JP4247156B2 - Processing method for starch food - Google Patents

Description

  The present invention relates to a starch food processing method capable of arbitrarily controlling the degree of pregelatinization of starch foods such as processed rice and processed noodles.

  Alpha rice, which is known as processed rice, has advantages such as the need for washing rice and soaking in water during cooking and shortening the heating time during rice cooking, but the inferior taste when cooking rice There have been various improvements. For example, only a surface layer portion of rice grains is gelatinized (pregelatinized), and then dried, and a process for producing processed rice that does not affect gelatinization to the inner layer portion (see Patent Document 1) or β inside the rice There is a method for producing processed rice in which starch is semi-alphabated by microwave heating and then frozen and stored (see Patent Document 2).

  According to the manufacturing method of the processed rice of the said patent document 1, only a surface layer part can be water-absorbed by adjusting the immersion time to the water of a rice grain, and only a surface layer part can be alpha-ized by heating. . However, when this processed rice is cooked with a home-use rice cooker, when the pregelatinization reaches the core of the rice grain, the surface layer is already in a state where the pregelatinization has proceeded excessively (the sticky and sticky State or a state of mud that draws the thread), there was a problem of poor taste.

  In addition, according to the method for producing processed rice in Patent Document 2 described above, “in microwave heating, alpha conversion proceeds from the inside of the rice, and therefore, when half-alpha is applied, the surface of the rice is the unprocessed rice and the appearance is There is almost no change. The semi-pregelatinized rice in the present invention refers to a state in which rice starch layer cell tissue is destroyed (pregelatinized) by 75 to 80% from the inside ”(paragraph number). However, when microwave heating is actually performed, radio waves are almost uniformly penetrated into each part of the rice, each part of the rice generates heat simultaneously, and the whole rice is 75-80% alpha. (See FIG. 6). If the processed rice obtained in this way is cooked in a cooking device such as a microwave oven, the entire rice is 100% alpha in a short time, so there is no problem, but heat conduction from the outside such as a domestic rice cooker When cooking with a heating type cooking device, when the alpha of the core of the rice grain reaches 100% as in the above, the superficial part becomes a state where the alpha is excessively advanced and the taste is poor. there were.

JP 60-16556 A JP-A-6-16556

  In view of the above problems, the present invention increases the degree of pregelatinization in the center of the starch food in advance, and optionally controls the degree of pregelatinization so that the surface is zero. Even if it is a case where it cooks with the type of cooking device heated by heat conduction, it is set as a technical subject to provide the processing method of the starch food product which does not deteriorate a taste.

In order to solve the above problems, the invention of claim 1 provides a processing method for starch food in which a temperature difference is provided between the central portion and the surface portion of a food material mainly composed of starch, and only the central portion is pregelatinized by microwave heating. In the above, after the food material is absorbed, it is immersed in a liquid refrigerant within 20 seconds to bring the temperature of the surface portion to -40 ° C to -30 ° C and the temperature of the central portion to -5 ° C to 0 ° C. The temperature was then maintained, followed by microwave heating for 30 seconds to maintain the center temperature at 80 ° C. and alphatize only the center.

  According to the present invention, the degree of pregelatinization of the food material mainly composed of starch is high, and the degree of pregelatinization is arbitrarily controlled so that the degree of pregelatinization of the surface portion is zero. Even when recooked in a cooker that heats from the outside by some heat conduction, when the heat reaches the center, the entire food material based on starch is almost uniformly 100% alpha. In this state, the pregelatinization of the surface portion does not proceed excessively, and a good taste value can be obtained.

  That is, the food material mainly composed of starch is immersed in a liquid refrigerant within 20 seconds, the temperature of the surface portion is set to -40 ° C to -30 ° C, and the temperature of the central portion is set to -5 ° C to 0 ° C. And then microwave heating is performed for 30 seconds to maintain the center temperature at 80 ° C. so that only the center is alpha, so that the surface of the food material is completely frozen and the center of the food material is not yet It is maintained in a frozen or semi-frozen state (a low temperature chilled state that does not freeze), and only the central portion is efficiently alphalated. The immersion time in the refrigerant varies depending on the type of refrigerant, the initial temperature of the food material, the shape of the food material, and the like. For example, when immersed in the refrigerant within 20 seconds, the temperature of the surface portion of the food material is −40 ° C. to −30 The temperature at the center can be maintained at -5 ° C to 0 ° C. At this time, if the temperature of the surface portion is lower than −40 ° C., the center portion is completely frozen, and if the temperature is higher than −30 ° C., the surface portion is not completely frozen. And if the temperature of a center part remove | deviates from the range of -5 degreeC-0 degreeC, an unfrozen or semi-frozen state cannot be maintained.

Hereinafter, the best mode for carrying out the present invention will be described.

First, rice will be described as an example of starch food (see FIG. 1). After harvesting, the raw rice is dried and chopped, and the raw moisture is about 16%. The milled rice is polished to obtain polished rice (step 1). As the polished rice, one sold at a general retail store or the like may be used. Thereafter, the polished rice is washed (step 2). The rice washing can be done by sharpening as in general households, but it may also be done by a machine such as a batch type rice washer or a continuous type rice washer. Moreover, washing and soaking can be performed simultaneously.

When the washing is completed in this manner, the next soaking is performed (step 3). Although this immersion may be performed in a water storage state, it may be performed in a flowing water state. The moisture of the rice after soaking for about 60 minutes is about 40%. After soaking, the rice is dehydrated until the water content is about 20 to 30%, and dried if necessary (step 4). A centrifugal dehydrator or the like may be used for dehydration, and a ventilation dryer may be used for drying.

  The rice is then frozen (step 5). In order to generate a temperature difference between the core of the rice and the surface layer, for example, the rice is added to a liquid refrigerant such as liquid nitrogen or dry ice ethanol whose temperature is maintained at −80 ° C. to −30 ° C. It is good to immerse within 20 seconds. In addition, the temperature difference may be generated by spraying a gaseous refrigerant. As a result, the surface layer of rice is completely frozen at a temperature of −40 ° C. to −30 ° C., and the core of the rice is unfrozen or semi-frozen at a temperature of −5 ° C. to 0 ° C. Maintained.

  Next, the rice is taken out of the liquid refrigerant and heated by microwaves (step 6). In microwave heating, radio waves penetrate into each part of rice almost uniformly, and each part of rice generates heat at the same time. At this time, the core of the rice is in an unfrozen or semi-frozen state, and this part is intensively heated, and only the core is alpha before the surface layer of the rice is thawed. . For example, when heating at 360 W with microwaves with a frequency of about 2.45 GHZ to 2.50 GHZ and a wavelength of about 12 cm, the temperature of the rice core increases by 2.8 ° C per second, and when irradiated for 30 seconds, only the core reaches 80 ° C. Could be heated. At this time, the surface layer portion was prevented from rising in temperature and dried by freezing, and was able to maintain a non-alpha state.

  Next, the processed rice obtained by the above production method is cooled (step 7). The cooling here may be room temperature cooling by air blowing. The pregelatinized starch in the core of the rice is aged and changed to aged starch, the surface layer of the rice is thawed, and the rice surface becomes a processed rice with almost no change in appearance.

Finally, such processed rice is packaged, packed as necessary, and shipped as a product (step 8).

In the processed rice produced by the above process (see FIG. 2), the starch layer of rice is clearly distinguished into two layers. That is, it is possible to arbitrarily control the degree of alpha conversion into an area where the degree of alpha is 0% and an area where the degree of alpha is 20 to 80%. Further, as in the past, the paste layer had a pregelatinization degree of 0%.

Next, the cooking method of this processed rice is demonstrated. When re-cooking with a type of cooker (for example, an electric rice cooker) that is heated by heat conduction in a general household, it is heated from the outside of the rice grain. In the processed rice of this embodiment, the region of 0% pregelatinization is sequentially heated from the region of 20-80% pretreatment, and when the heat reaches the core of the rice grains, Evenly, the degree of pregelatinization was 100%, and the surface layer portion was not excessively pregelatinized, and processed rice with good taste was obtained.

Next, noodles will be described as an example of starch food (see FIG. 3). First, commercially available noodles are soaked (step 1). Although this immersion may be performed in a water storage state, it may be performed in a flowing water state. Immersion was carried out for about 30 minutes, and then the mixture was left to homogenize the moisture (Step 2). After standing, drain the water and dry as necessary (step 3). A drain or a dehydrator may be used for draining, and an air dryer may be used for drying.

Next, the noodle strings are frozen (step 4). In order to cause a temperature difference between the center portion and the surface portion of the noodle strings, for example, the noodles are mixed with a liquid refrigerant such as liquid nitrogen or dry ice ethanol whose temperature is maintained at −80 ° C. to −30 ° C. The wire should be immersed within 20 seconds. In addition, the temperature difference may be generated by spraying a gaseous refrigerant. In a preferred embodiment, when the temperature of the liquid refrigerant is −72 ° C., the initial temperature of the noodle strings is 20 ° C., and the diameter of the noodle strings is 7 mm, the noodle strings are immersed in the refrigerant for 15 seconds. Thereby, the surface part of the noodle strings is completely frozen at a temperature of −40 ° C. to −30 ° C., and the center part of the noodle strings is unfrozen or semi-frozen at a temperature of −5 ° C. to 0 ° C. ).

  Next, the noodle strings are taken out from the liquid refrigerant and heated by microwaves (step 5). In microwave heating, radio waves are almost uniformly permeated into each part of the noodle strings, and each part of the noodle strings generates heat at the same time. At this time, the center part of the noodle strings is in an unfrozen or semi-frozen state, this part is heated intensively, and only the center part is alpha before the surface part of the noodle strings is thawed It becomes. For example, if microwaves with a frequency of 2.45GHZ to 2.50GHZ and a wavelength of about 12cm are heated at an output of 360W, the center of the noodle strings is heated at a rate of 2.8 ° C per second, and when irradiated for 30 seconds, only the center is 80 ° C. Could be heated. At this time, the surface portion was prevented from rising in temperature and dried due to freezing, and the non-alpha state could be maintained.

  Next, the noodle strings obtained by the above production method are cooled (step 6). The cooling here may be room temperature cooling by air blowing. The pregelatinized starch at the center of the noodle strings is aged and changed to aged starch, the surface of the noodle strings is thawed, and the surface of the noodle strings becomes a processed noodle with almost no change in appearance.

Finally, such processed noodles are packaged and packed as necessary to be shipped as a product (step 7).

The degree of alpha conversion of the processed noodles produced by the above process and the conventional noodles was compared by the degree of disappearance of birefringence (see FIG. 4). Starch grains contained in starch foods have a crystal structure, are optically anisotropic, have birefringence when viewed with a polarizing microscope, and a polarized cross that intersects with the formation nuclei of the grains appears. If the starch granules are pregelatinized, the polarized cross observed with a polarizing microscope disappears. In other words, if the disappearance of birefringence is 0%, there are sufficient polarization crosses, and there are sufficient starch grains. If the disappearance of birefringence is 100%, there is no polarization cross. Rather, it is a measure that indicates that the starch granules have been pregelatinized.

4 and 5, when the noodle strings are microwave-heated without freezing (prior art), the birefringence disappearance is 100% in all the cross sections of the noodle strings having a diameter of about 7.0 mm. It can be seen that the whole noodle strings are alpha. On the other hand, when the noodle strings are frozen and microwave heated (the present invention), the disappearance of birefringence is 0% at both ends of the cross section of the noodle strings having a diameter of about 7.0 mm. It can be seen that is not alpha. That is, it can be seen that the surface portion from the outside of the noodle strings to about 0.5 mm is an unalphared region, and the center portion of the noodle strands about 6.0 mm is an alpha region.

When the processed noodles were boiled, the ratio of the boiled surface portion decreased compared to ordinary dry noodles, and the taste of the finished noodles was good.

In the present embodiment, the heating source is described as being limited to microwave heating. However, the present invention is not limited to this, and for example, it is possible to use a configuration in which each part of food such as laser irradiation heating generates heat almost simultaneously.

  The present invention can be used for starch foods such as processed rice and processed noodles.

It is process drawing for enforcing the processing method of the starch food which made rice the example. It is sectional drawing which shows the pregelatinization area | region of the processed rice of this invention. It is process drawing for enforcing the processing method of the starch food which made noodles the example. It is the figure which compared the alpha-ization degree of the processed noodles of this invention, and the conventional noodles by the birefringence loss | disappearance degree. It is sectional drawing which shows the pregelatinized area | region of the processed noodles of this invention, and the conventional noodles. It is sectional drawing which shows the pregelatinization area | region of the conventional process rice.

Claims (1)

In the starch food processing method in which a temperature difference is provided between the central part and the surface part of the food material mainly composed of starch, and only the central part is pregelatinized by microwave heating,
After the food material is absorbed, the surface material is maintained at -40 ° C to -30 ° C and the temperature at the central portion is maintained at -5 ° C to 0 ° C by immersion in a liquid refrigerant within 20 seconds. Then, microwave heating is performed for 30 seconds, the temperature of the central part is maintained at 80 ° C., and only the central part is pregelatinized.

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