JP2739212B2 - Rice grain additive and its use - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an additive for rice grains and a method for using the same.

[Prior Art] The quality of rice, especially its taste, is determined by production means such as varieties, production areas, cultivation methods, harvesting methods, etc., and is determined at post-harvest processing stages such as drying, storage, and rice milling. It is said that the taste of rice is most affected at the production stage, and the varieties are most affected next.

Conventionally, the taste evaluation of rice has been done by cooking white rice, eating the cooked rice by a plurality of expert examiners, and comparing the comparison items such as the appearance, aroma, taste, stickiness, and hardness of the rice to be evaluated for taste. It is carried out by a so-called sensory test in which a test is repeatedly performed to determine whether the rice is superior or inferior to those of a reference rice as an evaluation standard, and an average value thereof is taken.

In recent years, the organization and physicochemical properties of rice have been scientifically measured and analyzed, and the correlation with the taste evaluation value obtained in the aforementioned sensory test has been investigated. Has been conducting research to evaluate rice quality from
Among the components that make up rice, those that are particularly important in evaluating the quality of rice have been found to be the amylose and amylopectin content ratio, protein content ratio, and water content ratio that constitute rice starch. It is getting.

Next, how the content of each component constituting rice affects the taste will be described. Generally, Koshihikari and Sasanishiki are popular brands with good taste in Japan. As an example, Table 1 shows a comparison between the protein content of white rice and the amylose content of starch in various brands of rice of various brands including Koshihikari and Sasanishiki in each standard milling degree. It should be noted that the content of each component is not always the same as that shown in Table 1 for the same brand, but also depends on the geological conditions (soil, water quality) of the cultivated production area, and also on the weather conditions (temperature, temperature, It goes without saying that the content of each component also slightly changes depending on the sunshine hours and the amount of rainfall. As shown in Table 1, Koshihikari and Sasanishiki have a lower protein content and a lower amylose content ratio in starchy substances than other general brand rice.

(The protein content indicates the weight ratio and the amylose content indicates the ratio to 100% starch.) As described above, the protein content and the amylose content ratio in the starch greatly affect the taste of rice. Apart from that, the moisture content of white rice also has a great influence on the taste in relation to the viscosity and hardness of cooked rice.

When the white rice has a water content of about 15%, even if immersed in water, the white rice does not crack and cooks into complete rice grains when cooked, but in the case of white rice with a water content of less than 14%, Water is rapidly absorbed from the ventral side of the white rice (there are relatively many intercellular spaces that serve as water penetration paths) to the endosperm, and instantaneous cracks occur due to volumetric distortion due to the difference in water with the dorsal side (the intercellular space is extremely small). When the rice is raised and cooked, low-quality cooked rice is obtained that has a sticky, non-sticky and sticky starch particle that blows from the crack.

Also, it is known that the broken rice absorbs water at a stretch, so that the cooked rice is cooked into a sticky rice and the rice is broken, resulting in a low-quality cooked rice that is neither chewy nor sticky.

Rice producers, on the other hand, have to worry about exceeding the government's upper limit of 15% for moisture testing, giving them a bit of overdrying, and also have a fever during rice polishing. It is known that 0.5% to 1.0% of water is lost from rice grains.

Therefore, the rice grains (brown rice and white rice) are brought into contact with water (steam) to adjust the humidity to maintain the water content of the rice grains at 15%. However, old rice and rice, which originally have a poor taste, have narrow cell gaps and do not absorb water to every corner of the rice grain even when immersed.
When cooked, the rice becomes low in pregelatinization and has poor taste.

[Problems to be solved by the invention]

The present invention provides a rice grain additive and a method of using the same, in which when polished rice grains (white rice) are immersed in water, the rice grains can be obtained as cooked rice having good softness, tension and stickiness after cooking. As an issue.

[Means for solving the problem]

An endosperm cell wall degrading enzyme of rice grains and lecithin are mixed in an appropriate amount to obtain an additive for rice grains.

The rice grain additive is added to rice or rice with water before cooking as a solid granule, powder, or a liquid dissolved in a solvent, or an aqueous solution or surfactant thereof. A solvent such as water is separately added to rice grains in the form of a mist or the like in the air.

At this time, in addition to the surfactant, vitamins or calcium may be added, or alcohols may be added to make a liquefied additive.

〔The invention's effect〕

By adding the additive for rice grains of the present invention to white rice grains, the endosperm cell wall of the rice grains can be decomposed by enzymes during rice cooking, and the taste of rice grains can be improved by the action of lecithin on starch.

(Example of the invention)

When cellulase was used as an endosperm cell wall degrading enzyme of rice grains, the following three kinds of mixtures were prepared for mixing with lecithin in an appropriate amount.

That is, lecithin was added to cellulase at a weight ratio of 0.1.
002, cellulase 0.1 to lecithin 0.002, and cellulase 0.01 to lecithin 0.002. The lecithin used was defatted with acetone.

At the time of cooking rice, the above three types of mixtures were separately added to the rice cooking liquid. The amount of the mixture was 1% of cellulase (namely, lecithin 0.002%) and 0.1% of cellulase (namely, lecithin 0.002%) based on the weight of rice grains. )
And 0.01% of cellulase (ie, lecithin 0.00
2%).

As a buffer, a mixture of acetic acid: sodium acetate having a ratio of 51:49 was also added.

The hardness and stickiness of the rice grains after cooking were measured with a texturometer and the degree of balance was calculated. The results were as follows.

Rice cooked without adding the rice grain additive, hardness H
= 2.65, stickiness-H = 0.22, balance-H / H = 0.08.

In the case where an additive consisting of a mixture of cellulase 1 and lecithin 0.002 was added, hardness H = 2.47, stickiness−H = 0.46,
Balance-H / H = 0.19.

In the case where an additive consisting of a mixture of cellulase 0.1 and lecithin 0.002 was added, hardness H = 2.46, stickiness−H = 0.42,
Balance-H / H = 0.17.

When an additive consisting of a mixture of cellulase 0.01 and lecithin 0.002 was added, hardness H = 2.55 and stickiness-H
= 0.38, balance-H / H = 0.15.

And all of them had a statistically significant difference.

Cellulase is an enzyme that breaks down the endosperm cell wall of rice grains, and when part or all of the endosperm cell walls are degraded, lecithin acts on the starch granules to reduce the hardness of the rice grains, increase the stickiness and improve the balance, and make it delicious. It is something to make rice. If the endosperm cell wall is not decomposed, the effect of lecithin on the starch granules becomes extremely small, and the values of the decrease in hardness and the improvement in stickiness are small, and the improvement in the degree of balance is not large.
The present invention is a synergistic effect of degrading endosperm cell wall and arrow of lecithin on starch granules.

It should be noted that the additive for improving the taste of the rice grains can be obtained by dissolving it in water and adding it to the rice grains when the rice grains in a rice mill are adjusted in humidity.

In the rice cooking test, Akihikari was used as test rice.

Although a texturometer was used to measure the effect of the present invention, the texturometer repeatedly pressed and pulled the rice grains placed in the saucer by a plunger in accordance with the human chewing speed, The tensile force, ie, the stickiness, is divided by the pressing force, ie, the hardness, and this value is used as the degree of balance. Generally, it is said that the higher the degree of balance, the better the taste.

Claims (4)

(57) [Claims] 1. An additive for rice grains, comprising an endosperm cell wall degrading enzyme of rice grains and lecithin. 2. The method according to claim 1, wherein said enzyme is cellulase.
The additive for rice grain as described above. 3. A method for cooking rice grains, comprising adding an enzyme for decomposing endosperm cell walls of rice grains and lecithin to the rice cooking liquid and cooking the rice. 4. The method according to claim 3, wherein the enzyme is cellulase.
Method for cooking rice grains described in the above.