CA1291661C - Production of low density materials - Google Patents

Abstract

PRODUCTION OF LOW DENSITY MATERIALS ABSTRACT A multi-fluid nozzle enabling the entrainment of a gas in finely atomized droplets of an aqueous stream is disclosed. The nozzle permits production of low density materials having a desirable particle size distribution and flowability. The invention is particularly useful for the production of a low density non-dairy creamer.

Description

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PRODUCTION OF LOW DENSITY MATERIALS

TECHNICAL FIELD
This invention relates to the production of low density materials possessing physical attributes which are highly desirable in many commercial appli-cations. The invention further relates to a method for producing a highly flowable, low density, material, as for example a non-dairy creamer, said method utilizing a multi-fluid nozæle of novel design. The multi-fluid nozzle provides for gas entrainment in finely atomized droplets under highly controlled conditions.

BACKGROUND OF THE INVENTION
It is known that low density spray-dried coffee powders may be produced by dispersing a gas in an aqueous coffee extract to produce a foam prior to the spray-drying step. In U.S. Pat. No. 2,788,276 a process i5 disclosed involving the introduction of a flow of gas into a coffee extract under pressure to form a foam, raising the pressure with a booster pump, and feeding the foam into a high-pressure reciprocating pump where the foam is compressed to a still higher pressure for spray-drying. In U.S.
Pat. No. 3,749,378 a mixing device is disclosed which comprises an inlet for gas and an inlet for liquid which lead into a mixing zone. The mixing .
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zone is conne~ted to a second zone containing a plurality of spaced plates through which coarse foam passes and is discharged as a fine foam. Similarly, U.S. Pat. Nos. 4,129,624 to Kate~ and 4,160,002 to 05 Janovtchik disclose fluid mixing or injection devices.
However, these references and the art as a whole fail to provide a system for producing a low density material with an acceptable level of proces~ control such that a low density material may be produced with a consistent and controllable density, particle size distribution, and flowability. Further, the prior art systems require downstream handling of a foamed material, as for example pumping, which is inherently inefficient and troublesome in a commercial environment Several references teach that a non-dairy creamer may be used in preparing a prelightened coffee composition. Non-dairy creamers normally contain fat, protein and carbohydrate. The ingredi-ents are normally formulated as an emulsion which issubse~uently dried, preferably spray-dried, and either sold as a bulk powder or further blended with other ingredients in preparing a final product. Two such references are Einstman et al. in U.S. Pat.
No. 3,706,572 and Mancuso et al. in U.S. Pat. No.

3,653,911. The Einstman et al. reference teaches homogeneously blending spray-dried coffee solids and spray-dried non-dairy lightener solids, grinding the blend to a particle size range of 90 to 150 microns, and agglomerating. Mancuso et al. teach blending a non-dairy lightener and a coffee percolate and then spray-drying. The improvement advanced by Mancuso et al. is the incorporation of a part of the buffering agents normally found in the lightener into the coffee percolate instead.

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16fii Gardiner in U.S. Pat. No. 4,046,926 teaches a process for preparing a non-dairy creamer which exhibits an improved resistance to "feathering", where feathering describes the precipitation from 05 solution of serum protein in the presence of an unfavorable acid-salt environment. Gardiner employs a mixture of sodium carbonate and dipotassium hydrogen phosphate to achieve this desirable result.
The physical attributes o~ a material such as a non-dairy creamer are exceedingly important in applications where the material is blended with other ingredients so as to produce a final dry-blended product. Some of the attributes which are particularly important in this regard are particle size distri-bution, density, and flowability. Particle sizedistribution is important in producing a dry-blended product which maintains its homogeneity during shipping and storage. Density is critical to deli~er-ing the proper recipe level of the material in a given serving preparation. Flowability is essential in ensuring smooth handling of the material during processing.
The physical attributes of a spray-dried material are generally controlled by the conditions attendant to the drying step. A need has developed to produce materials having a density considerably lower than previously practiced in the art, while at the same time having good flowability and a particle size distribution which ensures homogeneity in a dry-blended product. This need is particularly pronounced for product formulations wherein it is desired to replace sugar with a non-caloric sweetener such as aspartame, since a dramatically lower level of aspartame is necessary to achieve the same level of sweetness perception.

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Thus, it is an object of the invention to produce spray-dried materials having a low density, while exhibiting good flowability, an acceptable particle size distribution, and acceptable organo-05 leptic characteristics.
It is another object that a method for producinga low density material be efficient and controllable.
These and other objects will become apparent as the invention is described below.
SUMMARY OF_THE INVENTION
It has been found that the objects of the invention are met by a novel method of spray-drying.
According to the invention, a uniquely designed spray-drying nozzle is employed which enables injec-tion of a gas into an aqueous stream prior to its introduction to the spray-drying chamber. The nozzle is of a multi-fluid design and it acts to atomize an aqueous stream into fine droplets and then enable injection of a gas into the atomized droplets, before spraying the droplets into the drying chamber.
Accordingly, a low density material is produced having a desirable particle size distribution and excellent flowability. The drying conditions are controlled to produce a dried material possessing good organoleptic quality. Materials produced according to the invention are suitable for many applications, but particularly for dry blending in product formulations where sugar is being replaced by a non-caloric sweetener such as *aspartame.

*Trade Mark .

~9~6~i1 BRIEE DESC~IPTION OF 1~ DRAWING
The foregoing and other features and advantages of the novel method and apparatus for atomizing and gas injecting a material in accordance with the 05 teachings of the present invention may be more readily understood by one skilled in the art, refer-ence being made to the following detailed description of several preferred embodiments thereof, taken in conjunction with the accompanying drawing.
Figure 1 is an elevational sectional view illustrating an embodiment of a two-fluid nozzle constructed in accordance with the teachings of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The mutli-fluid nozzle of the present invention provides a means for atomizing an aqueous stream into fine droplets, a means for injecting a gas stream such that gas is entrained in the atomized droplets, and a means for spraying the atomized, gas-entrained droplets into a chamber, typically a drying chamber. The multi-fluid nozzle permits controlled gas injection at a point immediately before the atomized droplets are introduced to the drying chamber, thus eliminating any need for pumping of a gas-entrained agueous stream. Because the multi-fluid nozzle allows such excellent control of the rate and degree of gas entrainment, an end-product may be produced having a desirable density, flow-ability and pa~ticle size distribution.
The multi-fluid nozzle of the invention is suitable for use with any agueous stream. The solids concentration of the stream effects the degree to which gas is entrained in the atomized droplets and the evaporative load placed on the ~ ~ 91 6~ ~

drye~. A more dilute aqueous stream places a higher evaporative load on the dryer and will tend to entrain more of the injected gas per pounds solids than a more concentrated aqueous stream, as would be apparent 05 to one with ordinary skill in the art. Additionally, the concentration of the aqueous stream will impact on the operating parameters selected within the drying chambe~ and thereby will have an effect on the flavor and other organoleptic characteristics of the finished product. Thus, the concentration of the aqueous stream entering the multi-fluid nozzle is selected based on many criteria well within the ordinary skill of one in the art for a given appli-cation of the invention.
The invention may be applied to aqueous streams such as coffee extracts, aqueous mixtures of flavor-ants, acids, emulsifiers, etc., and has been found to be particularly suitable for use with an aqueous non-dairy creamer stream. Non-dairy creamer formu-lations typically contain a fat, a protein, and a carbohydrate. Such formulations may also contain a buffer, flow agent, and emulsifying agent, as is well known in the art. For the purposes of illustra-tion, the discussion below will be directed to producing a low density non-dairy creamer, but such discussion is limited thereto merely for the purposes of illustration. The scope of the invention, however, is not limited thereto, but encompasses the production of low density products from any aqueous stream.
The invention may be more fully understood by reference to Figure 1, which is an elevational sectional view of a two-fluid nozzle lO constructed pursuant to the teachings of the invention. In this embodiment of the invention, the aqueous stream enters the nozzle through a conduit 12 provided in ~ 9~ 6~ ~

its ~ight-hand portion (as viewed in Figure 1) and is first directed radially inwardly and then axially downwardly through an aperture 14 formed in the central portion of the nozzle. An insert 16 is oS located in the lower portion of the aperture 14 serving to atomize the aqueous stream into fine droplets. A second conduit 18 is located in the left-hand portion of the nozzle (as viewed in Figure 1) for the introduction of a gas. The gas flows ~hrough the conduit 18 to an annular manifold 20 positioned about the downwardly-extending aperture 14, and downwardly through a gas injection aperture 22 to a gas injection chamber or gas cap 24, in which gas is entrained in the finely atomized drop-lets.
The gas cap 24 is fully sealed except for theaperture 14 with insert 16, the gas injection aperture 22, and spray aperture 26 through which the gas-entrained finely atomized droplets exit. As such, the gas cap is generally at a positive pressure, typically at or near the pressure of the gas as it enters the second conduit 18. The gas-entrained droplets typically enter a drying chamber ~not pictured) after exiting the spray aperture 26, in which the droplets are dried to a powder.
While Figure 1 illustrates a preferred embodi-ment of the multi-fluid nozzle of the invention, other nozzie configurations providing for the atomi-zation of an aqueous stream into fine droplets and the entrainment of a gas in said droplets, fall within the scope of the invention. The nozzle components are typically constructed of a metal or a plastic material of sufficient hardness. Stainless steel is a preferred metal of construction and is suitable for food processing. The insert 16 shown 1~9~

in Fi~ur~ 1 is typically of a harder material of construction, as for example tungsten carbide.
Any gas may be employed according to the inven-tion. Gases such as air, carbon dioxide and nitrogen 05 are particularly suitable because they are relative-ly inexpensive and inert. The pressure at which the gas is injected is a critical control parameter in determining the physical properties of the end-product, particularly the end-product density. For example, when operating with a non-dairy creamer stream, a gas pressure of about 60-80 psi yields about a 20-40% density reduction versus a control.
Having thus described the invention, the inven-tion is further illustrated by reference to the following examples.

EXAMPLE I
A non-dairy creamer stream was prepared by blending the ingredients from Table I with water such that a solids concentration of 60% by weight was achieved. The aqueous stream was agitated for 30 minute~ to ensure homogeneity.
TABLE I
Ingredient Weight Percent Hydrogenated Coconut Oil 47.0 Corn Syrup Solids 40.8 Sodium Caseinate Solids 5.8 Dipotassium Phosphate (Buffer) 2.6 Glycerides 1.7 Sugar 1.7 Silicon Dioxide (Flow Agent) 0.3 Lecithin (Emulsifying Agent) 0.1 100.O

The aqueous stream was fed to a two-fluid nozzle of the design illustrated in Figure 1. The stream was thus atomized into fine droplets. Air was fed to the nozzle as the second fluid at a 05 pressure of about 60 psi. The finely atomized droplets exited the nozzle entrained with air into a drying chamber and were dried to a powder.
The physical attributes exhibited by the non-dairy creamer produced are summarized in Table II.

TABLE II
Density 0.26 gm/cc Flowability 43 cc Particle Size Distribution (U.S. Sieve) + 30 Mesh %
+ 60 Mesh 10%
+ 140 Mesh 70%
Pan 20%
Moisture Content 1.2%
pH
A control run was made using an aqueous stream identical to that described above. The control stream was dried using a typical high pressure nozzle as is known in the art, i.e., absent gas injection.
The control non-dairy creamer exhibited the physical attributes summarized in Table III.
TABLE III
Density 0.45 gm/cc Flowability 43 cc Particle Size Distribution + 30 Mesh 0%
+ 60 Mesh 10%
+ 140 Mesh 70%
Pan 20%
Moisture Content 1.2%
pH 7.5 ~9~6Gl As is apparent, a 42% reduction in density was achieved by practicing the present invention, but other physical attributes were uneffected. An expert panel judged both the control and low density non-oS dairy creamer to be of good quality, with no discern-ible flavor difference be~ween the two samples.

EXAMPLE II
An aqueous stream containing tea solids at a concentration of 20% by weight was fed to a two-fluid nozzle of the design illustrated in Figure 1. Air was fed to the nozzle as the second fluid at a pressure of about 60 psi. The aqueous stream was atomized into fine droplets and air was entrained in the fine droplets within the nozzle. The air-entrained fine droplets were then sprayed from the nozzle and dried in a drying chamber. The density of the spray-dried tea was found to be 0.21 gm/cc.
A control run was made by spray-drying the same aqueous tea stream using a standard high pressure nozzle with a final density of 0.46 gm/cc being obtained. The products were very similar in all other physical and organoleptic attributes.

Claims (12)

1. A non-dairy creamer comprising fat, protein and carbohydrate, said non-dairy creamer having a density of less than 0.35 gm/cc.

2. The creamer of claim 1 wherein said creamer has a particle size distribution of:
U.S. Sieve % By Weight

3. A spray-dried tea having a density of less than 0.25 gm/cc.

4. A method for producing a low-density material which comprises:
(a) feeding the material as an aqueous stream to a multi-fluid nozzle, said nozzle comprising a means for atomizing the aqueous stream into fine droplets, a means for injecting a gas and entraining gas in the finely atomized droplets, and a means for spraying the atomized, gas-entrained droplets from the nozzle;
(b) feeding a gas into the multi-fluid nozzle at a pressure effective to entrain gas in the fine droplets of the aqueous material;
and (c) spraying the injected material into a drying chamber.

5. The method of claim 4 wherein said gas is chosen from the group consisting of air, carbon dioxide and nitrogen.

6. The method of claim 4 wherein said material is a non-dairy creamer.

7. The method of claim 6 wherein said non-dairy creamer has a density of less than 0.35 gm/cc.

8. The method of claim 7 wherein said non-dairy creamer has a particle size distribution of:

U S. Sieve % By Weight

9. The method of claim 6 wherein said non-dairy creamer comprises fat, protein and carbohydrate.

10. The method of claim 6 which further comprises blending said non-dairy creamer with instant coffee.

11. The method of claim 6 which further comprises blending said non-dairy creamer with instant coffee, non-caloric sweetener, and flavorant.

12. The method of claim 4 wherein said material is tea.