JPH09163949A - Instant rice gruel and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an instant rice gruel having a completely gelatinized surface layer, etc., and exhibiting excellent taste and palatability in a short hydration time by passing rice through a cooking extruder, etc., and extruding under specific condition. SOLUTION: Rice is passed through a cooking extruder and a die 5 and extruded through the die 5 to obtain an extrudate composed of an essentially completely gelatinized surface part and a partly gelatinized core part. The extrudate is expanded at the outlet and cut into expanded chips of a rice grain size to obtain an instant rice gruel. The rice is preferably supplied by mixing with <=40wt.% (based on the rice) of water.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to instant rice porridge.

[0002]

BACKGROUND OF THE INVENTION Rice porridge, which is very popular in Asian societies, cooks rice grains in excessive amounts of water by the time the rice grains begin to lose their identity but still retain some tissue. Usually cooked at home by cooking until it's too late. In the final product with a gelatinized starch matrix, the rice grain has a core that is somewhat resistant to chewing, and a significantly softened outer layer, which combination gives the product a mouthfeel and Making rice porridge at home, which gives a certain degree of density, that is, ease of chewing, is a time-consuming operation. Because it takes a long time to cook rice grains to the right degree of softening, and the kernel of the rice grains is too hard because the product is not cooked enough, or the whole product is liquid porridge. This is because it is necessary to constantly monitor what happens.

[0003]

Various attempts have heretofore been made to prepare instant rice porridge in the form of a dry product, which can be hydrated with hot, especially boiling water. Such products, in some cases, take a long time to hydrate, and in other cases, the feel or mouth feel or other organoleptic properties of the freshly made rice porridge. It's not the same as the ones so far, so far it's been largely unsuccessful.

[0004] In one proposed method, rice is cooked in hot water to the usual extent. The rice porridge is then air dried and flaked on a flaking machine. The flaked rice is then evaporatively expanded before packaging. This product has a hard and brittle texture which means that it is easily broken into small pieces. It also tends to have a low specific gravity and a hard surface crust, thus the product floats when water is added and takes a considerable amount of time (10 minutes or more) to hydrate and sink. Even though the product is evaporatively expanded, the grain shape of the rice tends to remain after hydration, thus giving the traditional slurry-like consistency of rice porridge even with very strong agitation. It is virtually impossible to obtain. There is less starch on the surface to form a gelatin matrix.

Another form of evaporatively expanded product is similar to the method used to make shrimp crackers by the subsequent application of heat to evaporatively expand the product without evaporative expansion at the die outlet. It is made using various methods. This product is a rice crispies
Very similar to the breakfast cereal diet known as. It has a very low specific gravity and floats on water for hydration.
When finally hydrated and mixed with water for complete hydration, the tissue in the product is very low.

In yet another attempt to make instant rice porridge, rice flour and water were passed through a heated extruder,
Cooked rice pellets or grains are made. These pellets are then ground to a fine powder with or without further water reduction steps. This cooked rice flour mixes almost immediately with hot water to form a porridge-like product with little or no tissue and no other desirable organoleptic properties of rice porridge.

[0007]

According to the first aspect of the present invention, an instant rice porridge has a relatively high density condensed central portion and a relatively high density of closed cells surrounding the central portion. It consists of evaporatively expanded, generally rice-grained, discontinuous pieces of rice having a small intermediate portion and a generally open-cell surface portion, the surface portion of which consists essentially of fully gelatinized starch. The central part consists of partially gelatinized starch.

According to a second aspect of the present invention, a method of making instant rice porridge comprises cutting the extrudate into discrete pieces, the product of which when leaving the die at the exit of the extruder. A temperature that has a foamy structure and is a fully cooked and gelatinized rice starch surface portion and a partially gelatinized rice starch central portion.
It consists of passing the rice, optionally mixed with a small amount of water, under pressure and screw speed conditions into a cooking extruder.

[0009] Preferably, after exiting the extruder, the product is passed through a flaking device to flatten the granules. Preferably, in a flaking device with a pair of nip rolls, the air bubbles inside the grains are collapsed and reduced in size, with still moist rice sticking together to form condensed nuclei. On the other hand, the outer bubbles are collapsed to form an open cell surface structure. A sealed cell can remain between the open cell surface layer and the core.

The open cell surface structure allows the penetration of water for hydration, and the dense core enhances mouthfeel and chewy feel.

In addition, the flattened granules have a higher packing density, which offers the advantage that the packing size of a given weight of product can be reduced.

The rice fed to the extruder may be unmilled rice or it may be milled prior to use. In the grinding process, the rice may be ground to a fine powder, or it may simply be reduced to pieces that are sized for the extruder used.

The water content of the rice fed to the extruder is usually 3 to 35% by weight, for example 28% by weight.

The addition of water may or may not be necessary, depending on the initial water content in the rice grain and the extrusion conditions. Sufficient water must be present to cook the rice in the extruder into fully gelatinized and partially gelatinized portions.

Generally, the maximum amount of water that needs to be added is 40% of the weight of rice, that is, 2 weight units of water is the maximum addition amount to 5 weight units of rice.

The amount of water in the rice helps control the extrusion temperature. There must be sufficient free water in the product exiting the extruder to cause the required degree of evaporative expansion and to allow nuclei binding in flaking,
There should not be so much water that the extruded product requires significant drying. Slight drying of the product is usually necessary to reduce the water activity of the product to the extent that it corresponds to the desired shelf life.

Drying under erroneous conditions impedes the hydration process around the product piece and prevents a gentle transition between the water-gelatinized phase and the grain phase of the porridge. there is a possibility. This should be avoided in the products of the invention.

Temperature control of the product at the extruder and at the outlet therefrom is a must. The temperature in the extruder depends on the temperature of the extruder cylinder, the extruder screw speed, the gap between the extruder screw and the cylinder, and the amount of water in the material. The higher the amount of water in the product, the lower the temperature rise in the extruder. The higher the extruder speed, the higher the product temperature, and the smaller the extruder gap, the higher the product temperature. The size of the space between the end of the screw where the product is cooked and the die can be varied, thereby changing the residence time of the product in the cooking space and allowing the product to be extruded. Ensure that it is cooked to the desired degree in the device.

The temperature of the product as it exits the extruder, along with the pressure drop, determines how much evaporative expansion takes place. The pressure drop can be adjusted by changing the screw speed to change the pressure in the extruder.

Any type of culinary extruder can be used to produce the products of this invention. The extruder may be a single or multiple screw extruder,
It may also have a grooved or flat cylinder.

The residence time of the rice in the extruder is preferably in the range of 4 to 7 seconds, and the preferred pass length of the extruder is about 15 cm, which is used. It depends to a great extent on the exact nature of the extrusion equipment. A skilled extrusion equipment operator will be able to look at the product and see if the extrusion conditions are correct and, if necessary, how they should be adjusted. When the product is subsequently subjected to a flaking operation, control of extrusion conditions is less critical.

[0022]

The accompanying single drawing shows one type of screw extruder for use in the method of the present invention.

Referring now to the drawings, a screw extruder for use in the method of the invention comprises a cylinder 1 having a shallow groove 2 and a piston 3 in the form of a screw 4 provided in the cylinder. Have The cylinder 1 is connected to the die 5 by a suitable connecting mechanism 6. Piston 3
As the rice rotates, the rice-water mixture moves forward. While passing through the extruder, the mixture is heated so that it is cooked and the cooked mixture is pushed through the opening 8 into the die mold 5 by the movement of the screw 7.
The pressure difference between the inside and the outside of the extruder leads to a sharp expansion of the water in the mixture which acquires a cellular structure. This product is
It is then cut with a high speed rotating blade (not shown) into a roughly rice grain sized product.

The product is then flaked by passing it through a roller machine (not shown).

The final product can be packaged with or without a dry process, depending on the desired shelf life of the product. The shelf life of the product is about 4 ~ water before packaging.
Drying to 6% can be very long.

The product characteristics are determined by several parameters: the temperature of the cylinder 1, the speed of the piston 3, the water content of the rice grain-water mixture before extrusion, the temperature of the die 5 and the walls and grooves 2 in the cylinder 1. And the distance between the piston head 7 and the die 5 and the length and diameter of the extruder. While some of the extruder properties can be varied within certain limits, other parameters are monitored during manufacture to obtain the desired properties of the final product, and individually or in combination. It can be adjusted.

The product is characterized in that it is a white to cream-colored, completely flattened oval shape. It has a slightly plastic surface and an open cell structure. Upon analysis, the internal structure showed cavities surrounding a compacted and compacted nucleus, in which the bubble structure was greatly reduced. The surface consists of a layer of fully gelatinized starch with a glassy appearance that is slightly translucent to the product. The core consists of partially gelatinized starch. The cream color of the product is believed to be due to the partially gelatinized starch in this structure. The combination of fully gelatinized starch and partially gelatinized starch constitutes a localized barrier to water for the product that prevents immediate hydration. This barrier is destroyed when heat and water are added to the product.

This textural structure allows the partially hydrolyzed starch to undergo complete hydration when fully gelatinized, and the mixture is made to look, feel and taste like traditional rice porridge. To The rate of hydration can be adjusted by adjusting the degree of evaporative expansion of the product and the degree of packing in the flaking operation. A hydration time of between about 3 and 5 minutes is desirable.

The product can be packaged with other ingredients, together or separately, to form a more complete meal. These ingredients include various flavors (eg, chicken, mushrooms, abalone, etc.), pigments, proteins (eg, soybean flour, beans), vegetables (eg, mushrooms, carrots,
Corn, peas, onions, etc.), fruits (eg, plums, apricots, apples, etc.), meat (eg, chicken,
Beef, lamb, etc.) and fish. They can be added in raw or processed form and may be added before or after extrusion or in a separate package in the packaged product.

Similarly, the health benefits of the product are, for example, vitamins, minerals, proteins, herbs, as well as traditional plants such as parsley, lotus seeds, barley, ginseng, ginger, sprouts, peppermint and the like. And enhanced by adding plant extracts.

[0031]

The following examples illustrate the invention. 50 kg of rice with a water content of 15-16% by weight was ground. The ground rice was mixed well with 7-10% water and passed through a screw extruder of the type suitable for food processing and shown schematically in the drawings.

The extruder had a cylinder inner diameter of 76 mm and a cylinder length of 200 mm. Inside the cylinder, at the inlet end of the cylinder, pitch 12 mm, depth 7 mm and width 6 mm
Then, along the length of the cylinder, a helical groove having a rectangular cross section with a depth reduced to zero was formed at the outlet end.

The extruder cylinder ended with a die-shaped plate having a plurality of rectangular openings of 7.times.1.5 mm.
A rotating knife was set to cut the material exiting the die plate to a length of 7 mm. The screw of the extruder has a diameter of 7 mm to form a 2 mm gap inside the cylinder.
4 mm. The screw pitch is 12.7 mm
And the thread had a width of 4 mm and a depth of 7 mm.

The rice / water mixture was fed to the extruder at a rate of 0.25 kg / min. The screw speed was set to 400 revolutions per minute and the temperature of the outer cylinder was set to 100 ° C.

When the steady state conditions were reached, the material exiting the extruder was a generally oval evaporatively expanded piece of rice having a general size close to that of rice grains. .

During the passage through the extruder with a residence time of 6 seconds, the rice particles coagulated as gelatinized starch. The outside of the coagulum was maximally cooked so that the starch was fully gelatinized as it was removed from the die. Inside, the starch remained partially gelatinized.
The inside of the strip coming out of the extruder was moist and colder than the outside and thus was not cooked to the same extent as the outside.

The product from the extruder was passed through a flaking unit consisting of a pair of counter-rotating nip rolls. In the nip, the surface cells were destroyed and the wet centers of the pieces were condensed and made more dense.

The product from the flaking device was then passed through a hot air tunnel to dry the moisture to less than 4% by weight to improve the storage capacity and shelf life of the product. The product was then packaged in hermetically sealed foil packaging.

The product floated for a short time when sprinkled with boiling water, but then hydrated and sank when stirred.
We were able to make a rice porridge that could be completely solidified within 3 minutes.

Using the same extruder, screw speeds between 300 and 450 rpm and a cylinder temperature of 8 rpm.
Further tests were carried out with the same rice / water mixture, varying between 00 and 120 ° C. and the residence time between 4 and 7 seconds. A satisfactory product was obtained which hydrated within about 3 minutes.

[Brief description of the drawings]

1 shows one type of screw extruder for use in the method of the present invention.

[Explanation of symbols]

 (1) Cylinder (2) Shallow groove (3) Piston (4) Screw (5) Die type (6) Connecting mechanism (7) Screw (8) Opening

Claims (13)

[Claims] 1. An evaporatively expanded generally portion having a relatively densely condensed central portion, a relatively less dense middle portion of closed cells surrounding the central portion, and a generally open cell surface portion. An instant characterized in that it consists of discontinuous rice pieces of grain size, the surface portion of which is substantially completely gelatinized starch and the central portion of which is partially gelatinized starch. Rice porridge product. 2. The product of claim 1, wherein the pieces are generally biconvex. 3. A product as claimed in claim 1 or 2, characterized in that said pieces consist of pieces of rice bound by a starch binder. 4. A product according to any of claims 1 to 3, characterized in that said piece is made by extrusion. 5. The product of claim 4, wherein the pieces are made by extrusion followed by flaking. 6. The product according to claim 1, which is capable of being hydrated within 3 to 5 minutes to form rice porridge. 7. Passing the rice through a cooking extruder and a die mold, inflating the product at the exit from the die mold, and then cutting into inflated products of substantially rice grain size pieces, and extrusion conditions. Is an instant rice porridge product characterized in that the product emerging from the die mold is in such a state that it has a substantially fully gelatinized surface portion and a partially gelatinized central portion. Manufacturing method. 8. A process according to claim 7, characterized in that the product from the extruder is passed through a flaking device. 9. The method according to claim 8, wherein the flaking device comprises a pair of nip rolls. 10. The method according to claim 7, wherein the rice is uncrushed rice. 11. The method according to claim 7, wherein the rice is crushed before being fed to the extruder. 12. The rice is supplied in admixture with water in an amount of up to 40% by weight of rice.
1. The method according to any one of 1. 13. A sealed first package containing a large amount of the product of any one of claims 1 to 6 or the product of the process of any one of claims 7 to 12, a seasoning ingredient and a food product. And at least one further package containing a large amount of at least one additive selected from
The first and further packages are cups sized to contain the contents of these packages and sufficient water to hydrate the contents into a slurry-like product with the consistency of ordinary rice porridge. A package of instant rice porridge product characterized by being packaged in a member.