Oatmeal peptide and preparation method thereof

Abstract

The present application relates to a kind of oat peptides and its preparation method, comprising the following steps: (1) oat is soaked and then germination treatment is carried out, and germinated oat is obtained;(2) germinated oat is carried out defatting treatment, and oat germination defatting powder is obtained;(3) oat germination defatting powder and water are mixed, first enzymolysis is carried out using composite protease, and then second enzymolysis is carried out using aspergillus oryzae aminopeptidase, and enzyme hydrolysate component is obtained;The composite protease includes papain and bacillus subtilis neutral protease;(4) enzyme hydrolysate component is separated, and supernatant is taken, then homogenization and drying treatment are carried out, and the oat peptide of the present application is obtained.The preparation method of the oat peptide provided by the present application is simple in operation, the prepared oat peptide has molecular weight below 1000 Da, has higher yield and good biological activity simultaneously, taste and good brewing property, slightly sweet taste, no bitter taste, has natural fragrance, liquid is clear and bright after dissolving, higher in sensory acceptance degree, can produce significant economic benefits.

Description

Technical Field

[0001] This invention relates to the field of oat deep processing technology, and in particular to an oat peptide and its preparation method. Background Technology

[0002] CN114438156A discloses a method for extracting oat peptides, comprising the following steps: crushing oats, mixing with water, sequentially adding 6.5-9.5% (by weight of oats) of alkaline protease and 0.5-3.5% (by weight of oats) of flavor protease for enzymatic hydrolysis, inactivating the enzymes after the reaction, allowing to stand, and drying the supernatant to obtain oat peptide powder. This method effectively improves the yield of oat peptides, maintains a stable yield, and yields oat peptides with an average molecular weight of approximately 1600-1800.

[0003] CN108977484A discloses a method for extracting oat polypeptides, specifically: removing impurities from coarse oat flour, freezing it, and then ultra-finely pulverizing it before stirring with an electromagnetic rod to obtain oat ultrafine powder; mixing the oat ultrafine powder with water evenly, and extracting it at low temperature, with the filtrate being the protein extract; adding a complex protease to the protein extract for enzymatic hydrolysis, and using an ultrafiltration membrane for ultrafiltration to obtain the ultrafiltrate; passing the clear filtrate through a nanofiltration membrane to obtain a concentrated polypeptide solution, and then freeze-drying it to obtain oat polypeptides.

[0004] Existing methods have drawbacks such as high peptide molecular weight and low extraction rate. Therefore, it is necessary to provide a method for preparing small molecule oat peptides with high extraction rate and high activity. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an oat peptide and its preparation method. The oat peptide preparation method provided by this invention is simple to operate, yields oat peptides with a molecular weight below 1000 Da, and exhibits high yield and good bioactivity. It has a good taste and solubility, a slightly sweet flavor without bitterness, a natural refreshing aroma, and the dissolved liquid is clear and transparent, demonstrating high sensory acceptance and significant economic benefits.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing oat peptides, the method comprising the following steps:

[0008] (1) Soak the oats and then germinate them to obtain germinated oats;

[0009] (2) The sprouted oats from step (1) are defatted to obtain defatted sprouted oat powder;

[0010] (3) Mix the oat sprouted defatted powder from step (2) with water, perform a first enzymatic hydrolysis using a complex protease, and then perform a second enzymatic hydrolysis using Aspergillus oryzae aminopeptidase to obtain the hydrolysate; the complex protease includes papain and Bacillus subtilis neutral protease;

[0011] (4) Separate the enzymatic hydrolysis components from step (3), take the clear liquid, and then homogenize and dry it to obtain the oat peptide.

[0012] In this invention, endogenous enzymes are first stimulated by germinating oats to promote the production of oat peptides. Then, exogenous enzymes are used for enzymatic hydrolysis. The stepwise enzymatic hydrolysis technology of endopeptidase and exopeptidase controls the peptide segments to 2-10 amino acids, increasing the content of small peptides. The resulting oat peptides have a high yield and good biological activity, and can be widely used in food, health products, cosmetics and other fields.

[0013] In this invention, a complex protease and Aspergillus oryzae aminopeptidase are used sequentially for enzymatic hydrolysis. The two-step enzymatic hydrolysis is carried out in sequence, which can synergistically improve the hydrolysis effect and increase the peptide content.

[0014] Preferably, step (1) further includes removing impurities and disinfecting the oats before soaking.

[0015] Preferably, the disinfectant used for disinfection includes sodium hypochlorite solution.

[0016] Preferably, the soaking temperature in step (1) is 20-25℃ (e.g., 20℃, 21℃, 22℃, 23℃, 25℃, etc.), the soaking time is 8-12 h (e.g., 8 h, 9 h, 10 h, 11 h, 12 h, etc.), and the water is changed and aerated once every 3-4 h (e.g., 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, etc.).

[0017] Preferably, the germination treatment in step (1) is carried out in the presence of a germination aid, which includes an aqueous solution of any one or at least two of calcium chloride, gibberellin, or 6-benzylaminopurine, preferably an aqueous solution of calcium chloride, gibberellin, and 6-benzylaminopurine.

[0018] In this invention, the three components calcium chloride, gibberellin and 6-benzylaminopurine can work synergistically to improve germination quality, better activate endogenous enzymes, and promote the production of oat peptides.

[0019] Preferably, the concentration of calcium chloride in the germination aid is 0.03-0.05 μmol / L (e.g., 0.03 μmol / L, 0.035 μmol / L, 0.04 μmol / L, 0.045 μmol / L, 0.05 μmol / L, etc.), the concentration of gibberellin is 8-12 mmol / L (e.g., 8 μmol / L, 9 μmol / L, 10 μmol / L, 11 μmol / L, 12 μmol / L, etc.), and the concentration of 6-benzylaminopurine is 0.01-0.03 μmol / L (e.g., 0.01 μmol / L, 0.015 μmol / L, 0.02 μmol / L, 0.025 μmol / L, 0.03 μmol / L, etc.).

[0020] Preferably, the germination aid is sprayed once every 3-5 hours (e.g., 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, etc.).

[0021] Preferably, the germination treatment in step (1) is performed at a temperature of 20-25℃ (e.g., 20℃, 21℃, 22℃, 23℃, 25℃, etc.), a relative humidity of 90-100% (e.g., 90%, 92%, 95%, 98%, 100%, etc.), and a time of 60-78 h (e.g., 60 h, 64 h, 68 h, 74 h, 78 h, etc.).

[0022] Preferably, step (2) further includes drying and grinding the sprouted oats before defatting.

[0023] Preferably, the defatting process in step (2) includes supercritical CO2 extraction.

[0024] Preferably, the pressure of the CO2 supercritical extraction is 18-28 MPa (e.g., 18 MPa, 20 MPa, 24 MPa, 26 MPa, 28 MPa, etc.), the temperature is 35-50℃ (e.g., 35℃, 40℃, 45℃, 50℃, etc.), the time is 1-2 h (e.g., 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, etc.), and the CO2 flow rate is 20-30 L / h (e.g., 20 L / h, 22 L / h, 25 L / h, 28 L / h, 30 L / h, etc.).

[0025] Preferably, the mass ratio of oat germinated defatted powder to water in step (3) is 1:(10-15) (for example, it can be 1:10, 1:11, 1:12, 1:14, 1:15, etc.).

[0026] Preferably, in step (3), the amount of compound protease used in the first enzymatic hydrolysis is 0.2-1% of the mass of the oat sprout defatted powder (for example, it can be 0.2%, 0.4%, 0.6%, 0.8%, 1%, etc.).

[0027] Preferably, in step (3), the first enzymatic hydrolysis is performed at a temperature of 48-58℃ (e.g., 48℃, 50℃, 52℃, 54℃, 58℃, etc.) and for a time of 6-8 h (e.g., 6 h, 6.5 h, 7 h, 7.5 h, 8 h, etc.).

[0028] Preferably, in step (3), the amount of Aspergillus oryzae aminopeptidase used in the second enzymatic hydrolysis is 0.1-0.5% of the mass of the oat germinated defatted powder (for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc.).

[0029] Preferably, in step (3), the second enzymatic hydrolysis is performed at a temperature of 48-58℃ (e.g., 48℃, 50℃, 52℃, 54℃, 58℃, etc.) and for a time of 1-1.5 h (e.g., 1 h, 1.1 h, 1.3 h, 1.4 h, 1.5 h, etc.).

[0030] Preferably, the mass ratio of papain and Bacillus subtilis neutral protease in the complex protease in step (3) is 1:(1-2) (for example, it can be 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, etc.).

[0031] Preferably, the separation in step (4) includes: extracting the enzymatic hydrolysate, precipitating the protein, centrifuging and membrane filtering, and taking the supernatant to obtain the oat peptide.

[0032] Preferably, the separation in step (4) specifically includes: mixing and extracting the enzymatic hydrolysate and buffer solution, centrifuging and taking the supernatant for protein precipitation, centrifuging again and taking the supernatant for membrane filtration, taking the supernatant to obtain the oat peptide.

[0033] Preferably, the buffer solution is a 0.05-0.1 mol / L HCl buffer solution (e.g., 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.1 mol / L, etc.).

[0034] Preferably, the precipitant used for protein precipitation is an aqueous solution of trichloroacetic acid.

[0035] Preferably, the concentration of the trichloroacetic acid aqueous solution is 10-12 wt% (e.g., 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, etc.), and the amount used is 1 / 3-1 / 2 of the system volume (e.g., 1 / 3, 2 / 5, 1 / 2, etc.).

[0036] Preferably, the membrane filtration uses a membrane pore size of 800-1000 Da (e.g., 800 Da, 850 Da, 900 Da, 950 Da, 1000 Da, etc.).

[0037] Preferably, the homogenization pressure is 20-40 MPa (e.g., 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, etc.), and the time is 60-120 s (e.g., 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 120 s, etc.).

[0038] Preferably, the drying process is carried out by spray drying.

[0039] Preferably, the inlet temperature of the spray dryer is 170-180℃ (e.g., 170℃, 172℃, 175℃, 178℃, 180℃, etc.), and the outlet temperature is 60-70℃ (e.g., 60℃, 62℃, 65℃, 68℃, 70℃, etc.).

[0040] Secondly, the present invention provides an oat peptide, which is prepared according to the oat peptide preparation method described in the first aspect.

[0041] Preferably, the molecular weight of the oat peptide is below 1000 Da (e.g., it can be 1000 Da, 900 Da, 800 Da, 600 Da, 500 Da, 400 Da, etc.), and more preferably 400-600 Da.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] This invention utilizes oat germination technology to activate endogenous proteases to degrade proteins, increasing the content of oat peptides. Then, it uses exogenous enzyme stepwise enzymatic hydrolysis technology to hydrolyze the proteins, obtaining oat small molecule peptides with higher content. The resulting product has good biological activity. Detailed Implementation

[0044] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0045] The materials used in the following embodiments are from the following sources:

[0046] Papain was purchased from Alibaba, Nanning Dongheng Huadao Biotechnology Co., Ltd.; Bacillus subtilis neutral protease was purchased from Alibaba, Nanning Dongheng Huadao Biotechnology Co., Ltd.; Aspergillus oryzae aminopeptidase was purchased from Alibaba, Nanning Dongheng Huadao Biotechnology Co., Ltd.

[0047] Example 1

[0048] This embodiment provides a method for preparing oat peptides, the preparation method comprising the following steps:

[0049] (1) Select and remove impurities from oats, disinfect them by soaking them in 0.5wt% sodium hypochlorite solution for 4 minutes, rinse them with water, and then soak them at 20℃ for 12 h, changing the water and ventilating them once every 4 h; after soaking, drain the water and put them into an oat germination bucket, set the germination temperature to 20℃ and the relative humidity to 90%, and spray the germination aid mixed aqueous solution (0.04μmol / L calcium chloride, 10 mmol / L gibberellin, 0.02 μmol / L 6-benzylaminopurine) once every 4 hours during the germination process. After 70 h, germinated oats are obtained.

[0050] (2) The sprouted oats from step (1) were dried in a ventilated place, ground into powder and passed through a 50-mesh sieve. Then, CO2 supercritical extraction was carried out for 1.5 h at a pressure of 25 MPa, a temperature of 40℃ and a CO2 flow rate of 25 L / h to obtain oat sprout defatted powder.

[0051] (3) Mix the oat sprout defatted powder and water in step (2) at a mass ratio of 1:12, heat to 60°C, add 0.6% of the mass of oat sprout defatted powder with compound protease (papain and Bacillus subtilis neutral protease at a mass ratio of 1:1.5), enzymatically hydrolyze at 58°C for 7 h, then heat to 80°C and keep warm for 20 minutes to inactivate the enzyme; then add 0.3% of the mass of oat sprout defatted powder with Aspergillus oryzae aminopeptidase, enzymatically hydrolyze at 58°C for 1.5 h, then heat to 80°C and keep warm for 20 minutes to inactivate the enzyme, and obtain the enzymatic hydrolysate;

[0052] (4) The enzymatic hydrolysis component from step (3) was mixed with 0.08 mol / L HCl buffer at a volume of 1:14 and extracted. The mixture was centrifuged at 5000 r / min for 15 min to separate the components. The supernatant was then added to a 1 / 3 volume of 10 wt% trichloroacetic acid aqueous solution. After standing, the mixture was centrifuged at 5000 r / min for 15 min to precipitate the large molecular weight protein. The supernatant was filtered through a ceramic filter with a molecular weight cutoff of 1000 Da. The resulting oat peptide solution was homogenized at 30 MPa for 120 s and then spray-dried. The inlet temperature of the equipment was 170 ℃ and the outlet temperature was 60 ℃ to obtain the oat peptide.

[0053] Example 2

[0054] This embodiment provides a method for preparing oat peptides, the preparation method comprising the following steps:

[0055] (1) Select and remove impurities from oats, disinfect them by soaking them in 0.5wt% sodium hypochlorite solution for 4 minutes, rinse them with water, and then soak them at 25℃ for 8 hours, changing the water and ventilating them once every 3 hours; after soaking, drain the water and put them into an oat germination bucket, set the germination temperature to 25℃ and the relative humidity to 95%, and spray the germination aid mixed aqueous solution (0.03 μmol / L calcium chloride, 12 mmol / L gibberellin, 0.01 μmol / L 6-benzylaminopurine) once every 3 hours during the germination process. After 68 hours, germinated oats are obtained.

[0056] (2) The sprouted oats from step (1) were dried in a ventilated place, ground into powder and passed through a 60-mesh sieve. Then, CO2 supercritical extraction was carried out for 2 h at a pressure of 18 MPa, a temperature of 35℃ and a CO2 flow rate of 20 L / h to obtain oat sprout defatted powder.

[0057] (3) Mix the oat sprout defatted powder and water in step (2) at a mass ratio of 1:10, heat to 55°C, add 0.2% of the mass of oat sprout defatted powder with compound protease (papain and Bacillus subtilis neutral protease at a mass ratio of 1:1), enzymatically hydrolyze at 48°C for 8 h, then heat to 80°C and keep warm for 20 minutes to inactivate the enzyme; then add 0.5% of the mass of oat sprout defatted powder with Aspergillus oryzae aminopeptidase, enzymatically hydrolyze at 48°C for 1.5 h, then heat to 80°C and keep warm for 20 minutes to inactivate the enzyme, and obtain the enzymatic hydrolysate;

[0058] (4) The enzymatic hydrolysis component from step (3) was mixed with 0.05 mol / L HCl buffer at a ratio of 1:13 and extracted. The mixture was centrifuged at 5000 r / min for 15 min to separate the components. The supernatant was then added to a 1 / 2 volume of 12 wt% trichloroacetic acid aqueous solution. After standing, the supernatant was centrifuged at 5000 r / min for 15 min to precipitate the large molecular weight protein. The supernatant was filtered through a ceramic filter with a molecular weight cutoff of 1000 Da. The resulting oat peptide solution was homogenized at 20 MPa for 120 s and then spray-dried. The inlet temperature of the equipment was 180 ℃ and the outlet temperature was 70 ℃ to obtain the oat peptide.

[0059] Example 3

[0060] This embodiment provides a method for preparing oat peptides, the preparation method comprising the following steps:

[0061] (1) Select and remove impurities from oats, disinfect them by soaking them in 0.5wt% sodium hypochlorite solution for 5 minutes, rinse them with water, and then soak them at 20℃ for 12 h, changing the water and ventilating them once every 4 h; after soaking, drain the water and put them into an oat germination bucket, set the germination temperature to 20℃ and the relative humidity to 95%, and spray the germination aid mixed aqueous solution (0.05μmol / L calcium chloride, 8 mmol / L gibberellin, 0.03 μmol / L 6-benzylaminopurine) once every 5 hours during the germination process. After 72 h, germinated oats are obtained.

[0062] (2) The sprouted oats from step (1) were dried in a ventilated place, ground into powder and passed through a 60-mesh sieve. Then, CO2 supercritical extraction was carried out for 1 h at a pressure of 28 MPa, a temperature of 50℃ and a CO2 flow rate of 30 L / h to obtain oat sprout defatted powder.

[0063] (3) Mix the oat sprout defatted powder and water in step (2) at a mass ratio of 1:15, heat to 60°C, add 1% of the mass of oat sprout defatted powder with compound protease (papain and Bacillus subtilis neutral protease at a mass ratio of 1:2), enzymatically hydrolyze at 58°C for 6 h, then heat to 80°C and keep warm for 20 minutes to inactivate the enzyme; then add 0.1% of the mass of oat sprout defatted powder with Aspergillus oryzae aminopeptidase, enzymatically hydrolyze at 58°C for 1 h, then heat to 80°C and keep warm for 20 minutes to inactivate the enzyme, and obtain the enzymatic hydrolysate;

[0064] (4) The enzymatic hydrolysis component from step (3) was mixed with 0.1 mol / L HCl buffer at a volume of 1:12 and extracted. The mixture was centrifuged at 5000 r / min for 15 min to separate the components. The supernatant was then added to a 1 / 3 volume of 10 wt% trichloroacetic acid aqueous solution. After standing, the mixture was centrifuged at 5000 r / min for 15 min to precipitate the large molecular weight protein. The supernatant was filtered through a ceramic filter with a molecular weight cutoff of 1000 Da. The resulting oat peptide solution was homogenized at 40 MPa for 120 s and then spray-dried. The inlet temperature of the equipment was 170 ℃ and the outlet temperature was 60 ℃ to obtain the oat peptide.

[0065] Example 4

[0066] This embodiment provides a method for preparing oat peptides. The only difference between this method and Example 1 is that the germination aid in step (1) does not contain calcium chloride, and its molar amount is allocated according to the ratio of gibberellin and 6-benzylaminopurine. Other aspects are the same as in Example 1.

[0067] Example 5

[0068] This embodiment provides a method for preparing oat peptides. The only difference between this method and Example 1 is that the germination aid in step (1) does not contain gibberellin, and its molar amount is allocated according to the ratio of calcium chloride and 6-benzylaminopurine. Other aspects are the same as in Example 1.

[0069] Example 6

[0070] This embodiment provides a method for preparing oat peptides. The only difference between this method and Example 1 is that the germination aid in step (1) does not contain 6-benzylaminopurine, and its molar amount is allocated according to the ratio of calcium chloride and gibberellin. Other aspects are the same as in Example 1.

[0071] Comparative Example 1

[0072] This comparative example provides a method for preparing oat peptides. The only difference between this method and Example 1 is that soaking and germination are not performed in step (1). In other words, step (2) directly uses cleaned, disinfected, and ungerminated oats for processing. Other operations are the same as in Example 1.

[0073] Comparative Example 2

[0074] This comparative example provides a method for preparing oat peptides. The only difference between this method and Example 1 is that enzymatic hydrolysis is performed only once in step (3). Specifically, oat germinated defatted powder and water from step (2) are mixed at a mass ratio of 1:12, heated to 60°C, and 0.6% of the mass of oat germinated defatted powder is added to a complex protease (papain and Bacillus subtilis neutral protease at a mass ratio of 1:1.5) and 0.3% of Aspergillus oryzae aminopeptidase. The mixture is then enzymatically hydrolyzed at 58°C for 7 h, and then heated to 80°C and kept warm for 20 minutes to inactivate the enzyme, thus obtaining the enzymatically hydrolyzed component. Other steps are the same as in Example 1.

[0075] Comparative Example 3

[0076] This comparative example provides a method for preparing oat peptides. The only difference between this method and Example 1 is that Aspergillus oryzae aminopeptidase is not used in step (3). Instead, its amount is added to the complex protease. Specifically, oat germinated defatted powder and water from step (2) are mixed at a mass ratio of 1:12, heated to 60°C, and 0.9% of the mass of oat germinated defatted powder is added to the complex protease (papain and Bacillus subtilis neutral protease at a mass ratio of 1:1.5). The mixture is then enzymatically hydrolyzed at 58°C for 7 h, and then heated to 80°C and kept warm for 20 minutes to inactivate the enzyme. Other steps are the same as in Example 1.

[0077] Comparative Example 4

[0078] This comparative example provides a method for preparing oat peptides. The only difference between this method and Example 1 is that the complex protease is not used in step (3). Instead, the amount of the complex protease is added to Aspergillus oryzae aminopeptidase. Specifically, the oat germinated defatted powder and water from step (2) are mixed at a mass ratio of 1:12, heated to 60°C, and 0.9% of the mass of the oat germinated defatted powder is added to Aspergillus oryzae aminopeptidase. The mixture is then enzymatically hydrolyzed at 58°C for 7 h, and then heated to 80°C and kept warm for 20 minutes to inactivate the enzyme. Other steps are the same as in Example 1.

[0079] Comparative Example 5

[0080] This comparative example provides a method for preparing oat peptides. The only difference between this method and Example 1 is that in step (3), the oat peptides are first hydrolyzed with Aspergillus oryzae aminopeptidase and then hydrolyzed with a complex protease. Specifically, the oat germinated defatted powder and water from step (2) are mixed at a mass ratio of 1:12, heated to 60°C, and 0.3% of Aspergillus oryzae aminopeptidase by mass of the oat germinated defatted powder are added. The mixture is hydrolyzed at 58°C for 1.5 h, and then heated to 80°C and kept warm for 20 minutes to inactivate the enzyme. Then, 0.6% of the complex protease (papain and Bacillus subtilis neutral protease by mass ratio of 1:1.5) by mass of the oat germinated defatted powder is added. The mixture is hydrolyzed at 58°C for 7 h, and then heated to 80°C and kept warm for 20 minutes to inactivate the enzyme, thus obtaining the hydrolyzed component. Other steps are the same as in Example 1.

[0081] Comparative Example 6

[0082] This comparative example provides a method for preparing oat peptides. The only difference between this method and Example 1 is that papain is not used in the first enzymatic hydrolysis in step (3), and its amount is allocated to Bacillus subtilis neutral protease. Other steps are the same as in Example 1.

[0083] Comparative Example 7

[0084] This comparative example provides a method for preparing oat peptides. The only difference between this method and Example 1 is that in step (3), the first enzymatic hydrolysis does not use Bacillus subtilis neutral protease, but allocates its amount to papain instead. The rest is the same as in Example 1.

[0085] The molecular weight, peptide content, and activity of the oat peptides obtained in the above examples and comparative examples were tested. The molecular weight was tested according to GB / T27843-2011, the peptide content was tested according to GB / T22492-2008, and the DPPH free radical scavenging rate was tested according to GB / T 39100-2020. The results are shown in Table 1.

[0086] Table 1. Results of molecular weight, peptide content, and DPPH free radical scavenging rate.

[0087]

[0088] As shown in Table 1, the oat peptide preparation method provided by this invention, through germination, defatting, and enzymatic hydrolysis, yields oat peptides with smaller molecular weight, higher peptide content, and better bioactivity. Specifically, the molecular weight is 476-520 Da, the peptide content is 20.3-27.7 g / 100 g, and the DPPH free radical scavenging rate reaches 75.7-86.7%.

[0089] The comparison between Examples 1 and Examples 4-6 shows that the germination aid of the present invention uses a combination of calcium chloride, gibberellin and 6-benzylaminopurine. The three components can synergistically promote oat germination, enabling it to better activate endogenous proteases to degrade proteins, which helps to increase the content and activity of oat peptides.

[0090] The comparison between Example 1 and Comparative Example 1 shows that when ungerminated oats are used directly for small molecule peptide extraction, the peptide content decreases significantly and the activity is reduced.

[0091] The comparison between Example 1 and Comparative Examples 2-7 shows that if the two-step enzymatic hydrolysis process and enzyme components of the present invention are not used, the enzymatic hydrolysis effect is significantly reduced, the peptide content is significantly reduced, and the activity is reduced.

[0092] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing oat peptides, characterized in that, The preparation method includes the following steps: (1) Soak the oats and then germinate them to obtain germinated oats; (2) The sprouted oats from step (1) are defatted to obtain defatted sprouted oat powder; (3) Mix the oat sprouted defatted powder from step (2) with water, perform a first enzymatic hydrolysis using a complex protease, and then perform a second enzymatic hydrolysis using Aspergillus oryzae aminopeptidase to obtain the hydrolysate; the complex protease includes papain and Bacillus subtilis neutral protease; (4) Separate the enzymatic hydrolysis components from step (3), take the clear liquid, and then homogenize and dry it to obtain the oat peptide.

2. The preparation method according to claim 1, characterized in that, The soaking temperature in step (1) is 20-25℃, the soaking time is 8-12h, and the water is changed and aerated once every 3-4h.

3. The preparation method according to claim 1, characterized in that, The germination treatment in step (1) is carried out in the presence of a germination aid, which includes an aqueous solution of calcium chloride, gibberellin and 6-benzylaminopurine.

4. The preparation method according to claim 3, characterized in that, The germination aid contains calcium chloride at a concentration of 0.03-0.05 μmol / L, gibberellin at a concentration of 8-12 mmol / L, and 6-benzylaminopurine at a concentration of 0.01-0.03 μmol / L.

5. The preparation method according to claim 1, characterized in that, The germination treatment in step (1) is performed at a temperature of 20-25℃, a relative humidity of 90-100%, and a time of 60-78h.

6. The preparation method according to claim 1, characterized in that, The degreasing treatment method in step (2) includes supercritical CO2 extraction, wherein the pressure of supercritical CO2 extraction is 18-28 MPa, the temperature is 35-50℃, the time is 1-2 h, and the CO2 flow rate is 20-30 L / h.

7. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of oat germinated defatted powder to water is 1:(10-15). In the first enzymatic hydrolysis, the amount of compound protease is 0.2-1% of the mass of oat germinated defatted powder, the hydrolysis temperature is 48-58℃, and the time is 6-8h. In the second enzymatic hydrolysis, the amount of Aspergillus oryzae aminopeptidase is 0.1-0.5% of the mass of oat germinated defatted powder, the hydrolysis temperature is 48-58℃, and the time is 1-1.5h.

8. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of papain to Bacillus subtilis neutral protease in the complex protease is 1:(1-2).

9. The preparation method according to claim 1, characterized in that, The separation in step (4) includes: extracting the enzymatic hydrolysate, precipitating the protein, centrifuging and membrane filtering, taking the supernatant, and obtaining the oat peptide.

10. An oat peptide, characterized in that, The oat peptide is prepared according to the oat peptide preparation method according to any one of claims 1-9.

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