Low-glycemic whole-grain food and preparation method thereof

Abstract

The invention provides a low-glycemic whole-grain food and a preparation method thereof, and belongs to the technical field of food processing. The low-glycemic whole-grain food comprises 60-80 parts of whole-grain mixed powder, 4-7 parts of inulin, 3-8 parts of resistant dextrin and 2-5 parts of konjaku flour, and the whole-grain mixed powder is obtained by solid-state fermentation of oats, quinoa and brown rice through compound microorganisms. The low-glycemic whole-grain food is prepared by low-temperature extrusion forming and drying. Test results show that the low-glycemic-index whole-grain food obtained by adopting the technical scheme is low in cooking loss, the texture characteristic and the sense of the cooked low-glycemic-index whole-grain food are close to those of northeast natural rice, the glycemic index is smaller than 55, and the low-glycemic-index whole-grain food is low in glycemic index and suitable for diabetics to eat.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing, and particularly relates to a low-glycemic-index whole grain food and a preparation method thereof. Background Art

[0002] With the change of modern diet structure, the incidence of metabolic diseases such as diabetes and obesity has been continuously rising. In this context, the development of low-glycemic-index (GI) foods has become a research hotspot in the fields of nutrition and food science. Whole grain foods are rich in dietary fiber, B vitamins and phenolic substances, and have better nutritional value than refined grains. However, during their processing, the increase in starch gelatinization degree often leads to an increase in the GI value, making it difficult to meet the core needs of special populations for blood glucose management.

[0003] Currently, there are mainly three major technical bottlenecks in whole grain foods on the market: First, traditional thermal processing techniques (such as high-temperature baking and puffing) will significantly damage the cell wall structure of grains and promote the rapid gelatinization of starch granules; second, the fine grinding treatment commonly used to improve the taste will result in a loss of 30%-50% of dietary fiber, leading to a decline in its function of delaying glucose absorption; third, existing GI reduction techniques mostly rely on adding exogenous components, but it is easy to cause the product viscosity to be too high and affect the palatability.

[0004] Therefore, developing a low-glycemic-index food that can achieve slow digestion of starch, efficient retention of dietary fiber, and good sensory quality at the same time has become a technical problem to be solved urgently. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a low-glycemic-index whole grain food and a preparation method thereof. The prepared whole grain food has good sensory properties, a low glycemic index, and is suitable for diabetics to eat.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a low-glycemic-index whole grain food, which comprises the following raw materials in parts by weight: 60-80 parts of whole grain mixed powder, 4-7 parts of inulin, 3-8 parts of resistant dextrin, and 2-5 parts of konjac powder; the whole grain mixed powder is obtained by compound microbial solid-state fermentation of oats, quinoa and brown rice.

[0008] Preferably, the weight ratio of oats, quinoa and brown rice is (3-8):(2-5):(3-8).

[0009] Preferably, the preparation method of the whole grain mixed powder includes: grinding oats, quinoa and brown rice, mixing them with water, inoculating composite microorganisms and solid-state fermenting them at 30-35°C and pH 6.8-7.2 for 3-5 days, drying, grinding and microwave treatment to obtain the whole grain mixed powder.

[0010] More preferably, the amount of water is 50%-60% of the total weight of the oats, quinoa and brown rice.

[0011] More preferably, the composite microorganism consists of Aspergillus cristatus and Bacillus subtilis subsp. subtilis.

[0012] More preferably, the solid-state fermentation is stirred once every 6-8 hours for 24 hours before and 1-2 times a day thereafter.

[0013] More preferably, the microwave treatment is performed at a power of 800-900 W, a temperature of 60-70° C., and a time of 20-30 min.

[0014] The present invention also provides a method for preparing the low-glycemic whole-grain food, comprising: mixing whole-grain mixed flour, inulin, resistant dextrin, konjac flour and water to obtain a mixture, extruding the mixture at low temperature, and drying the mixture to obtain the low-glycemic whole-grain food.

[0015] Preferably, the weight percentage of water in the mixture is 20%-30%.

[0016] Preferably, the twin screw speed for low-temperature extrusion molding is 100-200 rpm, the temperature of zone I is 50-60°C, the temperature of zone II is 60-70°C, the temperature of zone III is 70-80°C, and the temperature of zone V is 80-100°C.

[0017] Preferably, the microwave sterilization has a power of 18-23 kW, a temperature of 75-85° C., and a time of 20-30 min.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a low-glycemic whole-grain food, comprising: 60-80 parts of whole-grain mixed flour, 4-7 parts of inulin, 3-8 parts of resistant dextrin and 2-5 parts of konjac flour, wherein the whole-grain mixed flour is obtained by solid-state fermentation of oats, quinoa and brown rice by composite microorganisms. The low-glycemic whole-grain food of the present invention is extruded and formed at low temperature and dried to obtain the low-glycemic whole-grain food. Test results show that the low-glycemic whole-grain food obtained by the technical solution of the present invention has low cooking loss, and the texture characteristics and sensory properties after cooking are close to those of natural rice in Northeast China, and the glycemic index is less than 55, making it a low-glycemic index food suitable for consumption by diabetics. DETAILED DESCRIPTION

[0020] The present invention provides a low-glycemic-index whole grain food, comprising the following raw materials in parts by weight: 60-80 parts of whole grain mixed powder, 4-7 parts of inulin, 3-8 parts of resistant dextrin, and 2-5 parts of konjac powder; the whole grain mixed powder is obtained by compound microbial solid-state fermentation of oats, quinoa, and brown rice.

[0021] The brown rice in the present invention is preferably black glutinous brown rice or milled brown rice, more preferably milled brown rice; the weight ratio of oats, quinoa, and brown rice is preferably (3-8):(2-5):(3-8), more preferably 5:3:5. When preparing the low-glycemic-index whole grain food of the present invention, oats are rich in β-glucan, which has the effects of reducing cholesterol and delaying the rise of blood sugar; quinoa is a whole-protein grain with comprehensive nutrition; brown rice retains rich dietary fiber and vitamins. The reasonable combination of the three lays the foundation for the low-glycemic-index recombined rice. After the oats (high amylose), brown rice (medium amylose), and quinoa (low amylose) in the present invention are compounded in proportion, a gradient starch structure can be formed, which is convenient for differential degradation by compound microorganisms to generate resistant starch and oligosaccharides. The saponins (source of bitterness) on the surface of quinoa and phytic acid in brown rice can be enzymatically hydrolyzed by compound microorganisms during the solid-state fermentation process, which not only removes anti-nutritional factors but also improves the flavor and the bioavailability of minerals. The β-glucan of oats provides a carbon source for Aspergillus cristatus, promoting the secretion of cellulase. The GABA precursor substance (glutamic acid) of brown rice is converted into active GABA under the action of Bacillus subtilis subsp.

[0022] The preparation method of the whole grain mixed powder in the present invention preferably includes: crushing oats, quinoa, and brown rice, mixing with water, inoculating compound microorganisms, and performing solid-state fermentation at 30-35 °C and a pH value of 6.8-7.2 for 3-5 d, followed by drying, crushing, and microwave treatment to obtain the whole grain mixed powder.

[0023] The amount of water used in the present invention is preferably 50%-60% of the total weight of oats, quinoa, and brown rice, more preferably 55%.

[0024] The compound microorganisms in the present invention preferably consist of Aspergillus cristatus and Bacillus subtilis subsp. Among them, Aspergillus cristatus is Aspergillus cristatus CICC ® 41701, and the number of bacteria in the compound microorganisms is preferably 1-2 billion cfu / g, more preferably 1.5 billion cfu / g. Bacillus subtilis subsp. is Bacillus subtilis subsp. Bacillus subtilis CICC ® 10753, and the number of bacteria in the compound microorganisms is preferably 1.5-2.5 billion cfu / g, more preferably 2 billion cfu / g; before the solid-state fermentation, it is preferably stirred once every 6-8 h for the first 24 h, and preferably stirred 1-2 times a day after 24 h.

[0025] On the one hand, the α-amylase secreted by Bacillus subtilis subsp. can directly hydrolyze the α-1,4 glycosidic bonds of amylose in whole grains, break it down into short-chain dextrins and oligosaccharides, loosen the starch molecular structure, and delay the release rate of glucose by α-glucosidase in the small intestine, thereby reducing the blood glucose peak value; the extracellular enzymes (such as cellulase and xylanase) of Aspergillus cristatus further decompose the dietary fiber in the cereal cell wall, release soluble fiber and resistant starch, and reduce the digestion rate; the combined action of the two can increase the proportion of starch converted into resistant starch and significantly delay glucose release. On the other hand, the antioxidant metabolites produced by the fermentation of Aspergillus cristatus can inhibit the activity of amylase and reduce the starch digestibility; Bacillus subtilis subsp. can generate GABA and surfactin by fermenting whole grain powder, form a colloidal structure that encapsulates starch, delay enzymatic hydrolysis and thus reduce the GI value of whole grain foods.

[0026] The power of the microwave treatment described in the present invention is preferably 800-900W, more preferably 850W, the temperature is preferably 60-70°C, more preferably 65°C, and the time is preferably 20-30min, more preferably 25min. Using microwave treatment can, on the one hand, destroy the microbial cell structure at low temperature and avoid the loss of nutrients caused by high temperature. On the other hand, microwave treatment can promote the generation of resistant starch and further reduce the GI value.

[0027] The present invention also provides a preparation method of the low-glycemic whole grain food according to the above, including: mixing whole grain mixed powder, inulin, resistant dextrin, konjac powder and water to obtain a mixture, extruding and forming at low temperature, and drying to obtain the low-glycemic whole grain food.

[0028] The weight percentage of water in the mixture described in the present invention is preferably 20%-30%, more preferably 25%. The rotation speed of the double-screw rod for low-temperature extrusion molding is preferably 100-200rpm, more preferably 150rpm. The temperature in zone I is preferably 50-60°C, more preferably 55°C. The temperature in zone II is preferably 60-70°C, more preferably 65°C. The temperature in zone III is preferably 70-80°C, more preferably 75°C. The temperature in zone V is preferably 80-100°C, more preferably 95°C. Using low-temperature extrusion molding can not only reduce the degree of starch gelatinization, increase the content of resistant starch, but also reduce the nutritional loss of heat-sensitive components.

[0029] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] In the following examples, unless otherwise specified, all are conventional methods.

[0031] In the following examples, materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial sources.

[0032] In the examples and comparative examples, inulin was purchased from Anhui Weimao Biotechnology Co., Ltd., product number 6686681029; resistant dextrin was purchased from Jiangsu Taize Biotechnology Co., Ltd., product number 052; konjac powder was purchased from Henan Meizhijie Food Additive Co., Ltd., product number 0213; Aspergillus cristatus was Aspergillus cristatus CICC ® 41701, and Bacillus subtilis subsp. Subtilis was Bacillus subtilis subsp. Subtilis CICC ® 10753, both were purchased from the China Center for Industrial Culture Collection.

[0033] Example 1

[0034] Low glycemic index whole grain food

[0035] (1) Preparation of whole grain mixed powder

[0036] Oats, quinoa, and Simaojing brown rice were respectively pulverized, passed through a 150-mesh sieve, and mixed according to a weight ratio of 5:3:5. 55% of the total weight of oats, quinoa, and brown rice of distilled water was added, and a composite microorganism was inoculated. After solid-state fermentation at 32 °C and pH 7 for 4 d (stirred every 6 h in the first 24 h and stirred 2 times a day after 24 h), it was dried to a water content of 5% (w / w), pulverized and passed through a 150-mesh sieve, and microwave-treated at 850 W and 65 °C for 25 min to obtain the whole grain mixed powder;

[0037] The composite microorganism was composed of Aspergillus cristatus and Bacillus subtilis subsp. Subtilis. The number of Aspergillus cristatus in the composite microorganism was 1.5 billion cfu / g, and the number of Bacillus subtilis subsp. Subtilis was 2 billion cfu / g. The inoculation amount of the composite microorganism was 3% of the total weight of oats, quinoa, and brown rice;

[0038] (2) Preparation of low glycemic index whole grain food

[0039] The whole grain mixed powder, inulin, resistant dextrin, konjac powder, and water obtained in step (1) were mixed according to a weight ratio of 70:6:5:3:21 to obtain a mixture, which was extruded and formed at low temperature, dried at 75 °C for 65 min, and sterilized to obtain the low glycemic index whole grain food;

[0040] Among them, the rotation speed of the double-screw rod for low-temperature extrusion molding is 150 rpm, the temperature in Zone I is 55 °C, the temperature in Zone II is 65 °C, the temperature in Zone III is 75 °C, and the temperature in Zone V is 95 °C.

[0041] Example 2

[0042] Low glycemic index whole grain food

[0043] (1) Preparation of whole grain mixed powder

[0044] Oats, quinoa, and black glutinous brown rice were respectively pulverized, passed through a 100-mesh sieve, mixed in a weight ratio of 3:2:3, added with distilled water accounting for 50% of the total weight of oats, quinoa, and brown rice, inoculated with a composite microorganism, and solid-state fermented at 30 °C and a pH value of 6.8 for 5 days (stirred every 8 hours in the first 24 hours and once a day after 24 hours), then dried to a water content of 4% (w / w), pulverized and passed through a 100-mesh sieve, and microwave-treated at 800 W and 60 °C for 30 minutes to obtain the whole grain mixed powder;

[0045] Among them, the composite microorganism consists of Aspergillus cristatus and Bacillus subtilis subsp. subtilis. The number of Aspergillus cristatus bacteria in the composite microorganism is 1 billion cfu / g, the number of Bacillus subtilis subsp. subtilis bacteria is 1.5 billion cfu / g, and the inoculation amount of the composite microorganism is 2% of the total weight of oats, quinoa, and brown rice;

[0046] (2) Preparation of low glycemic index whole grain food

[0047] The whole grain mixed powder, inulin, resistant dextrin, konjac powder, and water obtained in step (1) were mixed in a weight ratio of 60:4:3:2:13.8 to obtain a mixture, which was formed by low-temperature extrusion molding, dried at 70 °C for 70 minutes, and sterilized to obtain the low glycemic index whole grain food;

[0048] Among them, the rotation speed of the double-screw rod for low-temperature extrusion molding is 100 rpm, the temperature in Zone I is 50 °C, the temperature in Zone II is 60 °C, the temperature in Zone III is 70 °C, and the temperature in Zone V is 80 °C.

[0049] Example 3

[0050] Low glycemic index whole grain food

[0051] (1) Preparation of whole grain mixed powder

[0052] Oats, quinoa, and Simaojaponica brown rice were respectively pulverized, passed through a 200-mesh sieve, and mixed at a weight ratio of 8:5:8. 60% of the total weight of oats, quinoa, and brown rice of distilled water was added, and a composite microorganism was inoculated. After solid-state fermentation at 35 °C and a pH value of 7.2 for 3 d (stirred every 6 h in the first 24 h and once a day after 24 h), it was dried to a water content of 4% (w / w), pulverized, passed through a 200-mesh sieve, and microwave-treated at 900 W and 70 °C for 20 min to obtain a whole grain mixed powder;

[0053] The composite microorganism consists of Aspergillus cristatus and Bacillus subtilis subsp. subtilis. The number of Aspergillus cristatus bacteria in the composite microorganism is 2 billion cfu / g, and the number of Bacillus subtilis subsp. subtilis bacteria is 2.5 billion cfu / g. The inoculation amount of the composite microorganism is 5% of the total weight of oats, quinoa, and brown rice;

[0054] (2)Preparation of low-glycemic whole grain food

[0055] The whole grain mixed powder, inulin, resistant dextrin, konjac powder, and water obtained in step (1) were mixed at a weight ratio of 80:7:8:5:30 to obtain a mixture, which was extruded into shape at low temperature and dried at 80 °C for 60 min and sterilized to obtain the low-glycemic whole grain food;

[0056] Among them, the rotation speed of the twin-screw for low-temperature extrusion molding is 200 rpm, the temperature in zone I is 60 °C, the temperature in zone II is 70 °C, the temperature in zone III is 80 °C, and the temperature in zone V is 100 °C.

[0057] Comparative Example 1

[0058] The specific implementation method is the same as that of Example 1, except that (1) the preparation method of the whole grain mixed powder is: oats, quinoa, and Simaojaponica brown rice were respectively pulverized, passed through a 200-mesh sieve, and mixed at a weight ratio of 8:5:8 to obtain a mixture. The water content of the mixture was adjusted to 30% (w / w) with water, microwave-treated at 450 W and 50 °C for 5 min, dried to a water content of 5% (w / w), pulverized, passed through a 150-mesh sieve to obtain a whole grain mixed powder.

[0059] Comparative Example 2

[0060] The specific implementation method is the same as that of Example 1, except that the preparation method of (1) the whole grain mixed powder is: oats, quinoa, and Simaojaponica brown rice were respectively pulverized, passed through a 150-mesh sieve, and mixed at a weight ratio of 5:3:5. 55% of the total weight of oats, quinoa, and brown rice of distilled water was added and mixed, and Aspergillus cristatus was inoculated. After solid-state fermentation at 28 °C and a pH value of 6.5 for 4 d (stirred every 6 h in the first 24 h and twice a day after 24 h), it was dried to a water content of 5% (w / w), pulverized, passed through a 150-mesh sieve, and microwave-treated at 850 W and 65 °C for 25 min to obtain a whole grain mixed powder;

[0061] Among them, the number of Aspergillus cristatus is 3.5 billion cfu / g, and the inoculation amount is 3% of the total weight of oats, quinoa and brown rice.

[0062] Comparative Example 3

[0063] The specific implementation method is the same as that of Example 1, except that (1) the preparation method of the whole grain mixed powder is as follows: oats, quinoa and Selenium-enriched brown rice are respectively crushed, passed through a 150-mesh sieve, mixed according to the weight ratio of 5:3:5, and 55% of the total weight of oats, quinoa and brown rice is added. Distilled water is mixed, inoculated with Bacillus subtilis subsp. subtilis, and solid-state fermented at 37 °C and pH 7.2 for 4 d (stirred every 6 h for the first 24 h, and stirred 2 times a day after 24 h), and then dried to a water content of 5% (w / w), crushed and passed through a 150-mesh sieve, and microwave-treated at 850 W and 65 °C for 25 min to obtain a whole grain mixed powder;

[0064] Among them, the number of Bacillus subtilis subsp. subtilis is 3.5 billion cfu / g, and the inoculation amount is 6% of the total weight of oats, quinoa and brown rice.

[0065] Comparative Example 4

[0066] The specific implementation method is the same as that of Example 1, except that (2) in the preparation of the low-glycemic whole grain food, the feeding speed of the twin-screw extrusion for extrusion molding is 2.5 kg / h, the rotation speed is 200 rpm, the temperature in zone I is 70 °C, the temperature in zone II is 80 °C, the temperature in zone III is 90 °C, and the temperature in zone V is 110 °C.

[0067] Test Example 1

[0068] Physical properties

[0069] 1. Cooking loss

[0070] Accurately weigh 2.00 g of the low-glycemic whole grain foods or Northeast natural rice of Examples 1-3 and Comparative Examples 1-4 respectively, pour 20 mL of distilled water, heat to boiling and cook for 10 min. Then weigh the mass of the supernatant (rice soup) and transfer it to a petri dish, heat it in an oven at 105 °C until it reaches a constant weight, and weigh the mass of the solid at this time. Calculate the cooking loss rate. The cooking loss rate = (mass of solid - mass of rice soup) / 2 × 100%. The cooking loss results of each group are shown in Table 1.

[0071] Table 1 Cooking loss rates of each group

[0072] Group Cooking loss rate (%) Group Cooking loss rate (%) Northeast natural rice 9.19 Comparative Example 1 6.93 Example 1 6.54 Comparative Example 2 6.68 Example 2 7.22 Comparative Example 3 5.70 Example 3 6.37 Comparative Example 4 7.45

[0073] It can be seen from the data in Table 1 that the cooking loss rates of the whole grain foods in Examples 1-3 and Comparative Examples 1-4 are all lower than that of Northeast natural rice.

[0074] 2. Texture properties

[0075] Weigh 20 g of the low - glycemic whole - grain foods or Northeast natural rice of Examples 1 - 3 and Comparative Examples 1 - 4 respectively, add them into the pot according to the weight ratio of 1:1 of rice to water, and heat and steam them with boiling water for 15 min. Then keep warm for 10 min to obtain the steamed low - glycemic whole - grain foods or Northeast natural rice.

[0076] Use a TA.XT Plus texture analyzer to measure the hardness and elasticity of the steamed whole - grain foods or Northeast natural rice. The specific results are shown in Table 2.

[0077] Table 2 Texture characteristics of each group

[0078] Group Hardness (g) Elasticity Northeast natural rice 2.27 0.95 Example 1 2.04 0.93 Example 2 1.91 0.89 Example 3 1.88 0.91 Comparative Example 1 1.83 0.84 Comparative Example 2 1.75 0.86 Comparative Example 3 1.72 0.85 Comparative Example 4 1.66 0.81

[0079] It can be seen from the data in Table 2 that there is little difference in the hardness and elasticity between the steamed Northeast natural rice and the low - glycemic whole - grain foods of Examples 1 - 3 of the present invention. It can be seen that the texture characteristics of the low - glycemic whole - grain foods obtained by the preparation method of the present invention are closest to those of Northeast natural rice after steaming. By comparing the data of Example 1 and Comparative Examples 1 - 4, different treatment methods, different microbial fermentations, and different extrusion conditions for whole grains will affect the texture characteristics of whole - grain foods.

[0080] Test Example 2

[0081] Sensory evaluation

[0082] Ten trained food professionals serve as sensory assessors to conduct sensory evaluation measurements on the steamed low - glycemic whole - grain foods and Northeast natural rice of Examples 1 - 3 and Comparative Examples 1 - 4 respectively.

[0083] The steaming method is as follows: Weigh 20 g of the whole - grain foods or Northeast natural rice of Examples 1 - 3 and Comparative Examples 1 - 4 respectively, add them into the pot according to the ratio of 1:1 of rice to water, and heat and steam them with boiling water for 15 min. Then keep warm for 10 min to obtain the steamed whole - grain foods or Northeast natural rice.

[0084] The sensory evaluation standard refers to GB / T 15682 - 2008 Cereals and oils inspection - Sensory evaluation method for cooking and eating quality of paddy rice and milled rice, as shown in Table 3, and the sensory evaluation results are shown in Table 4.

[0085] Table 3 Sensory evaluation standard for low - glycemic whole - grain foods

[0086] Table 4 Sensory scores of each group

[0087] Group Odor Appearance structure Palatability Taste Texture of cold rice Sensory score Northeast natural rice 18.1 19.3 26.4 23.0 4.8 91.6 Example 1 18.5 17.9 25.1 22.2 4.2 87.9 Example 2 17.4 18.8 24.6 21.9 4.4 87.1 Example 3 18.0 17.1 25.8 22.4 4.1 87.4 Comparative Example 1 16.7 15.6 20.2 18.7 2.3 73.5 Comparative Example 2 17.2 16.0 21.7 19.3 2.9 77.1 Comparative Example 3 15.3 14.7 22.5 17.8 3.5 73.8 Comparative Example 4 13.6 12.2 19.3 15.1 2.7 62.9

[0088] As can be seen from the data in Table 4, there is little difference in the sensory properties between Examples 1-3 of the present invention and Northeast natural rice, and they have excellent sensory properties. From the data of Example 1 and Comparative Examples 1-4, it can be seen that different treatment methods, different microbial fermentations, and different extrusion conditions for whole grains will have varying degrees of influence on the sensory properties of whole grain foods.

[0089] Test Example 3

[0090] Determination of glycemic index

[0091] Select 60 healthy adults aged 20-25 years old, with an equal number of men and women, no history of diabetes, metabolic diseases or digestive system diseases. Divide them into 5 groups, with 12 people in each group, and determine the glycemic index of the whole grain foods of Example 1 and Comparative Examples 1-4.

[0092] Before the test, fasting for more than 10 hours is required, avoiding high-fiber and high-sugar diets, and not taking drugs that affect glucose metabolism recently. Determine the fasting blood glucose value. Select pure glucose powder (50 g per person) as a reference, dissolve it in 200 mL of warm water and drink it within 5 minutes, and then measure the blood glucose value at 15, 30, 45, 60, and 120 minutes after eating respectively.

[0093] Those with qualified glucose tolerance (fasting blood glucose ≤ 6.1 mmol / L, blood glucose at 120 minutes after taking glucose ≤ 7.8 mmol / L) can participate in the food glucose tolerance test. After the subjects measure the fasting blood glucose value, they eat the cooked whole grain foods of Example 1 and Comparative Examples 1-4 or Northeast natural rice with 50 g of carbohydrates as the raw material, and finish eating within 5 minutes, and then measure the blood glucose value at 15, 30, 45, 60, and 120 minutes after eating respectively.

[0094] Taking time (min) as the abscissa and the blood glucose value (mmol / L) at each time point as the ordinate, make a blood glucose response curve. Calculate the area under the blood glucose response curve and calculate the glycemic index of the food.

[0095] Glycemic index = area under the blood glucose response curve at 120 minutes after eating the test food / area under the blood glucose response curve of 50 g of glucose at 120 minutes × 100.

[0096] The results of the glycemic index of each group are shown in Table 5.

[0097] Table 5 Results of the glycemic index of each group

[0098] Group Glycemic index Group Glycemic index Northeast natural rice 87.24 Comparative Example 1 63.84 Example 1 43.60 Comparative Example 2 58.36 Example 2 44.15 Comparative Example 3 56.51 Example 3 43.49 Comparative Example 4 52.78

[0099] It can be seen from the data in Table 5 that the glycemic index of Northeast natural rice and whole grain foods of Comparative Examples 1-4 is greater than 55, and they are high glycemic index foods. The glycemic index of Examples 1-3 of the present invention is less than 55, and they are low glycemic index foods. As can be seen from the comparison between Example 1 and Comparative Example 1, fermentation and wet heat treatment of whole grains have different effects on the glycemic index. As can be seen from Example 1 and Comparative Examples 2-3, Aspergillus cristatus and Bacillus subtilis subsp. subtilis have a synergistic effect, which can significantly reduce the glycemic index of whole grain foods. As can be seen from Example 1 and Comparative Example 4, the use of a higher extrusion temperature can increase the glycemic index.

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A low glycemic index whole grain food, characterized in that, The invention comprises the following raw materials in parts by weight: 60-80 parts of whole grain mixed flour, 4-7 parts of inulin, 3-8 parts of resistant dextrin and 2-5 parts of konjac flour; The whole grain mixed flour is obtained by solid-state fermentation of oats, quinoa and brown rice through composite microorganisms.

2. The low glycemic index whole grain food according to claim 1, wherein The weight ratio of the oats, quinoa and brown rice is (3-8):(2-5):(3-8).

3. The low glycemic index whole grain food according to claim 1, wherein The preparation method of the whole grain mixed powder comprises: grinding oats, quinoa and brown rice, mixing the mixture with water, inoculating composite microorganisms, and performing solid-state fermentation for 3-5 days at 30-35° C. and pH 6.8-7.2, and drying, grinding and microwave treatment to obtain the whole grain mixed powder.

4. The low glycemic index whole grain food according to claim 3, wherein The amount of water used is 50%-60% of the total weight of the oats, quinoa and brown rice.

5. The low glycemic index whole grain food according to claim 3, wherein The composite microorganism consists of Aspergillus cristatus and Bacillus subtilis subspecies subtilis.

6. The low glycemic index whole grain food according to claim 3, wherein The solid-state fermentation was stirred once every 6-8 hours for 24 hours before and 1-2 times a day after 24 hours.

7. The low glycemic index whole grain food according to claim 3, wherein The microwave treatment has a power of 800-900W, a temperature of 60-70°C, and a time of 20-30 minutes.

8. A method for preparing the low-glycemic-index whole grain food according to any one of claims 1-7, characterized in that, include: Whole grain mixed flour, inulin, resistant dextrin, konjac flour and water are mixed to obtain a mixture, which is then subjected to low-temperature extrusion molding and drying to obtain the low-glycemic whole grain food.

9. The preparation method according to claim 7, wherein The weight percentage of water in the mixture is 20%-30%.

10. The preparation method according to claim 7, characterized in that, The twin screw speed of the low-temperature extrusion molding is 100-200 rpm, the temperature of zone I is 50-60°C, the temperature of zone II is 60-70°C, the temperature of zone III is 70-80°C, and the temperature of zone V is 80-100°C.

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