阅读说明：本技术 一种低血糖指数糯米粉的制备方法及其产物 (Preparation method of glutinous rice flour with low glycemic index and product thereof ) 是由 郭元新 王东旭 叶华 张喜玲 于 2021-09-24 设计创作，主要内容包括：本发明涉及一种低血糖指数糯米粉的制备方法及其产物,包含如下步骤：选取糯米为原料,经过浸泡、粉碎、高效蛋白酶水解、低功率超声波调质反应和湿热干燥等工艺。该方法的创新性在于首先通过加入桑黄酮和α-萘黄酮辅助蛋白酶水解,提高蛋白酶活性,并更大程度释放糯米粉原料本身化学组成和结构中具有辅助降低血糖指数功效的成分,而后利用低功率超声波协同湿热处理调质关键技术,降低酶解反应时间,并增加糯米淀粉的晶体结构、提高抗消化淀粉组分含量,赋予制备得到的糯米粉具有较低血糖指数值的属性。(The invention relates to a preparation method of glutinous rice flour with low glycemic index and a product thereof, comprising the following steps: selecting glutinous rice as a raw material, and carrying out processes such as soaking, crushing, high-efficiency protease hydrolysis, low-power ultrasonic conditioning reaction, moist heat drying and the like. The innovativeness of the method is that firstly, the mulberry flavone and the alpha-naphthyl flavone are added to assist the hydrolysis of protease, so that the activity of the protease is improved, the components with the effect of assisting the reduction of the blood sugar index in the chemical composition and structure of the glutinous rice flour raw material are released to a greater extent, then the key technology of conditioning by low-power ultrasonic wave and moist heat treatment is utilized, so that the enzymolysis reaction time is reduced, the crystal structure of the glutinous rice starch is increased, the content of digestion-resistant starch components is improved, and the prepared glutinous rice flour has the attribute of lower blood sugar index value.)

1. A preparation method of glutinous rice flour with low glycemic index is characterized in that protease, morin and alpha-naphthalenone are added into the glutinous rice flour, low-power ultrasonic wave is utilized to assist combined moist heat treatment, and finally drying is carried out to prepare the glutinous rice flour with low glycemic index.

2. The method for preparing low-glycemic-index glutinous rice flour according to claim 1, wherein the step of adding the protease, the morin and the alpha-naphthoflavone is preceded by soaking and semi-drying crushing, the concentration of the crushed rice milk is 15% -35%, and the pH value of the rice milk is adjusted to 5.5-7.0.

3. The preparation method of the low-glycemic-index glutinous rice flour according to claim 1, wherein the low-power ultrasonic wave-assisted combined wet and heat treatment is carried out by continuously stirring with low-power ultrasonic waves at a reaction temperature of 40-55 ℃ for 20-60 min.

4. The method according to claim 1, wherein the protease type is neutral or a combination of neutral and acidic.

5. The method for preparing low-glycemic-index glutinous rice flour according to claim 1, wherein the mass ratio of the morin and the alpha-naphthalenone to the protease is 1: 100-1: 200.

6. the method according to claim 1 or 3, wherein the low-power ultrasonic waves have a power of 20 to 60W and a frequency of 20 to 40 kHz.

7. The method according to claim 3, wherein the stirring speed is 20 to 80 rpm.

8. The glutinous rice flour with low glycemic index is prepared by the preparation method according to any one of claims 1 to 7, and is characterized in that the glutinous rice flour with low glycemic index has a glycemic index of 45-55% and a hydrolysis index of 30-45%; the content of the digestion-resistant starch is 65-75%.

Technical Field

The invention belongs to the technical field of food processing, and particularly relates to a method for preparing glutinous rice flour with low glycemic index by ultrasonic combined enzymolysis and the glutinous rice flour prepared by the method.

Background

Glutinous rice and food made of the same are deeply favored by residents in China due to unique taste, texture and nutritional value, and besides being eaten directly, the glutinous rice is usually processed into glutinous rice flour and then used for making dishes with rather traditional Chinese characteristics, such as rice dumplings, rice cakes, rice dumplings and the like. In recent years, the pace of life of people is accelerated, living habits, eating habits and the like are changed to a certain extent, and the number of people suffering from diabetes in China is increased. The Glycemic Index (GI) value of a food, which is the rate at which carbohydrates are digested and absorbed by the body after eating the food, is an effective assessment criterion for influencing the response of carbohydrates to blood glucose. The food with lower GI value has slow absorption speed, is not easy to increase sugar, and the slow change of the blood sugar is beneficial to controlling the blood sugar and maintaining the blood sugar balance. The glutinous rice flour is a recognized high GI food, the application range of the glutinous rice flour is greatly limited by the characteristic, and potential health risks are increased for people who like eating glutinous rice products.

The development of the low GI glutinous rice flour also meets the pursuit of people on healthy diet, and has great market potential. Therefore, how to reduce the GI value of the glutinous rice flour has positive significance for promoting intestinal peristalsis, slowing down digestion efficiency, maintaining blood sugar stability and the like. The current main processing technology of the low-GI glutinous rice flour is hydrolysis drying, but the method has some problems, such as large using amount of protease, long enzymolysis time, poor thermal stability of starch crystals in the drying process, unstable crystals in the drying process, unfavorable increase of the content of anti-digestion starch, and the like.

Disclosure of Invention

The present invention is to solve the above problems and to provide a method for producing low-glycemic-index glutinous rice flour. According to the invention, the protease auxiliary factors of the morin and the alpha-naphthylflavone are simultaneously added into the glutinous rice flour, so that the hydrolysis capacity of the protease is improved, the using amount of the protease is reduced, the low-power ultrasonic wave auxiliary conditioning technology is utilized, the hydrolysis capacity of the protease is further maintained and improved, the components with the effect of assisting in reducing the blood sugar index in the chemical composition and structure of the glutinous rice flour raw material are released to a greater extent, in addition, the morin and the alpha-naphthylflavone also have the effect of assisting in reducing the blood sugar index, and then the moist heat treatment technology is utilized to improve the heat stability of glutinous rice starch crystals and increase the content of digestion resistant starch, so that the glutinous rice flour with low blood sugar index is prepared.

The invention provides a preparation method of glutinous rice flour with low glycemic index, which comprises the following steps:

(1) selecting a glutinous rice raw material, cleaning impurities, and then adding water for soaking at the temperature of 20-50 ℃ until the water absorption rate of rice grains approaches to balance.

(2) And (3) taking the soaked glutinous rice, and crushing by a semidry method, wherein the water content of the glutinous rice flour is 25-50% during crushing, and the average particle size (D50) of the crushed rice milk is 10-20 microns.

(3) Adjusting the concentration of the crushed rice pulp to 15-35%, adjusting the pH value of the rice pulp to 5.5-7.0, adding neutral or neutral and acidic protease into the crushed glutinous rice flour, adding mulberry flavone and alpha-naphthalene flavone serving as enzymolysis auxiliary factors when the materials are uniformly mixed, wherein the mass ratio of the mulberry flavone to the alpha-naphthalene flavone to the protease is 1: 100-1: 200. the enzymolysis reaction adopts wet method enzymolysis.

(4) After the enzymolysis reaction is started, carrying out quenching and tempering reaction at the temperature of 40-55 ℃ under the continuous stirring condition with the stirring speed of 20-80 rpm by using low-power ultrasonic assistance with the power of 20-60W and the frequency of 20-40 kHz; the reaction time is 20-60 min.

(5) Taking the glutinous rice flour after the enzymolysis reaction, controlling the water content of the glutinous rice flour to be 20-30%, and drying at 90-120 ℃ for 1-2.5 h to obtain the glutinous rice flour product with low glycemic index.

The invention has the advantages of

(1) And (5) cleaning production. After the glutinous rice flour is processed by the soaking process, no additional water is added in the steps of crushing, specific enzymolysis and quenching and tempering reaction, no processing wastewater is discharged in the production process, and the integral water content of the glutinous rice flour is kept between 20 and 50 percent. In the conventional water-milled glutinous rice flour production process, water with the mass about 3 times that of the glutinous rice is required for production and processing in the crushing process, and meanwhile, after solid-liquid separation and before the drying process, the water with the mass about 3 times that of the glutinous rice is discharged as waste water. In contrast, the combined process flow adopted by the invention meets the requirement of clean production.

(2) The production cost is reduced. The amount of protease used is one of the most costly raw materials in the production of low-glycemic-index glutinous rice flour. The invention adopts a method of combining protease auxiliary factors and low-power microwave assistance, obviously reduces the use amount and reaction time of protease and greatly reduces the production cost.

(3) The production process is novel. The conventional drying process has poor thermal stability of starch crystals, unstable crystals in the drying process and is not beneficial to increase of the content of the digestion-resistant starch. The invention adopts a damp-heat drying technology to overcome the problems, obviously improves the thermal stability of the glutinous rice starch crystal and increases the content of the digestion-resistant starch.

Drawings

FIG. 1 is an X-ray diffraction pattern of a glutinous rice flour sample prepared according to the present invention;

FIG. 2 is a Raman spectrum of a sample of glutinous rice flour according to the present invention;

FIG. 3 is a graph showing the hydrolysis characteristics of the glutinous rice flour according to the present invention;

fig. 4 is a graph showing the digestion components, hydrolysis index and GI value of the glutinous rice flour prepared according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

Example one

Selecting a glutinous rice raw material, cleaning impurities, adding water for soaking, and setting the soaking temperature at 25 ℃ until the water absorption rate of rice grains approaches to balance. And (3) taking the soaked glutinous rice, and crushing by a semi-dry method, wherein the water content of the glutinous rice flour is 30% during crushing, and the average particle size (D50) of the crushed rice milk is 15 microns. Adding 5% neutral protease and 0.05% of morin and alpha-naphthoflavone into the pulverized glutinous rice flour, and starting enzymolysis reaction. After the enzymolysis reaction starts, the glutinous rice flour is assisted by low-power ultrasonic waves with the power of 40W and the frequency of 30kHz, and the quenching and tempering reaction temperature is 45 ℃ under the continuous stirring condition that the stirring speed is 50 rpm; the reaction time was 30 min. Taking the glutinous rice flour after the enzymolysis reaction, controlling the water content of the glutinous rice flour to be 20%, drying for 1.5h at 100 ℃ to obtain a glutinous rice flour product with low glycemic index, wherein the measured glycemic index of the glutinous rice flour is 52%.

Example two

Selecting a glutinous rice raw material, cleaning impurities, adding water for soaking, and setting the soaking temperature to 35 ℃ until the water absorption rate of rice grains approaches to balance. And (3) taking the soaked glutinous rice, and crushing by a semi-dry method, wherein the water content of the glutinous rice flour is 25% during crushing, and the average particle size (D50) of the crushed rice milk is 20 microns. Adding 6% neutral protease and 0.03% of morin and alpha-naphthoflavone into the pulverized glutinous rice flour, and starting an enzymolysis reaction. After the enzymolysis reaction starts, the glutinous rice flour is assisted by low-power ultrasonic waves with the power of 50W and the frequency of 40kHz, and the quenching and tempering reaction temperature is 40 ℃ under the condition of continuous stirring at the stirring speed of 60 rpm; the reaction time was 60 min. Taking the glutinous rice flour after the enzymolysis reaction, controlling the water content of the glutinous rice flour to be 20%, drying for 1.5h at 110 ℃ to obtain a glutinous rice flour product with low glycemic index, wherein the measured glycemic index of the glutinous rice flour is 49%.

EXAMPLE III

Selecting a glutinous rice raw material, cleaning impurities, adding water for soaking, and setting the soaking temperature at 45 ℃ until the water absorption rate of rice grains approaches to balance. And (3) taking the soaked glutinous rice, and crushing by a semi-dry method, wherein the water content of the glutinous rice flour is 30% during crushing, and the average particle size (D50) of the crushed rice milk is 18 microns. Adding 10% neutral protease and 0.05% of morin and alpha-naphthoflavone into the pulverized glutinous rice flour, and starting enzymolysis reaction. After the enzymolysis reaction starts, the glutinous rice flour is assisted by low-power ultrasonic waves with the power of 60W and the frequency of 40kHz, and the quenching and tempering reaction temperature is 55 ℃ under the continuous stirring condition that the stirring speed is 80 rpm; the reaction time was 60 min. Taking the glutinous rice flour after the enzymolysis reaction, controlling the water content of the glutinous rice flour to be 20%, drying for 2 hours at 120 ℃ to obtain a glutinous rice flour product with low glycemic index, wherein the measured glycemic index of the glutinous rice flour is 45%.

Example four

The X-ray diffraction pattern of the glutinous rice flour prepared in example 3 above is shown in FIGS. 1 and 2, from which it can be seen that: the glutinous rice flour sample prepared by the invention shows that the 2 theta value has strong diffraction peaks at 15 degrees and 23 degrees, and has unseparated double peaks at 17 degrees and 18 degrees, which indicates that the preparation process does not change the X-ray diffraction pattern characteristics of the starch A in the glutinous rice flour. In addition, the short-range order degree and the crystallinity of the molecules of the glutinous rice flour prepared by the method are increased, and the crystallinity is increased by 5-8%. FIG. 3 further shows the hydrolysis characteristics of the conventional glutinous rice flour and the glutinous rice flour prepared according to the present invention, and it can be seen from the comparison of the data in the graph that: the processing technology of the invention obviously reduces the hydrolysis characteristic of the starch. Fig. 4 further lists the digestion components, hydrolysis index and GI value of the conventional glutinous rice flour and the glutinous rice flour prepared by the present invention, and the processing technology of the present invention significantly increases the content of anti-digestion starch and reduces the hydrolysis index and GI value, so that the GI value of the glutinous rice flour prepared by the present invention is 45-55%, and belongs to the category of middle and low GI foods.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.