Preparation method of low-GI recombinant brown rice in whole grain

Abstract

The invention discloses a preparation method of whole-grain medium-low GI recombinant brown rice, the whole-grain medium-low GI recombinant brown rice takes whole-grain brown rice nutritional components as guidance, and raw material powder is prepared by mixing 72% of high-straight-chain indica rice flour, 18% of defatted rice bran powder, 9.5% of germ flour and 0.5% of monoglyceride according to a mass ratio, adding water, tempering, extruding and recombining. The high straight-chain long-shaped rice is aged at low temperature under the regulation and control of a variable temperature field to increase the content of resistant starch after being subjected to curing treatment, and then is extruded and recombined to form a novel compound from starch, germ lipid and rice bran fibers in mixed powder, so that the digestion resistance is further improved. The recombinant brown rice completely reserves the nutritional ingredients of whole-grain brown rice, has the characteristics of simple raw material ingredients, easiness in cooking and the like, the blood glucose generation index pGI value estimated by in-vitro digestion is 52-60 and reaches the medium-low GI standard, high-valued utilization of rice byproducts including rice bran, broken rice and rice embryos is realized, and the production cost is reduced. And a new choice is provided for functional staple food requirements of patients with controlled sugar and chronic diseases.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a method for preparing low-GI reconstituted brown rice in whole grains. Background Art

[0002] A whole grain refers to a grain kernel that retains its intact seed coat, aleurone layer, germ, and endosperm after removing inedible parts like the husk. This structure preserves nutrients including dietary fiber, polyunsaturated fatty acids, B vitamins, minerals, and bioactive components. Brown rice is a typical whole grain product, preserving a higher degree of the rice grain's full nutritional value compared to white rice. With rising public awareness of nutrition and health, and strong national support for the development of the whole grain industry, consumers are increasingly replacing refined and white rice with whole grains, a trend that has become a new staple food. Low-glycemic index (GI) foods have also become increasingly popular in recent years. Low-GI foods have a longer gastrointestinal tract residence time, resulting in less postprandial blood sugar fluctuations. Low-GI foods can meet the needs of those seeking to control blood sugar and lose weight. Therefore, achieving both whole grains and a low GI is a key research direction for the future development of functional and nutritious rice-based foods.

[0003] In recent years, functional nutritional recombinant rice has been significantly better in nutritional value and market demand than ordinary rice because it is formulated on demand and contains essential nutrients for the human body, such as minerals, vitamins, and dietary fiber. It is a functional staple food product with great potential. The outer layer of traditional whole-grain brown rice contains a high level of crude fiber and has a dense texture. It is difficult for water to enter the endosperm during direct cooking, and the starch in the endosperm is not easy to gelatinize, resulting in poor palatability and cooking properties. These problems can be solved through extrusion recombinantization, germination and other technologies. Although research on recombinant rice has always attracted much attention, there are relatively few studies on whole-grain low-GI recombinant brown rice. Previous studies mostly used brown rice as raw material, crushed the brown rice, and extruded it to produce recombinant brown rice, or used a variety of grains such as quinoa, barley, mung bean powder, chickpeas, and the medicinal and edible Polygonatum to fortify the rice to achieve low GI. CN202111527167.X discloses a fast-brewing coarse-grain reconstituted rice and a preparation method thereof, which is formed by extruding and granulating ten kinds of coarse-grain flours, including rice flour, black rice flour, oat flour, brown rice flour, etc., and compounding yeast powder, high-amylose corn starch, and soy protein isolate powder in proportion. The prepared reconstituted rice optimizes the edible taste and blood sugar-lowering effect, but ignores the problem that the raw material composition is too complicated and the cost is high. CN202310479566.6 and CN202210904203.8 respectively disclose a nutritional reconstituted rice and a preparation method thereof and a preparation method of nutritional reconstituted rice with zero additives and low GI. The pGI value of the prepared nutritional reconstituted rice is between 49.25-52.01 by using wet heat-microwave combined treatment to physically modified quinoa flour, brown rice flour and potato flour as raw materials. Although it has a lower GI value, it does not meet the concept of whole grains. CN202311121916.8 discloses a method for preparing low-GI recombinant Polygonatum rice, which uses rice flour, modified corn starch, and Polygonatum powder as raw materials and is extruded and recombined to obtain low-GI recombinant Polygonatum rice with good palatability and edible quality. Although the functional properties of the nutritional recombinant rice have been enhanced to a certain extent and the taste has been improved, the cost of raw materials is relatively high, and by-products such as broken rice and rice bran produced during rice processing have not been utilized in a high-value manner, and the low GI target is still achieved by adding exogenous functional raw materials. Therefore, the development of key preparation technologies for whole-grain low-GI recombinant brown rice is of great significance to solving the urgent need for high-value utilization of rice processing by-products and iterative development of whole-grain functional products.

[0004] The present invention designs a new type of whole-grain medium-low GI reconstituted brown rice, which uses natural high-straight-chain indica rice and rice processing by-products such as broken rice, rice bran, and rice germ as the main raw materials. The raw material composition is simple, the cost is low, and the optimal ratio of monoglycerides is added to make it through extrusion and reconstitution granulation. It can also achieve large-scale production and high-value utilization of rice by-products such as rice bran and broken rice. The product prepared by this method not only retains the nutrients contained in whole-grain brown rice, but also has the characteristics of easy cooking and medium-low GI, which is in line with the concept of whole-grain food. The glycemic index pGI value tested in vitro is between 52 and 60, which meets the medium-low GI standard. It is suitable for people with high blood sugar and those who control sugar, and has broad market prospects. Summary of the Invention

[0005] In response to the problems in the prior art whereby a large amount of exogenous functional raw materials are added to recombinant brown rice to achieve a low GI, resulting in a complex raw material composition and high cost, the present invention provides a method for preparing whole-grain medium-low GI recombinant brown rice. This recombinant brown rice uses natural high-amylose indica rice and rice processing by-products such as broken rice, rice bran, and rice germ as main raw materials. The raw material composition is simple and the cost is low, enabling large-scale production and high-value utilization of rice by-products such as rice bran and broken rice. Furthermore, the rice rice conforms to the concept of whole-grain food, retains the nutrients contained in whole-grain brown rice, and has the characteristics of being easy to steam and having a medium-low GI.

[0006] The present invention discloses a method for preparing low-GI whole-grain reconstituted brown rice. The specific technical scheme is as follows: The whole grain flour comprises high-amylose indica rice flour, refined rice bran powder, germ powder and monoglyceride, which are fully mixed and uniformly prepared.

[0007] Preferably, the refined rice bran powder is obtained by micronizing rice bran, using a high-energy nano-impact mill and low-temperature ball milling, using zirconium oxide balls as grinding media, and crushing and ball milling to obtain rice bran powder with a particle size of about 18 μm.

[0008] Preferably, the high-amylose indica rice and broken indica rice are steamed and cooked after impurities are removed. After aging, the rice is aged at a variable temperature field at 4°C for 24 hours. The aged rice is dried at 55°C to a moisture content of no more than 10%. After drying, the rice is ground using an ultracentrifugal grinder with a 0.25 mm screen for later use. Preferably, the rice germ is obtained by grinding through a 60-mesh screen.

[0009] Preferably, the whole grain flour is obtained by fully and evenly mixing high-linear indica rice flour (72%): rice bran powder (18%): germ powder (9.5%): monoglyceride (0.5%) according to different ingredient ratios, and water is added to adjust the moisture content of the whole grain flour to 28%.

[0010] The method for preparing the whole grain low GI reconstituted brown rice comprises the following steps: The whole grain flour is loaded into a twin-screw extruder, and after various screw parameters are set, extrusion recombined granulation and low-temperature drying, the whole grain medium-low GI recombined brown rice is obtained.

[0011] Preferably, the screw parameters are: screw speed is 20 Hz, feed speed is 29 Hz, cutting speed is 41 Hz, heating section is zone V temperature 85 ° C, zone VI temperature 95 ° C, zone VII temperature 95 ° C, zone VIII temperature 80 ° C.

[0012] Preferably, the drying temperature is (45°C) and the drying time is (12h). The present invention is beneficial in that: The present invention selects high-linear indica rice and rice processing by-products such as broken rice, rice bran, and rice germ as main raw materials. The raw material composition is simple and the cost is low, and large-scale production and high-value utilization of rice by-products such as rice bran and broken rice can be achieved.

[0013] The present invention meets the concept of whole-grain food, not only retains the nutrients contained in whole-grain brown rice, but also has the characteristics of easy steaming and low GI. The estimated glycemic index (pGI) value through in vitro testing is between 52 and 60, which meets the low-medium GI standard. It is suitable for people with high blood sugar and those who control sugar, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 :Hydrolysis curves of recombinant rice starch from different raw materials DETAILED DESCRIPTION The present invention will be further described below with reference to specific implementation examples so that relevant technical personnel can fully and thoroughly understand the present invention.

[0014] Example 1 Whole-grain flour preparation: Rice bran was ground using different mills to a particle size of approximately 18 μm. High-amylose indica rice and broken indica rice were removed from impurities and then steamed and cooked. After cooking, the indica rice was aged at 4°C for 24 hours under a variable temperature control. The aged indica rice was dried at 55°C to a moisture content of no more than 10%. After drying, the rice was ground using an ultracentrifugal grinder with a 0.25 mm mesh. The rice germ was ground and passed through a 60-mesh sieve. Whole-grain flours were prepared by thoroughly mixing different ingredients: 72% high-amylose indica rice flour, 18% rice bran flour, 9.5% germ flour, and 0.5% monoglyceride. Water was then added to adjust the moisture content of the whole-grain flour to 26%, 28%, and 30%.

[0015] Preparation of whole-grain medium-low GI reconstituted brown rice: Whole-grain flour was loaded into a twin-screw extruder. Screw parameters were set at 20 Hz, a feed rate of 29 Hz, a cutting speed of 41 Hz, and heating zones of 85°C (zone V), 95°C (zone VI), 95°C (zone VII), and 80°C (zone VIII). Once the heating zone temperatures reached the set values, feeding was resumed. The rice was then extruded, reconstituted, and granulated, and then dried at 45°C for 12 hours to produce whole-grain medium-low GI reconstituted brown rice.

[0016] Example 2 The same operation as in Example 1 was performed, but the barrel temperatures in zones VI and VII were changed to 90°C, 95°C, and 100°C.

[0017] Rice bran, impurity-removed high-amylose indica rice, and broken indica rice are ground using an ultracentrifugal mill with a 0.25mm screen. The rice germ is ground and passed through a 60-mesh screen for later use. Whole grain flour is prepared by thoroughly mixing 72% high-amylose indica rice flour, 18% rice bran powder, 9.5% germ powder, and 0.5% monoglyceride. Water is added to adjust the moisture content of the whole grain flour to 28%.

[0018] The whole grain flour was loaded into a twin-screw extruder, and the screw parameters were set as follows: the screw speed was 20 Hz, the feed rate was 29 Hz, the cutting speed was 41 Hz, the temperature of zone V in the heating section was 85°C, the temperature of zone VIII was 80°C, the temperatures of zones VI and VII were changed to 90°C, 95°C, and 100°C, and the whole grain medium-low GI reconstituted brown rice was obtained after the temperatures of each zone in the heating section reached the set values.

[0019] Example 3 The operation was the same as in Example 1, but the screw speed was changed to 20 Hz and 23 Hz.

[0020] Rice bran, impurity-removed high-amylose indica rice, and broken indica rice are ground using an ultracentrifugal mill with a 0.25mm screen. The rice germ is ground and passed through a 60-mesh screen for later use. Whole grain flour is prepared by thoroughly mixing 72% high-amylose indica rice flour, 18% rice bran powder, 9.5% germ powder, and 0.5% monoglyceride. Water is added to adjust the moisture content of the whole grain flour to 28%.

[0021] The whole grain flour was loaded into a twin-screw extruder, and the screw parameters were set as follows: the screw speed was 20 Hz and 23 Hz, the feed rate was 29 Hz, the cutting speed was 41 Hz, the heating section temperature was 85°C in zone V, 95°C in zone VI, 95°C in zone VII, and 80°C in zone VIII. After the temperatures of each zone in the heating section reached the set values, feeding was carried out, and the whole grain medium-low GI reconstituted brown rice was obtained after extrusion recombinant granulation and drying at 45°C for 12 hours.

[0022] Example 4 Whole-grain flour preparation: Rice bran was pulverized using different mills to produce three different types of rice bran flour, with particle sizes of approximately 123 μm, 70 μm, and 18 μm, respectively. High-amylose indica rice and broken indica rice were removed from impurities and then steamed and cooked. After cooking, the indica rice was aged at 4°C for 24 hours under a variable temperature control. The aged indica rice was dried at 55°C to a moisture content of no more than 10%. After drying, the rice was ground using an ultracentrifugal grinder with a 0.25 mm mesh for later use. The rice germ was ground and passed through a 60-mesh sieve for later use. A mixture of 72% high-amylose indica rice flour, 18% rice bran flour, 9.5% germ flour, and 0.5% monoglyceride was thoroughly mixed to create the whole-grain flour. Water was added to adjust the moisture content of the whole-grain flour to 28%.

[0023] Preparation of whole-grain low-GI reconstituted brown rice: whole-grain flour was loaded into a twin-screw extruder, and the screw parameters were set as follows: screw speed was 20 Hz, feed rate was 29 Hz, cutting speed was 41 Hz, heating section temperature was 85°C in zone V, 95°C in zone VI, 95°C in zone VII, and 80°C in zone VIII. After the temperatures of each zone in the heating section reached the set values, feeding was carried out. After extrusion recombinant granulation and drying at 45°C for 12 h, five different recombinant rices were produced, namely recombinant rice 1 (99.5% high-amylose indica rice flour + 0.5% monoglyceride), recombinant rice 2 (90% high-amylose indica rice flour + 9.5% germ powder + 0.5% monoglyceride), recombinant rice 3 (72% high-amylose indica rice flour + 9.5% germ powder + 18% large-particle rice bran powder + 0.5% monoglyceride), recombinant rice 4 (72% high-amylose indica rice flour + 9.5% germ powder + 18% medium-particle rice bran powder + 0.5% monoglyceride) and recombinant rice 5 (72% high-amylose indica rice flour + 9.5% germ powder + 18% small-particle rice bran powder + 0.5% monoglyceride).

[0024] The above describes the implementation mode of the present invention in detail, but the scope of protection of the present invention is not limited to this. If technicians in this field make equivalent substitutions or changes based on the concept and technical solution of the present invention, they should fall within the scope of protection of the present invention.

Claims

1. A method for preparing low GI reconstituted brown rice in whole grains, characterized in that: The medium-low GI reconstituted brown rice is prepared by using high-amylose indica rice and broken indica rice, defatted rice bran and rice germ as main raw materials to construct whole grain flour, which is prepared by adding monoglyceride and water to mix and condition, and then extruding and reconstructing the mixture.

2. The method for preparing low GI reconstituted brown rice in whole grains according to claim 1, wherein High-amylose indica rice and broken indica rice were removed from the rice and then steamed and aged. After aging, the rice was aged at 4°C for 24 hours under a variable temperature control. The aged rice was dried at 55°C to a moisture content of no more than 10%. After drying, the rice was sieved through a 0.25 mm mesh using an ultracentrifugal grinder and set aside.

3. The method for preparing low GI reconstituted brown rice in whole grains according to claim 1, wherein: The defatted rice bran is ultrafinely pulverized using high-energy nano-impact milling and low-temperature ball milling, with zirconium oxide balls used as grinding media, to obtain micronized rice bran powder with a particle size of about 18 μm. The rice germ is centrifugally ground and then passed through a 60-mesh sieve for later use.

4. The method for preparing low GI reconstituted brown rice in whole grains according to claim 1, wherein The mixing ratio of the raw materials is based on the mass ratio: high-straight-chain indica rice flour (72%): defatted rice bran powder (18%): germ powder (9.5%): monoglyceride (0.5%). Water is added to adjust the moisture content of the whole grain flour to 28%.

5. The method for preparing low GI reconstituted brown rice in whole grains according to claim 1, wherein: The parameters of the twin-screw extruder are as follows: screw speed of 20 Hz, feed speed of 29 Hz, cutting speed of 41 Hz, heating section temperatures of 85°C in zone V, 95°C in zone VI, 95°C in zone VII, and 80°C in zone VIII.

6. The method for preparing low GI reconstituted brown rice in whole grains according to claim 1, wherein: The recombinant brown rice was obtained and low-temperature dried at 45°C for 12 hours. The estimated glycemic index (pGI) value of the whole-grain recombinant brown rice was between 52 and 60, which met the low-medium GI requirements.

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