The major portion of the cooking or gelatinization of the material occurs within the chamber, however, a minor amount of cooking or gelatinization may occur upon exit of the material from the chamber (from the vent aperture) which is due to the heat and moisture the material is subjected to within the chamber.
Thus, the cooking or gelatini~ation time as herein defined includes the cooking or gelatinization which occurs within the chamber, as well as the cooking or gelatinization which occurs upon exit of the material from the chamber which is due to the maintenance of the material at a temperature and moisture content effective to cook or gelatinize the material.
Accordingly, the nozzle cap 44 (therefore -the chamber size and shape) and the size of the vent aperture 5.~
can be adjusted to control the temperature and moisture content in the chamber and the residence time of the material in the chamber and hence the cooking or gelatinization conditions and time to which the material is subjected.
Figure 5 is a top view of a spray drying tower 60, illustrating schematically an array of two-fluid ~3~7 nozzles 10 provided therein. Figure 5 illustrates one Pmbodiment of how a plurality of nozzles may be combined in one spray drying tower to provide the desired volume throughput of cooked or gelatinized material. A spray drying tower can be approximately twelve feet in dianleter and thirty fee-t in height, and in another embodiment, seven nozzles can be positioned at the top thereof spaced apart at approx-imately two-foot intervals, with a further nozzle being arranged at -the center.
Figure 6 illustrates an elevational sectional view of a second embodimen-t of a two-fluid nozzle 62 constructed pursuant to the teachings of the present invention. In this embodiment of the invention, the liquified material to be processed enters the nozzle through a conduit 64 provided in its right-hand portion (as viewed in Figure 6) and is first direct-ed radially inwardly and then axially downwardly through an atomization aperture 66 formed in the central portion of the nozzle 62 into a spinner and orifice 68 arranged in the lower portion of the atomization aperture 66. The spinner and orifice 68 assists in atomizing `the material so as to convert the material into a fine spray. The viscosity of the liquified material is initially low, and this allows for the atomization of the material b~ the small orifice and spinner, and results in the pro-duction of a relatively fine spray. Steam (or other heating medium3 enters through a conduit 70 in the left-hand portion of the nozzle (as viewed in Figure 6), and enters an annular manifold 72 posi-tioned about the longitudinally-extending atomi-zation aperture 66. The annular manifold is grad-ually reduced in diame-ter towards its lower end forming a heating mediu~ interjection aperture 73.
~Z~ 7 From the hea-ting medium interjection aperture 73 the steam is interjected into the atomized material being sprayed from the atomization aperture 66.
~ nozzle cap 75 encloses the atomization and heating medium interjection apertures (66 and 73 respectively), the nozzle cap 75 containing a vent aperture 74 positioned opposite the atomization and heating medium apertures ~66 and 73 respectively).
The enclosed area between the nozzle cap 75 and the atomization and heating medium apertures (66 and 73 respectively) forms the enclosed chamber wherein the heating medium is interjected into the spray o~
atomized material to cook or gelatinize the material As with the previous nozzle illustrated in Figure 1, the size and shape of the chamber and vent aperture is effective to maintain the temperature and mois-ture content of the material for a period of time sufficient to cook or gelatinize the material. The period of time for the passage of the atomized material through the chamber defines the cooking or ~elatinization time of the material. The enclosed chamber maintains a desired temperature and moisture content enabling the material to be uniformly cooked or gelatinized therein.
While Figures 1, 4 and ~ illustrate preferrecl embodiments for the nozzle cap design and hence the preferred size and shape of the enclosed chamber, other designs are also comprehended by the instant invention, as illustrated in Figure 7. The design of the nozzle cap and the positioning, size and number of vent apertures can be adjusted to obtain the desired cooking or gelatinization conditions (temperature, vapor pressure or moisture co~tent~
and time. Care must be taken in designing the nozzle cap and positioning the vent aperture so that ~Z~:133~7 the atomized material will be uniformly mixed with the heatiny medium and substantial clogging of the vent aperture is avoided.
As previously mentioned with regard to the various embocliments, the nozzle components may be constituted of metal, such as stainless steel, which is suitable for the processing of food products.
Also, in some embodiments, the internal surfaces of the nozzle may be coated with Teflon (registered trademark) to further ensure that the material does not agglomerate therein and form deposits on the interior surfaces of the nozzle, thereby resulting in clogs~ing thereof.
In various designs of a two-fluid nozzle, several parameters may be varied from embodiment to embodiment, such as the number of injection aper-tures, and the degree of atomization. For instance, if the throughput of liguified material i5 constant or unchanged, one relatively large atomization aperture, as opposed to several small atomization apertures, should result in a cooked or gelatinized material having a larger average particle size.
The distance between the atomization aperture and the nozzle vent aperture is important, as that dis~ance determines the time over which the material is cooked or gelatinized. In the illustrated embod iment, the distance between the atomizing aperture and the nozzle vent aperture has optimally been selected to be approximately .875 inches (2~ mm) for a material such as starch, a nominally optimal value when considering other parameters in thé
system and the products processed therein. Prefer-ably, the distance between the atomixing aperture and the nozzle vent aperture is within the range of about .125 inches (13 mm~ to 1~5 inches (38 mm), `" ~2~3~7 however, that dista~ce may be varied from a smaller distance to a larger distance in other operational models. The larger distances result in a greater degree of cooking or gelatinization of the mater-ials, and may conceivably result in overcooking andfouling of the nozzle cap and nozzle vent aperture with caked and agglomerated materials whereas, contrastingly, the shorter distances may not provide for a sufficient cooking or gelatinization time.
However, this is all dependent on the degree of cooking or gelatinization desired for the particular material with the size of the chamber and hence the time the material spends in the chamber being ad-justed accordingly. By cooking, what is meant is that the material is pxepared for subseguent use by subjecting it to the ac-tion of heat and moisture (or other vapor pressure) for a period of time, with gelatinization being a category of cooking in that a suitable material by subjecting it to the action of heat and moisture over time is converted into a gelatinous form ~e.g., by starch granules absorbing water and swelling).
Other apparent variables in the practice of the present invention are the temperature and vapor pressure (moisture content) within the chamber which is controlled, by the size and shape of the chamber and vent aperture, as well as the temperature, ~ressure and flow rates of the heating medium (e.g., steam, super heated steam, heated gases, heated fluids etc.)j concentration and flow rate of the liquified material, etc. In the present invention, steam supplied at a pressure above 50 psig ~3.~
Kg/cm ) would appear to be adeguate to result in cooking or gelatinization of a material such as starch. The nozzle of the disclosed embodiment has ~ o - 17 ~
been utilized with steam pressures varying from 90 to 160 psig (6.~ to 11.3 Kg/cm2), although either higher or lower steam pressures could also be em-ployed. The steam provides temperatures within the 5 chamber in the range of from about 300 to 340~F (150 to 170C), although either higher or lower tempera-tures may also be utilized depending upon other variables (pressure of steam, type of heating medium, size and s~lape of c~l~mber and verlt aperture, solids content, feed rate of liquified material, proportion of heating medium to li~uified material, gelatiniza-tion or cooking temperature, type of material, additives or modifications of material, etc.).
Generally, a temperature of 5QC to 300C within the chamber can be utilized to gelatinize starch, al-though preferably the chamber temperature is main-tained within the range of 120C to 200C.
Another variable which may be changed to con~
trol the temperature and thus the cooking or gela-tinization of the material is the proportion ofheating medium (e.g., steam~ to liquified material with the proportion, for example, for starch being preferably controlled to within the range of .5 to 3 (part by weight steam/part by weight starch slurry).
~5 Operation of the invention is affected by the size of the nozzle vent aperture, with it generally being desirable to maintain a greater area for the heating medium interjection apertures than for the nozzle vent aperture, such that the chamber is maintained at a temperature and moisture content ~vapor pres-sure) which enables the material to be cooked or gelatinized to the desired degree. Preferably the size of the nozzle vent aperture is within the range of about .125 inches (3mmt to .5 inches (13mm), however, this size may be varied from a smaller to a larger size in other operational models depending upon the temperature and moisture content desired as well as the flow rates of the heating medium and atomized material.
Another variable which may be altered in dif-ferent nozzlle designs is the direction in which the heatiny medium is interjected into the spray of atomized material, with it being possible to direct the interjected heating medium directly toward the nozzle vent aperture, or deflect it off the side wall of the nozzle cap towards the vent aperture, or direct the interjected heating medium tangentially to the axis of the chamber. The enclosed chamber should be sufficiently large and the heating medium should be interjected so as to mix the heating medium with the spray of atomized material before the material makes contact with the chamber wall, thus insuring a uniform and desired degree of cook-ing or gelatinization of the material.
Generally, the material must be liquified or mixed with a solvent to enable it to be pumped and atomized. By liquified, what is meant is that the material is reduced to a liquid state (flows freely) by mixing the material with a solvent, which may be carried out by forming a solution or a slurry (in-cludes suspensions, etc.). While water is the preferred solvent other solvents such as alcohol, acetone etc. or combinations thereof may also be employed. When the material is a starch, the starch is liquified or mixed with an aqueous solvent by forming a slurry which may comprise at least 15%
starch, preferably 35 to 45% starch by weight, as compared to prior art spray drying processes which generally have a maximum solids content of about 10%
of gelatinized starch.
3~7 The starch may be derived from any suitable s~urce such as corn, sago, wheat, tapioca, rice, potatoes, sweet potatoes or waxy maize. Further, it may be in a raw unmodified state, or it may have been previously modified in any desired manner, as for example, by hydrolysis, oxidation, dextrini-æation, esterification, etherification, etc. or any combination of these treatments. As well, a material such as a starch may be combined or slur-ried with other ingredients, e.g., emulsifiers (monoand diglycerides, polysorbates, etc.), colors, flavors, carbohydrates (e.g. sugars), proteins, ats, processing aids, etc. followed by atomization and gelatinization or cooking by the process of this invention. In the treatment of starch from whatever source, it is important that the starch is capable of being gelatinized, preferably in an ungelatinized state, and in the form of its original unbroken granules, and that it remain in that form throughout its derivation process prior to being atomized and gelatinized by the present invention. Moreover, the material feed temperature may range from above freezing, to ambient, to 140~ (60C~, and the feed pH may range from 2 to 12 (preferably 5 to 7). The starch may be uniformly ~elatinized by the present invention to any desired degree, but preferably the starch is uniformly substantially completely gela-tinized, as measured under a polari~ed light by the starch losing its birefringent patterns.
The present invention is able to subject the individual particles of the atomized material to a constant environment and gently, quickly and uni!
formly cook or gelatinize the atomized ~aterial while avoiding overcooking. Thus, the gelatinized starch granules obtained are uniformly swelled to the maximum extent, while maintaining whole granule integrity without the need of heavy chemical modi-fication and with a minimum of granule breakage, or heat damage.
The present invention produces a unique spray dried gelatinized starch heretofore unattainable by conventional processes. The dried gelatinized starch contains starch granules in the form of indented spheres. By indented spheres it is meant that the gelatinized spherical starch granules during drying lose moisture causing the partial collapse of the sphere which forms at least one dimple or indentation on the surface of the sphere.
The starch granules are uniformly gelatinized and lS possess at least a majority of granules which are whole and unbroken, and preferably approximately 100% whole and unbroken granules. The starch of the present invention contains a greater degree of whole, unbroken granules than a starch prepared by conventional spray drying processes with similar degrees of modification (chemical or physical) of the starch. Uniquely, the present inveniion enables the control of the pa~ticle size of the dried starch without subsequent grinding obtaining a desired size of agglomerates of starch granules or even individual whole starch granules, without excessive sh~ar and breaking of the granules. The starch agglomerates formed are loosely bound starch yran-ules and upon hydration, the agglomerates break up and disperse into the individual granules which swell. This property is paramount for products such as instant puddings in order to obtain upon hydra-tion a smooth, uniform, homogeneous, continuous and non-grainy texture.
, .
~Z~3~
A comparision with conventional gelatinization and drying processes demonstrates the novelty of the gelatinized spray dried starch prepared b~ the process of the present invention. Drum drying produces sheets of gelatinized starch which are subsequently ground to a desired particle size, The drum dried starch flakes are in agglomerate form and posses a high degree of broken granules and free starch due to the grinding. The drum dried agglom-erates (fractured sheets or flakes) swell and break - up slightly upon hydration. Conventional spray drying of gelatinized starch must be carried out at extremely low concentrations (less than 10%~ to enable the starch slurry to be pumped and atomized, thus ren~ering the process economically unfeasable.
Even lower concentrations must be employed if whole granules are desired, as conventional methods xe-~uire subjecting fragile swollen (gelatinized) granules to the sheer associated with atomization.
The conventional spray dried starch is in the form of tightly bound agglomerates due to the free starch from the sheared granules binding the agglomerates together. Upon hydràtion, in general, the agglom-erates swell and stay bound together, which could result in a grainy texture in products such as instant puddings. As well, in conventional spray drying of gelatinized starch one cannot control the particle size of the dried starch to obtain fine starch particles (small agglomerates or individual whole granules) without excessive shear and breaking of the granules. E`urther, with conventional gela tinization processes the uniformity of gelatiniæa-tion cannot be effectively and consistently con-trolled.
~2g~3~
In comparison, with the same level of ~hemical modification of the starch, the present invention is able to produce a starch wi-th a greater percent of whole granules than that obtained by conventional spxay dryiny of gelatinized starch. Further, the dried starch prepared by the present invention requires a lower level of chemical modification and even no chemical modification to obtain whole gran-ules and a dried starch which upon hydration posses desireable appearance -(high sheen) and textural characteristics (smooth, continuous, homogeneous and non-grainy), which conventionally required higher levels of chemical modification to obtain. The identified differences between conventionally spray dried gelatinized starch and the dried starch pre-pared by the present invention become even more pronounced the lower the level of chemical modifi-cation of the starch.
After the material is cooked or gelatinized by 2n the method of the present invention the material is then preferably dried, preferably in a spray drying tower although other dryiny techniques, such as belt dryers or flash dryers, may also be employed.
The teachings of the present invention also have applicability in the processing of other mat-erials, such as proteins, dextrins or even other non-food materials, with the resultant advantage that the protein or dextrin may receive ~inlmAl shearing or heat treatment, and result in a product having good dispersibility and solubility charac-teristics.
While several embodiments of a process and apparatus have been disclosed for cooking or gelat-inizing a material in an atomized state so that there is obtained thereby an easily dryablP, uniform ~ 3~
and finely-sized product, the teachings of the present invention as set forth herein will sugge~t many alternative embodiments and variations to those of ordinary skill in the art.
EXAMPLE I
Seven two-fluid nozzles constructed as illus-trated in Figure 1 were arranged iIl a spray drying tower as illustrated in Figure 5. The atomization apertures contained a spinner and orifice having a spinner with 4 grooves of .020 inches t.51 mm) wide and .035 inches ~.89 mm) deep and having an orifice size of .016 inches (.41 mm). The distance between the atomization apertures and the nozxle vent aper-ture was .875 inches (22 mm~, with the vent aperture having a diameter of .25 inches (6.4 mm). Ungel~
atinized tapioca starch cross-linked with about .01%
of phosphorus oxychloride (by weight of the starch) was sluxried in water at a pH of 6 and at a level of 35% solids by weight.
The slurry at a temperature of 69F (21C) was pumped into each nozzle at a rate of 1.2 gal/min (4.6 liters/ min) per nozzle, with s~eam as the heating medium at a` pressure of 150 psig (10.5 Kg/cm2) being pumped into each nozzle at an esti-mated flow rate of 380 lbs/hr ~172 Kg/hr) per nozzle.
The temperature within the nozzle ch~mber is esti-mated to be approximately 310F (155C). The spray drying tower had an inlet temperature o~ about 300 to 370~F (about 150 to 195C) and an outlet tempera-ture of a~out 175 to 205F (about 80 to 95C).
As the starch was ungelatinized, the slurry flowed readily and was easily pumped into the nozzle wh~re the starch underwent gentle, quick and uniform gelatinization by being subjected to high tempera-,, 3~7 tures in the presence of moisture for an amount of time suficient to gelatiniz~ the starch granules.
The resultant starch possessed approximately 80 whole granules and was uniformly and substantially completely gelatinized (birefringent patterns lost under polarized light) while avoiding overcooking with a minimum of heat damage or granule breakage.
On exiting the nozzle vent aperture, the resultant gelatinized starch was in a finely-sized atomized state and was easily dried in the spray drying tower. The dried pregelatinized starch had a mesh size wherein about 80% by weight of the starch passed through a 230 mesh U.S. Standard Screen and was readily useable, as is, in products such as instant pudding mixes. When used in an instant pudding mix the resultant prepared pudding had the desireable texture (smooth, continuous, homogeneous, non-grainy), appearance (high sheen), mouthfeel and viscosity as is characteristic of puddings prepared with heavily modified starches (e.g. cross-linked and substituted). The dried pregelatinzed starch granules were in the form of indented spheres and the granules were l`oosly bound as agglomerates, which upon hydration separated into individual granules which swelled.
EXAMPLE II
Seven two-fluid nozzles constructed as illus-trated in Figure 6 were arranged in a spray drying tower as illustrated in Figure 5. The atomization aperture contained a spinner and orifice having a spinner with 4 grooves of .025 inches (.S4 mm3 wide and .048 inches (1.22 mm3 deep and having an orifice size of .042 inches (1.07 mm). The distance between the atomization aperture and the nozzle vent aper-~2~13~7 ture was .875 inches (~2 mm), with the vent aperture having a diameter of .25 inches (6.4 mm~. Ungelat-inized tapioca starch cross-linked wi~h about .01%
of phosphorus oxychloride and hydroxypropylated with about 8% of propylene oxide (by weight of the starch) was slurried :in water at a pH of 6 and at a level of 40% solids by weight.
The slurry at a tempera-ture of 69~F (21C) was pumped into each nozzle at a rate of 1.2 gal/min (4.6 liters/ min) per nozzle, with steam as the heating medium at a pressure of 150 psig (10.
Kg/cm2) being pumped into each nozzle at an esti-mated flow rate of 3ao lbs/hr (172 Kg/hr) per nozzle.
The temperature ~ithin the nozzle chamber is esti-mated to be approximately 310F (155C). The spray drying tower had an inlet temperature of about 300 to 370F (about 150 to 195C) and an outlet temper-ature of about 175 to 205F (about 80 to 95C).
As the starch was ungelatinized, the slurry flowed readily and was easily pumped into the nozzle where the starch underwent gentle, quick and uniform gelatinization by being subjected to high tempera-tures in the presence of moisture for a~ amount of time sufficient to gelatinize the starch granules.
The resultant starch possessed approximately 100 whole granules which were uniformly and substan-tially completely gelatinized while avoiding over cooking with a minimum of heat damage or granule breakage. On exiting the nozzle vent aperture, the res~ultant gelatinized starch was in a finely-sized atomized state and was easily dried in the spray drying tower. The dried pregelatinized starch granules had a mesh size wherein about 80% by weight of the starch passed through a 230 mesh U.S.
Standard Screen and was readily useable, as is, in 3~7 products such as instant pudding mixes. When used in an instant pudding mix the resultant prepared pudding had the desireable texture (smooth, contin~
uous, homogeneous, non-grainy), appearance (high sheen), mouthfeel and viscosity as is characteristic of puddings prepared with heavily modified starches.
The dried pregelatinized starch granules are in the form of indented spheres and the granules were loosly bound as agglomerates, which upon hydration 0 separated into individual granules which swelled.
Example III
The following samples of raw un~elatinized tapioca starch were chemically modified as in Examples I and II, then conventionally gelatinized (cooked~ followed by conventional spray drying to enable a comparison to be made between a conven-tional cooking and spray drying process verses the method of uniformly cooking a starch by the process of the instant invention. Sample I of xaw ungela-tinized tapioca starch was cross-linked with about .01% of phosphorus oxychloride (as in Example I~, then cooked at 188F (87C) for about 4 minutes to gelatinize the starch, followed by cooling to about 125F to 140F (50C to 60C). Sample II of raw ungelatinized tapioca starch was cross-linked with about .01% of phosphorus oxychloride and hydroxy-propylated with about 8% of propylene oxide (as in Example II), then cooked at 170F (75C) for about 4 minutes to gelatinize the starch, followed by cool ing to about 125~F to 140F (50C to 60C~. Each sample was microscopically examined to ensure that all the granules were swollen while maint~;ning 100 whole granules.
Each gelatinized starch sample at a solids level of about 1.5% was then conventionally spray - ~LZ~3~l7 .
- 2~ -dryed through a standard pressure nozzle (ST type) manufactured by Spraying Systems Co (Wheaton, Ill.).
The nozzle contained an orifice with a diameter of .020 inches ~.51 mm) and a spinner with 4 grooves of .020 inches (.51 mm) wide and .031 inches (.79 mm) deep. The samples of gelatinized starch slurries were pumped t~rough the pressure nozzle at a pres-sure of 300 to 350 psig (20 to 25 Kg/cm2) and at a rate of about 1.5 pounds (.7 Kg) of dry starch per hour into a spray drying tower having an inlet temperature of ahout 375F ~190C) and an outlet temperature of about 190F ~90C).
Each spray dried starch sample ~ormed tightly bound agglomerates which upon hydration swelled as agglomerates and did not break up into individual granules. Individual dried whole granules could not be consistently obtained since when finer atomiza-t~ n was attempted excessive shear occurred, result-il.j in an inordinate percent of broken granules. As well, gelatinized starch slurries with higher per-cents of solids could not be effectively spray dried due to the excessive shear resulting in an inor-dinate percent of broken granules. The spray dried starch of Sample I possessed approximately 40 to 50%
by wei~ht of whole granules (in comparison to the starch of Example I with 80% whole granules), and the spray dried starch of Sample II possessed approx imately 75% by weight of whole granules ~in compar-ison to the starch of Example II with 100% of whole granules~.
When each sample was employed in an instant puddiny composition then hydrated and compared to the counterparts in Examples I and II, the puddings of Samples I and II had less sheen and were grainy and non-continuous. This texture and appearance in ~2C)3~
Samples I and II ~ere the result of agglomerates swelling leaving large voids, as compared to Examples I and II where individual starch granules swelled and were more widely dispersed.
The nozzle contained an orifice with a diameter of .020 inches ~.51 mm) and a spinner with 4 grooves of .020 inches (.51 mm) wide and .031 inches (.79 mm) deep. The samples of gelatinized starch slurries were pumped t~rough the pressure nozzle at a pres-sure of 300 to 350 psig (20 to 25 Kg/cm2) and at a rate of about 1.5 pounds (.7 Kg) of dry starch per hour into a spray drying tower having an inlet temperature of ahout 375F ~190C) and an outlet temperature of about 190F ~90C).
Each spray dried starch sample ~ormed tightly bound agglomerates which upon hydration swelled as agglomerates and did not break up into individual granules. Individual dried whole granules could not be consistently obtained since when finer atomiza-t~ n was attempted excessive shear occurred, result-il.j in an inordinate percent of broken granules. As well, gelatinized starch slurries with higher per-cents of solids could not be effectively spray dried due to the excessive shear resulting in an inor-dinate percent of broken granules. The spray dried starch of Sample I possessed approximately 40 to 50%
by wei~ht of whole granules (in comparison to the starch of Example I with 80% whole granules), and the spray dried starch of Sample II possessed approx imately 75% by weight of whole granules ~in compar-ison to the starch of Example II with 100% of whole granules~.
When each sample was employed in an instant puddiny composition then hydrated and compared to the counterparts in Examples I and II, the puddings of Samples I and II had less sheen and were grainy and non-continuous. This texture and appearance in ~2C)3~
Samples I and II ~ere the result of agglomerates swelling leaving large voids, as compared to Examples I and II where individual starch granules swelled and were more widely dispersed.
Claims (15)
1. Apparatus for uniformly cooking a liquified material comprising:
(a) a means for atomizing a liquified material;
(b) a means for interjecting a heating medium into said atomized material to cook the material;
(c) an enclosed chamber means in which said heating medium is interjected into said atomized material, said chamber containing a vent aperture means positioned to enable the atom-ized material to exit the chamber, the size and shape of the chamber means and vent aperture means being effective to maintain the temperature and vapor pressure of the material for a period of time sufficient to cook said material.
(a) a means for atomizing a liquified material;
(b) a means for interjecting a heating medium into said atomized material to cook the material;
(c) an enclosed chamber means in which said heating medium is interjected into said atomized material, said chamber containing a vent aperture means positioned to enable the atom-ized material to exit the chamber, the size and shape of the chamber means and vent aperture means being effective to maintain the temperature and vapor pressure of the material for a period of time sufficient to cook said material.
2. Apparatus of claim 1 further comprising a nozzle means through which the liquified material is pumped to the atom-izing means.
3. Apparatus of claim 2 wherein the atomizing means is a first atomization aperture in the nozzle.
4. Apparatus of claim 3 wherein the means for inter-jecting a heating medium is a second aperture in the nozzle.
5. Apparatus of claim 4 wherein there are a plurality of second apertures surrounding said first atomization aperture.
6. Apparatus of claim 5 wherein there are a plurality of first atomization apertures in the nozzle.
7. Apparatus of claim 5 wherein the chamber means surrounds said first and second apertures and the vent aperture means of the chamber means is positioned opposite said first and second apertures.
8. Apparatus of claim 5 further comprising a means for pumping said liquified material to said nozzle.
9. Apparatus of claim 5 further comprising a means for drying said cooked spray of material after it exits the chamber means.
10. Apparatus of claim 9 wherein said drying means is a spray drying tower.
11. Apparatus of claim 10 wherein there are a plurality of said nozzles positioned within said spray drying tower.
12. Apparatus of claim 5 further comprising an annular lip on the outer circumference of the nozzle to help prevent the vent aperture means from becoming clogged.
13. Apparatus of claim 11 wherein the heating medium to be interjected is steam.
14. Apparatus of claim 13 wherein the liquified material is an aqueous starch slurry and the period of time for passage of the atomized starch through the chamber means is sufficient to gelatinize the starch.
15. Apparatus of claim 14 wherein the distance be-tween the first atomization aperture and the vent aperture means is within the range of about .5 inches to 1.5 inches and the vent aperture means has a diameter within the range of .125 inches to .5 inches.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000444888A CA1203117A (en) | 1979-12-14 | 1984-01-06 | Apparatus for cooking or gelatinizing materials |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US103,779 | 1979-12-14 | ||
| US06/103,779 US4280851A (en) | 1979-12-14 | 1979-12-14 | Process for cooking or gelatinizing materials |
| CA000364964A CA1172091A (en) | 1979-12-14 | 1980-11-19 | Process for cooking or gelatinizing materials and products |
| CA000444888A CA1203117A (en) | 1979-12-14 | 1984-01-06 | Apparatus for cooking or gelatinizing materials |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000364964A Division CA1172091A (en) | 1979-12-14 | 1980-11-19 | Process for cooking or gelatinizing materials and products |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1203117A true CA1203117A (en) | 1986-04-15 |
Family
ID=25669189
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000444888A Expired CA1203117A (en) | 1979-12-14 | 1984-01-06 | Apparatus for cooking or gelatinizing materials |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1203117A (en) |
-
1984
- 1984-01-06 CA CA000444888A patent/CA1203117A/en not_active Expired
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