A method for preparing a low-bitterness sesame protein hydrolysate having antioxidant properties

Abstract

The application belongs to the field of deep processing of agricultural products, and particularly relates to a preparation method of low-bitterness sesame protein hydrolysate with antioxidant property. The sesame protein hydrolysate prepared by the method has strong free radical scavenging capacity and weak bitterness. In the application, sesame cake meal is used as raw material, and the sesame protein hydrolysate with low bitterness is prepared through defatting, protein extraction, homogenization, enzymolysis, resin adsorption and membrane separation. The sesame protein hydrolysate has strong antioxidant property, good taste and good applicability, and can be used as main material to produce oral liquid, capsule and other products, or be used as an ingredient in other food, and has wide market prospect.

Description

Technical Field

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

[0002] Sesame is one of the world's major oilseed crops, and my country is a major producer and consumer of sesame. In 2023, sesame production and consumption were approximately 435,300 tons and 1.5 million tons, respectively. Currently, sesame in my country is mainly used for oil extraction. The production of sesame oil produces high-temperature sesame cake, a byproduct of oil extraction after a high-temperature roasting process (temperature above 150℃, heating time exceeding 30 minutes). Approximately 600,000 tons of high-temperature sesame cake are produced annually. While high-temperature sesame cake is rich in protein (around 40%), the protein has poor water solubility due to high-temperature denaturation, making it difficult to extract and utilize. It is primarily used as animal feed and fertilizer, and the protein in high-temperature sesame cake is not fully utilized.

[0003] Studies have shown that the hydrolysates of sesame cake protein obtained through enzymatic hydrolysis at high temperatures possess various biological activities, such as antioxidant and hypotensive activities. Therefore, converting high-temperature sesame cake protein into bioactive hydrolysates is an effective way to improve quality and efficiency. However, high-temperature sesame cake protein hydrolysates have a bitter taste, which impairs the sensory quality of the product and affects its sales and promotion. To remove the bitterness from protein hydrolysates, two main methods have been developed: physicochemical debittering and biological debittering. Physicochemical debittering includes methods such as encapsulation, masking, and separation. Biological debittering mainly utilizes enzymes or microorganisms to modify or metabolize bitter substances to achieve the debittering effect. Physicochemical debittering methods have advantages such as ease of operation and low cost, but they also have disadvantages such as safety risks associated with the addition of chemicals and unstable debittering effects. While biological debittering methods have the advantages of significant debittering effects and mild conditions, they require longer processing times and strict control of processing conditions. Therefore, a reasonable combination of physicochemical and biological debittering methods is needed to achieve the best debittering effect for protein hydrolysates. Furthermore, the poor dispersibility of high-temperature sesame cake protein in water hinders enzymatic hydrolysis, thereby reducing peptide yield and increasing production costs. Therefore, relevant technologies are needed to improve the dispersion stability of high-temperature sesame cake protein in water to enhance enzymatic hydrolysis efficiency. Thus, to improve the sensory quality of sesame protein hydrolysates, increase enzymatic hydrolysis efficiency, and control production costs, it is necessary to develop a method for preparing low-bitterness sesame protein hydrolysates.

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

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

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a low-bitter sesame protein hydrolysate with antioxidant properties includes defatting sesame cake, protein extraction, protein dispersion treatment, multi-enzyme hydrolysis, resin adsorption, membrane separation desalting and concentration, and freeze drying. The specific steps are as follows:

[0008] 1) Defatting of sesame cake and extraction of sesame protein:

[0009] After removing impurities such as stones, burnt material, and straw, the sesame cake is pulverized (to 40-100 mesh) and defatted using Soxhlet extraction. The defatted sesame cake is then added to distilled water, and the pH is adjusted to 9-12 using NaOH solution. The mixture is stirred at room temperature for 15-50 minutes, centrifuged, and the supernatant is collected. The pH is then adjusted to 4-5 using HCl solution, allowed to stand, centrifuged again, and the precipitate is collected and freeze-dried to obtain sesame protein.

[0010] 2) Protein dispersion treatment:

[0011] The sesame protein obtained in step 1) is pulverized (to 80-120 mesh), distilled water is added, and the pH is adjusted to 8-11 to obtain a sesame protein solution. After high-temperature treatment and cooling to room temperature, it is dispersed at high speed (10000-15000r / min for 10-30s, 3-6 times) and homogenized under high pressure. The homogenized solution is then stored at 4-10℃ for later use.

[0012] 3) Multi-enzyme combined hydrolysis:

[0013] Heat the solution obtained in step 2) to a set temperature of 40-60℃, adjust the pH to 7-10.5, add multi-enzyme for enzymatic hydrolysis, after 3-7 hours of enzymatic hydrolysis, adjust the pH to neutral, centrifuge (8000-10000 r / min for 20-40 min), and take the supernatant.

[0014] 4) Resin adsorption:

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

[0016] The resin adsorption conditions were as follows: sample loading volume of 0.5-1.0 BV (bed volume), sample loading rate of 0.25-0.75 BV / h, column washing volume with distilled water of 2.5-4.0 BV, and elution volume with ethanol solution of 2-4 BV.

[0017] 5) Membrane separation

[0018] The eluent from step 4) is subjected to rotary evaporation to remove ethanol. Distilled water is then added to the original volume before rotary evaporation. Ultrafiltration is performed using an ultrafiltration membrane, and the permeate is collected and concentrated using a nanofiltration membrane. The concentrated solution is then freeze-dried under vacuum to obtain the product. This product exhibits strong antioxidant properties, a good taste, and wide applicability. It can be used as a main ingredient in the production of oral liquids, capsules, and other products, or as an ingredient in other health foods, demonstrating broad market prospects.

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

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

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

[0022] Furthermore, in step 2), the high-pressure homogenization pressure is 100 MPa-200 MPa, and it can be processed 2-6 times.

[0023] Specifically, in step 3) multi-enzyme combined hydrolysis, the amount of multi-enzyme added can be 0.5-2.5% of the sesame protein mass; the multi-enzyme can be composed of three or more of alkaline protease, aminopeptidase, flavor protease, chymotrypsin, and neutral protease, among which aminopeptidase and flavor protease are essential components, and 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] Furthermore, in step 4), the resin adsorption is composed of non-polar and weakly polar macroporous resins, wherein the mass ratio of the non-polar to weakly polar macroporous resins is 1:4-8, and the concentration of the eluent ethanol solution is 50-85% (volume percentage). The non-polar macroporous resins can be D101, HP20, HPD100, HPD910, XAD-2, etc., and the weakly polar macroporous resins can be CAD40, AB-8, HPD722, HZ-841, etc.

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

[0026] This invention provides a low-bitter sesame protein hydrolysate with antioxidant properties prepared by the above preparation method. The sesame protein hydrolysate has a good taste, weak bitterness (bitterness is hard to detect, and the bitterness value measured by electronic tongue is less than 0.5), and more than 80% of the sesame protein hydrolysate has a molecular weight of less than 3000 Da, making it easy to accept. It can be widely used in the health food industry.

[0027] This invention also provides the application of the above-mentioned low-bitter sesame protein hydrolysate with antioxidant properties as a main ingredient or additive in the preparation of antioxidant drugs, health products, 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 this invention is high-temperature sesame cake meal, which is abundant in resources, has obvious cost advantages, and has high added value and high processing and utilization value.

[0030] 2) This invention improves the dispersibility of high-temperature sesame cake protein by high-temperature and high-pressure pretreatment and high-pressure homogenization, reduces protein size, increases the probability of enzyme-protein contact, and improves the enzymatic hydrolysis effect.

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

[0032] 4) The sesame protein hydrolysate provided by this invention has high antioxidant activity and good taste, and can be used as a functional ingredient in pharmaceuticals, health products and daily chemical products. Detailed Implementation

[0033] The technical solution of the present invention will be further described in detail below with reference to embodiments, but the scope of protection of the present invention is not limited thereto. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0034] Unless otherwise specified, all raw materials used in the following examples are commercially available products that can be directly purchased or prepared using conventional methods in the art. For example, the alkaline protease was derived from Bacillus licheniformis and purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd., with an enzyme activity of 200,000 u / g. The flavor protease was derived from Aspergillus oryzae and purchased from Novozymes, with an enzyme activity of approximately 200,000 u / g. The neutral protease was derived from Bacillus subtilis and purchased from Shaanxi Benhe Biotechnology Co., Ltd., with an enzyme activity of 100,000 u / g.

[0035] The aminopeptidase was purchased from Zhejiang Yicun Biotechnology Co., Ltd., in 25kg packages, with an enzyme activity of 50,000 u / g. Trypsin-Chymotrypsin, also known as chymotrypsin, was purchased from Aladdin Biochemical Technology Co., Ltd., product number T118254-100g, with an enzyme activity ratio of 2400:400 (6:1), and a total enzyme activity close to 400,000 u / g.

[0036] Room temperature refers to 25±5℃.

[0037] Example 1

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

[0039] 1) High-temperature defatting of sesame cake and extraction of sesame protein:

[0040] Take 1 kg of high-temperature sesame cake meal, remove impurities (stones, burnt material, straw, etc.), pulverize to 40 mesh, and defatt with n-hexane as the extraction solvent at 70℃ for 9 hours, with a residual oil rate of less than 1%. Spread the defatted sesame cake meal evenly in a fume hood to remove residual solvent and weigh. Add 12.75 L of distilled water to the defatted sesame cake meal, stir evenly, adjust the pH to 11 with 5 mol / L NaOH solution, stir at room temperature for 40 min, centrifuge at 4500 r / min for 20 min, collect the supernatant, adjust the pH to 4.4 with 5 mol / L HCl solution, let stand for 1 h, centrifuge at 5000 r / min for 30 min, collect the precipitate, and freeze-dry (-40℃, -0.1 MPa for 36 h, the same below) to obtain sesame protein;

[0041] 2) Protein pretreatment:

[0042] Grind 200g of the sesame protein obtained in step 1) to 100 mesh, add 3L of distilled water, adjust the pH to 9 to obtain a sesame protein solution, add it to a high-temperature pressure-resistant tube and maintain stirring at 150 rpm, then heat in an oil bath at 130℃ for 35 min. After cooling to room temperature, disperse at 12000 rpm for 30 s, repeat 5 times, then homogenize at 150 MPa three times. After homogenization, store the solution at 10℃ for later use.

[0043] 3) Multi-enzyme combined hydrolysis:

[0044] Heat the solution obtained in step 2) to 50°C, adjust the pH to 8.7, add 2g of multi-enzyme (composed of alkaline protease, chymotrypsin, flavor protease and aminopeptidase, with the four enzymes accounting for 40%, 30%, 15% and 15% of the mass of the multi-enzyme, respectively) for enzymatic hydrolysis. After 6 hours of enzymatic hydrolysis, adjust the pH to neutral, centrifuge at 8000 r / min for 20 min, and take the supernatant.

[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) in a mass ratio of 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 eluent was collected.

[0047] 5) Membrane separation

[0048] The eluent from step 4) was subjected to rotary evaporation at 80°C to remove ethanol. Then, distilled water was added to the volume of the solution before rotary evaporation. Ultrafiltration was performed using an ultrafiltration membrane with a molecular weight cutoff of 10,000 Da. The permeate was collected and then concentrated using a nanofiltration membrane with a molecular weight cutoff of 500 Da to 10% of the initial liquid volume. The solution was then freeze-dried under vacuum (-40°C, -0.1 MPa for 30 hours, the same below) to obtain a low-bitter sesame protein hydrolysate product.

[0049] This 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 3000 Da.

[0050] Example 2

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

[0052] 1) High-temperature defatting of sesame cake and extraction of sesame protein:

[0053] Take 3 kg of high-temperature sesame cake meal, remove impurities (stones, burnt material, straw, etc.), and grind it to 60 mesh. Use petroleum ether (boiling range 30-60℃) as the extraction solvent and defatt it at 65℃ for 8 hours, with a residual oil rate of less than 1%. Place the defatted sesame cake meal in a fume hood to remove residual solvent and weigh it. Add 50 L of distilled water to the defatted sesame cake meal, stir well, adjust the pH to 12 with 5 mol / L NaOH solution, stir at room temperature for 30 min, centrifuge at 5000 r / min for 30 min, collect the supernatant, adjust the pH to 4.2 with 5 mol / L HCl solution, let stand for 1 hour, centrifuge at 5000 r / min for 30 min, collect the precipitate, and freeze-dry to obtain sesame protein.

[0054] 2) Protein pretreatment:

[0055] 500g of the sesame protein obtained in step 1) was pulverized to 120 mesh, and 10L of distilled water was added to adjust the pH to 10 to obtain a sesame protein solution. The solution was then added to a high-temperature and high-pressure reactor and stirred at 180 rpm for 25 min. After cooling to room temperature, the solution was dispersed at 15000 rpm for 30 s, and this process was repeated 6 times. The solution was then homogenized 4 times under high pressure at 180 MPa. The homogenized solution was then stored at 5℃ for later use.

[0056] 3) Multi-enzyme combined hydrolysis:

[0057] Heat the solution obtained in step 2) to 45°C, adjust the pH to 8, add 10g of multi-enzyme (the multi-enzyme is composed of neutral protease, chymotrypsin, flavor protease and aminopeptidase, the four enzymes account for 25%, 40%, 20% and 15% of the mass of the multi-enzyme, respectively) for enzymatic hydrolysis, after 5h of enzymatic hydrolysis, adjust the pH to neutral, centrifuge at 10000r / min for 30min, and take the supernatant.

[0058] 4) Resin adsorption debittering:

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

[0060] 5) Membrane separation

[0061] The eluent from step 4) was subjected to rotary evaporation at 75°C to remove ethanol. Then, distilled water was added to the volume of the solution before rotary evaporation. Ultrafiltration was performed using an ultrafiltration membrane with a molecular weight cutoff of 10,000 Da. The permeate was collected and then concentrated using a nanofiltration membrane with a molecular weight cutoff of 500 Da to 15% of the initial liquid volume. After freeze-drying, a low-bitter sesame protein hydrolysate product was obtained.

[0062] This 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 3000 Da.

[0063] Antioxidant activity application test

[0064] In the following application tests, the DPPH and ABTS scavenging rates were determined as follows. The sesame protein hydrolysate solution was prepared by diluting the lyophilized powder with distilled water to form an aqueous solution of a specific concentration.

[0065] 1) DPPH scavenging assay: 100 μL of sesame protein hydrolysate solution was added to a 96-well microplate, followed by 100 μL of 0.2 mmol / L DPPH ethanol solution. The plate was shaken for 30 s and incubated at room temperature in the dark for 30 min. The absorbance (A) was measured at 517 nm. i The absorbance A of a mixture of 100 μL sesame protein hydrolysate solution and 100 μL ethanol was measured simultaneously using the same method. j The absorbance A of 100 μL of 0.2 mmol / L DPPH ethanol solution mixed with 100 μL of ethanol. o DPPH free radical scavenging rate (D I The calculation formula is shown below. The results are shown in Table 1.

[0066]

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

[0068] Table 1.

[0069]

[0070] The antioxidant application of low-bitter sesame polypeptides was demonstrated in the analysis of sesame protein hydrolysates obtained in Examples 1 and 2. These hydrolysates exhibited high scavenging rates of DPPH and ABTS, approximately 89% and 95%, respectively, showing strong antioxidant activity (see Table 1). This indicates that the sesame protein hydrolysates of the present invention can be used as antioxidants in the preparation of antioxidant drugs, health products, cosmetics, etc.

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

[0072] sample DPPH removal 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 determining the DPPH and ABTS clearance rates, the concentration of the sesame protein hydrolysate solution was 2 mg / mL.

[0074] 3) The taste characteristics (bitterness, bitter aftertaste, astringency, astringency aftertaste, umami, umami aftertaste, sweetness, saltiness, and sourness) of sesame protein hydrolysate were determined using an SA402B electronic tongue. Test conditions: Samples were diluted to a concentration of 5 mg / mL sesame protein hydrolysate with 30 mmol / L KCl (containing 0.3 mmol / L tartaric acid). Data for each sample was collected four times, with a collection time of 120 s. The minimum error from the three measurements was taken as the measurement data for each sample using the mean square method. The reference solution was a 30 mmol / L KCl solution (containing 0.3 mmol / L tartaric acid). When the taste data of a test sample was higher than the corresponding taste data of the reference solution, the sample exhibited that taste; the greater the difference, the stronger the taste. Conversely, if the difference was less than the reference value, the taste was absent. A significant difference was defined as a difference of more than one scale increment between the taste data of two samples, allowing humans to easily distinguish the differences in taste between the 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 astringent -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 sweet -4.40±0.13 -5.51±0.11 0 Salty 0.93±0.04 0.62±0.05 -6 sour taste -40.57±0.11 -44.82±0.19 -13

[0077] As shown in Table 2, the sesame protein hydrolysate solutions obtained in Examples 1 and 2 have a weak bitter taste, presenting a slightly salty and umami taste, while other tastes are lost, which provides favorable conditions for their application as an excipient in health foods.

[0078] 4) The determination of amino acids in proteins and polypeptides was performed in accordance with GB / T 18246-2000, and the results are shown in Table 3.

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

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

[0081] amino acids High-temperature sesame cake 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 ]]> glutamic acid <![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). The test conditions were: column temperature 25℃, flow rate 0.7 mL / min, injection volume 20 μL, BioCore SEC-300 5 μm column (7.8 × 300 mm), mobile phase 150 mmol / L phosphate, and detection wavelength UV 214 nm. An appropriate amount of sesame protein hydrolysate was dissolved in ultrapure water, filtered through a 0.22 μm filter membrane, and the supernatant was transferred to a 250 μL inner liner tube for analysis. The results are shown in Table 4 below.

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

[0084]

[0085]

[0086] As can be seen from Table 4, the molecular weights of the sesame protein hydrolysates prepared in Examples 1 and 2 are mainly concentrated in the range of 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 within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a low-bitterness sesame protein hydrolysate with antioxidant properties, characterized in that, Includes the following steps: 1) Defatting of sesame cake and extraction of sesame protein: The sesame cake meal after impurity removal is crushed and degreased by Soxhlet extraction. The degreased sesame cake meal is added to distilled water, the pH is adjusted to 9-12, stirred at room temperature, centrifuged, the supernatant is collected, the pH is adjusted to 4-5, allowed to stand, centrifuged, the precipitate is collected, and freeze-dried to obtain sesame protein. 2) Protein dispersibility treatment: The sesame protein obtained in step 1) is crushed, added to distilled water, and the pH is adjusted to 8-11 to obtain a sesame protein solution. After high-temperature treatment and cooling to room temperature, it is dispersed and homogenized under high pressure. The homogenized solution is then stored at 4-10℃ for later use. 3) Multi-enzyme combined hydrolysis: Heat the solution obtained in step 2) to a set temperature of 40-60°C. o C. Adjust the pH to 7-10.5, add a multi-enzyme for enzymatic hydrolysis, and after 3-7 hours of enzymatic hydrolysis, adjust the pH to neutral, centrifuge, and collect the supernatant. The amount of the multi-enzyme added is 0.5-2.5% of the sesame protein content; the multi-enzyme is composed of alkaline protease, chymotrypsin, flavor protease, and aminopeptidase, with the four enzymes accounting for 40%, 30%, 15%, and 15% of the multi-enzyme mass, respectively; or the multi-enzyme is composed of neutral protease, chymotrypsin, flavor protease, and aminopeptidase, with the four enzymes accounting for 25%, 40%, 20%, and 15% of the multi-enzyme mass, respectively. 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 eluent. 5) Membrane separation The eluent from step 4) is ultrafiltered using an ultrafiltration membrane, the permeate is collected, and then concentrated using a nanofiltration membrane. The concentrate is then freeze-dried under vacuum to obtain the final product. In step 2), sesame protein solution is obtained by adding distilled water at a ratio of 1g:10-20mL; in the high-temperature treatment, the heating temperature is 100-160°C. o C, heating time 10-50 min; In step 4), the resin adsorption is composed of non-polar and weakly polar macroporous resins, wherein the mass ratio of non-polar and weakly polar macroporous resins is 1:4-8. In step 5), the eluent is ultrafiltered using an ultrafiltration membrane with a molecular weight cutoff of 5000-10000 Da, the permeate is collected, and then concentrated using a nanofiltration membrane with a molecular weight cutoff of 200-500 Da to 10-20% of the feed volume.

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

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

4. The method for preparing the low-bitter sesame protein hydrolysate with antioxidant properties as described in claim 1, characterized in that, In step 2), the high-pressure homogenization pressure is 100 MPa-200 MPa, and the treatment is repeated 2-6 times.

5. A low-bitter sesame protein hydrolysate with antioxidant properties prepared by any of the preparation methods described in claims 1 to 4.

6. The use of the low-bitter sesame protein hydrolysate with antioxidant properties as described in claim 5 in the preparation of antioxidant drugs, health products or cosmetics.

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