JPH0336497B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a method for producing instant rice, that is, boiled rice that has a long shelf life and can be restored to an edible state in a very short time by adding boiling water. . (Prior Art) Rice has been a staple food in Japan since ancient times, and therefore various methods have been proposed for producing instant rice that can be easily prepared for emergency use. First, there is a method that has been known since ancient times, in which cooked rice or steamed rice is dried in the sun to form a so-called paste. A portion of the rice becomes beta during drying, so even if hot water is added before use, it will not be completely restored to cooked rice. JP-A-53-12438 discloses a method for preventing excess starch from flowing out during cooking by adding organic acids such as citric acid, tartaric acid, malic acid, acetic acid, and succinic acid to the water used for soaking raw rice. A method for producing portable cooked rice is disclosed in which the taste of the organic acid is suppressed and then dried, but according to this method, the taste of the added organic acid remains and coloring occurs due to the drying process. Furthermore, JP-A-53-136547 discloses instant rice in which a mixture of edible oil and fat and/or an edible emulsifier and glycerin is added to steamed rice starch to prevent the cooked rice from agglomerating into lumps during drying. However, according to this method, added fats and oils adhere to the product, resulting in poor storage stability. (Problems to be Solved by the Invention) Instant rice is naturally produced by cooking or steaming raw rice to produce gelatinized cooked rice, which is then dried while maintaining its gelatinized state. be done. However, cooked rice obtained by cooking or steaming has strong stickiness due to gelatinization of starch, and adjacent rice grains are stuck to each other, so drying cannot be performed in that state. Otherwise, the drying process of each rice grain will be different,
As a result, when boiling water is added to the cooked rice before use, there will be a difference in the resilience of the cooked rice, which will have a negative effect on the texture and taste. (needs to be broken up into pieces). Therefore, in order to produce good instant rice, it is important to ensure that each grain of cooked rice is loosened before it is transferred to the drying process, thereby enabling uniform drying. . In this case, in order to obtain cooked rice that is easy to loosen, if organic acids are added to the raw rice soaking water and the rice is cooked or steamed, the result will be as described above, and the instant rice obtained by drying such cooked rice will be The taste of the organic acid remains and coloring occurs, and therefore, cooked rice that is restored by adding boiling water has poor taste and appearance, and does not stimulate appetite. On the other hand, if edible oils and fats are added to improve the loosening of cooked rice obtained by cooking or steaming using conventional methods, the oils and fats that adhere to the rice grains will oxidize during the subsequent drying process, so However, instant rice poses a problem in its shelf life. The present invention has been made by focusing on these points, and has developed a rice loosening solution that improves the loosening of cooked rice, brings about uniformity in subsequent drying, and reduces the incidence of broken rice. To provide a method for producing instant rice, which can improve the quality of cooked rice without adversely affecting the quality of the rice. (Means and effects for solving the problems) To this end, according to the present invention, the method for producing instant rice includes a step of soaking washed raw rice in water, a step of cooking or steaming the rice, and a step of cooking or steaming the raw rice. The process consists of a step of cooling the cooked rice, a step of adding an ethanol aqueous solution containing a nonionic sea surfactant to the cooled cooked rice to loosen the cooked rice, and a step of drying the loosened cooked rice. The ethanol aqueous solution containing the type surfactant loosens cooked rice efficiently and reliably, and reduces the occurrence of broken rice during drying. The amount of the nonionic surfactant-containing ethanol aqueous solution (hereinafter simply referred to as "loaning liquid") used in the method of the present invention is approximately 2
~10% by weight. If the amount added is less than 2% by weight, the amount of cooked rice in the form of agglomerates increases (see late test example 4), and the degree of drying in the subsequent drying process becomes uneven. The ethanol component in the above-mentioned loosening liquid contributes to loosening the cooked rice, and in order to express the quick loosening effect, the content needs to be about 10% by weight or more (Test Example 3 described later). reference),
Although there is no reason to restrict the upper limit, it is generally about 70% by weight. The nonionic surfactant component in the above-mentioned loosening liquid contributes to suppressing the agglomeration of loosened cooked rice and the suppression of broken rice when dried to produce the final product, instant rice. If the amount is too low, the effect of suppressing rice crumbling will be insufficient, and if it is too large, the effect of suppressing the agglomeration of cooked rice will not improve significantly, so it is appropriate to set the content to about 0.1 to about 1.0% by weight ( (See Test Example 2 below). As the nonionic surfactant, sucrose fatty acid ester, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, lecithin, etc., or a mixture thereof can be used. In the embodiment of the method of the present invention, it is appropriate to add the loosening liquid to cooked rice that has been left to cool naturally or forced to cool after cooking. In this case, the appropriate temperature of the cooked rice is about 55°C or lower; if the temperature is too high, the loosening effect of the loosening liquid will decrease (see Test Example 1 below). The addition of the loosening liquid itself can be carried out in an appropriate manner, but in order to uniformly adhere the loosening liquid to the rice grains, for example, it is necessary to fill a rotary pot with a baffle plate inside or a horizontal single-shaft mixer with cooked rice. Conveniently, the addition is carried out by tumbling the loosening liquid onto the mixture and spraying or dropping the loosening liquid thereon. The cooked rice to which the loosening liquid has adhered can be dried by hot air drying or by combining this with dielectric heating drying. Drying using only dielectric heating is not preferred because the core tends to burn. A suitable hot air temperature is 60 to 100°C. The moisture content of instant rice, a product obtained by drying, is approximately 7.5% by weight.
A value below this level is appropriate. In addition, in the method of the present invention, the raw rice is soaked in water after being washed, but the amount of soaking water is equal to 1 raw rice.
It is preferably about 0.9 to 1.3 parts by weight. If the amount of soaking water is too low, cores will remain in the rice after cooking, and even if boiling water is added after drying, the recovery will be poor and the texture will deteriorate.On the other hand, if it is too much, excess water will remain in the cooked rice. This makes subsequent drying difficult and also increases the time required. On the other hand, when obtaining pregelatinized steamed rice through a steaming process, steaming is performed on the soaked rice obtained by soaking washed raw rice in water or warm water at 5 to 50°C for about 2 hours to overnight. However, depending on the type of raw rice used, it is necessary to increase the water content in the steamed rice by sprinkling or soaking it in water 1 to 3 times during the steaming process so that no core remains in the cooked rice after steaming. There is. According to the present invention, a nonionic surfactant can further be added to the soaking water, thereby improving the loosening effect when a loosening liquid is added to cooked rice or steamed rice. (See Test Example 5 below). As nonionic surfactants for this purpose, those already mentioned, such as sucrose fatty acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, lecithin, etc. can be used, and the amount added is determined depending on the raw rice. It is about 1% by weight or less. This is because if the amount of this surfactant is excessive, not only will the flavor remain in the cooked or steamed rice, which is undesirable, but also the synergistic effect on the loosening action of the loosening liquid will be noticeable even if it is added in excess. This is because no significant difference can be recognized. The instant rice according to the present invention has less broken rice, and this instant rice can be easily and quickly restored to cooked rice by pouring hot water, and this restored cooked rice has the same stickiness, texture, and taste as cooked rice using conventional methods. It has the advantage of being (Examples and Effect Test Examples) Example 1 1 kg of glutinous rice (product name: Koshihikari) was lightly washed with water to remove dust, water was added to make a total amount of 2.25 kg, and after being left for 5 hours, the gauge vapor pressure was 0.2 Kg/
Rice was cooked for 50 minutes in a cm ² retort. Thereafter, the pressurization was stopped and the rice was left to steam for 10 minutes. The cooked rice was taken out and the temperature was lowered to 50°C under forced air flow from an electric fan. Next, transfer the cooked rice to a rotary pot and add ethanol.
Using a sprayer, apply 0.1 kg of a loosening solution consisting of an aqueous solution containing 40% by weight and 0.3% by weight of sucrose fatty acid ester (F-160 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).
The mixture was added by spraying to the cooked rice that was being transferred in the rotary pot. Take out 100g of the cooked rice with the loosening liquid attached,
After passing through a 2-mesh sieve (JIS), it was spread uniformly on a nonconductor tray to a thickness of 0.5 cm, loaded into a dielectric heating dryer (output 1 KW, 2450 MHz microwave oven), and treated for 2.7 minutes to remove moisture. Content 35% by weight
The rice was then transferred to a wire mesh tray and treated in a hot air dryer at 80°C for 60 minutes to obtain instant rice with a moisture content of 7.3% by weight. This instant rice is passed through a Yamato sieve vibrator (type V-
1), after shaking for 10 minutes, the amount of rice adhering on a 4-mesh sieve (JIS) was measured to be 2.9% by weight.
A bar of 2.5 cm) was placed on the 4-mesh sieve and vibrated for an additional minute, and the amount of broken rice under 10 meshes was determined to be 1.6% by weight. I put 200g of the above instant rice into a container, added 280ml of boiling water, put a lid on it and left it for 10 minutes, then turned the container over and left it for another 5 minutes.When I tried the restored cooked rice, I found that it was sticky. There was almost no difference in texture and taste from regular cooked rice. Example 2 In the same manner as in Example 1, cooked rice was loosened and passed through a 2-mesh sieve, dried in a hot air dryer at 80°C to reduce the moisture content to 30% by weight, and then dried in a dielectric heating dryer. (a microwave oven with an output of 1 KW and 2450 MHz) to a moisture content of 23% by weight, and then dried again in a hot air dryer at 80°C to obtain instant rice with a moisture content of 6.5% by weight. The adhering rice and broken rice of this instant rice were determined in the same manner as in Example 1, and were found to be 2.5% by weight and 2.0% by weight, respectively.
It was hot. When the instant rice obtained in this example was reconstituted in the same manner as in Example 1 and the cooked rice was tasted, there was almost no difference in stickiness, texture, and taste from normal cooked rice. Example 3 2.25 kg of cooked rice obtained in the same manner as in Example 1 was left to cool to 50°C, and while stirring, ethanol was added to it.
40% by weight and propylene glycol fatty acid ester (Homotex PS manufactured by Kao Atlas Co., Ltd.)
-90) 0.1 kg of a loosening solution consisting of an aqueous solution containing 0.5% by weight was added by spraying to the cooked rice. Next, this cooked rice coated with the loosening liquid was passed through a 2-mesh sieve (JIS), spread evenly on a wire mesh tray to a thickness of 0.5 cm, and treated in a hot air dryer at 80°C for 110 minutes to determine the moisture content. Instant rice of 7.3% by weight was obtained. The adhering rice and broken rice of this instant rice were determined in the same manner as in Example 1, and were found to be 10.5% by weight and 2.3% by weight, respectively. When the instant rice obtained in this example was reconstituted in the same manner as in Example 1 and the cooked rice was tasted, there was almost no difference in stickiness, texture, and taste from normal cooked rice. Example 4 1 kg of standard glutinous rice was lightly washed with water to remove dust.
On the other hand, an aqueous solution containing 0.5% by weight of sucrose fatty acid ester (F-160 manufactured by Daiichi Pharmaceutical Co., Ltd.) based on the raw rice was prepared, and this aqueous solution was added to the washed rice to make a total amount of 2.2 kg. The rice was placed in a retort at an ambient temperature of 100°C for 60 minutes, and after steaming for 10 minutes, it was taken out to obtain cooked rice. Cold air was sent through the cooked rice to lower the temperature to 55°C. Next, while stirring this cooked rice, 30% by weight of ethanol and purified lecithin (RICELAND) were added.
0.1 kg of a loosening solution consisting of an aqueous solution containing 0.5% by weight of LECIGRAN F) manufactured by FOODS was added by spraying to the cooked rice. After passing through a 2-mesh sieve (JIS), this cooked rice coated with the loosening liquid was spread evenly on a wire mesh tray to a thickness of 0.5 cm, and was processed in a hot air dryer at 80°C for 90 minutes to reduce the moisture content to 6.0% by weight. I got instant rice. The adhering rice and broken rice of this instant rice were determined in the same manner as in Example 1, and were found to be 3.3% by weight and 1.71% by weight, respectively. When the instant rice obtained in this example was reconstituted in the same manner as in Example 1 and the cooked rice was tasted, there was almost no difference in stickiness, texture, and taste from normal cooked rice. Example 5 1 kg of standard glutinous rice was washed with water and added to the raw rice.
Immersion water, which is an aqueous solution containing 0.2% by weight of glycerin fatty acid ester (Atomul T-95 manufactured by Kao Atlas Co., Ltd.), was added to bring the total amount to 2.25 kg, and alarming was carried out for 1 hour. Next, this soaked rice was cooked for 50 minutes in a retort with a gauge steam pressure of 0.2 Kg/cm ² , and then the steam was turned off and steamed for 10 minutes, and the temperature of the rice was lowered to 50° C. under forced air flow from an electric fan. This cooked rice was transferred to a rotary pot, and 0.1 kg of loosening liquid, which is an aqueous solution containing 40% by weight of ethanol and 0.5% by weight of glycerin fatty acid ester (Atomul P-40S manufactured by Kao Atlas Co., Ltd.), was used in a sprayer, and the rice was rotated. The mixture was added by spraying to cooked rice that was rolling in a pot. After passing through a 2-mesh sieve (JIS), this cooked rice with the loosening liquid attached was spread evenly on a wire mesh tray to a thickness of 0.5 cm, and was processed in a hot air dryer at 80°C for 110 minutes to reduce the moisture content to 7.3% by weight. Got instant rice. The adhering rice and broken rice of this instant rice were determined in the same manner as in Example 1, and were found to be 9.8% by weight and 2.0% by weight, respectively.
It was hot. When the instant rice obtained in this example was reconstituted in the same manner as in Example 1 and the cooked rice was tasted, there was almost no difference in stickiness, texture, and taste from normal cooked rice. Example 6 1.0 kg of standard glutinous rice was washed with water and soaked in tap water at 15° C. overnight to obtain soaked rice with a total weight of 1.32 kg including moisture. The soaked rice was placed in a square steamer with a side of 27 cm and a depth of 13 cm, with a lid on, and steam at 98°C was introduced from the bottom for 20 minutes. Then heat the whole steamer to 30℃
The rice was immersed in water for 30 seconds, drained, and steamed at 98°C again for 30 minutes to obtain cooked rice with a water content of 60% by weight. This cooked rice is left to cool to lower its temperature to 50℃, transferred to a rotary pot, and loosened with an aqueous solution containing 40% by weight of ethanol and 0.5% by weight of glycerin fatty acid ester (Atomul P40S manufactured by Kao Atlas Co., Ltd.). A 0.1 kg aqueous solution containing 5.0% by weight of common salt and 0.05% by weight of sodium glutamate was sprayed onto the cooked rice that was being rolled in the rotary pot using a sprayer. This cooked rice coated with the loosening liquid was passed through a 2-mesh sieve (JIS), spread evenly on a wire mesh tray to a thickness of 0.5 cm, and processed in a hot air dryer at 80°C for 110 minutes to reduce the moisture content to 7.2 weight. % instant rice was obtained. The adhering rice and broken rice of this instant rice were determined in the same manner as in Example 1, and were found to be 6.8% by weight and 1.5% by weight, respectively.
It was hot. When the instant rice obtained in this example was reconstituted into cooked rice and tasted in the same manner as in Example 1, there was almost no difference in stickiness, texture, and taste from normal cooked rice. Example 7 2.25 kg of cooked rice obtained in the same manner as in Example 1 was left to cool to a temperature of 50°C, and while stirring, ethanol was added.
40% by weight and propylene glycol fatty acid ester (Homotex PS manufactured by Kao Atlas Co., Ltd.)
−90) 5.0% by weight of salt and sodium glutamate in a loosening solution, which is an aqueous solution containing 0.5% by weight.
0.225 kg of an aqueous solution containing 0.05% by weight was added by spraying to the cooked rice. This cooked rice coated with the loosening liquid was passed through a 2-mesh sieve (JIS), spread evenly on a wire mesh tray to a thickness of 0.5 cm, and treated in a hot air dryer at 80°C for 130 minutes to reduce the moisture content to 7.5 weight. % instant rice was obtained. The adhering rice and broken rice of this instant rice were determined in the same manner as in Example 1, and were found to be 5.7% by weight and 2.1% by weight, respectively.
It was hot. The instant rice obtained in this example was reconstituted into cooked rice in the same manner as in Example 1, and when it was tasted, there was almost no difference in stickiness, texture, and taste from normal cooked rice. Example 1 (Relationship between loosening liquid and product temperature) 200 g of standard glutinous rice was washed with water, water was added as a soaking liquid to make a total amount of 440 g, and the rice was left to stand and then cooked at normal pressure. On the other hand, 20% by weight of ethanol and purified lecithin (manufactured by RICELAND FOODS)
A loosening solution, which is an aqueous solution containing 0.5% by weight of LECIGRANF), was prepared, and this loosening solution was sprayed to 3% by weight of the above-mentioned cooked rice at various temperatures. After each piece of cooked rice with the loosening liquid attached was passed through a 2-mesh sieve (JIS), the weight percent of the agglomerated rice remaining on the sieve was determined, and the relationship between this and the temperature of the cooked rice was plotted. The results shown in FIG. 1 were obtained. From this figure, it can be seen that a good loosening effect is achieved when the loosening liquid is added after the temperature of the cooked rice has decreased to approximately 55°C or lower. Example 2 (Relationship between the content of surfactant in the loosening liquid and its effect) 200g of standard glutinous rice was washed with water, water was added as a soaking liquid to make a total amount of 440g, and after being left to stand, it was washed under normal pressure. Cook the rice and then let it cool to bring the temperature of the cooked rice to 50℃.
It was lowered to. For each cooked rice prepared in this way, various loosening liquids shown in Table 1 below were applied to the cooked rice.
It was added by spraying to 3% by weight. After the cooked rice with the loosening liquid attached is passed through a 2-mesh sieve (JIS), the agglomerated cooked rice remaining on the sieve and the bottom of the sieve are dried at 80℃ in a hot air dryer to reduce the moisture content to 6 weight. % instant rice and eggplant. Next, this instant rice was sieved in the same manner as described in Example 1 using 4, 7, and 10 mesh sieves (JIS) to examine the particle size distribution. The results are shown in Table 2 below. It was hot. From Tables 1 and 2, it can be seen that the nonionic surfactant in the loosening solution has the effect of reducing the proportion of crushed rice in the final product, instant rice, at about 0.1% by weight, and that at about 1.0% by weight or more It can be seen that the amount of cooked rice that becomes agglomerated cannot be significantly reduced even if it is added at the same mixing ratio, that is, the appropriate content of nonionic surfactant in the loosening liquid is about 0.1 to about 1.0% by weight. .

【table】

【table】

【table】

[Table] Test example 3 (Relationship between the content of ethanol in the loosening liquid and its effect) Wash 200g of standard glutinous rice with water, add water as a soaking liquid to make a total amount of 440g, and leave it to stand at normal pressure. Cook the rice, then let it cool to bring the temperature of the cooked rice to 50℃.
It was lowered to. On the other hand, purified lecithin (RICELAND)
Various loosening solutions were prepared as aqueous solutions containing 0.5% by weight of LECIGRAN F) manufactured by FOODS, and the amount of ethanol was varied, and each loosening solution was added by spraying to each cooked rice sample in an amount of 2% by weight. . After passing each cooked rice sample with the loosening liquid attached to it through a 2-mesh sieve (JIS), determine the amount of agglomerated cooked rice (% by weight) remaining on the sieve, and the relationship between this and the ethanol content in the loosening liquid. When I plotted
The results shown in FIG. 2 were obtained. From this figure, the ethanol content in the loosening solution is approximately 10% by weight.
It can be seen that a good loosening effect can be obtained when the amount is 100% or more. Test Example 4 (Relationship between the amount of loosening liquid added and its effect) 200g of standard glutinous rice was washed with water, water was added as a soaking liquid to make a total amount of 440g, and the rice was left to stand, then cooked at normal pressure, and then left to stand. The product temperature was lowered to 50°C by cooling. On the other hand, ethanol 10% by weight and purified lecithin (LECIGRAN manufactured by RICELAND FOODS)
F) A loosening solution containing 0.5% by weight was prepared and sprayed on the cooked rice in various amounts.After each cooked rice sample with the loosening solution attached was passed through a 2-mesh sieve (JIS), the remaining amount remained on the sieve. The amount of agglomerated cooked rice (wt%) was determined and the relationship between this and the amount of loosening liquid added was plotted, and the results shown in FIG. 3 were obtained. From this figure, it can be seen that the appropriate amount of loosening liquid to be added is about 2 to 10% by weight based on the cooked rice. Test Example 5 (Relationship between the amount of nonionic surfactant added to soaking water and its effect) Various nonionic surfactants were used and the amount added was changed to create a soaking solution (aqueous solution) for raw rice. )
Standard glutinous rice soaked in each of the soaking solutions was cooked according to the method described in Example 4, and the loosening solution was added by spraying. After each cooked rice sample with the loosening liquid attached was passed through a 2-mesh sieve (JIS), the amount of agglomerated cooked rice remaining on the sieve (volume %) was determined, and it was as shown in Table 3 below. Ta. From this table, it can be seen that when raw rice is cooked using an aqueous solution containing a nonionic surfactant as an immersion liquid and the cooked rice is treated with a loosening liquid, the loosening rate is higher than when simply using water as the immersion liquid. In other words, it can be seen that the use of an aqueous solution containing a nonionic surfactant as a soaking liquid for raw rice produces a synergistic effect on the loosening effect of the loosening solution.

【table】

【table】 [Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the temperature of cooked rice to which loosening liquid has been added and the proportion of cooked rice that exhibits an agglomerated form.
Figure 2 is a graph showing the relationship between the ethanol content in the loosening liquid and the proportion of cooked rice that forms agglomerates, and Figure 3 shows the relationship between the amount of loosening liquid added and the proportion of cooked rice that forms agglomerates. It is a graph.

Claims (1)

[Claims] 1. A step of soaking washed raw rice in water, a step of cooking or steaming, a step of cooling the cooked or steamed rice, and a step of cooling an ethanol aqueous solution containing a nonionic surfactant. A method for producing instant rice, comprising a step of adding it to cooked rice to loosen it, and a step of drying the loosened rice. 2. The manufacturing method according to claim 1, characterized in that cooked or steamed rice is cooled to about 55°C or lower by natural cooling or forced cooling. 3. Claim 1, wherein the nonionic surfactant is selected from at least one of sucrose fatty acid ester, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, and lecithin.
The manufacturing method described in section. 4. The manufacturing method according to claim 1, wherein the amount of the nonionic surfactant-containing ethanol aqueous solution added is about 2 to 10% by weight based on the cooked rice. 5 The nonionic surfactant content in the nonionic surfactant-containing ethanol aqueous solution is approximately 0.1 to
The manufacturing method according to claim 1, characterized in that the content is 1.0% by weight. 6. The production method according to claim 1, wherein the ethanol content in the nonionic surfactant-containing ethanol aqueous solution is about 10 to 70% by weight. 7. A step of soaking the washed raw rice in an aqueous solution containing a nonionic surfactant, and a cooking or steaming step,
The method comprises a step of cooling cooked or steamed rice, a step of adding an ethanol aqueous solution containing a nonionic surfactant to the cooled cooked rice to loosen the cooked rice, and a step of drying the loosened cooked rice. A method for producing instant rice, characterized by: 8. The nonionic surfactant-containing aqueous solution contains about 1% by weight of a surfactant selected from at least one of sucrose fatty acid ester, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, and lecithin based on the raw rice. The manufacturing method according to claim 7, characterized in that the aqueous solution contains an amount less than that amount. 9. The manufacturing method according to claim 7, wherein the amount of the nonionic surfactant-containing aqueous solution is about 0.9 to 1.3 parts by weight per 1 part by weight of raw rice.