Low-GI tartary buckwheat nutritional meal replacement powder as well as preparation method and application thereof

Abstract

The invention relates to the technical field of food processing, in particular to low-GI tartary buckwheat nutritional meal replacement powder as well as a preparation method and application thereof. The low-GI tartary buckwheat nutritional meal replacement powder comprises the following components: enzyme-deactivated rice meal, enzyme-deactivated tartary buckwheat bran powder, milk powder, tartary buckwheat active polypeptide, xylitol, sodium carboxymethyl cellulose, monoglyceride and maltodextrin. According to the characteristics of the rice and tartary buckwheat bran raw materials, high-efficiency enzyme deactivation and sterilization are respectively performed in a targeted manner. The tartary buckwheat active peptide is efficiently obtained by combining pressure cooking with a compound enzyme method. The tartary buckwheat bran is rich in functional active ingredients such as dietary fibers and flavonoid compounds and can be combined with the rice to achieve complementary nutritional advantages, tartary buckwheat functional active peptide ingredients are added, and the low-GI tartary buckwheat nutritional meal replacement powder which is stable in quality, rich in nutrition and has a clean label is developed on the basis of the three main raw materials. Technical support is provided for optimizing the grain processing technology and improving the quality and the storage period of whole grain food, and important practical value and application prospects are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to a low GI tartary buckwheat nutritious meal replacement powder and a preparation method and application thereof. Background Art

[0002] As people's demand for nutritious and healthy food continues to increase, low GI foods are favored by consumers because they can effectively control blood sugar levels, reduce insulin secretion, and thus reduce the risk of cardiovascular diseases. As a low GI food, buckwheat is rich in a variety of bioactive ingredients, such as flavonoids, phenols, polysaccharides, etc., and has multiple physiological functions such as lowering blood sugar, lowering blood lipids, anti-inflammatory, and anti-oxidation. It is widely used in food, medicine, and health products.

[0003] Buckwheat, especially its bran, is rich in active peptides. Due to its close combination with other non-starch polysaccharides, the extraction and production of buckwheat peptides are difficult, which restricts its industrial development. Buckwheat bran has high crude fiber and fat content, and lacks effective deep processing and enzyme sterilization technology, resulting in poor product taste, easy rancidity and deterioration, and affecting product quality and shelf life. Technical problems: microwave treatment and baking extrusion combined technology are used to modify the physical properties of raw materials, and enzyme sterilization is carried out efficiently. Microwave wet heat treatment can effectively passivate the activity of various lipases in rice during storage, delay the oxidative rancidity of rice lipids, and extend its storage period. Baking extrusion dry heat treatment can effectively degrade cellulose and hemicellulose components, inhibit the activity of various lipases in buckwheat bran, and improve the physical properties and storage characteristics of buckwheat bran. The acquisition efficiency of buckwheat active peptides is not high, and the activity is not ideal. Technical problems: Buckwheat bran is pretreated by pressure cooking and buckwheat protein is extracted. After being hydrolyzed by a composite protease (alkaline protease + papain), buckwheat protein exhibits stronger in vitro antioxidant, hypoglycemic, lipid-lowering and antibacterial abilities, solving the problem of low efficiency and unsatisfactory activity of the traditional single enzymatic hydrolysis method for preparing bioactive peptides. This patent uses pressure cooking combined with a composite enzyme method to prepare buckwheat active peptide functional ingredients. Most existing buckwheat products contain antioxidant and preservative additives, which do not meet the needs of modern people for healthy diets. Technical issues: Develop a low-GI buckwheat nutritional meal replacement powder with a clean label, effectively inactivate enzymes and sterilize through new physical technologies, so that the product can be safely stored for more than 3 months without the use of antioxidant and preservative additives.

[0004] It is impossible to effectively and thoroughly inactivate enzymes in grains: In the process of grain processing and storage, inactivation of enzymes is an essential process. Clarifying the inactivation effects and mechanisms of different processing conditions on different grain raw materials is a key issue in ensuring the shelf life of grain products. At present, the effects of enzyme inactivation technologies such as microwaves, baking, and extrusion on the internal moisture migration and structure of grains are still unclear, and the relationship between various lipases, lipid oxidation products, and oxidation intermediates is intricate. It is difficult for existing technologies to achieve the effect of complete enzyme inactivation, which makes it very easy for the lipases remaining in the grains during storage to be reactivated during the processing process, causing the product to spoil. The cost of obtaining buckwheat active peptides is high: The buckwheat processing technologies commonly used in the food industry, such as steaming, extrusion, steam explosion, and microwaves, have problems such as high energy consumption and damage to the structure of active ingredients. There are still some problems in the production process of buckwheat active peptides, such as low extraction efficiency and low purity, and a large-scale production line has not yet been established.

[0005] Therefore, it is necessary to find a low GI buckwheat nutritious meal replacement powder to fill the market gap and promote the development of healthy food. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a low GI tartary buckwheat nutritious meal replacement powder and a preparation method and application thereof. The present invention develops a low GI tartary buckwheat nutritious meal replacement powder, and performs different enhancement treatments on raw rice, tartary buckwheat bran and tartary buckwheat active peptides, respectively, to comprehensively enhance the sensory, storage and nutritional quality of the product. The present invention not only provides technical support for the development of tartary buckwheat functional food ingredients, but also opens up a new way for the high-value utilization of tartary buckwheat bran, and has important practical value and application prospects.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a low GI tartary buckwheat nutritional meal replacement powder, comprising the following components in parts by weight:

[0009] 44.15-56 parts of enzyme-killed rice flour, 10-20 parts of enzyme-killed tartary buckwheat bran powder, 8-12 parts of milk powder, 8-10 parts of tartary buckwheat active polypeptides, 10-20 parts of xylitol, 0.3-0.4 parts of sodium carboxymethyl cellulose, 0.25-0.4 parts of monoglyceride and 0.25-0.35 parts of maltodextrin;

[0010] The enzyme-killed rice flour is obtained by subjecting the rice flour to microwave treatment; the power of the microwave treatment is 650-950W, and the time is 25-75s;

[0011] The enzyme-inactivated tartary buckwheat bran powder is obtained by baking and extruding tartary buckwheat bran; the baking temperature is 180-220° C., and the time is 10-20 minutes; the water content of the tartary buckwheat bran is 20-30%;

[0012] The extrusion conditions include: the temperature of the treatment zone is 70-90°C, the temperature of the mixing zone is 90-110°C, the temperature of the shearing zone is 110-130°C, and the temperature of the pressure relief zone is 110-130°C;

[0013] The tartary buckwheat active polypeptide is obtained by pressure cooking and enzymolysis of tartary buckwheat bran;

[0014] The pressure cooking conditions include: pressure of 0.05-0.2 MPa, temperature of 120° C., and time of 20 min;

[0015] The enzymes used in the enzymolysis include papain and / or alkaline protease.

[0016] Preferably, the following components are included in parts by weight:

[0017] 48.2-51.1 parts of enzyme-killed rice flour, 15 parts of enzyme-killed tartary buckwheat bran powder, 10 parts of milk powder, 8-10 parts of tartary buckwheat active polypeptides, 15 parts of xylitol, 0.35 part of sodium carboxymethyl cellulose, 0.3-0.35 parts of monoglyceride and 0.3 part of maltodextrin.

[0018] Preferably, the power of the microwave treatment is 750-850 W, and the time is 50 s.

[0019] Preferably, the baking temperature is 200° C. and the baking time is 15 minutes.

[0020] Preferably, the extrusion conditions include: the temperature of the treatment zone is 80°C, the temperature of the mixing zone is 100°C, the temperature of the shearing zone is 120°C, and the temperature of the pressure relief zone is 120°C.

[0021] Preferably, when the enzymes are papain and alkaline protease, the mass ratio of papain to alkaline protease is 1-1.5:1-1.5.

[0022] Preferably, the conditions for the enzymatic hydrolysis include: temperature of 50° C., pH value of 7.0, rotation speed of 100 rpm, and time of 3 hours.

[0023] Preferably, the method for preparing the active buckwheat polypeptide comprises the following steps:

[0024] 1) adjusting the moisture content of tartary buckwheat bran to 40% and then performing pressure cooking, drying and pulverizing at 60° C. to obtain cooked tartary buckwheat bran;

[0025] 2) defatting the steamed buckwheat bran obtained in step 1) to obtain defatted bran;

[0026] Use n-hexane for degreasing, with a solid-liquid ratio of 1:4, a rotation speed of 200 rpm, and a time of 12 h;

[0027] 3) mixing the defatted bran obtained in step 2) with water, adjusting the pH value to 10.0, stirring and centrifuging to obtain a supernatant;

[0028] The mass ratio of the defatted bran to water is 1:10;

[0029] The stirring conditions include: magnetic stirring at a temperature of 35° C. for 90 min;

[0030] The centrifugal conditions include: temperature of 4°C, rotation speed of 8000 rpm, and time of 20 min;

[0031] 4) adjusting the pH value of the supernatant obtained in step 3) to 4.5, and obtaining a precipitate after centrifugation;

[0032] The centrifugal conditions include: temperature of 4°C, rotation speed of 8000 rpm, and time of 20 min;

[0033] 5) re-dissolving the precipitate obtained in step 4), placing it into a dialysis bag with a molecular cutoff of 8000 to 14000 Da, dialyzing it, and vacuum freeze-drying it to obtain tartary buckwheat protein;

[0034] The vacuum freeze drying temperature is -80°C and the time is 10h;

[0035] The buffer used for the re-dissolution is PBS buffer with a pH value of 7.0;

[0036] The dialysis conditions include: the time is 24 hours, and the PBS buffer is replaced once every 3 hours;

[0037] 6) mixing the tartary buckwheat protein obtained in step 5) with water to obtain a tartary buckwheat protein solution, mixing the tartary buckwheat protein solution with an enzyme, performing enzymolysis, inactivating the enzyme, and centrifuging the obtained supernatant by vacuum freeze-drying to obtain tartary buckwheat active polypeptides;

[0038] The vacuum freeze drying temperature is -80°C and the time is 10h;

[0039] The enzymes were mixed at an enzyme:substrate mass ratio of 1:100;

[0040] The enzyme inactivation conditions include: boiling for 10 minutes;

[0041] The centrifugal conditions include: temperature of 4°C, time of 10 min, and rotation speed of 10000 rpm.

[0042] The present invention also provides a method for preparing the low GI tartary buckwheat nutritious meal replacement powder described in the above technical scheme, comprising the following steps: mixing the enzyme-killed rice flour, enzyme-killed tartary buckwheat bran powder, milk powder, tartary buckwheat active polypeptides, xylitol, sodium carboxymethyl cellulose, monoglyceride and maltodextrin, spray drying to remove moisture, and obtaining the low GI tartary buckwheat nutritious meal replacement powder.

[0043] The present invention also provides the use of the low GI tartary buckwheat nutritional meal replacement powder described in the above technical solution in extending the shelf life.

[0044] Beneficial effects of the present invention:

[0045] The present invention carries out targeted and efficient enzyme inactivation and sterilization according to the characteristics of rice and buckwheat bran raw materials. Buckwheat active peptides are efficiently obtained by pressure cooking combined with a composite enzyme method (alkaline protease + papain). Buckwheat bran is rich in functional active ingredients such as dietary fiber and flavonoid compounds, which can achieve nutritional complementary advantages when combined with rice. At the same time, buckwheat functional active peptide ingredients are added to develop a low-GI buckwheat nutritional meal replacement powder with stable quality, rich nutrition and clean label based on the above three main raw materials. It provides technical support for optimizing grain processing technology and improving the quality and storage period of whole grain foods, and has important practical value and application prospects.

[0046] (1) Highly efficient enzyme inactivation technology

[0047] In the process of grain processing and storage, enzyme inactivation is an indispensable process. The research on enzyme inactivation of grains is currently facing some challenges. The enzyme inactivation effect and enzyme inactivation mechanism of different treatment conditions are the key issues of enzyme inactivation of grains. Therefore, the present invention utilizes different heat treatments to efficiently inactivate enzymes in the product raw materials, buckwheat bran and rice, so as to improve the storage stability of the raw materials.

[0048] At present, the research on the application of microwave treatment to rice enzyme inactivation is mostly focused on the indicators for evaluating enzyme activity and fatty acid value, while the water migration in the grain raw materials after enzyme inactivation, the effect of heat treatment on the internal structure, and the relationship between various lipases, lipid oxidation products and oxidation intermediates are still unclear, so it is impossible to fundamentally achieve the ideal enzyme inactivation effect. The technology of the present invention strictly controls the enzyme inactivation indicators, and through the determination of all fat-related enzyme activities and their end product indicators, water migration, changes in grain morphological structure and changes in volatile components of grains during storage and their correlation analysis, the degree of hydrolysis and rancidity of rice and buckwheat bran before and after different treatments during storage and its influencing mechanism are explored, so as to accurately regulate the safe storage of raw materials.

[0049] (2) High-efficiency preparation technology of buckwheat active peptides

[0050] The invention firstly adopts pressure cooking technology to pre-activate tartary buckwheat bran to improve the extractability and structure of protein, and then adopts optimized composite enzyme method to hydrolyze and prepare tartary buckwheat peptide, which greatly improves the enzymatic hydrolysis efficiency and polypeptide activity.

[0051] (3) Clean label low GI buckwheat meal replacement powder formulation process

[0052] The present invention adopts microwave treatment and baking extrusion combined treatment technology to improve the nutritional properties of tartary buckwheat rice flour with tartary buckwheat bran and rice as basic raw materials, and improves the problems of poor sensory quality, processing and storage properties of tartary buckwheat bran. In addition, tartary buckwheat active peptides with antioxidant, hypoglycemic and antibacterial effects are prepared and added, and are reasonably proportioned with different additives without adding chemical preservatives. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0054] Figure 1 The scanning electron microscope images of rice before and after microwave treatment;

[0055] Figure 2 Heat map of the effect of microwave treatment on the volatile components of rice, C-: untreated; W-: microwave treatment; red: positive correlation; blue: negative correlation;

[0056] Figure 3 Heat map of correlation analysis of microwave treatment on rice fat-related enzyme activities, oxidation indexes and volatile components, red: positive correlation; blue: negative correlation;

[0057] Figure 4 The scanning electron micrographs of tartary buckwheat bran before and after heat treatment;

[0058] Figure 5 It is the hydrolysis degree diagram of tartary buckwheat protein. Note: QPP, CQPP are alkaline protease hydrolysates QPA, CQPA is papain hydrolysate QPC, CQPC is composite protease hydrolysate;

[0059] Figure 6 This is the interaction diagram of the amount of added raw material of buckwheat flour;

[0060] Figure 7 This is the interaction diagram of the addition amount of each stabilizer in buckwheat flour. DETAILED DESCRIPTION

[0061] The present invention provides a low GI tartary buckwheat nutritional meal replacement powder, comprising the following components in parts by weight:

[0062] 44.15-56 parts of enzyme-killed rice flour, 10-20 parts of enzyme-killed tartary buckwheat bran powder, 8-12 parts of milk powder, 8-10 parts of tartary buckwheat active polypeptides, 10-20 parts of xylitol, 0.3-0.4 parts of sodium carboxymethyl cellulose, 0.25-0.4 parts of monoglyceride and 0.25-0.35 parts of maltodextrin;

[0063] The enzyme-killed rice flour is obtained by subjecting the rice flour to microwave treatment; the power of the microwave treatment is 650-950W, and the time is 25-75s;

[0064] The enzyme-inactivated tartary buckwheat bran powder is obtained by baking and extruding tartary buckwheat bran; the baking temperature is 180-220° C., and the time is 10-20 minutes; the water content of the tartary buckwheat bran is 20-30%;

[0065] The extrusion conditions include: the temperature of the treatment zone is 70-90°C, the temperature of the mixing zone is 90-110°C, the temperature of the shearing zone is 110-130°C, and the temperature of the pressure relief zone is 110-130°C;

[0066] The tartary buckwheat active polypeptide is obtained by pressure cooking and enzymolysis of tartary buckwheat bran;

[0067] The pressure cooking conditions include: pressure of 0.05-0.2 MPa, temperature of 120° C., and time of 20 min;

[0068] The enzymes used in the enzymolysis include papain and / or alkaline protease.

[0069] In the present invention, the low GI bitter buckwheat nutritional meal replacement powder preferably includes the following components in parts by weight: 48.2-51.1 parts of enzyme-killed rice flour, 15 parts of enzyme-killed bitter buckwheat bran powder, 10 parts of milk powder, 8-10 parts of bitter buckwheat active polypeptides, 15 parts of xylitol, 0.35 parts of sodium carboxymethyl cellulose, 0.3-0.35 parts of monoglycerides and 0.3 parts of maltodextrin. The present invention has no special restrictions on the milk powder, and conventional commercial products can be used. In a specific embodiment of the present invention, the milk powder is preferably derived from Inner Mongolia Mengniu Dairy (Group) Co., Ltd., Mengniu pure milk powder 240g / bag (12*20), product model 40820BE1M3. In the present invention, the role of the milk powder is to improve the taste of the meal replacement powder. In the present invention, the role of the xylitol is a sweetener and humectant, so that people with high blood sugar can also eat it with confidence. In the present invention, the role of the sodium carboxymethyl cellulose is a stabilizer and a water retaining agent to improve the taste of the meal replacement powder. In the present invention, the monoglyceride acts as an emulsifier and stabilizer, allowing the product to quickly disperse and dissolve in water and be uniform and delicate. In the present invention, the maltodextrin acts as a thickener and stabilizer.

[0070] In the present invention, the power of the microwave treatment of the rice is preferably 750-850W, and the time is 50s. In the present invention, the rice is preferably put into a food-grade special high-temperature resistant transparent bag, the water content of the rice is adjusted to 20%, the bag is vented and sealed, and the microwave treatment is performed after soaking for 2h. In the present invention, the moisture on the surface of the rice is preferably dried at 40°C after the microwave treatment.

[0071] In the present invention, the temperature of baking the tartary buckwheat bran is preferably 200°C and the time is 15 minutes. In the present invention, the tartary buckwheat bran is preferably evenly spread on a baking tray with a thickness of 2 to 3 mm, baked, crushed and adjusted to a moisture content of 25%, and then extruded by a twin-screw extruder. In the present invention, the extrusion conditions preferably include: a treatment zone temperature of 80°C, a mixing zone temperature of 100°C, a shear zone temperature of 120°C, and a pressure relief zone temperature of 120°C.

[0072] In the present invention, when the enzyme is preferably papain and alkaline protease, the mass ratio of papain and alkaline protease is preferably 1-1.5:1-1.5. In the present invention, the conditions for the enzymolysis preferably include: temperature of 50°C, pH of 7.0, rotation speed of 100 rpm, and time of 3 hours.

[0073] In the present invention, the method for preparing the active buckwheat polypeptide preferably comprises the following steps:

[0074] 1) adjusting the moisture content of tartary buckwheat bran to 40% and then performing pressure cooking, drying and pulverizing at 60° C. to obtain cooked tartary buckwheat bran;

[0075] 2) defatting the steamed buckwheat bran obtained in step 1) to obtain defatted bran;

[0076] Use n-hexane for degreasing, with a solid-liquid ratio of 1:4, a rotation speed of 200 rpm, and a time of 12 h;

[0077] 3) mixing the defatted bran obtained in step 2) with water, adjusting the pH value to 10.0, stirring and centrifuging to obtain a supernatant;

[0078] The mass ratio of the defatted bran to water is 1:10;

[0079] The stirring conditions include: magnetic stirring at a temperature of 35° C. for 90 min;

[0080] The centrifugal conditions include: temperature of 4°C, rotation speed of 8000 rpm, and time of 20 min;

[0081] 4) adjusting the pH value of the supernatant obtained in step 3) to 4.5, and obtaining a precipitate after centrifugation;

[0082] The centrifugal conditions include: temperature of 4°C, rotation speed of 8000 rpm, and time of 20 min;

[0083] 5) re-dissolving the precipitate obtained in step 4), placing it into a dialysis bag with a molecular cutoff of 8000 to 14000 Da, dialyzing it, and vacuum freeze-drying it to obtain tartary buckwheat protein;

[0084] The vacuum freeze drying temperature is -80°C and the time is 10h;

[0085] The buffer used for the re-dissolution is PBS buffer with a pH value of 7.0;

[0086] The dialysis conditions include: the time is 24 hours, and the PBS buffer is replaced once every 3 hours;

[0087] 6) mixing the tartary buckwheat protein obtained in step 5) with water to obtain a tartary buckwheat protein solution, mixing the tartary buckwheat protein solution with an enzyme, performing enzymolysis, inactivating the enzyme, and centrifuging the obtained supernatant by vacuum freeze-drying to obtain tartary buckwheat active polypeptides;

[0088] The vacuum freeze drying temperature is -80°C and the time is 10h;

[0089] The enzymes were mixed at an enzyme:substrate mass ratio of 1:100;

[0090] The enzyme inactivation conditions include: boiling for 10 minutes;

[0091] The centrifugal conditions include: temperature of 4°C, time of 10 min, and rotation speed of 10000 rpm.

[0092] The present invention has no special limitation on the method for using the low GI tartary buckwheat nutritional meal replacement powder, and the method for using conventional meal replacement powder can be used.

[0093] The present invention also provides a method for preparing the low GI tartary buckwheat nutritious meal replacement powder described in the above technical scheme, comprising the following steps: mixing the enzyme-killed rice flour, enzyme-killed tartary buckwheat bran powder, milk powder, tartary buckwheat active polypeptides, xylitol, sodium carboxymethyl cellulose, monoglyceride and maltodextrin, spray drying to remove moisture, and obtaining the low GI tartary buckwheat nutritious meal replacement powder.

[0094] The present invention also provides the use of the low GI tartary buckwheat nutritional meal replacement powder described in the above technical solution in extending the shelf life.

[0095] In order to further illustrate the present invention, the present invention is described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0096] Materials and Reagents:

[0097] Buckwheat bran was purchased from Yulin City, Shaanxi Province, and Daohuaxiang No. 2 (both japonica rice) was purchased from Beijing Qiheyuan Food Technology Co., Ltd.

[0098] DPPH, ABTS, TPTZ, Trolox, Folin, methanol, anhydrous ethanol, sodium hydroxide, hydrochloric acid, potassium hydroxide, hydrogen peroxide, trichloroacetic acid, isooctane, sodium chloride, phenolphthalein, petroleum ether, potassium persulfate, ferric chloride hexahydrate, 2,4-dinitrophenylhydrazine, guaiacol, borax, toluene, linoleic acid, Tween-20, 2,4,6-trimethylpyridine, and n-alkane standards (C7-C30) were all analytical grade; yeast extract, tryptone, and agar were all biological reagent pure; α-amylase, α-glucosidase, pancreatic lipase, and protease were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; papain and alkaline protease were purchased from Tianjin Taijin Technology Co., Ltd.

[0099] Instruments and equipment:

[0100] Constant temperature incubator (DHP-2042BS), Thermo Corporation, USA; high pressure steam autoclave (YQX-LS-50G), Shanghai Boxun Industrial Co., Ltd.; vacuum freeze dryer (ALpHA 1-2LD PLUS), Marin Christ, Germany; spray dryer (YC-015), Marin Christ, Germany; V-type mixer (V1000), Jiangsu Daikin Drying Technology Co., Ltd.; high performance liquid chromatograph (1260infinity), Agilent Technologies Co., Ltd.; scanning electron microscope (SU-1510), Hitachi, Japan; low field nuclear magnetic resonance (MicorMR-25), Suzhou Newmai Analytical Instrument Co., Ltd.; desktop high speed refrigerated centrifuge (Neo fuge 13R); pulverizer (30b), Changzhou Panfeng Drying Equipment Co., Ltd.; multifunctional microplate reader (Epoch 2), Thermo Fisher Scientific, USA; Fourier transform infrared spectrometer (IS50), ThermoFisher Scientific, USA; gas chromatography-mass spectrometer (ISQ 7000), Thermo Fisher Scientific, USA.

[0101] Example 1

[0102] Microwave treatment can effectively inactivate enzymes in rice. The method is as follows:

[0103] Fresh rice samples were placed in food-grade high-temperature resistant transparent bags, the moisture content of the samples was adjusted to 20%, and the bags were shaken thoroughly to evenly distribute the moisture on the surface of the rice grains. The bags were vented and sealed, and soaked for 2 hours to balance the moisture content in the rice grains. The bags were treated with a microwave power of 850 W for 50 seconds, and the surface moisture was dried at 40°C after cooling.

[0104] Example 2

[0105] Example 2 is similar to Example 1, except that the microwave power is 950W.

[0106] Example 3

[0107] Example 3 is similar to Example 1, except that the microwave power is 750W.

[0108] Example 4

[0109] Example 4 is similar to Example 1, except that the microwave power is 650W.

[0110] Example 5

[0111] Example 5 is similar to Example 1, except that the treatment is performed for 25 seconds.

[0112] Example 6

[0113] Example 6 is similar to Example 1, except that the treatment is performed for 75 seconds.

[0114] Comparative Example 1

[0115] Comparative Example 1 is similar to Example 1, except that the cooking process is performed at 100° C. for 5 min.

[0116] Comparative Example 2

[0117] Comparative Example 2 is similar to Example 1, except that no microwave treatment is performed.

[0118] Example 7

[0119] The method for efficiently inactivating enzymes in tartary buckwheat bran is as follows:

[0120] The buckwheat bran was evenly spread on a baking tray with a thickness of 2-3 mm, baked at 200°C for 10 minutes, cooled and ground to powder and passed through an 80-mesh sieve. The moisture content of the baked buckwheat bran was adjusted to 25%, and the buckwheat bran was extruded using a twin-screw extruder. The temperatures of the treatment zone, mixing zone, shear zone and pressure relief zone were 80°C, 100°C, 120°C and 120°C respectively. After the sample was cooled, the surface moisture was dried at 55°C, ground to powder and sieved, and stored in a sealed state at low temperature for later use.

[0121] Example 8

[0122] Example 8 is similar to Example 7, except that it is baked at 180° C. for 10 min.

[0123] Example 9

[0124] Example 9 is similar to Example 7, except that it is baked at 220° C. for 10 min.

[0125] Example 10

[0126] Example 10 is similar to Example 7, except that it is baked at 200° C. for 15 min.

[0127] Embodiment 11

[0128] Example 11 is similar to Example 7, except that it is baked at 200° C. for 20 min.

[0129] Example 12

[0130] Example 12 is similar to Example 7, except that the moisture content of tartary buckwheat bran is adjusted to 20%.

[0131] Example 13

[0132] Example 13 is similar to Example 7, except that the moisture content of tartary buckwheat bran is adjusted to 30%.

[0133] Embodiment 14

[0134] Example 14 is similar to Example 7, except that the temperature of the treatment zone during the extrusion treatment is 70°C.

[0135] Embodiment 15

[0136] Example 15 is similar to Example 7, except that the temperature of the treatment zone during the extrusion treatment is 90°C.

[0137] Example 16

[0138] Example 16 is similar to Example 7, except that the temperature of the mixing zone during the extrusion process is 90°C.

[0139] Embodiment 17

[0140] Example 17 is similar to Example 7, except that the temperature of the mixing zone during the extrusion process is 110°C.

[0141] Embodiment 18

[0142] Example 18 is similar to Example 7, except that the temperature of the shear zone during the extrusion process is 110°C.

[0143] Embodiment 19

[0144] Example 19 is similar to Example 7, except that the temperature of the shear zone during the extrusion process is 130°C.

[0145] Embodiment 20

[0146] Example 20 is similar to Example 7, except that the temperature of the pressure relief zone during the extrusion process is 110°C.

[0147] Embodiment 21

[0148] Example 21 is similar to Example 7, except that the temperature of the pressure relief zone during the extrusion process is 130°C.

[0149] Comparative Example 3

[0150] Comparative Example 3 is similar to Example 7, except that it is only baked without extrusion.

[0151] Comparative Example 4

[0152] Comparative Example 4 is similar to Example 7, except that the samples are directly extruded without baking.

[0153] Comparative Example 5

[0154] Comparative Example 5: The tartary buckwheat bran raw material was not subjected to any treatment.

[0155] Embodiment 22

[0156] Buckwheat bran was pressure cooked and buckwheat protein was extracted. Buckwheat bran was crushed and passed through an 80-mesh sieve, and its moisture content was adjusted to 40% and then treated at 0.1MPa and 120°C for 20min. Then it was dried and crushed at 60°C and passed through an 80-mesh sieve. Buckwheat bran was defatted with n-hexane (solid-liquid ratio 1:4) at a speed of 200r / min for 12h. Defatted buckwheat bran powder was added to distilled water at a mass ratio of 1:10, and the pH of the solution was adjusted to 10.0 with 2mol / L sodium hydroxide. After magnetic stirring at 35°C for 90min, the solution was centrifuged at 8000rpm and 4°C for 20min to obtain the supernatant. The pH of the supernatant was adjusted to 4.5 with 0.1mol / L hydrochloric acid, and the precipitate was collected by centrifugation at 8000rpm and 4°C for 20min. The precipitate was re-dissolved with a PBS buffer solution at pH = 7.0, placed in a dialysis bag with a molecular cutoff of 8000-14000Da, and dialyzed in a low-temperature PBS buffer for 24 hours, with the buffer replaced every 3 hours. Finally, the pH value was adjusted to 7.0, and vacuum freeze-dried (-80°C, 10 hours) to obtain buckwheat protein.

[0157] Enzymatic hydrolysis of buckwheat protein: adjust the protein concentration to 4% (w / v) with distilled water, and enzymatic hydrolyze buckwheat protein with a composite protease (mass ratio of papain and alkaline protease = 1:1) under the condition of an enzyme: substrate ratio of 1:100 (w / w), and adjust the pH value of the suspension to 7.0 with 0.5 mol / L sodium hydroxide. Subsequently, the protein hydrolysate was placed in a constant temperature water bath at 50°C, treated at 100r / min for 3h, and then boiled for 10min. Centrifuge at 10000rpm for 10min at 4°C, collect the supernatant, and vacuum freeze-dry (-80°C, 10h), which is the active buckwheat polypeptide.

[0158] Embodiment 23

[0159] Example 23 is similar to Example 22, except that the pressure cooking conditions are 0.2 MPa and 120°C.

[0160] Embodiment 24

[0161] Example 24 is similar to Example 22, except that the pressure cooking conditions are 0.05 MPa and 120°C.

[0162] Embodiment 25

[0163] Example 25 is similar to Example 22, except that only papain was used for buckwheat protein hydrolysis.

[0164] Embodiment 26

[0165] Example 26 is similar to Example 22, except that only a single alkaline protease is used for buckwheat protein hydrolysis.

[0166] Embodiment 27

[0167] Example 27 is similar to Example 22, except that the mass ratio of the enzymatic hydrolysis of tartary buckwheat protein by papain and alkaline protease is 1:1.5.

[0168] Embodiment 28

[0169] Example 28 is similar to Example 22, except that the mass ratio of the enzymatic hydrolysis of tartary buckwheat protein by papain and alkaline protease is 1.5:1.

[0170] Comparative Example 6

[0171] Comparative Example 6 is similar to Example 22, except that no enzymatic hydrolysis is performed.

[0172] Comparative Example 7

[0173] Comparative Example 7 is similar to Example 22, except that normal pressure cooking is performed.

[0174] Embodiment 29

[0175] The formula (mass percentage) of the low GI tartary buckwheat nutritional meal replacement powder is: 51.1% of rice flour prepared in Example 1, 15% of tartary buckwheat bran prepared in Example 7, 10% of milk powder, 8% of tartary buckwheat active peptide prepared in Example 22, 15% of xylitol, 0.35% of sodium carboxymethyl cellulose, 0.25% of monoglyceride, and 0.3% of maltodextrin.

[0176] Embodiment 30

[0177] Example 30 is similar to Example 29, except that the rice flour prepared in Example 1 is 56%, the tartary buckwheat bran prepared in Example 7 is 10%, the milk powder is 10%, the tartary buckwheat active peptide prepared in Example 22 is 8%, xylitol is 15%, sodium carboxymethyl cellulose is 0.35%, monoglyceride is 0.3%, and maltodextrin is 0.35%.

[0178] Embodiment 31

[0179] Example 31 is similar to Example 29, except that the rice flour prepared in Example 1 is 47.05%, the tartary buckwheat bran prepared in Example 7 is 20%, the milk powder is 12%, the tartary buckwheat active peptide prepared in Example 22 is 10%, xylitol is 10%, sodium carboxymethyl cellulose is 0.4%, monoglyceride is 0.25%, and maltodextrin is 0.3%.

[0180] Embodiment 32

[0181] Example 32 is similar to Example 29, except that the rice flour prepared in Example 1 is 48.2%, the tartary buckwheat bran prepared in Example 7 is 15%, the milk powder is 8%, the tartary buckwheat active peptide prepared in Example 22 is 8%, xylitol is 20%, sodium carboxymethyl cellulose is 0.35%, monoglyceride is 0.2%, and maltodextrin is 0.25%.

[0182] Embodiment 33

[0183] Example 33 is similar to Example 29, except that the rice flour prepared in Example 1 is 44.15%, the tartary buckwheat bran prepared in Example 7 is 15%, the milk powder is 12%, the tartary buckwheat active peptide prepared in Example 22 is 8%, xylitol is 20%, sodium carboxymethyl cellulose is 0.3%, monoglyceride is 0.25%, and maltodextrin is 0.3%.

[0184] Comparative Example 8

[0185] Comparative Example 8 is similar to Example 25, except that tartary buckwheat bran is not added.

[0186] Evaluation of the effects of different embodiments on the storage stability of rice and buckwheat bran as raw materials for meal replacement powder

[0187] (1) Lipase was determined using a lipase activity kit (BC 2345) produced by Beijing Solebow Technology Co., Ltd. The results were calculated using the oleic acid standard curve (y = 0.0043x + 0.0632, R 2 =0.9993).

[0188] (2) Lipoxygenase assay: 1.5 g of rice or processed buckwheat bran was ground into powder and weighed. 10 mL of phosphate buffer solution (0.1 mol / L, pH = 7.5) was added. The mixture was stirred evenly in an ice-water bath for 30 min. The mixture was centrifuged at 8000 g and 4 °C for 10 min. 20 μL of the supernatant was taken and added with 2.89 mL of sodium acetate buffer solution (0.05 mol / L, pH = 5.5) and 90 μL of linoleic acid substrate. The mixture was evenly mixed and the absorbance at 234 nm was measured.

[0189] (3) Peroxidase: Weigh 1 g of sample into a 50 mL centrifuge tube, add 20 mL of phosphate buffer (0.05 mol / L, pH = 5.5), let stand for 30 min, centrifuge at 4000 r / min for 10 min, and retain the supernatant. Mix 1 mL of 2% hydrogen peroxide, 2 mL of phosphate buffer, 1 mL of peroxidase extract and 1 mL of guaiacol (0.05 mol / L) evenly and measure quickly, record the change of absorbance at 470 nm within 0-4 min, and express it in U / g·min.

[0190] (4) Catalase determination shall refer to GB / T 5522-2008.

[0191] (5) Determination of fat hydrolysis and oxidation indicators includes: fatty acid value determination according to GB / T 15684-2015. Peroxide value determination according to GB 5009.227-2016. Carbonyl value determination: Use petroleum ether as solvent, solid-liquid ratio 1:16, and extract rice oil at room temperature for 6 hours. Weigh 0.025g of oil in a 50mL centrifuge tube, fully dissolve it with toluene solution and dilute it to 25mL, shake it thoroughly to make it fully dissolved, take 5mL in a 25mL stoppered test tube, add 3mL of toluene solution (containing 4.3% trichloroacetic acid by mass) and 5mL of 0.05% 2,4-dinitrophenylhydrazine toluene solution, mix thoroughly, heat in a 60℃ water bath for 30min, cool, add 10mL of ethanol solution (containing 4% potassium hydroxide) and dilute to the scale, shake well, and leave at room temperature for 10min. The blank is toluene solution, and the absorbance is measured at a wavelength of 453nm. The carbonyl value is expressed as the number of millimoles of carbonyl compounds per 1 kg of oil.

[0192] (6) Volatile components: Accurately weigh 5 g of sample into a 30 mL headspace extraction bottle, quickly add 20 μL of 10 mg / L 2,4,6-trimethylpyridine internal standard, balance in an 80 °C water bath for 15 min, headspace extraction for 30 min, desorb in the injection port of GC-MS (ISQ 7000) Thermo Fisher Scientific Inc., USA for 5 min. Chromatographic conditions: HP-5MS capillary column (30 m × 0.25 μm × 0.25 μm), injection port temperature of 250 °C, carrier gas of high purity helium, flow rate of 1.0 mL / min, split ratio of 10:1, heating program: initial temperature of 40 °C, hold for 3 min, then heat to 150 °C at a rate of 4 °C / min, hold for 1 min, then heat to 250 °C at a rate of 8 °C / min, hold for 6 min, detection time of 50 min. Mass spectrometry conditions: EI ion source, electron energy of 70 eV, ion source temperature of 250 °C, interface temperature of 220 °C, acquisition mode of full scan, acquisition mass range of 35-500 m / z.

[0193] (7) Water distribution: Take 2 g of sample, wrap it in fresh-keeping wrap, put it into a nuclear magnetic resonance tube, place it in a low-field nuclear magnetic resonance instrument (MicroMR-25), and measure the transverse relaxation time using the CPMG sequence. The parameters are set as follows: echo time TE = 0.11 ms, 90°C hard pulse RF pulse width P1 = 6 μs, 180°C hard pulse RF pulse width P2 = 11 μs, sampling point number TD = 123348 ms, and scanning number NS = 4.

[0194] Evaluation of the effects of different embodiments on the physical properties of buckwheat bran

[0195] (1) Particle size analysis: The particle size distribution of buckwheat bran was determined using a laser diffraction particle size analyzer (Bettersize 2600, Bettersize Instrument Co., Ltd., Dandong, China). The results were expressed as the average diameter D 50 and ((D 90 -D 10 ) / D 50 )express.

[0196] (2) Hydration properties: 1.0 g of sample was added with 20 mL of distilled water and boiled for 15 min. After cooling, it was centrifuged at 4000 g for 15 min and freeze-dried in vacuum (-80 °C, 10 h) until a constant weight was obtained. WAI was expressed as g sediment / g dry sample weight, and WSI was expressed as g soluble solids / 100 g dry sample weight.

[0197] (3) Color value: The color of buckwheat bran was measured using a colorimeter (SC-80C), Beijing Kangguang Optical Instrument Co., Ltd., and expressed as L* (brightness), a* (redness), and b* (yellowness). The whiteness index (WI) and total color difference (ΔE) were calculated according to the following equations:

[0198]

[0199] (4) Gelatinization properties: The gelatinization properties of buckwheat bran were measured by a rapid viscosity analyzer (RVA-TecMaster, Perdon Instruments, Sweden). 3.0 g of sample was weighed in an aluminum can, and then 25.0 mL of distilled water was added. The test procedure was as follows: the initial temperature was 50 °C, and heating continued after 1 min, and it took 3.45 min to heat to 95 °C, and then it began to cool down after 2.4 min, and it cooled to the initial test temperature in about 3 min, and kept at the initial test temperature for 2.5 min.

[0200] Determination of antioxidant capacity

[0201] (1) DPPH free radical scavenging ability: Trolox solution with a concentration of 400 μmol / L was prepared using anhydrous ethanol. Trolox solution of different volumes (0, 2, 4, 6, 8 mL) was placed in a 10 mL volumetric flask and fixed to volume. Then, a certain amount of DPPH was taken and placed in a 10 mL volumetric flask, and the volume was fixed with anhydrous ethanol to prepare a DPPH solution with a concentration of 200 μmol / L. Trolox solution of different concentrations, DPPH solution and anhydrous ethanol were fully mixed in a volume ratio of 1:4:5, and reacted in the dark for 30 minutes. Finally, the absorbance value was measured at 517 nm. Buckwheat bran after different pretreatments and buckwheat peptides before and after pressure cooking were prepared into a solution. Sample solution, DPPH solution and anhydrous ethanol were fully mixed in a volume ratio of 1:4:5. After reacting in the dark for 30 minutes, the absorbance value was measured at 517 nm. Based on the standard curve y DPPH1 =-0.0011x+0.6978, R 2 =0.9981,y DPPH2 =-0.0011x+0.0748, R 2 =0.9994, calculate the free radical scavenging ability of the sample.

[0202] (2) ABTS free radical scavenging ability: Use anhydrous ethanol to prepare a Trolox solution with a concentration of 1000 μmol / L. Place different volumes of Trolox solution (0, 2, 4, 6, 8 mL) in a 10 mL volumetric flask and adjust the volume. Then, take a certain amount of ABTS and place it in a volumetric flask, adjust the volume, and prepare a 7 mmol / L ABTS solution. ABTS free radical stock solution: Mix potassium persulfate (2.45 mmol / L) and ABTS solution in a volume ratio of 1:2. React in a dark environment for 16 hours. ABTS working solution: When the ABTS free radical stock solution is diluted with anhydrous ethanol to 30°C, the absorbance value at a wavelength of 734 nm is about 0.70, and it is prepared and used immediately. Take the ABTS solution and mix it evenly with Trolox solutions of different concentrations at a volume ratio of 25:1, and react in the dark for 10 minutes. Finally, record the absorbance value measured at 734 nm. The tartary buckwheat bran after different pretreatments and the tartary buckwheat peptides before and after pressure cooking were prepared into sample solutions and mixed evenly with the ABTS free radical working solution at a volume ratio of 1:25. After 10 minutes, the absorbance value was measured at 734 nm. Based on the ABTS standard curve: ABTS1 =-0.00007x+0.6632, R 2 =0.9997,y ABTS2 =-0.0007x+0.6578, R 2 =0.9985, calculate the free radical scavenging ability of the sample.

[0203] (3) FRAP antioxidant capacity determination: Use anhydrous ethanol to prepare a Trolox solution with a concentration of 1000 μmol / L. FRAP working solution: Dilute it with distilled water to the same gradient as the above standard curve. Sodium acetate solution (300 mmol / L, pH = 3.6), ferric chloride hexahydrate solution (20 mmol / L) and TPTZ solution (10 mmol / L) were mixed at a volume ratio of 10:1:1 and used immediately. Take the FRAP solution and mix it with Trolox solutions of different concentrations at a volume ratio of 100:1 and place it in a 37°C constant temperature water bath. After 30 minutes, the absorbance value was measured at 593 nm. The buckwheat bran after different pretreatments and the buckwheat active peptides before and after pressure cooking were prepared into sample solutions and mixed with the FRAP free radical working solution at a volume ratio of 100:1 and fully shaken, and then placed in a 37°C constant temperature water bath. After 30 minutes, the absorbance value was measured at 593 nm. Based on the FRAP standard curve y FRAP1 =0.0002x+0.1252, R 2 =0.993,y FRAP2 =0.0002x+0.1252, R 2 =0.9993, calculate the iron reducing ability of the sample.

[0204] Determination of the degree of hydrolysis of buckwheat active peptides: First, a protein standard curve was prepared, and then the o-phthalaldehyde (OPA) assay was used to determine the degree of hydrolysis (DH) of the sample. 25 mL, 100 mM sodium tetraborate, 1 mL of OPA solution (0.3 M OPA dissolved in methanol), 100 μL of 2-mercaptoethanol, and 2.5 mL of 20% (w / v) SDS were added to deionized water to obtain 50 mL of OPA reagent. Dissolve the isolated protein in 0.1 M sodium hydroxide and configure it to a concentration of 20 mg / mL. In a 96-well plate, add 10 μL of isolated protein and 200 μL of OPA reagent and repeat three times. Then, immediately read the absorbance at a wavelength of 340 nm. The formula for calculating the degree of hydrolysis is as follows:

[0205]

[0206] Abs is the absorbance at 340 nm, 134 is the molar mass of OPA, and C is the protein content determined by Lowry analysis.

[0207] Determination of the blood sugar lowering ability of buckwheat active peptides

[0208] (1) Inhibition of α-amylase activity: Use PBS buffer (0.1M, pH=6.8) to prepare a 1U / mL α-amylase solution and a 1% (w / v) starch solution. Add the α-amylase solution and starch solution to the sample solution in turn and mix well, and react at 37°C for 5 minutes. Subsequently, add the DNS reagent, and heat the reaction solution in a boiling water bath for 15 minutes, then quickly take it out and cool it. Mix the sample solution, α-amylase, starch solution, and DNS reagent in a volume ratio of 2:2:5:2. After the reaction is completed, add 2mL of distilled water to the mixture and record the absorbance value measured at a wavelength of 540nm. Based on the absorbance value, calculate the α-amylase inhibition rate according to the following formula:

[0209]

[0210] A: control group, absorbance value of PBS buffer instead of sample; B: blank group, absorbance value of PBS buffer instead of enzyme; C: sample group, absorbance value of supernatant of test sample.

[0211] (2) α-glucosidase inhibition: Prepare 0.2U / mL α-glucosidase solution with PBS buffer (0.1M, pH=6.8), and then prepare 4mmol / L 4-nitrophenyl-β-D-pyranoglucoside (PNPG) solution. Mix equal amounts of PBS buffer, PNPG solution and sample solution and react at 37°C for 5 minutes, then add the same volume of α-glucosidase solution and react at 37°C for 30 minutes. Finally, add an appropriate amount of Na2CO3 (1mol / L) to terminate the reaction. Record the absorbance measured at 405nm. According to the experimental results, the inhibition rate of α-glucosidase is calculated as follows:

[0212]

[0213] A: control group, absorbance value after the reaction of enzyme and substrate; B: blank group, absorbance value of PBS buffer instead of the tested sample and α-glucosidase solution; C: sample group, absorbance value of sample supernatant; D: sample control group, absorbance value of α-glucosidase solution replaced by an equal amount of PBS buffer.

[0214] (3) Pancreatic lipase inhibition: Use PBS buffer (0.1M, pH = 7.3) to prepare a 0.2U / mL pancreatic lipase solution, and then prepare a 10mM p-nitrophenylbutyric acid solution. Pre-react the PBS buffer, p-nitrophenylbutyric acid solution and sample solution at a volume ratio of 2:1:2 at 37°C for 15 minutes and mix thoroughly. Then, add an equal amount of pancreatic lipase solution to the p-nitrophenylbutyric acid solution and react at 37°C for 30 minutes. Finally, measure the absorbance at 405nm and record the content of p-nitrophenyl released. Based on the experimental results, calculate the pancreatic lipase inhibition rate:

[0215]

[0216] A: control group, absorbance value after the reaction of enzyme and substrate; B: blank group, absorbance value of PBS buffer instead of the tested sample and pancreatic lipase solution; C: sample group, absorbance value of sample supernatant; D: sample control group, absorbance value of pancreatic lipase solution replaced by an equal amount of PBS buffer.

[0217] Determination of antibacterial ability of buckwheat active peptides

[0218] The test strains of the present invention are selected from Escherichia coli and Staphylococcus aureus, and the antibacterial activity of the active peptide of bitter buckwheat is measured. First, the strains are activated. Under sterile conditions, the test strains are picked up by three-zone lines with an inoculation loop and inoculated into LB solid culture medium, cultured in a constant temperature incubator at 37°C for 24 hours, and repeatedly cultured and activated to 2-3 generations. Subsequently, the activated test strain is inoculated into LB liquid culture medium, cultured in an air bath shaker (37°C, 180r / min) for 6-8 hours, and then its absorbance is measured at 600nm, and a bacterial solution with a concentration of 1×106CFU / mL is selected. When the absorbance reaches 0.78±0.02, the bacterial solution is stored at 4°C for use. Subsequently, the minimum inhibitory capacity (MIC) test is performed, and the antibacterial experiment is performed by a two-fold dilution method. A 50mg / mL bitter buckwheat peptide solution is used as the initial concentration. Under sterile conditions, 150 μL of LB liquid culture medium and 150 μL of sample solution were placed in a 96-well plate and mixed thoroughly. Then 150 μL of the mixture was drawn from it and mixed thoroughly with 150 μL of LB liquid culture medium, and six groups of different concentration gradients were formed, and a group of parallel experiments were performed. Finally, 5 μL of diluted bacterial solution was added to each well and mixed thoroughly. In the positive control group, 5 μL of bacterial solution was mixed with 150 μL of LB liquid culture medium, and only 150 μL of LB liquid culture medium was added to the negative control group. Next, the sealed 96-well plate was placed in a constant temperature incubator and cultured at 37°C for 24 hours. For those samples where no obvious bacterial growth was observed in the wells, the corresponding lowest concentration was regarded as the minimum inhibitory concentration (MIC) of the bacteria. Inhibitory growth curve: Under sterile conditions, equal volumes of sample solution and LB liquid culture medium were added to a 96-well plate and mixed thoroughly. Subsequently, a diluted trace amount of bacterial solution was added to each well and mixed again. Place the sealed 96-well plate in a constant temperature incubator and culture at 37°C for 48 hours. Record the absorbance of the bacterial solution at a wavelength of 600nm every 3 hours. Compare the bacteria cultured after adding the sample with the bacteria that grow normally to draw a bacterial growth curve.

[0219] Quality evaluation of tartary buckwheat flour in different embodiments

[0220] (1) Analysis of starch HI and GI values: The product was hydrolyzed using amyloglucosidase and pepsin, and fully hydrolyzed using a constant temperature water bath shaker. The starch hydrolyzate was measured at 0, 30, 60, 90, 120, 150, and 180 min of hydrolysis. The glucose standard curve (y = 2.7997x + 0.1358, R 2 =0.9912) to calculate the starch hydrolysis index (HI) and glycemic index (GI) of the samples.

[0221] (2) Sensory evaluation: During the test, sensory assessors were selected and trained according to ISO standards, and 10 sensory assessors were selected. After the preparation of tartary buckwheat rice flour, the tartary buckwheat rice flour showed different sensory properties in terms of taste, aroma, etc. In order to better understand the sensory properties of tartary buckwheat rice flour, it can be scored according to the sensory scoring criteria in Table 1.

[0222] Table 1 Sensory scoring criteria

[0223]

[0224] (3) Acid value

[0225] The acid value of tartary buckwheat flour under different storage conditions was determined. The national standard GB 5009.229-2016 was adopted with appropriate modifications.

[0226] (4) Total colony count

[0227] The national standard GB 4789.2-2016 was used with appropriate modifications to determine the changes in the total number of bacterial colonies in buckwheat flour during storage. 5 CFU / g, buckwheat flour should not be eaten.

[0228] Table 2 Lipase and related indexes after rice storage for 90 days

[0229]

[0230] Note: Different lowercase letters indicate significant differences among different pretreatments of buckwheat bran (P<0.05).

[0231] Example 1 has the best enzyme inactivation effect on rice. When the rice is treated at 850W microwave power for 50s and then stored for 90 days, its lipase, lipoxygenase, peroxidase, catalase, fatty acid value, peroxide value and carbonyl value are all the lowest values ​​and the enzyme activity is relatively stable. It shows that microwave treatment can effectively inhibit the activity of lipase during rice storage, and then inhibit the generation of free fatty acids after hydrolysis of rice fat. It can effectively reduce the production of rice polyunsaturated fatty acids and their harmful substances and bad flavors, inhibit the generation of hydroperoxides, and effectively prevent further oxidation and rancidity of rice lipids. Even after storage at 37°C for 90 days, the fatty acid value of rice after microwave treatment is 14.64mg / 100g, which is far below the national limit standard of 25mg / 100g. Therefore, the heat treatment of Example 1 can most effectively extend the storage period of rice products.

[0232] Table 3 Lipase and related indexes of tartary buckwheat bran stored for 90 days

[0233]

[0234] Note: Different lowercase letters indicate significant differences among different pretreatments of buckwheat bran (P<0.05).

[0235] After the tartary buckwheat bran was subjected to baking extrusion heat treatment, its fatty acid value, peroxide value and carbonyl value were all maintained at an acceptable level, and the enzyme inactivation effect was the best. Baking extrusion heat treatment can effectively reduce the production of unsaturated fatty acids and harmful substances in tartary buckwheat bran, inhibit the production of hydroperoxides, and prevent further oxidation and rancidity of tartary buckwheat bran. After heat treatment, the peroxide value and carbonyl value of tartary buckwheat bran were significantly reduced (P<0.05), and the heat treatment in Example 7 had the best enzyme inactivation effect, which can effectively extend the storage period of tartary buckwheat bran.

[0236] Table 4 Antioxidant capacity and active ingredient content of tartary buckwheat bran

[0237]

[0238] Note: Different lowercase letters indicate significant differences among different pretreatments of buckwheat bran (P<0.05).

[0239] After the tartary buckwheat bran was baked and extruded and heat-treated in Example 7, the antioxidant capacity of the tartary buckwheat bran was significantly enhanced (P<0.05), and its DPPH, ABTS free radical scavenging ability and iron ion reducing ability were the highest. After the tartary buckwheat bran was treated in Example 7, its polyphenol and flavonoid contents were significantly increased (P<0.05), which was the highest among all groups. This may be due to the high pressure and high shear force during the extrusion process, which destroyed the covalent bonds between the phenolic compounds and the cell wall, promoting the release of bound phenolic and flavonoid compounds. Therefore, the heat treatment in Example 7 has the best effect in improving the nutritional properties of tartary buckwheat bran.

[0240] Table 5 Gelatinization characteristics of tartary buckwheat bran

[0241]

[0242] Note: Different lowercase letters indicate significant differences among different pretreatments of buckwheat bran (P<0.05).

[0243] The peak viscosity, valley viscosity, final viscosity, breakage value and retrogradation value after baking extrusion heat treatment of buckwheat bran in embodiment 7 are significantly reduced (P<0.05), indicating that the thermal stability of the buckwheat bran after baking extrusion is higher, not easy to age, and the adhesion to other particles is stronger, and the swelling degree is reduced. This may be caused by partial gelatinization of starch or damage after baking and extrusion, and the disordered starch structure causes the starch swelling to reduce, the dispersion of starch granules and the decomposition of protein increase the water binding site, and are more conducive to improving its solubility and water absorption. Therefore, the improvement effect of embodiment 7 on the physical properties of buckwheat bran is the most significant.

[0244] Table 6 Particle size, water absorption index (WAI), water solubility index (WSI) and chromaticity value of buckwheat bran

[0245]

[0246]

[0247] Note: Different lowercase letters indicate significant differences among different pretreatments of buckwheat bran (P<0.05).

[0248] Example 7 D of tartary buckwheat bran 50 The value was significantly reduced, and the dispersion result was significantly increased (P<0.05), indicating that the particle size of buckwheat bran in Example 7 was significantly reduced. The water absorption index and water solubility index of buckwheat bran in Example 7 were also significantly increased, thanks to the specific surface exposure and degradation of buckwheat bran polysaccharides by baking and extrusion, which increased the binding sites of water. Baking and extrusion will greatly destroy the fiber polymer of buckwheat bran and improve the solubility of buckwheat bran. In addition, the L* value of buckwheat bran in Example 7 was significantly reduced (P<0.05), the a* value and b* value were significantly increased (P<0.05), and the WAI value and total chromaticity value ΔE were significantly reduced (P<0.05). The total chromaticity value after baking and extrusion is lower than that of baking, which may be due to the occurrence of Maillard reaction and phospholipid degradation, causing browning.

[0249] Table 7 In vitro antioxidant, hypoglycemic, lipid-lowering and antibacterial activities of buckwheat active peptides

[0250]

[0251]

[0252] Note: Different lowercase letters indicate significant differences in active peptides of buckwheat under different pretreatments (P<0.05).

[0253] Analysis of antioxidant results: The buckwheat active peptides obtained by pressure cooking with composite protease (alkaline protease: papain = 1:1) in Example 22 have the highest DPPH, ABTS free radical scavenging ability and iron ion reducing ability, which are significantly higher than the hydrolyzates obtained by treating with a single alkaline protease or papain alone. Pressure cooking reduces the antioxidant capacity of buckwheat bran protein hydrolyzates, which may be because the protein undergoes thermal denaturation during the heating process, which means that the three-dimensional structure of the protein may change, including changes in the secondary structure. The antioxidant capacity is positively correlated with the content of active peptides. The hydrolyzate obtained by treating buckwheat protein in Example 22 has the highest content, which is the main method for enzymatic extraction of buckwheat peptides, and will greatly enhance the activity of this functional ingredient.

[0254] Analysis of hypoglycemic and hypolipidemic results: The tartary buckwheat bran protein hydrolysate before and after treatment in Example 22 had significant inhibitory effects on α-amylase, α-glucosidase and pancreatic lipase, and the inhibitory effects were greatly improved compared with those of tartary buckwheat protein. Among them, the tartary buckwheat active peptides obtained by composite protease treatment had better inhibitory effects on the three enzymes. Therefore, the tartary buckwheat active peptides obtained by treatment in Example 22 had the strongest hypoglycemic and hypolipidemic activities in vitro.

[0255] Analysis of antibacterial results: The inhibitory ability of the buckwheat bran protein hydrolysate treated in Example 22 on Escherichia coli and Staphylococcus aureus is enhanced to varying degrees. For Escherichia coli, the minimum inhibitory concentration of the buckwheat active peptide obtained by the composite protease treatment is 3.75g / L regardless of whether the raw material has been subjected to pressure cooking, which is significantly lower than that of buckwheat protein, and the inhibitory effect is stronger than that of alkaline protease and papain alone. For Staphylococcus aureus, the minimum inhibitory concentration of the buckwheat peptide obtained by the raw material without pressure cooking and using the composite protease treatment is 1.88g / L, while the minimum inhibitory concentration after pre-treatment is 3.75g / L. Pressure cooking can cause some heat-sensitive amino acids and protein structure changes, thereby affecting the antibacterial properties of buckwheat peptides. The buckwheat active peptides obtained by the treatment in Example 22 can significantly inhibit the growth of Escherichia coli and Staphylococcus aureus, and have the best antibacterial effect.

[0256] Table 8 Physicochemical properties of buckwheat meal replacement powder formula

[0257]

[0258] Note: Different lowercase letters indicate significant differences among buckwheat meal replacement powder samples with different formulas (P<0.05).

[0259] The GI value of the low GI nutritional meal replacement powder obtained by Example 29 is 54.5, which is a low GI food. The GI value of the meal replacement powder with added tartary buckwheat bran is significantly lower than that of the meal replacement powder without addition. And 15% tartary buckwheat bran makes the meal replacement powder not easy to clump, 10% milk powder addition can best stabilize the dissolution performance of the meal replacement powder, 15% xylitol has the best taste, and the addition of 8% tartary buckwheat active peptides significantly improves the nutritional value of the meal replacement powder, with the highest sensory score. The addition of 0.35% sodium carboxymethyl cellulose, 0.25% monoglyceride and 0.3% maltodextrin improves the dissolution stability of the meal replacement powder. Therefore, the formula of the best low GI nutritional meal replacement powder in Example 29 is 51.2% rice flour, 15% tartary buckwheat bran, 10% milk powder, 8% tartary buckwheat active peptides, 15% xylitol, 0.35% sodium carboxymethyl cellulose, 0.25% monoglyceride, and 0.3% maltodextrin.

[0260] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A low GI tartary buckwheat nutritional meal replacement powder, characterized in that: The composition comprises the following components in parts by weight: 44.15-56 parts of enzyme-killed rice flour, 10-20 parts of enzyme-killed tartary buckwheat bran powder, 8-12 parts of milk powder, 8-10 parts of tartary buckwheat active polypeptides, 10-20 parts of xylitol, 0.3-0.4 parts of sodium carboxymethyl cellulose, 0.25-0.4 parts of monoglyceride and 0.25-0.35 parts of maltodextrin; The enzyme-killed rice flour is obtained by subjecting the rice flour to microwave treatment; the power of the microwave treatment is 650-950W, and the time is 25-75s; The enzyme-inactivated tartary buckwheat bran powder is obtained by baking and extruding tartary buckwheat bran; the baking temperature is 180-220° C., and the time is 10-20 minutes; the water content of the tartary buckwheat bran is 20-30%; The extrusion conditions include: the temperature of the treatment zone is 70-90°C, the temperature of the mixing zone is 90-110°C, the temperature of the shearing zone is 110-130°C, and the temperature of the pressure relief zone is 110-130°C; The tartary buckwheat active polypeptide is obtained by pressure cooking and enzymolysis of tartary buckwheat bran; The pressure cooking conditions include: pressure of 0.05-0.2 MPa, temperature of 120° C., and time of 20 min; The enzymes used in the enzymolysis include papain and / or alkaline protease.

2. The low GI tartary buckwheat nutritional meal replacement powder according to claim 1, characterized in that The composition comprises the following components in parts by weight: 48.2-51.1 parts of enzyme-killed rice flour, 15 parts of enzyme-killed tartary buckwheat bran powder, 10 parts of milk powder, 8-10 parts of tartary buckwheat active polypeptides, 15 parts of xylitol, 0.35 part of sodium carboxymethyl cellulose, 0.3-0.35 parts of monoglyceride and 0.3 part of maltodextrin.

3. The low GI tartary buckwheat nutritional meal replacement powder according to claim 1, characterized in that: The power of the microwave treatment is 750-850W, and the time is 50s.

4. The low GI tartary buckwheat nutritional meal replacement powder according to claim 1, characterized in that: The baking temperature is 200° C. and the baking time is 15 minutes.

5. The low GI tartary buckwheat nutritional meal replacement powder according to claim 1, characterized in that: The extrusion conditions include: the temperature of the treatment zone is 80°C, the temperature of the mixing zone is 100°C, the temperature of the shearing zone is 120°C, and the temperature of the pressure relief zone is 120°C.

6. The low GI tartary buckwheat nutritional meal replacement powder according to claim 1, characterized in that: When the enzymes are papain and alkaline protease, the mass ratio of papain to alkaline protease is 1-1.5:1-1.

5.

7. The low GI tartary buckwheat nutritional meal replacement powder according to claim 1, characterized in that: The conditions for the enzymatic hydrolysis include: a temperature of 50° C., a pH value of 7.0, a rotation speed of 100 rpm, and a time of 3 hours.

8. The low GI tartary buckwheat nutritional meal replacement powder according to claim 1, characterized in that: The method for preparing the tartary buckwheat active polypeptide comprises the following steps: 1) adjusting the moisture content of tartary buckwheat bran to 40% and then performing pressure cooking, drying and pulverizing at 60° C. to obtain cooked tartary buckwheat bran; 2) defatting the steamed buckwheat bran obtained in step 1) to obtain defatted bran; Use n-hexane for degreasing, with a solid-liquid ratio of 1:4, a rotation speed of 200 rpm, and a time of 12 h; 3) mixing the defatted bran obtained in step 2) with water, adjusting the pH value to 10.0, stirring and centrifuging to obtain a supernatant; The mass ratio of the defatted bran to water is 1:10; The stirring conditions include: magnetic stirring at a temperature of 35° C. for 90 min; The centrifugal conditions include: temperature of 4°C, rotation speed of 8000 rpm, and time of 20 min; 4) adjusting the pH value of the supernatant obtained in step 3) to 4.5, and obtaining a precipitate after centrifugation; The centrifugal conditions include: temperature of 4°C, rotation speed of 8000 rpm, and time of 20 min; 5) re-dissolving the precipitate obtained in step 4), placing it into a dialysis bag with a molecular cutoff of 8000 to 14000 Da, dialyzing it, and vacuum freeze-drying it to obtain tartary buckwheat protein; The vacuum freeze drying temperature is -80°C and the time is 10h; The buffer used for the re-dissolution is PBS buffer with a pH value of 7.0; The dialysis conditions include: the time is 24 hours, and the PBS buffer is replaced once every 3 hours; 6) mixing the tartary buckwheat protein obtained in step 5) with water to obtain a tartary buckwheat protein solution, mixing the tartary buckwheat protein solution with an enzyme, performing enzymolysis, inactivating the enzyme, and centrifuging the obtained supernatant by vacuum freeze-drying to obtain tartary buckwheat active polypeptides; The vacuum freeze drying temperature is -80°C and the time is 10h; The enzymes were mixed at an enzyme:substrate mass ratio of 1:100; The enzyme inactivation conditions include: boiling for 10 minutes; The centrifugal conditions include: temperature of 4°C, time of 10 min, and rotation speed of 10000 rpm.

9. A method for preparing the low GI tartary buckwheat nutritional meal replacement powder according to any one of claims 1 to 8, characterized in that: The following steps are involved: The enzyme-killed rice flour, enzyme-killed tartary buckwheat bran powder, milk powder, tartary buckwheat active polypeptide, xylitol, sodium carboxymethyl cellulose, monoglyceride and maltodextrin are mixed, and spray-dried to remove moisture to obtain low-GI tartary buckwheat nutritional meal replacement powder.

10. Use of the low GI tartary buckwheat nutritional meal replacement powder according to any one of claims 1 to 8 in extending the shelf life.

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