Preparation method of low-GI-value rice added with tea polyphenol

Abstract

The invention discloses a preparation method of low-GI-value rice added with tea polyphenol. The preparation method comprises the following steps: step 1, cleaning unhulled rice; step 2, adding the rice into an aqueous solution of tea polyphenol, and performing ultrasonic soaking; step 3, cooking the rice subjected to ultrasonic soaking at high temperature and high pressure, draining water, cooling to room temperature, and refrigerating at low temperature; step 4, drying the refrigerated rice by adopting a hot air drying technology; and step 5, preparing the rice dried in the step 4 into rice. The rice prepared by the invention has a relatively low glycemic index, and can provide a staple food choice for people who need to control blood sugar.

Description

Technical Field

[0001] The invention relates to the field of rice preparation methods, in particular to a method for preparing tea polyphenol-added low GI rice. Background Art

[0002] Rice is an important part of the dietary structure of Chinese residents and one of the main sources of carbohydrates. Rice is rich in starch and digests quickly, providing the human body with quick energy and necessary nutrition. However, with the advancement of modern processing technology, most of the rice currently circulating on the market is refined white rice. In the production process of refined white rice, the rice grains undergo husking, bran removal and polishing. After removing the outer rice husk and bran layer, the germ and seed coat of the rice grains are also removed, and only most of the endosperm is retained. Although this processing makes the rice grains whiter and smoother, it also causes the rice to lose a lot of nutrients, such as fiber, minerals, vitamins, and a variety of plant active substances. As a result, the main component of refined white rice is only starch, which makes it quickly decomposed and absorbed in the human digestive tract, resulting in a sharp increase in blood sugar levels after meals.

[0003] The effect of dietary carbohydrates on blood sugar levels is usually measured by the glycemic index (GI value). The GI value is used to assess the effect of food on the rate of increase in blood sugar during digestion. The higher the GI value of a food, the faster it is digested and the more dramatic the rise in blood sugar. Depending on the GI value, foods can be divided into three categories: high GI (greater than 70), medium GI (56 to 69), and low GI (less than 55). High GI foods will rapidly increase blood sugar and insulin levels after ingestion, and long-term consumption may increase the risk of chronic metabolic diseases such as obesity, diabetes, hyperlipidemia, and cardiovascular disease. In contrast, low GI foods help maintain stable blood sugar levels and reduce insulin fluctuations by slowing down the release of sugar, thereby reducing the risk of metabolic diseases. Summary of the invention

[0004] The invention provides a method for preparing tea polyphenol-added low GI rice, so as to solve the problem of high GI value of rice prepared from paddy in the prior art.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing tea polyphenols-added low GI rice comprises the following steps:

[0007] Step 1: Clean the rice;

[0008] Step 2: Ultrasonic immersion. The process is as follows:

[0009] A 1% aqueous solution is prepared using food additive-grade tea polyphenols, and the rice cleaned in step 1 is added to the prepared aqueous solution, and then an ultrasonic treatment device is used to perform ultrasonic treatment on the aqueous solution soaked with the rice, wherein the power of the ultrasonic treatment device during the ultrasonic treatment is 200-300 W / L, the ultrasonic frequency is 20 kHz, the ultrasonic treatment time is 30-60 minutes, and the rice is continued to be soaked for 1 hour after the ultrasonic treatment is completed;

[0010] Step 3, steaming the rice soaked in ultrasound in step 2 at high temperature and high pressure, draining the water, cooling it to room temperature, and refrigerating it in a low temperature environment for 12-14 hours;

[0011] Step 4, using hot air drying technology to dry the refrigerated rice to a moisture content of 12-14%;

[0012] Step 5: Process the rice dried in step 4 into rice to obtain rice with low GI value.

[0013] In the further step 2, the purity of the food additive grade tea polyphenols is 98%.

[0014] In the further step 3, the temperature during high temperature and high pressure cooking is 110-115°C, the pressure is 143-170 kPa, and the cooking time is 10-15 minutes.

[0015] In the further step 3, the low temperature environment temperature during refrigeration is 4°C.

[0016] In the further step 4, when the refrigerated rice is treated with hot air drying technology, the rice is first dried with hot air at 45-55°C for 1-2 hours for the first drying; then the ventilation and drying is stopped for 2-4 hours for slow revival; after the slow revival is completed, the rice is dried again with hot air at 40-45°C to make the moisture content of the rice reach 12-14%.

[0017] Tea polyphenols are a natural substance in tea leaves that has multiple physiologically active functions. Extensive studies have shown that it has antioxidant, anti-aging, lipid-lowering, blood sugar-lowering, and antibacterial effects. In particular, recent studies have found that when tea polyphenols react with starch under hydrothermal conditions, they can form more slowly digestible starch and resistant starch. The special structure of these starch types has a lower digestion rate, so they can significantly reduce the GI value of food.

[0018] Specifically, tea polyphenols interact with starch molecules, change their molecular structure, inhibit the rapid digestion of starch, and thus delay the release of sugar. Slowly digestible starch and resistant starch can not only slow down the rise of blood sugar, but also improve intestinal health, promote the growth of probiotics, and further improve the nutritional value of food. Tea polyphenols play an auxiliary role in controlling blood sugar by regulating glucose metabolism, inhibiting the sharp rise of blood sugar after meals, and helping to improve insulin sensitivity. In addition, tea polyphenols can also slow down the digestion and absorption of carbohydrates in the gastrointestinal tract, thereby reducing the digestion rate of rice, delaying the release of blood sugar, and further improving the health value of food. Adding tea polyphenols to rice as a functional ingredient can not only improve the nutritional value and antioxidant capacity of rice, but also enrich the taste of rice, meeting the needs of modern people for a healthy diet.

[0019] Therefore, in view of the fact that refined white rice on the market is generally a high GI food, and its over-refining leads to the loss of nutrients, the present invention, based on the role of tea polyphenols in starch processing, proposes to add tea polyphenols during rice processing to prepare low GI rice. This innovative process can not only reduce the GI value of rice, delay the rise of blood sugar after a meal, and improve blood sugar control, but also make rice more healthful by retaining more nutrients. The introduction of tea polyphenol low GI rice meets the needs of modern people for a low GI diet, helps to improve the dietary structure, and reduce the risk of chronic metabolic diseases, thereby providing consumers with a healthier diet choice. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will describe the implementation methods of the present invention in detail in combination with the embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve corresponding technical effects can be fully understood and implemented accordingly. The embodiments of the present invention and the various features in the embodiments can be combined with each other without conflict, and the technical solutions formed are all within the protection scope of the present invention.

[0021] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "include" and "have" in the description and claims of the present invention and any variations thereof are intended to cover non-exclusive inclusions.

[0023] Example 1

[0024] This embodiment discloses a method for preparing low GI rice with added tea polyphenols, wherein the rice grains are indica rice, comprising the following steps:

[0025] Step 1: Rice cleaning:

[0026] Obvious impurities in the indica rice are removed, and then the dust and shriveled grains are sieved to remove them, and the indica rice with full grains is selected. The indica rice is then immersed in clean water for washing to remove floating empty grains, floating dust and impurity particles that have sunk to the bottom, and then taken out and drained.

[0027] Step 2: Ultrasonic immersion. The process is as follows:

[0028] A 1% aqueous solution is prepared using food additive grade tea polyphenols, wherein the food additive grade tea polyphenols is green tea extract with a purity requirement of 98%.

[0029] The indica rice cleaned in step 1 is added to the prepared aqueous solution, and then the aqueous solution soaked with the indica rice is ultrasonically treated by an ultrasonic treatment device, the ultrasonic treatment device is a KQ5200DE numerically controlled ultrasonic cleaner, the power of the ultrasonic treatment device during the ultrasonic treatment is 200 W / L, the ultrasonic frequency is 20 kHz, the ultrasonic treatment time is 30 minutes, and the indica rice is continued to be soaked for 1 hour after the ultrasonic treatment is completed.

[0030] Step 3: Put the indica rice soaked in the ultrasonic step 2 into a high pressure cooking pot and cook it at a temperature of 110° C. and a high pressure of 143 kPa for 10 minutes.

[0031] After high-temperature and high-pressure cooking, the water of the indica rice is drained, and then the indica rice is cooled to room temperature and refrigerated at a low temperature of 4°C for 12 hours.

[0032] Step 4: Use hot air drying technology to treat the refrigerated indica rice. The process is as follows:

[0033] First, the indica rice is dried for 1 hour using hot air at 55°C for the first drying; then the ventilation and drying is stopped for 2 hours for slow revival; after the slow revival is completed, the indica rice is dried again using hot air at 45°C to control the moisture content of the indica rice at 13%.

[0034] Step 5: Husking, milling and color sorting the indica rice dried in step 4 to obtain low GI rice, which is then packaged to obtain a low GI rice product.

[0035] Example 2

[0036] This embodiment discloses a method for preparing rice with low GI value by adding tea polyphenols, wherein the rice is japonica rice, comprising the following steps:

[0037] Step 1: Rice cleaning:

[0038] Obvious impurities in the japonica rice are removed, and then the dust and shriveled grains are sieved to remove them, and the japonica rice with full grains is selected. The japonica rice is then immersed in clean water for washing to remove floating empty grains, floating dust and impurity particles that have sunk to the bottom, and then taken out and drained.

[0039] Step 2: Ultrasonic immersion. The process is as follows:

[0040] A 1% aqueous solution is prepared using food additive grade tea polyphenols, wherein the food additive grade tea polyphenols is green tea extract with a purity requirement of 98%.

[0041] The japonica rice cleaned in step 1 is added to the prepared aqueous solution, and then the aqueous solution soaked with the japonica rice is ultrasonically treated with an ultrasonic treatment device, the ultrasonic treatment device is a KQ5200DE CNC ultrasonic cleaner, the power of the ultrasonic treatment device during the ultrasonic treatment is 200W / L, the ultrasonic frequency is 20kHz, the ultrasonic treatment time is 30 minutes, and the japonica rice is continued to be soaked for 1 hour after the ultrasonic treatment is completed.

[0042] Step 3: Put the japonica rice soaked with ultrasound in step 2 into a high pressure cooking pot and cook it at a temperature of 115° C. and a high pressure of 170 kPa for 10 minutes.

[0043] After high-temperature and high-pressure cooking, the water of the japonica rice is drained, and then the japonica rice is cooled to room temperature and refrigerated at a low temperature of 4°C for 12 hours.

[0044] Step 4: Using hot air drying technology to treat the refrigerated japonica rice, the process is as follows:

[0045] First, the japonica rice is dried for 1 hour using hot air at 55°C for the first drying; then the ventilation and drying are stopped for 3 hours for slow revival; after the slow revival is completed, the japonica rice is dried again using hot air at 45°C to control the moisture content of the japonica rice at 14%.

[0046] Step 5: Husking, milling and color sorting the japonica rice dried in step 4 to obtain low GI rice, which is then packaged to obtain a low GI rice product.

[0047] Two groups of comparative examples without adding tea polyphenols are provided below. By comparing the two groups of comparative examples with Examples 1 and 2, the finished rice products obtained in Examples 1 and 2 are further described.

[0048] Comparative Example 1

[0049] Comparative Example 1 uses indica rice to prepare rice, and the process is as follows:

[0050] (1) Rice cleaning: Remove obvious impurities from the indica rice, then sieve to remove dust and shriveled grains, select the indica rice with full grains, and then immerse the indica rice in clean water to wash, remove floating empty grains, floating dust and impurity particles that have sunk to the bottom, and then take it out and drain the water.

[0051] (2) Ultrasonic soaking: The cleaned indica rice is soaked in clean water, and ultrasonic treatment is performed at an auxiliary ultrasonic power of 200 W / L and an ultrasonic frequency of 20 kHz. The ultrasonic treatment is stopped after 30 minutes, and the soaking is continued for 1 hour.

[0052] (3) Steaming: The treated indica rice is placed in a high-pressure steamer and steamed at 110°C for 10 minutes.

[0053] (4) Refrigeration: Drain the cooked indica rice, cool it to room temperature, and then refrigerate it at 4°C for 12 hours.

[0054] (5) Drying: The refrigerated indica rice is dried using hot air at 55°C for 1 hour for the first drying; then the ventilation is stopped and the drying is performed for 2 hours for slow revival; after the slow revival is completed, the indica rice is dried again using hot air at 45°C to reach a moisture content of 13%.

[0055] (6) Husking, milling, color sorting and packaging the dried indica rice to obtain the finished rice product.

[0056] Comparative Example 2

[0057] Comparative Example 2 uses japonica rice to prepare rice, and the process is as follows:

[0058] (1) Rice cleaning: Remove obvious impurities from japonica rice, then sieve to remove dust and shriveled grains, select the japonica rice with full grains, and then immerse the japonica rice in clean water to wash, remove floating empty grains, floating dust and impurity particles that have sunk to the bottom, and then take it out and drain the water.

[0059] (2) Ultrasonic soaking: The cleaned japonica rice is soaked in clean water, and ultrasonic treatment is performed at an auxiliary ultrasonic power of 200 W / L and an ultrasonic frequency of 20 kHz. The ultrasonic treatment is stopped after 30 minutes and the soaking is continued for 1 hour.

[0060] (3) Steaming: Place the treated japonica rice into a high-pressure steamer and steam at 115°C for 10 minutes.

[0061] (4) Refrigeration: Drain the cooked japonica rice, cool it to room temperature, and then refrigerate it at 4°C for 12 hours.

[0062] (5) Drying: The refrigerated japonica rice was dried using hot air at 55°C for 1 hour for the first drying; then the ventilation was stopped and the drying was continued for 3 hours for slow revival; after the slow revival, the japonica rice was dried again using hot air at 45°C to reach a moisture content of 14%.

[0063] (6) The dried japonica rice is husked, milled, color-sorted and packaged to obtain a low GI rice product.

[0064] The GI values ​​of the rice prepared from indica rice in Example 1, the rice prepared from japonica rice in Example 2, the rice prepared from indica rice in Comparative Example 1, and the rice prepared from japonica rice in Comparative Example 2 are shown in Table 1. Table 1 is as follows:

[0065] Table 1 GI value index table:

[0066] Indicator Group Comparative Example 1 Comparative Example 2 Example 1 Example 2 GI value 56 63 48 52

[0067] Table 1 is measured by the in vivo digestion test of mice. During the experiment, 24 grams of rice obtained by Example 1, Example 2, Comparative Example 1 and Comparative Example 2 were steamed and crushed, and then dispersed in 100ml water to form a rice suspension. After healthy C57BL / 6J mice (6 weeks old, male) were fasted for 12h, rice suspension and glucose were gavaged with 2.4g / kg and 2.0g / kg dosages respectively. After collecting the tail vein blood of each mouse, the blood glucose concentration at 0, 15, 30, 60, 90 and 120min was detected using a blood glucose meter. The area under the glucose tolerance curve (0-120min) was calculated using the trapezoidal method. The glycemic index of rice, i.e., the GI value, was calculated using the ratio of the AUC of rice to the AUC of glucose.

[0068] It can be seen from Table 1 that the GI value of the rice prepared by indica rice in Example 1 of the present invention is less than the GI value of the rice prepared by indica rice in Comparative Example 1; the GI value of the rice prepared by japonica rice in Example 2 of the present invention is less than the GI value of the rice prepared by japonica rice in Comparative Example 1; and the GI values ​​of the rice prepared by Examples 1 and 2 of the present invention are both less than the GI values ​​of the rice prepared by Comparative Examples 1 and 2. It can be seen that in Examples 1 and 2 of the present invention, by adding tea polyphenols, and performing ultrasonic immersion, high temperature and high pressure cooking, refrigeration, and hot air drying, the GI value of the final rice product can indeed be effectively reduced.

[0069] The embodiments of the present invention described above are merely descriptions of preferred embodiments of the present invention, and are not intended to limit the concept and scope of the present invention. The various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and such combinations, as long as they do not violate the concept of the present invention, should also be regarded as the contents disclosed in the present disclosure. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0070] The present invention is not limited to the specific details of the above-mentioned embodiments. Within the technical concept of the present invention and without departing from the design concept of the present invention, various modifications and improvements made to the technical solution of the present invention by technical personnel in this field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have been fully recorded in the claims.

Claims

1. A method for preparing low GI rice with added tea polyphenols, characterized in that: The following steps are involved: Step 1: Clean the rice; Step 2: Ultrasonic immersion. The process is as follows: A 1% aqueous solution is prepared using food additive-grade tea polyphenols, and the rice cleaned in step 1 is added to the prepared aqueous solution, and then an ultrasonic treatment device is used to perform ultrasonic treatment on the aqueous solution soaked with the rice, wherein the power of the ultrasonic treatment device during the ultrasonic treatment is 200-300 W / L, the ultrasonic frequency is 20 kHz, the ultrasonic treatment time is 30-60 minutes, and the rice is continued to be soaked for 1 hour after the ultrasonic treatment is completed; Step 3, steaming the rice soaked in ultrasound in step 2 at high temperature and high pressure, draining the water, cooling it to room temperature, and refrigerating it in a low temperature environment for 12-14 hours; Step 4, using hot air drying technology to dry the refrigerated rice to a moisture content of 12-14%; Step 5: Process the rice dried in step 4 into rice to obtain rice with low GI value.

2. The method for preparing low GI rice with added tea polyphenols according to claim 1, characterized in that: In step 2, the purity of the food additive-grade tea polyphenols is 98%.

3. The method for preparing low GI rice with added tea polyphenols according to claim 1, characterized in that: In step 3, the temperature during high temperature and high pressure cooking is 110-115° C., the pressure is 143-170 kPa, and the cooking time is 10-15 minutes.

4. The method for preparing low GI rice with added tea polyphenols according to claim 1, characterized in that: In step 3, the low temperature environment temperature during refrigeration is 4°C.

5. The method for preparing low GI rice with added tea polyphenols according to claim 1, characterized in that: In step 4, when the refrigerated rice is treated with hot air drying technology, the rice is first dried with hot air at 45-55°C for 1-2 hours for the first drying; then the ventilation and drying is stopped for 2-4 hours for slow revival; after the slow revival is completed, the rice is dried with hot air at 40-45°C again to make the moisture content of the rice reach 12-14%.