CA1066942A - Process for manufacture of fast cooking rice - Google Patents

Abstract

Title of the Invention: PROCESS FOR MANUFACTURE OF FAST
COOKING RICE
Abstract of the Disclosure:
Fast cooking rice which readily reconstitutes itself into cooked rice is manufactured by a process which comprises causing a specified thickener to be diffused from the surface to the inside center of rice grains puffed in advance to a high degree and subsequently subjecting the treated puffed rice grains to drying and shrinking treatments.

Description

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The cooked rice which is a staple food in the countries of the East ~sia'is so-called "steamed and bo.led rice". It is cooked by a time-consuming procedure which comprises the steps of first washing raw rice (which means hul~ed rice in the instant specification and claims) with water, allowing the washed rice to absorb water amply and thereafter steaming and boiling the water-impregnated rice for a long time. Ample impregnation with water and appropriate extents of boiling and steaming are required for preparing the cooked rice of soft texture and agreeable teeth-resistance. RequiremeIIt for rigid control of these conditions bottlenecks a quick cooking. The fact that LhiS cooking consumes much time also ,constitutes one disadvantage.
' Another typical example of cooked rice is pllaf. This is prepared by frying washed rice with oil and then the fried rice is steamed and boiled in the presence of added water. It has a dis-advantage that the texture is generally nard. Althougn this dis-' advantage can be overcome by continuing the treatmPnt of steaming and boiling for a relatively long time. Nevertheless, it still has a.drawback that the cooking consumes much time.
In such state of affairs, a need is felt for development offast cooking rice which readily provides cooked ric,e of the class described above.
What is called "gelatinized rice" has heretofore been regarded as a kind of fast cooking rice. This is usually prepared by subjecting the rice to the ordinary treatment of steaming and boiling for thereby gelatinizing the rice starch and thereafter drying the starch-gelatinized rice. By mere addition of hot water of a temperature of about 80C or over, however, the fast cooking bm/~g ~

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~z rice prepared as descxibed aboYe fails to xeconstitute`itself into cooked rice possessed of desired texture.` It is not converted in-to desira~le cooked rice unless it is boiled for several minutes by heating. Such time-consuming treatment does not befit the fast cooking rice for which the instantaneousness counts strongly.
A method which produces coo}~ed rice by mere addition of hot water has been disclos~d by Japanese Patent Publication No. 5729/
1959. The method disclosed therein comprises first steaming and boiling the raw rice to a mild extent enough to pregelatinize the surface layer of the rice grains, then causing the steamed and boiled rice to absorb a paste such as dextrin or sodium carboxy-methyl cellulose, subjecting the t~ea~ed rice to a treatment for regular steaming and boiling for thereby completely gelatinizing the rice grains to the inside center and finally drying the gelatinized rice. The fast cooking rice which is obtained by this method has a disadvantage that, when hot water is added thereto ` immediately before its consumption, required reconstitution takes much time for the reconstituted rice has rather hard texture possibly because the rice, in the final treatment of drying, suffers partial retrogradation of the rice starch which has once been gelatinized. Furtherm~re, the process of manufacture is complicated.
Studies have also be~n continued with a view to producing fast cooking rice which can be reconstituted into as exact an equivalent of regular boiled and steamed rice as practicable. For example, there is a method which utilizes puffed rice, with due consideration of the fact that gelatinized rice is obtained by puffing rice grains.
, If simply puffed rice is used as a fast cookin~ rice, it is quickly softened in the presence of hot water added thereto prior to its ` bm/ - 2 -.' .
consumption. Nevertheless~ it has a disadvantage that the hot '' water deprives the'rice grains of their shape'and renders them heavily different rom re~ular boiled and steamed rice in taste, texture, viscoelasiicity, e~c. Japanese Patent Publication No.
27700/1971 discloses a method which comprises the steps of first puffing raw rice to a slight exient, then immersing the puffed rice in water for thereby heightening the water content thereof subsequently gelatinizing the puffed rice of an increased water content, thereafter drying the gelatinized rice until the water content thereof decreases to a prescribed level and finally re-puffing the dried rice. The fast cooking rice produced by this method, however, suffers from undesirable spongy texture and poor . .
teeth-resistance. It has the further disadvantages that the process'for manufacture is complicated and the yield is con-sequently low.
As described above, there have been conceived methods for the manufacture of fast cooking rice which combine the treatment of puffing with other treatments. These conventional methods, how-ever, are complicated from the operational point of view because the water content of rice grains must be rigidly regulated in the course of treatments and consequently because the rigid regu]ation of water content calls for additional treatments, and so on.
Methods which involve use of oil and fat are not desirable because the oil ' and fat incorporated into the rice grains degrade the taste and induce oxidation of itself to the extent of heavily impairing the quality of fast cooking rice and also because th~
removal of excess oi~ and fat in the course of manufacture demands much time'and labor.

' ' . '' `' ' ' ' - ' ' bm/~ - 3 -~ . . . -- - ~ . .: : --` lQ66942 Summa_x_~L the Inve.nt_on The prima~y ~bject of the pxesent inYention is to pro~ide a process for the manu~acture of fast cooking rice easily providing cooked rice which, when served for meal, retains the shape of xice gralns unlmpaired, and permits the rice grains to remain in their inherent shape and also excels in texture, taste, flavor, etc.
~ nother object of this invention is to provide a fast cooking rice which is so easily reconstituted that it can be ready for meal after several minutes of standing in hot water of a tempe-~: 10 rature of not less than about 80C.
Still another object of the present invention is to provide bm/ 4 ~
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a fast cooking rice which is so ea6ily reconstituted that it affords pilaf of a desirable texture after several minutes of cooking, such as in a frying pan in the presence of a small amount of water and preferably with some oil added thereto.
Yet another object of this invention is to provide a fast cooking rice capable of a wide range of applications such that it readily produces curry-flavored fried rice and many other kinds of cooked rice when cooked in combination with seasoning agents, d~y-vegetables, dry meat and other foodstuffs.
It is also an object of this invention to provide a simple process for the manufacture of fast cooking rice with-out entailing, from the operational point of view, complicated treatment steps.
: Detailed DescriPtion of the Invention:
A study continued with a view to materializing the objects of this invention has led to a discovery that a fast cooking rice of excellent quality can be obtained by a simple process using specific additives. This invention has been accomplished on the basis of this discovery.
In brief, this invention comprises the steps of preparing a rice puffed to a high degree and adding to the puffed rice the additives to be described hereinafter and a step of drying and shrinking the treated puffed rice grains. Thus, this invention is characterized by the combination of the rice, puffed in advance to the extent of acquiring an enhanced porous texture, with the specific additives. The invention will be ; described in further detail below.
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The first step i~ to prepare rice puffed to a high degree.
The rice grains to be used in making the puffed rice may be of - any of the numerous species available. For the purpo~e of this invention, the puffed rice grains obtained by any methods other than the method resorting to the treatment in heated oil and fat can be used. For example, the puffed rice obtained by first treating rice grains in a closed container kept at elevated temperatures under increased pressure and releasing the rice grains into the atmosphere for thereby allowing them to puff, those puffed by means of heated air, those puffed by having rice grains heat-ed with high frequency waves and those puffed by having rice grains roasted in conjunction with heated grains such as of commom salt, fine sand, ceramic, or those puffed by some other similar puffing method are all usable for this invention. The degree of puffing is desired to be from 6 to 16 times, preferably from 9 to 12 times, but preferably from 10 to 12 times in case of using a thickener to be gelled by metallic ions (to be decribed later), as large in volume (hereinafter the degrees of puffing will be expressed in terms of "volume") as the raw rice grains. The degree of puffing of the figures (6 to 16) as used in the instant specification and claims illustrates an average of each rice grain because the size and quality of each rice grain are different with one another. For example, "6 times" includes the degree of puff-ing of a little bit smaller and also larger than 6 times.

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Then there follows the step of adding a thickener to the puffed rice grains. The term "thickener" as used in the instant specification and also in claims refers to polysaccharides of plant origins, their derivatives, polysaccharides produced by the agency of microorganisms, some of the polymerized substances derived by artificial production including derivation and -- synthesis. According to the present invention, the thickener may be one of those described hereinafter.
There are polysaccharides derived from marine plants:
~ Agar, carrageenin, alginate, alginic acid and furcellaran belong to this class.
There are gums originating in seeds from ground plants:
` Locust bean gum, guar gum, tamarind gum, phyllium seed gum and quince seed gum belong to this class.
~: There is karaya gum obtained from plant exudate.
There is pectin which is derived from fruits.
; Besides, glucomannan which is contained in Amorphop-; hallus Konjak in large amounts is also usable.

i There are artificially produced thickeners: Propylene glycol alginate, low methyl ester pectin, sodium polyacrylate and cellulose derivatives such as carboxylmethylcellulose salt, methylcellulose, hydroxymethylcellulose, methylethylcellulose and hydroxypropylcellulose belong to this class.
There are microorganically produced thickeners: Xanthan gum, caxdrun, scleroglucan, succinoglucan and pullulan belong to this class.
The present invention requires use of at least one of the thickeners enumerated above.

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To be moxe specific~ b~ using a specific thickener selected frol~ the thickeners enumeratea above,' there can be manufactured a ` fast cooking rice which produces cooked rice of more excellent texture after several minutes of standing with added hot water of a temperature of not less than about 80C. The fast cooking rice ob'tained with such a thickener, of course, is suitable for pre-paration of pilaf and other cooked rice.
~' Group (A) of the specifically selected thickeners consist~ of agar, carrageenin, propylene glycol alginate, carboxymethyl-cellulose salt, methylcellulose and glucomannan.
The other group of the specifically selectèd thickeners, - referred to as Group (B), consists of those thickeners which are ;` gelled by metallic ions. Although the thickeners of Group (B) cannot be expected to bring about a conspicuous effect when they are used in the same way as those of Group (A), they manifest a conspicuous effect once they are gelled and consequently allowed to produce a fast cooking rice of all the more excellent quality.
Where the~e is used a thickener capable of being gelled by metallic ions, therefore, the process of manufacture of fast cooking rice is desired to incorporate an extra step for the formation of gel.
This formation of gel is accomplished by first adding the thickener to the puffed rice and subsequently adding thereto a metallic ion capable of inducing gelation of said thickener or conversely by first adding said metallic ion to the puffed rice and subsequently adding thereto the thickener.
The thickeners of thls class are alginic acid, alginate, .

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-~ 1066~42 DD calcium-sensitive ~q~cen~n~potassium-sensitive C~rr~aieeQn~n and low methyl ester pectin.
In the present invention, the various thickeners described above can be used in the form of mixtures of varying combinations.
The method by which the thickener is added to the puffed rice will now be described. This addition is accomplished by causing the thickener to penetrate into the puffed rice. As - a concrete method, it is desirable to e~ploy one which uses the thickener in the form of an aqueous solution. For example, the addition is effectively carried out by immersing the puffed rice in an aqueous solution containing the thickener or by spraying or sprinkling said aqueous solution on the puffed rice.
The advantage of this method is the fact that the individual rice grains can be uniformly treated throughout from the surface to the inside center. In contrast, the method of addition - which uses the powdered thickener in its unaltered form fails to attain the object of this invention, because the thickener cannot uniformly penetrate into the interior texture of rice grains.
This is also true for the addition of metallic ion. The most advantageous method is to use an aqueous solution containing the metallic ion.
Various conditions of treatment ~uch as con-centration of the aqueous solution of thickener and temperature will be described. It is natural that the conditions are variable to some extent because the thickeners themselves have properties different from one another. It is generally desirable, however, to avoid heightening the viscosity of the aqueous solution of .:.

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thickener more than i.t is required, If the viscosity Of the aqueous solution is high~ there is a fear possibility that the ~: treatment aimed at is obtainea only on the s~rface of puffed rice and not sufficiently inside the rice grains and, the ind~vidual - rice grains tend to conglomerate into lumps. The increase in - viscosity further renders the handling of the aqueous solution itself difficult proportionally. Moreover, after the treatment for the addition of thickener, required removal of the excess aqueous solution adhering to the puffed rice cannot be fulfilled satisfactorily. The high viscosity also raises a difficulty in immersing the puffed rice having a low specific gravity in the aqueous solution.
The conditions of the treatment involving use of thickeners which belong to the class consisting of gums of plant origin, polysaccharides originating in marine plants and polysaccharides originating in animals and microorganisms and which there~fore are free from formation~of gel by metallic ion will be described below.
The ranges of concentration suitable for the use of aqueous solutions of these thickeners are substantially similar and the other treatments such as for addition of thickeners can be carried out under similar conditions. The description, therefore, will be given generally to cover ~11 the thickeners.
The concentration of the thickener in the aqueous solution is generally desired to fall in the range of from 0.1 w/w percent (hereinafter indicated invariably in percent by weight/weight), preferably in the neighborhood of 0.5 percent. The range of concentration, however, is variable slightly from one thickener to another. When the concentration fails to reach the lower limit 0~1 percent, the effect aimed at cannot be obtained satisfactorily.

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When it exceeds the upper limit 1,0 percent~ howeyex, the ~iscosity ` of the aqueous solution becomes so high that the solution cannot be handled easily, the individual rice grains tend to adhere mutually to form lumps and the final product has no desirable flavor.
The temperature of the aqueous solution is only required to be such as to permit thorough solution of the thickener. In the case of the aqueous solution of agar, for example, the temperature high-er than 40C. is enough. In the immersion of the puffed rice in the aqueous solution of a thickener, the duration of immersion can be decreased in proportion as the temperature of the solution is increased. In the use of 0.4% aqueous solution of agar, or example, the immersion given for ten seconds at 65C or for one minute at 40~C will suffice for the purpose. Where the addition is effected by spraying or sprinkling, the treated rice is, as a matter of course, desired to be left to stand at rest for a while to ensure uniform and thorough penetration of the aqueous solution into the individual grains of puffed rice. No matter whether the addition is effected by immersion, spraying or sprinkling, the purpose of the treatment is attained insofar as the aqueous solution is throughly penetrated from the surface to the inside center of the puffed rice which has a porous texture.
Then, the conditions of treatment involving the use of thickeners to be gelled by metallic ion and the conditions of said gelation will be described. This gelling treatment substantially comprises causing the thickener and the metallic ion both in the form of aqueous solutions to be penetrated into the puffed rice in two steps. Since the present invention uses a rice puffed to a high degree of from 6 to 16 times the original volume and . , bm/~

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consequently possessed of a porous texture, the rice grains readily permit penetration of said thickener and metallic ion.
The two steps of addition may be effectively carried out in any desired order.
; The addition of the thickener and that of the metallic ion will be described in order.
The concentration of the aqueous solution of a thickener involving formation of gel by metallic ion is generally desired to fall in the range of from 0.2 to 3.0 percent. This range is variable to some extent with the particular kinds of thlckeners to be used. To attain the effect aimed at in a short time, the concentration below the lower limit 0.2 percent does not suffice.

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When the concentration exceeds the upper limit 3.0 percent, however, the viscosity of the aqueous solution increases to an extent such that the solution will not permit ready penetration in the puffed rice nor easy handling, the individual rice grains tend to adhere ~ mutually and the final product gives no desirable taste. The ; temperature of the aqueous solution and the duration of immersion in this aqueous solution are not specifically limited by the present invention. The purpose of the immersion is amply attained when the i~nersion is given for a brief period of about 30 seconds at a temperature falling within the range extending from normal room temperature to 90C, for example. Where the addition is effected by spraying or sprinkling, the treated rice is, as a matter of course, desired to be left to stand at rest for a while to ensure ~niform and thorough penetration of the aqueous solution into the puffed rice. Consequently, the thickener is thoroughly penetrated from the surface to the inside center of the puffed rice having a porous texture! Then, the puffed rice treated abbve is subjected to .

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the same treatment with an aqueous solution containing a metallic on .
The expression "aqueous solution containing a metallic ion"
-. as used in the present invention refers to an aqueous solution . containing free metallic ion. Examples of the aqueous solution satisfying this definition include aqueous solutions prepared by addition.of metallic salts, solutions prepared by an ion-exchange treatment, naturally occurring mineral waters containing metallic ions and natural aqueous solutions which originate in animals and . 10 plants. Of the various aqueous solutions described above, the aqueous solutions prepared by addition of metallic salts will be described by way of exemplification.
In the preparation of aqueous solutions containing metallic salts, examples of the metallic salts usable for this purpose include calcium salts, potassium salts, magnesium salts and other similar metallic salts of carbonic acid, hydrochloric acid, ; sulfuric acid, phosphoric acid, acetic acid, lacti.c acid, citric acid, ascorbic acid, glycerophosphoric acid and other similar acids.
In the solution containing a metallic ion capable of reacting ~0 upon the thickener and consequently including gelation, the . eoncentration of the metallic ion is only required to be such that the absolute amount of metallic ion present therein is enough to bring about the effect of gelation. Whether the combination of respective kind of the aqueous solutions containing the thickener and the metallic ion separately and the combination of their respective concentrations are proper or not for the purpose of this invention ean be eonfirmed by mixing the two aqueous solutions in the absence of puffed rice and examining the resultant mixture .
to find the presence or absence of the ensuing.reaction of gelation.

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Thus the selection ~f a proper combination can easil~ be accomplished.
`` The contact time between the thickener and the metallic ion has some bearing on the strength of gel to be consequently formed. For example, a strong gel is formed by allowing an ample contact time, so that the finally produced fast cooking rice provides enhanced teeth resistance when it is reconstituted with hot water and served for meal. Thus, the degree of resistance to the teeth can be controlled by suitably selecting the length of contact time for , gelation. The kinds and concentrations of the aqueous solutions, the temperature, contact time and pH status involved in the treat-ment can be suitably selected as are generally practi~ed in most ` treatments for gelation. Further and more specific information thereon is made apparent in several examples to be cited afterward.
The puffed rice to which the thickener or the gelled`thickener has been incorporated as described above is now dried by an ordinary method. The drying may be carried out under normal atmospheric pressure or under vacuum, either in the absence or in the presence ~;
of heating. During the drying, the individual grains of the puffed rice may be kept stationary or may be moved. The method of drying, therefore, can suitably be selected by taking into due consideration the amount of puffed rice, the desired duration of drying time (reflecting readiness of handling), the desircd quality of the fast cooking rice to be produced, etc. Where the drying is effected by application of heat, due attention should be paid to avoiding excessive heating which frequently r~sults in occur~enoe of burnt rice emitting an objectionable odor. Concrete examples of the.drier well known for this purpose include a tunnel and band dryer, a chamber dryer, an infrared dryer, etc.
~ In consequence of the gradual vaporization of water, the puffed :. , bm/ pl', ~06694Z
, rice diminishes in Yolume eventually to approach the volume of raw rice while the incorporated thickener or gelled thickener is re-tained throughout from the surface to the inside center of individual rice grains. To obtain a fast cooking rice which gives " a desirable texture when served for meal and yet is not so bulky as to impair the ease of handling, the process of drying is desired to - be terminated at the time by which the volume of the treated puffed rice has decreased to less than three times the volume of raw rice.
; To the aqueous solution of a thickener, to the aqueous solu-tion of a metallic ion, to the pu~fed rice which has incorporated a thickener or a gelled thickener, or to the fast cooking rice which has undergone the treatment of dr~ing, various seasoning agents, nutrition enriching agents, color-improving agents, etc. may be suitably added and blended therewith. As a result, there can easily be produced a flavored fast cooking rice.
As described in detail up to this point, this invention com-prises the first step of puffing rice grains to a high degree for thereby gelatinizing rice starch, inducing cleavage of rice starch micelle, forming a porous texture in rice grains and causing a specific thickener in an unaltered form or a gelled form to be amply entrapped within the ~ice grains and the subsequent step of drying the treated puffed.rice to the extent of allowing the rice grains to dwindle to a prescribed volume. The f~st cooking rice which is ~ d~as described above enjoys high yields of production and high preservability and, upon reconstitution, converts itself into a cooked rice excelling in taste, texture and flavor.
Reconstitution of this fast cooking rice, for example, into ordinarily cooked rice can be obtained by adopting a method which is , bm/~B
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is generally practiced in preparing fast cooking Xices o~ this kind. To be specific, desired reconstitution into cooked rice can be accomplished by allowing this fast cooking rice to stand for one to two minutes in hot water heated in advance to about 80C or over . and added in a volume roughly 1 to 1.5 times the volul~e of rice, then discarding an excess portion of said hot water and thereafter allowing the rice to be steamed for three to four minutes with the remaining heat. The fast cooking rice can be reconstituted into a soup containing rice grains by following the same procedure except for removal of excess hot water. The fast cooking rice produced by this invention can be also amply reconstituted into a cooked rice of good quality when it is left to stand in water of normal - room temperature for about 30 minutes. When the fast cooking rice is reconstituted with milk instead of water of normal room temperature, the resultant cooked rice tastes good. For a user who feels like eating pilaf, a pilaf of mild texture can be obtained by heating the fast cooking rice of this invention such as in a frying pan in the presence of a small amount of oil and fat and a suitable. amount of water.
Obviously modifications and variations are possible insofar as they do not depart from the spirit and scope of the present in-vention. This invention is not limited to the specific embodiments thereof as defined in the appended claims.
Example 1 ~ A raw rice was expanded by a puffing gun into a puffed rice ; having a volume of 9 times the original. Two t2.0) Kg of this puffed rice was immersed for 10 - 15 seconds in a 0.4~ aqueous ; solution of agar-agar képt at 65C~ It was immediately placed in an electric constant-temperature hot-air dryer at 90C and dried : ' bm/ ~

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therein for 2,5 hours to produce 1.9 kg of fast cooking rice having a volume of about twice as large as that of the raw rice. This fast cooking rice was placed in a container provided with a lid.
The same volume of hot water at 95C was poured into the container.
The rice and the hot water in the container were left to stand for 90 seconds. Then, the excess hot water was discarded. Thereafter, the fast cooking rice was left to be steamed for three minutes with the remaining heat. Consequently, there was obtained a cooked rice ( . .
excellent in taste, texture and flavor.
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A raw rice was expanded by a puffing gun into a puffed rice having a volume of 16 times as large. Two (2.0) Kg of this puffed rice was sprayed with 5.3 kg of 0.3% aqueous solution of sodium carboxymethylcellulose at normal room temperature, then left to stand at normal room temperature for ten minutes, thereafter placed in a drying oven at 70C and dried therein for four hours to afford

2.0 kg of fast cooking rice having a volume about twice as large as - the volume of raw rice. ~ -A cooked rice of excellent quality was obtained by subjecting the fast cooking rice to the treatment of the same procedure as in Example 1.
Example 3:
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A raw rice was expanded by a puffing gun into a puffed rice having a volume of 9 times as large. One (1.0) Kg of this puffed rice was sprayed with 2.5 kg of 1.0% aqueous solution of lambda carrageenin at 44C, then left to stand for ten minutes at normal room temperature, subsequently placed in a vacuum dryer, dried first at 65C under normal atmospheric pressure for one hour to vaporize the water and then at 65C under a vacuum of less than 10 mm~lg for

3.5 hours. ~hus there was obtained 0.98 kg of a fast cooking rice bm/J~ -17-~ . .

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-having a yolume of about 1.7 times the-,volume Of the raw rice. A
cooked rice'o~ excellent quality could be obtained by treating this fast cooking rice by the treatment of the same procedure as ln Example 1.
Example 4:
- A raw rice was expanded by use of heated air at 300C into a puffed rice having a volume of 6 times as large. Three (3.0) Kg of this puffed rice was immersed in 0.45% aqueous so]ution of guar gum kept at 65C, then immediately placed in a drying oven at 90C and dried for three hours to afford 2.9 Kg of a fast cooking rice having a volume of about 1.7 times as large as that of the raw rice. ~wo hundred (200) g of this fast cooking rice was placed in a frying pan and heated in the presence of 600 g of water and a small amount of salad oil added thereto. There was consequently obtained a cooked rice excellent in taste, texture and flavor.
Example 5:
A raw rice was expanded by a puffing gun into a puffed rice having a volume of 10 times as large. One and a half (1.5) kg of this puffed rice was immersed in a seasoning aqueous solution con- ' taining 0.3~ of propylene glycol alginate, 0.3% of sodium starch phosphate, 0.5% of sodium chloride and a small proportion of season,ing agent. After about lS seconds of lmmer'sion in the solution, the puffed rice was immediat,ely placed in a drying oven at 85C and dried therein for three hours to afford 1.4 kg of a fast cooking rice having a volume of about 1.9 times as large as that of the raw rice. A curry-flavored cooked rice was obtained by cooking this fast cooking rice in the presence of curry powder and raisin added thereto by a proce,dure similar to that of Example

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Example 6;
A raw rice was expanded by a puffing gun into a puffed rice having a volume of 11 times as large. One (1.0) kg of this puffed rice was immersed in 0.5~O aqueous solution of low me~hyl ester pectin at normal room temperature for 60 seconds and then immersed again in 0.5% aqueous solution of calcium chloride at 60C for 60 seconds. The puffed rice thus treated was dried in a drying oven at 60C for four hours to afford 0.98 kg of a fast cooking rice having a volume of 2.4 times as large as that of the raw rice. A
cooked rice of excellent quality was obtained by subjecting this fast cooking rice to a treatment similar to that of ~xample 4.
Example 7:
A raw rice was expanded by a puffing gun into a puffed rice having a volume of 15 times as large. One (1.00) Kg of this puffed rice was immersed in 2.0~ aqueous solution of calcium and potassium-sensitive carrageenin at 80C for 30 seconds, and then immersed again in an aqueous solution containing 1.0~ of calcium la~tate and 1.0~ of potassium monohydrogenphosphate at 80C for 60 seconds.
When the treated rice was dried for five hours under conditions of 45C + 5C and a vacuum of less than 10 mmHg, there was obtained 1.0 Kg of fast cooking rlce having a volume of 1.6 times that of the raw rice. A cooked rice of excellent quali.ty was obtained by subjectin,g this fast cooking rice to a treatment s.imilar to that of Example 1.
Example 8:
A raw rice was expanded by a puffing gun ihto a puffed rice having a volume of 11 times as large. One (1.0) Kg of this puffed rice was sprayed with 2.5 kg of 1.0% aqueous solution of calcium lactate at normal room temperature, then left to stand at normal b~
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room temperature for about ten ~inutes~ and thereafter immersed in 0,6% aqueous solution of sodium alginate at ~0C for two minutes.
When the treated rice-was dried in a drying oven at 80C for three hours, there was consequently obtained 0.9 kg of fast cooking rice having a volume of 2.6 times as large as that of the raw rice. A
flavored steeped rice of excellent taste was obtained by adding to this fast cooking rice small amounts of powdered sea weed and powdered green tea, a suitable amount of sodium chloride and a small amount of dried salmon flakes and allowing the resulting mixture to stand in hot water at 90C for three minutes.
Example 9:
A raw rice was expanded by a puffing gun into a puffed rice having a volume of 15 times as large. One (1.0) Kg of this puffed rice was immersed in an aqueous solution of 0.5% sodium alginate and 0.1% cardrun for 30 seconds, then immersed again in an aqueous solution containing 3.0% of calcium lactate, 3.0% of chicken soup, 0.5% of sodium chloride and 0.03% of seasoning agent at normal room temperature for 45 seconds, and thereafter dried in a drying oven -at 95C for 2.5 hours. Consequently, there was obtained 0,97 kg of fast cooking rice having a volume of 2.7 times as large as that of the raw rice. A flavored cooked rice of excellent taste was obtained by subjecting this fast cooking rice to a treatment similar to that of Example 1.

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Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the manufacture of fast cooking rice, which comprises: puffing a raw rice into a puffed rice having a volume of 6 to 16 times as large: contacting said puffed rice with a solution of a thickener in a concentration of about 0.1 to about 1.0% by weight, or when using a thickener which forms a gel in the presence of a metallic ion, a solution of the thickener in a concentration of about 0.2 to about 3.0% by weight and a solution of the metallic ion, sufficiently to penetrate to the inside center of the puffed rice; and thereafter drying and shrinking the treated puffed rice.

2. A process according to claim 1, wherein at least one member selected from the group consisting of agar, carrageenin, propylene glycol alginate, glucomannan, methylcellulose and carboxymethylcellulose salt is used as the thickener.

3. A process according to claim 1, wherein a thickener which forms a gel in the presence of a metallic ion is used, and the solution of the metallic ion is added before or after adding the solution of the thickener.

4. A process according to claim 3, wherein the thickener is at least one member selected from the group consisting of alginic acid, an alginate, calcium-sensitive carrageenin, potassium-sensitive carrageenin, and low methyl ester pectin.

5. A fast cooking rice produced according to the process of claim 1.

6. A fast cooking rice produced according to the process of claim 2.

7. A fast cooking rice produced according to the process of claim 3.

8. A fast cookinq rice produced according to the process of claim 4.