Preparation method of low-bitterness sesame protein hydrolysate with oxidation resistance

Abstract

The invention belongs to the field of deep processing of agricultural products, and particularly relates to a preparation method of low-bitterness sesame protein hydrolysate with oxidation resistance, and the sesame protein hydrolysate prepared by the method has strong free radical scavenging ability and weak bitterness. The low-bitterness sesame protein hydrolysate is prepared by taking sesame cake meal as a raw material through degreasing, protein extraction, homogenization, enzymolysis, resin adsorption and membrane separation. The sesame protein hydrolysate has strong oxidation resistance, good taste and good applicability, can be used as a main material for producing oral liquid, capsules and other products, can also be used as an ingredient for other foods, and has a wide market prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of deep processing of plant protein, and specifically relates to a method for preparing a low-bitter sesame protein hydrolyzate with antioxidant properties and its application in food. The method uses high-temperature sesame cake as raw material, and obtains low-bitter sesame hydrolyzate through protein extraction, protein dispersion, multi-enzyme hydrolysis, resin adsorption, membrane separation, etc. Background Art

[0002] Sesame is one of the world's major oil crops. my country is a major producer and consumer of sesame. In 2023, sesame output and sesame consumption will be about 435,300 tons and 1.5 million tons respectively. At present, sesame in my country is mainly used for oil extraction. The production of sesame oil will produce high-temperature sesame cake, which is a by-product of oil extraction after high-temperature baking and fragrance production process (temperature above 150°C, heating time more than 30 minutes). About 600,000 tons of high-temperature sesame cake are produced each year. High-temperature sesame cake is rich in protein (protein content is about 40%), but due to high-temperature denaturation, the protein in high-temperature sesame cake has poor water solubility and is difficult to extract and utilize. It is mostly used as feed and fertilizer, and the protein in high-temperature sesame cake is not fully utilized.

[0003] Studies have shown that the enzymatic hydrolyzate of high-temperature sesame meal protein has a variety of biological activities, such as antioxidant and antihypertensive activities. Therefore, making high-temperature sesame meal protein into a bioactive hydrolyzate is an effective way to improve quality and efficiency. However, the high-temperature sesame meal protein hydrolyzate has a bitter taste, which damages the sensory quality of the product and affects product sales and promotion. In order to remove the bitterness of protein hydrolyzates, people have developed two types of methods: physicochemical debittering and biological debittering. Among them, physicochemical debittering includes embedding method, masking method, and separation method. Biological debittering mainly uses enzymes or microorganisms to modify or metabolize bitter substances to achieve a debittering effect. The physicochemical debittering method has the advantages of easy operation and low cost, but the addition of chemicals has safety risks and the debittering effect is unstable. Although the biological debittering method has the advantages of significant debittering effect and mild conditions, it takes a long time to process and requires strict control of the processing conditions. Therefore, the debittering of protein hydrolyzates requires a reasonable combination of physicochemical and biological debittering methods to obtain the best debittering effect. In addition, since the high-temperature sesame meal protein has poor dispersibility in water, it hinders enzymolysis, thereby reducing the polypeptide yield and increasing the production cost. It is necessary to use relevant technologies to improve the dispersion stability of high-temperature sesame meal protein in water to improve the enzymolysis effect. Therefore, in order to improve the sensory quality of sesame protein hydrolysate, improve enzymolysis efficiency, and control production costs, it is necessary to develop a preparation method for low-bitter sesame protein hydrolysate.

[0004] This application was developed based on this. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a method for preparing a low-bitter sesame protein hydrolyzate with antioxidant properties from sesame cake that can be industrially produced. The method has the advantages of high production efficiency, green environmental protection, low product bitterness, good antioxidant activity, etc.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a low-bitter sesame protein hydrolyzate with antioxidant properties, comprising defatting sesame cake, extracting protein, dispersing protein, multi-enzyme hydrolysis, resin adsorption, membrane separation, desalting and concentration, freeze drying, etc. The specific steps are as follows:

[0008] 1) Defatting sesame cake and extracting sesame protein:

[0009] The sesame cake was crushed to 40-100 mesh after removing stones, burnt materials, straws and other impurities, and defatted by Soxhlet extraction. Distilled water was added to the defatted sesame cake, and the pH was adjusted to 9-12 with NaOH solution, stirred at room temperature for 15-50 minutes, centrifuged, and the supernatant was collected. The pH was adjusted to 4-5 with HCl solution, allowed to stand, centrifuged, and the precipitate was collected and freeze-dried to obtain sesame protein;

[0010] 2) Protein dispersion treatment:

[0011] The sesame protein obtained in step 1) is crushed (crushed to 80-120 mesh), distilled water is added, and the pH is adjusted to 8-11 to obtain a sesame protein solution, which is subjected to high temperature treatment, cooled to room temperature, and then dispersed at high speed (10000-15000 r / min for 10-30 s, 3-6 times of treatment), and homogenized at high pressure. After homogenization, the solution is kept at a low temperature of 4-10° C. for standby use;

[0012] 3) Multi-enzyme combined hydrolysis:

[0013] The solution obtained in step 2) is heated to a set temperature of 40-60°C, the pH is adjusted to 7-10.5, and multiple enzymes are added for enzymolysis. After enzymolysis for 3-7 hours, the pH is adjusted to neutral, and centrifuged (8000-10000 r / min for 20-40 minutes), and the supernatant is taken;

[0014] 4) Resin adsorption:

[0015] Add the supernatant from step 3) to a resin adsorption column. After adsorption, wash the column with distilled water, elute with 50-85% ethanol solution, and collect the eluate.

[0016] Among them, the resin adsorption conditions are: the sample volume is 0.5-1.0BV (Bed Volume), the sample loading rate is 0.25-0.75BV / h, the column washing volume of distilled water is 2.5-4.0BV, and the elution volume of ethanol solution is 2-4BV;

[0017] 5) Membrane separation

[0018] The ethanol is removed from the eluate in step 4) by rotary evaporation, and then distilled water is added to the volume of the solution before rotary evaporation, ultrafiltration is performed using an ultrafiltration membrane, the permeate is collected, and the concentrated solution is concentrated by a nanofiltration membrane, and the concentrated solution is freeze-vacuum dried to obtain the product. The product has strong antioxidant properties, good taste, and good applicability. It can be used as a main ingredient to produce oral liquids, capsules and other products, and can also be used as an ingredient for other foods, and has broad market prospects.

[0019] Specifically, in step 1), the sesame cake can be high-temperature sesame cake; and the amount of distilled water added is 10-20 times the mass of the sesame cake.

[0020] Furthermore, in step 1), the extraction solvent used for Soxhlet extraction can be n-hexane or petroleum ether (boiling range 30-90°C), the degreasing temperature is 50-100°C, the degreasing time is 6-10h, and the residual oil rate after degreasing is less than 1%. The concentration of the NaOH solution or HCl solution for adjusting the pH can be 3-6 mol / L. Centrifugation can be performed at 4000-5000 r / min for 15-30 min.

[0021] Specifically, in step 2), 1 g: 10-20 mL of distilled water can be added to obtain a sesame protein solution; in the high temperature treatment, the heating temperature is 100-160° C. and the heating time is 10-50 min. The high temperature and high pressure treatment can be completed by a high temperature and high pressure reactor or a high temperature and pressure tube.

[0022] Furthermore, in step 2), the high-pressure homogenization pressure is 100 Mpa-200 Mpa, and the process can be performed 2-6 times.

[0023] Specifically, in step 3) multi-enzyme combined hydrolysis, the added amount of the multi-enzyme can be 0.5-2.5% of the mass of sesame protein; the multi-enzyme can be composed of three or more of alkaline protease, aminopeptidase, flavor protease, trypsin, and neutral protease, among which aminopeptidase and flavor protease are essential components, the sum of the two accounts for 25%-40% of the mass of the multi-enzyme, and the ratio of the two is 3-0.5:1.

[0024] Further, in step 4), the resin adsorption is composed of non-polar and weak polar macroporous resins, wherein the mass ratio of non-polar and weak polar macroporous resins is 1:4-8, and the concentration of the eluent ethanol solution is 50-85% (volume percentage). The non-polar macroporous resin can be D101, HP20, HPD100, HPD910, XAD-2, etc., and the weak polar macroporous resin can be CAD40, AB-8, HPD722, HZ-841, etc.

[0025] Furthermore, in step 5), the eluate is ultrafiltered using an ultrafiltration membrane with a molecular weight cutoff of 5000-10000Da, the permeate is collected, and concentrated using a nanofiltration membrane with a molecular weight cutoff of 200-500Da, and the nanofiltration concentration is to 10-20% of the volume of the feed liquid.

[0026] The invention provides a low-bitter sesame protein hydrolyzate with antioxidant properties prepared by the preparation method. The sesame protein hydrolyzate has good taste and weak bitterness (the bitterness is difficult to detect, and the bitterness value measured by an electronic tongue is less than 0.5). Moreover, more than 80% of the sesame protein hydrolyzate has a molecular weight below 3000Da, has an easily acceptable taste, and can be widely used in the food industry.

[0027] The present invention also provides the use of the above-mentioned low-bitter sesame protein hydrolyzate with antioxidant properties as a main ingredient or ingredient in the preparation of antioxidant drugs, health products, foods, cosmetics, etc., which has broad application prospects.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1) The raw material used in the present invention is high-temperature sesame cake, which is rich in resources and has obvious cost advantages. In addition, the product has high added value and high processing and utilization value;

[0030] 2) The present invention improves the dispersibility of high-temperature sesame meal protein through high-temperature and high-pressure pretreatment and high-pressure homogenization, reduces the protein size, increases the contact probability between enzyme and protein, and improves the enzymatic hydrolysis effect;

[0031] 3) The multi-enzyme hydrolysis technology established by the present invention can effectively convert high-temperature sesame cake into sesame protein hydrolyzate with antioxidant activity and reduce bitterness;

[0032] 4) The sesame protein hydrolyzate provided by the present invention has high antioxidant activity and good taste, and can be used not only for food development, but also as a functional ingredient in medicines, health products and daily chemical products. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in the field without creative work are all within the protection scope of the present invention.

[0034] In the following examples, unless otherwise specified, the raw materials used are all common commercial products that can be directly purchased, or can be prepared by conventional methods in the art. For example, alkaline protease is derived from Bacillus licheniformis and purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd., with an enzyme activity of 200,000 u / g. Flavor protease is derived from Aspergillus oryzae and purchased from Novozymes, with an enzyme activity of about 200,000 u / g. Neutral protease is derived from Bacillus subtilis and purchased from Shaanxi Benhe Bioengineering Co., Ltd., with an enzyme activity of 100,000 u / g.

[0035] Aminopeptidase was purchased from Zhejiang Yicun Biotechnology Co., Ltd., 25 kg packaging, enzyme activity 50,000 u / g. Trypsin-Chymotrypsin, also known as chymotrypsin, was purchased from Aladdin Biochemical Technology Co., Ltd., item number T118254-100g, the ratio of the two enzyme activities was 2400:400 (6:1), and the total enzyme activity was close to 400,000 u / g.

[0036] Room temperature refers to 25±5°C.

[0037] Example 1

[0038] A method for preparing a low-bitter sesame protein hydrolyzate with antioxidant properties, which specifically comprises the following steps:

[0039] 1) High temperature sesame cake degreasing and sesame protein extraction:

[0040] Take 1kg of high-temperature sesame cake, remove impurities (remove stones, burnt objects, grass sticks and other debris), crush to 40 mesh, use n-hexane as the extraction solvent to degrease at 70℃ for 9h, and the residual oil rate is less than 1%. Spread the defatted sesame cake flat in a fume hood to remove the residual solvent and weigh it. Add 12.75L of distilled water to the defatted sesame cake, stir evenly, adjust the pH to 11 with 5mol / LNaOH solution, stir at room temperature for 40min, centrifuge at 4500r / min for 20min, collect the supernatant, adjust the pH to 4.4 with 5mol / LHCl solution, let stand for 1h, centrifuge at 5000r / min for 30min, collect the precipitate, freeze-dry (-40℃, -0.1Mpa for 36h, the same below), and obtain sesame protein;

[0041] 2) Protein pretreatment:

[0042] 200g of sesame protein obtained in step 1) was crushed to 100 mesh, 3L of distilled water was added, and the pH was adjusted to 9 to obtain a sesame protein solution, which was added to a high-temperature pressure-resistant tube and stirred at 150r / min, and heated in an oil bath at 130°C for 35min. After cooling to room temperature, high-speed dispersion was performed at 12000r / min for 30s, and after repeating 5 times, high-pressure homogenization was performed at 150MPa for 3 times. After homogenization, the solution was kept at 10°C for standby use;

[0043] 3) Multi-enzyme combined hydrolysis:

[0044] The solution obtained in step 2) was heated to 50°C, the pH was adjusted to 8.7, 2g of multienzyme (composed of alkaline protease, trypsin, flavor protease and aminopeptidase, the four enzymes accounting for 40%, 30%, 15% and 15% of the mass of the multienzyme respectively) was added for enzymolysis, and after 6h of enzymolysis, the pH was adjusted to neutral, centrifuged at 8000r / min for 20min, and the supernatant was collected;

[0045] 4) Resin adsorption debittering:

[0046] The supernatant from step 3) was added to a resin adsorption column with a bed volume (BV) of 1 L. The resins were AB-8 (weakly polar macroporous resin) and D101 (non-polar macroporous resin), and the mass ratio of the two was 5:1. The loading volume was 1 L, and the loading rate was 0.5 L / h. After adsorption, the column was washed with 3 L of distilled water, followed by elution with 3 L of 75% ethanol solution, and the eluate was collected;

[0047] 5) Membrane separation

[0048] The ethanol is removed from the eluate of step 4) by rotary evaporation at 80° C., and then distilled water is added to the volume of the solution before rotary evaporation, and ultrafiltration is performed using an ultrafiltration membrane with a molecular weight cutoff of 10,000 Da. The permeate is collected and then concentrated using a nanofiltration membrane with a molecular weight cutoff of 500 Da to 10% of the initial feed liquid volume, and freeze-dried in a vacuum (-40° C., -0.1 MPa for 30 h, the same below) to obtain a low-bitter sesame protein hydrolyzate product.

[0049] The product has good antioxidant activity, no bitter taste (bitterness value measured by electronic tongue is less than 0.5), and molecular weight is concentrated below 3000Da.

[0050] Example 2

[0051] A method for preparing a low-bitter sesame protein hydrolyzate with antioxidant properties, which specifically comprises the following steps:

[0052] 1) High temperature sesame cake degreasing and sesame protein extraction:

[0053] Take 3kg of high-temperature sesame cake, remove impurities (remove stones, burnt objects, grass sticks and other debris), crush to 60 mesh, use petroleum ether (boiling range 30-60°C) as extraction solvent to degrease at 65°C for 8 hours, and the residual oil rate is less than 1%. Put the defatted sesame cake into a fume hood to remove the residual solvent and weigh it. Add 50L of distilled water to the defatted sesame cake, stir evenly, adjust the pH to 12 with 5mol / LNaOH solution, stir at room temperature for 30min, centrifuge at 5000r / min for 30min, collect the supernatant, adjust the pH to 4.2 with 5mol / L HCl solution, let stand for 1h, centrifuge at 5000r / min for 30min, collect the precipitate, freeze-dry, and obtain sesame protein;

[0054] 2) Protein pretreatment:

[0055] 500g of sesame protein obtained in step 1) was crushed into 120 mesh, 10L of distilled water was added, and the pH was adjusted to 10 to obtain a sesame protein solution, which was added to a high-temperature and high-pressure reactor and stirred at 180r / min and heated at 140°C for 25min. After cooling to room temperature, high-speed dispersion was performed at 15000r / min for 30s, and after repeating 6 times, high-pressure homogenization was performed at 180MPa for 4 times. After homogenization, the solution was kept at 5°C for standby use;

[0056] 3) Multi-enzyme combined hydrolysis:

[0057] The solution obtained in step 2) was heated to 45°C, the pH was adjusted to 8, 10 g of multienzyme (the multienzyme consisted of neutral protease, chymotrypsin, flavor protease and aminopeptidase, and the four enzymes accounted for 25%, 40%, 20% and 15% of the mass of the multienzyme, respectively) was added for enzymolysis, and after 5 h of enzymolysis, the pH was adjusted to neutral, centrifuged at 10000 r / min for 30 min, and the supernatant was collected;

[0058] 4) Resin adsorption debittering:

[0059] The supernatant from step 3) was added in batches to a resin adsorption column with a bed volume of 2 L. The resins were CAD40 (weakly polar macroporous resin) and HP20 (non-polar macroporous resin), and the mass ratio of the two was 6:1. The loading volume was 1 L, and the loading rate was 0.75 L / h. After adsorption, the column was washed with 6 L of distilled water, and then eluted with 6 L of 85% ethanol solution, and the eluate was collected;

[0060] 5) Membrane separation

[0061] The ethanol is removed from the eluate in step 4) by rotary evaporation at 75° C., and then distilled water is added to the volume of the solution before rotary evaporation. Ultrafiltration is performed using an ultrafiltration membrane with a molecular weight cutoff of 10,000 Da, and the permeate is collected. The permeate is then concentrated using a nanofiltration membrane with a molecular weight cutoff of 500 Da and concentrated to 15% of the initial feed liquid volume, and then freeze-vacuum dried to obtain a low-bitter sesame protein hydrolyzate product.

[0062] The product has good antioxidant activity, no bitter taste (bitterness value measured by electronic tongue is less than 0.5), and molecular weight is concentrated below 3000Da.

[0063] Antioxidant activity application test

[0064] In the following application test, the DPPH and ABTS clearance rate determination was carried out as follows: The sesame protein hydrolyzate solution was prepared by adding lyophilized powder to distilled water to dilute it into an aqueous solution of a certain concentration.

[0065] 1) DPPH scavenging assay: 100 μL of sesame protein hydrolyzate solution was added to a 96-well ELISA plate, followed by 100 μL of 0.2 mmol / L DPPH ethanol solution, shaken for 30 seconds, reacted at room temperature in the dark for 30 minutes, and the absorbance A was measured at a wavelength of 517 nm. i The absorbance A of 100 μL sesame protein hydrolysate solution mixed with 100 μL ethanol was measured in the same way. j , and the absorbance A after mixing 100 μL 0.2 mmol / L DPPH ethanol solution with 100 μL ethanol o DPPH free radical scavenging rate (D I The calculation formula is as follows. The results are shown in Table 1.

[0066]

[0067] 2) ABTS scavenging ability assay: 25 μL of sesame protein hydrolyzate solution was added to a 96-well ELISA plate, followed by 200 μL of 3.7 mmol / L ABTS solution. The plate was incubated at room temperature in the dark for 6 min and the absorbance A was measured at a wavelength of 734 nm. i ', respectively measure the absorbance A after mixing 25 μL sesame protein hydrolyzate solution with 200 μL methanol j ', absorbance A after mixing 25 μL methanol with 200 μL 3.7 mmol / L ABTS solution o '. ABTS free radical scavenging rate (A I ) The calculation formula is as follows. The results are shown in

[0068] Table 1.

[0069]

[0070] The antioxidant application of low-bitter sesame polypeptides, the sesame protein hydrolysates obtained in Example 1 and Example 2 have high scavenging rates for DPPH and ABTS, which are about 89% and 95% respectively, and both show strong antioxidant activity (see Table 1). This shows that the sesame protein hydrolysate of the present invention can be used as an antioxidant for the preparation of antioxidant drugs, health products, foods, cosmetics, etc.

[0071] Table 1. Antioxidant activity of sesame protein hydrolysate products obtained in Examples 1 and 2

[0072] sample DPPH clearance rate (%) ABTS clearance rate (%) Example 1 90.56±0.38 97.37±0.61 Example 2 88.89±0.52 92.72±0.47

[0073] Note: When measuring the DPPH and ABTS clearance rates, the concentration of sesame protein hydrolysate solution was 2 mg / mL.

[0074] 3) The taste characteristics of sesame protein hydrolysate (bitterness, bitter aftertaste, astringency, astringent aftertaste, umami, umami aftertaste, sweetness, saltiness, and sourness) were determined using the SA402B electronic tongue. Test conditions: The sample was diluted to a sesame protein hydrolysate concentration of 5 mg / mL using 30 mmol / L KCl (containing 0.3 mmol / L tartaric acid). The data of each sample was collected 4 times, and the collection time was 120 s. The minimum error of 3 times was taken as the measurement data of each sample by the staggered method. The reference solution was a 30 mmol / L KCl solution (containing 0.3 mmol / L tartaric acid). When a certain taste data of the test sample was higher than the corresponding taste data of the reference solution, the sample presented that taste, and the greater the numerical difference, the stronger the taste, and vice versa, there was no such taste. When the difference between a certain taste data of the two samples was more than 1 scale, the difference was significant, and people could easily distinguish the difference in a certain taste of the above samples. The results are shown in Table 2.

[0075] Table 2. Taste characteristics of sesame protein hydrolysates obtained in Examples 1 and 2

[0076] index Example 1 Example 2 Reference solution bitterness 0.31±0.09 0.43±0.04 0 Bitter aftertaste -0.78±0.02 -0.42±0.02 0 Astringency -1.05±0.09 -0.89±0.08 0 Astringent aftertaste -1.46±0.05 -1.29±0.03 0 Umami 2.23±0.31 2.56±0.12 0 Umami aftertaste 0.73±0.07 0.53±0.08 0 Sweetness -4.40±0.13 -5.51±0.11 0 Salty 0.93±0.04 0.62±0.05 -6 sour -40.57±0.11 -44.82±0.19 -13

[0077] It can be seen from Table 2 that the sesame protein hydrolyzate solutions obtained in Examples 1 and 2 have weak bitterness, and exhibit weak saltiness and umami, while other tastes are lost, which provides favorable conditions for use as auxiliary materials in food.

[0078] 4) The determination method of protein and polypeptide amino acids was carried out according to GB / T 18246-2000. The results are shown in Table 3.

[0079] As shown in Table 3, after debittering, the content of hydrophobic amino acid residues (valine, proline, phenylalanine, methionine, leucine, isoleucine, alanine) in sesame protein hydrolysate decreased, and the arginine content also decreased. Studies have shown that the presence of hydrophobic amino acids or arginine at the N-terminus in sesame protein hydrolysate will enhance bitterness. Therefore, the above-mentioned changes in polypeptide amino acids also support the change in the decrease in bitterness of sesame protein hydrolysate.

[0080] Table 3. Amino acid composition of high temperature sesame meal protein and the products of Examples 1 and 2

[0081] Amino Acids High temperature sesame meal protein Example 1 Example 2 Aspartic acid <![CDATA[9.05±0.07 a ]]> <![CDATA[8.23±0.06 b ]]> <![CDATA[8.05±0.13 b ]]> Glutamate <![CDATA[20.84±0.09 a ]]> <![CDATA[20.05±0.07 b ]]> <![CDATA[20.09±0.10 b ]]> Arginine <![CDATA[13.11±0.15 a ]]> <![CDATA[12.68±0.09 b ]]> <![CDATA[12.65±0.12 b ]]> Lysine <![CDATA[3.59±0.06 b ]]> <![CDATA[5.51±0.06 a ]]> <![CDATA[5.59±0.02 a ]]> Histidine <![CDATA[2.85±0.08 b ]]> <![CDATA[3.49±0.01 a ]]> <![CDATA[3.40±0.03 a ]]> Cysteine <![CDATA[1.65±0.05 a ]]> <![CDATA[0.99±0.02 b ]]> <![CDATA[0.90±0.03 c ]]> Glycine <![CDATA[4.98±0.11 ab ]]> <![CDATA[4.96±0.06 b ]]> <![CDATA[5.13±0.05 a ]]> Serine <![CDATA[5.19±0.07 b ]]> <![CDATA[6.89±0.05 a ]]> <![CDATA[6.97±0.07 a ]]> Threonine <![CDATA[3.94±0.06 c ]]> <![CDATA[5.20±0.08 a ]]> <![CDATA[5.05±0.05 b ]]> Tyrosine <![CDATA[3.12±0.04 b ]]> <![CDATA[5.59±0.06 a ]]> <![CDATA[5.62±0.08 a ]]> Alanine <![CDATA[5.12±0.05 a ]]> <![CDATA[4.15±0.08 b ]]> <![CDATA[4.19±0.06 b ]]> Leucine <![CDATA[6.74±0.13 a ]]> <![CDATA[6.06±0.03 b ]]> <![CDATA[6.11±0.05 b ]]> Isoleucine <![CDATA[3.85±0.07 a ]]> <![CDATA[3.59±0.05 b ]]> <![CDATA[3.61±0.09 b ]]> Methionine <![CDATA[2.47±0.04 a ]]> <![CDATA[1.76±0.06 b ]]> <![CDATA[1.63±0.03 c ]]> Phenylalanine <![CDATA[5.02±0.07 a ]]> <![CDATA[3.87±0.04 b ]]> <![CDATA[3.91±0.02 b ]]> Proline <![CDATA[3.59±0.03 a ]]> <![CDATA[2.57±0.02 b ]]> <![CDATA[2.62±0.05 b ]]> Valine <![CDATA[4.89±0.12 a ]]> <![CDATA[4.41±0.03 b ]]> <![CDATA[4.48±0.06 b ]]>

[0082] 5) The molecular weight composition of sesame protein hydrolysate was determined by size exclusion chromatography (SEC), and the test conditions were: column temperature 25°C, flow rate 0.7mL / min, injection volume 20μL, chromatographic column BioCore SEC-300 5μm, 7.8×300mm, mobile phase 150mmol / L phosphate, detection wavelength: UV 214nm. Take an appropriate amount of sesame protein hydrolysate and dissolve it in ultrapure water, pass it through a 0.22μm filter membrane, and take the supernatant into a 250μL liner tube for determination. The results are shown in Table 4 below.

[0083] Table 4. Molecular weight distribution of products of Examples 1 and 2 (%)

[0084]

[0085]

[0086] It can be seen from Table 4 that the molecular weights of the sesame protein hydrolysates prepared in Examples 1 and 2 are mainly concentrated in 1000-3000 Da and 200-1000 Da, and more than 82% of the sesame protein hydrolysates have a molecular weight below 3000 Da.

[0087] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a low-bitter sesame protein hydrolyzate with antioxidant properties, characterized in that: The following steps are involved: 1) Defatting sesame cake and extracting sesame protein: The sesame cake after impurities removal is crushed, and degreased by Soxhlet extraction. Distilled water is added to the defatted sesame cake, and the pH is adjusted to 9-12. The mixture is stirred at room temperature, centrifuged, and the supernatant is collected. The pH is adjusted to 4-5, the mixture is allowed to stand, centrifuged, and the precipitate is collected and freeze-dried to obtain sesame protein. 2) Protein dispersion treatment: The sesame protein obtained in step 1) is crushed, distilled water is added, and the pH is adjusted to 8-11 to obtain a sesame protein solution, which is subjected to high temperature treatment, cooled to room temperature, dispersed, and homogenized under high pressure. The homogenized solution is kept at a low temperature of 4-10° C. for later use; 3) Multi-enzyme combined hydrolysis: Heat the solution obtained in step 2) to a set temperature of 40-60 o C, adjust the pH to 7-10.5, add multi-enzyme for enzymolysis, after 3-7 h of enzymolysis, adjust the pH to neutral, centrifuge, and take the supernatant; 4) Resin adsorption: Add the supernatant from step 3) to the resin adsorption column. After adsorption, wash the column with distilled water, elute with 50-85% ethanol solution, and collect the eluate. 5) Membrane separation The eluate in step 4) is ultrafiltered using an ultrafiltration membrane, the permeate is collected and concentrated using a nanofiltration membrane, and the concentrate is freeze-dried in a vacuum to obtain the concentrate.

2. The method for preparing the low-bitter sesame protein hydrolyzate with antioxidant properties as claimed in claim 1, characterized in that: In step 1), the sesame cake is high-temperature sesame cake; and the amount of distilled water added is 10-20 times the mass of the sesame cake.

3. The method for preparing the low-bitter sesame protein hydrolyzate with antioxidant properties as claimed in claim 1, characterized in that: In step 1), the extraction solvent used in Soxhlet extraction is n-hexane or petroleum ether, and the degreasing temperature is 50-100 o C, degreasing time 6-10h; the concentration of NaOH solution or hydrochloric acid for adjusting pH is 3-6 mol / L.

4. The method for preparing the low-bitter sesame protein hydrolyzate with antioxidant properties as claimed in claim 1, characterized in that: In step 2), 1g:10-20 mL of distilled water is added to obtain a sesame protein solution; in the high temperature treatment, the heating temperature is 100-160 o C, heating time 10-50 min.

5. The method for preparing the low-bitter sesame protein hydrolyzate with antioxidant properties as claimed in claim 1, characterized in that: In step 2), the high-pressure homogenization pressure is 100 Mpa-200 Mpa, and the process is performed 2-6 times.

6. The method for preparing the low-bitter sesame protein hydrolyzate with antioxidant properties as claimed in claim 1, characterized in that: In step 3), the amount of the multi-enzyme added is 0.5-2.5% of the mass of sesame protein; the multi-enzyme is composed of three or more of alkaline protease, aminopeptidase, flavor protease, trypsin, and neutral protease, among which aminopeptidase and flavor protease are essential components, the sum of the two accounts for 25%-40% of the mass of the multi-enzyme, and the ratio of the two is 3-0.5:

1.

7. The method for preparing the low-bitter sesame protein hydrolyzate with antioxidant properties as claimed in claim 1, characterized in that: In step 4), the resin adsorption is composed of non-polar and weak polar macroporous resins, wherein the mass ratio of the non-polar and weak polar macroporous resins is 1:4-8.

8. The method for preparing the low-bitter sesame protein hydrolyzate with antioxidant properties as claimed in claim 1, characterized in that: In step 5), the eluate is ultrafiltered using an ultrafiltration membrane with a molecular weight cutoff of 5000-10000 Da, the permeate is collected, and concentrated using a nanofiltration membrane with a molecular weight cutoff of 200-500 Da to 10-20% of the volume of the feed liquid.

9. A low-bitter sesame protein hydrolyzate with antioxidant properties prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the low-bitter sesame protein hydrolyzate with antioxidant properties as claimed in claim 1 in the preparation of antioxidant drugs, health products, foods and cosmetics.

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