CN107723328B

CN107723328B - Guar active peptide and preparation method thereof

Info

Publication number: CN107723328B
Application number: CN201711208898.1A
Authority: CN
Inventors: 闫巧娟; 袁江宏; 江正强; 刘燕静; 张彬; 张伟
Original assignee: Beijing Guaerrun Technology Co ltd; China Agricultural University
Current assignee: Beijing Guaerrun Technology Co ltd; China Agricultural University
Priority date: 2017-11-27
Filing date: 2017-11-27
Publication date: 2021-03-23
Anticipated expiration: 2037-11-27
Also published as: CN107723328A

Abstract

The invention discloses a guar active peptide and a preparation method thereof, wherein guar protein extracted from guar or guar meal is used as a raw material, and the guar active peptide with ACE inhibitory activity, antioxidant activity and/or metal ion chelating activity is prepared by the steps of water dissolution, protease hydrolysis, enzyme deactivation, slag removal and the like, and can be widely applied to functional feeds, food raw materials or food additives. The guar active peptide prepared by the method firstly realizes secondary development and utilization of guar meal which is a byproduct in production, increases the overall value of guar, secondly fills up the defects of guar in the development of guar protein source products with high added values, and has great value.

Description

Guar active peptide and preparation method thereof

Technical Field

The invention belongs to the technical field of biology, and particularly relates to guar active peptide and a preparation method thereof.

Background

Guar is an annual crop belonging to the genus guar of the family leguminosae and is widely planted in india, pakistan, sudan and parts of the united states as a superior crop that is drought tolerant, barren tolerant, improves soil fertility and is suitable for machine farming. Guar comprises mainly carbohydrates, fats, proteins, moisture and the like, wherein non-ionic galactomannan (i.e. guar gum) is the main product of the guar industry. Guar meal is a byproduct of guar gum processing, is rich in protein (about 50%), and is currently used mainly as feed. However, even though the guar meal has a high protein content, when used as a feed, the components contained therein, such as trypsin inhibitor, saponin, and residual guar gum, have adverse effects on the growth, feed utilization, and transformation of livestock.

Another use of guar meal is in the preparation and application of functional proteins therein. Studies have shown that extraction of guar meal by 0.1M NaOH/1M NaCl makes it possible to obtain a protein fraction with a high lysyl content, which is known to have good foaming power. The protein component obtained by acid precipitation of the above components is the main reason for the good foaming of guar protein. The protein can obviously reduce the surface tension of water and obtain the foaming capacity 20 times higher than that of egg white protein, thereby being used as a food additive. Some researches on the development and application of guar protein are carried out at present, but the related researches are still few in general, and the utilization condition is obviously insufficient. Therefore, the development of guar protein source products with high added value is of great significance for further improving the utilization condition of the guar protein source products.

Bioactive peptides have been prepared from a variety of different sources of proteins, particularly leguminous plant proteins, and their functional activities have been extensively studied. For example, the antioxidant peptide is obtained by hydrolyzing soybean protein with alkaline protease, and the antioxidant ability of the peptide can be improved by about 70 times after ultrafiltration and combined column chromatography (Park et al, Journal of Food Biochemistry,2010,34(SI-1): 120-132). Alkaline protease, neutral protease and trypsin are used for compositely hydrolyzing soybean protein in Liu Dian mountain and the like, and low molecular weight bean ACE inhibitory peptide (CN 105368) with low molecular weight is prepared by purification methods such as activated carbon adsorption and ultrafiltration903A) In that respect In addition, calcium chelating peptide can be obtained by hydrolyzing soybean protein with alkaline protease, and the calcium ion chelating capacity of the peptide reaches 41mg/g (Zhang et al, Journal of Food Biochemistry,2014,38(3): 374-380). Zhouyousong, et al, disclose a method for preparing mung bean ACE inhibitory peptide (CN103290086A) by using alkaline protease hydrolysis, activated carbon adsorption, rough filtration, fine filtration, nanofiltration, drying and other processes. Xin et al obtained an ACE inhibitory activity of red bean protein hydrolysate, IC thereof, using alkaline protease, papain and simulated digestion of the gastrointestinal tract in vitro₅₀A value of 67.2. mu.g protein/ml and IC after separation by ultrafiltration, gel filtration and reverse phase high performance liquid chromatography₅₀The value was further reduced to 19.3. mu.g protein/ml (Xin et al, Journal of Functional Foods,2013,5(3): 1116-1124). In addition, some studies have reported the use of black soybean protein (Evangelho et al, Food Science and Technology,2016,36(1): 23-27; Evangelho et al, Food Chemistry,2017,214: 460-.

Although extensive research on bioactive peptides has been conducted at present, no report has been made on guar bioactive peptides and methods for their preparation. Therefore, the development of the guar active peptide has important value on the efficient utilization of the guar meal.

Therefore, in order to overcome the above disadvantages, the present invention urgently needs to provide a guar active peptide and a preparation method thereof.

Disclosure of Invention

The invention aims to provide a guar active peptide and a preparation method thereof, wherein guar protein is used as a raw material to prepare the guar active peptide with high activity, so that the added value of guar meal is improved, the utilization rate of guar is improved, and the blank state of the research area is filled.

The invention provides the following scheme:

the preparation method of the guar active peptide is characterized by comprising the following steps: (1) dispersion and dissolution of guar protein: adding guar protein into water, stirring and dispersing to prepare a suspension, wherein the content of the guar protein is 2.5-15% of the water content; (2) enzymolysis: adjusting the pH value of the suspension in the step (1) to 3-9, adding protease with the activity of 100-2000U/g according to the content of the guar protein, and hydrolyzing at the constant temperature of 30-50 ℃ for 1-12h to obtain a mixed aqueous solution; (3) heating and enzyme deactivation: heating the mixed aqueous solution in the step (2) to inactivate the protease in the mixed aqueous solution; (4) impurity removal: and (4) removing solid residues in the mixed aqueous solution in the step (3) to obtain the guar active peptide solution.

In the method for preparing the guar active peptide, the guar protein in the step (1) is preferably extracted from guar or guar meal, and the extraction method is an alkali extraction and acid precipitation method.

In the preparation method of the guar active peptide, preferably, the protease in the step (2) includes one or more of animal-derived protease, plant-derived protease or microbial-derived protease.

In the method for producing the guar active peptide as described above, it is further preferable that the protease is a microbial protease.

In the method for preparing the guar active peptide, it is further preferred that, in the step (2), the pH of the suspension is adjusted according to the pH value of the selected protease; wherein the pH range corresponding to the acidic protease is 3.0-6.0, the pH range corresponding to the neutral protease is 6.0-8.0, and the pH range corresponding to the alkaline protease is 7.0-9.0.

In the preparation method of the guar active peptide, preferably, in the step (2), the pH value is adjusted by using NaOH or HCl solution, and the concentration of the NaOH or HCl solution is 0.5-4 mol/L.

In the method for producing the guar active peptide as described above, it is more preferable that the guar protein content in the added water is 10% of the water content in the step (1).

In the method for producing the guar active peptide as described above, it is more preferable that the time for the isothermal hydrolysis in step (2) is 6 hours.

The method for producing a guar active peptide as described above further preferably further comprises the step (5): and (3) drying the guar active peptide solution obtained in the step (4) by adopting a spray drying method or a vacuum freeze drying method to obtain guar active peptide powder.

In the method for producing the above-described guar active peptide, the guar active peptide is preferably used as a functional feed, a food material or a food additive.

Compared with the prior art, the invention has the following advantages:

the invention discloses a preparation method of guar active peptide, which takes guar protein extracted from guar or guar meal as raw material, and prepares the guar active peptide with ACE inhibitory activity, antioxidant activity and metal ion chelating activity through the steps of water dissolution, protease hydrolysis, enzyme deactivation, slag removal and the like, and can be widely applied to functional feed, food raw materials or food additives. The guar active peptide prepared by the method firstly realizes secondary development and utilization of guar meal which is a byproduct in production, increases the overall value of guar, secondly fills up the defects of guar in the development of guar protein source products with high added values, and has great value.

Drawings

Fig. 1 is a flow chart of the preparation process of guar active peptide in the invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The experimental procedures used in the following examples are conventional ones unless otherwise specified.

In the following examples, the specifications and sources of the proteases used were respectively: pepsin (more than or equal to 250U/mg, Sigma); trypsin (250NF U/mg, Amresco); flavourzyme Flavourzyme500MG (500LAPU/g, Novozymes); protamex (TM) (1.5AU/g, Novozymes) complex protease and Alcalase (2.4AU/g, Novozymes) alkaline protease 2.4L.

In the following examples, materials, reagents and the like used were commercially available unless otherwise specified.

In the following examples, the protease activity was determined using the "SB/T10317-1999 protease Activity assay", the unit of enzyme activity being defined as: the amount of enzyme required to hydrolyze casein at 40 ℃ per minute to produce 1ug of tyrosine.

In the following examples, the concentration of the polypeptide in solution was determined using the ortho-phthalaldehyde (OPA) method (Yan, et al, Food Chemistry,2015,179: 290-. The specific method is as follows: mu.l of the polypeptide solution was mixed with 1ml of OPA reagent (containing 50ml of an aqueous sodium tetraborate solution (100mmol/L), 20ml of an aqueous sodium dodecylsulfonate solution (5%, w/v), 2ml of a methanolic OPA solution (40mg/ml), 200. mu.l of beta-mercaptoethanol and 27.8ml of water per 100ml of OPA reagent) with shaking, kept at room temperature for 8min, and the absorbance was measured at 340 nm. Polypeptide concentration was calculated using Gly-Leu dipeptide as standard.

In the following examples, the polypeptide yield was calculated from the polypeptide concentration determined by the OPA method, wherein the polypeptide yield was defined as:

in the following examples, polypeptide recovery was calculated from multiple concentrations determined by the OPA method, and was defined as:

in the following examples, ACE inhibitory activity was determined using the method described by Cushman et al (Cushman et al, Biochemical Pharmacology,1971,20(7): 1637-. The specific method is as follows: mu.L of hippuryl-L-histidyl-L-leucine (5mM, formulated with 0.1mol/L borate buffer (pH 8.3) containing 0.3mol/L NaCl) was mixed with 20. mu.L of the polypeptide sample and incubated for 5min at 37 ℃. Subsequently, 10. mu.L of angiotensin converting enzyme (ACE,0.1U/mL) was added. The mixture was reacted at 37 ℃ for 60 min. Subsequently, 150. mu.L of a 1mol/L HCl solution was added to terminate the reaction. For the blank sample, 150. mu.L of 1mol/L HCl solution was added to inactivate the ACE before the reaction started. After the reaction was completed, hippuric acid formed in the reaction was extracted by adding 1ml of ethyl acetate. Subsequently, the mixture was centrifuged at 4000 Xg for 10min, and then 0.75ml of the upper ethyl acetate solution was aspirated and dried in an oven at 105 ℃. Then, 1ml of deionized water was added thereto, and after sufficiently dissolving, the absorbance at 228nm was measured. For the control sample, the above measurement procedure was carried out using 0.1mol/L borate buffer (pH 8.3) containing 0.3mol/L NaCl instead of the polypeptide sample. ACE inhibitory activity was calculated according to the following formula:

in the following examples, ABTS was used⁺Clearance determines the antioxidant activity of the polypeptide (Re, et al, Free radial Biology and Medicine,1999,26(9-10): 1231-1237). Specifically, 0.15mL of sample solution is added into 2.85mL of ABTS working solution, the mixture is uniformly mixed and then is subjected to dark reaction for 10min, and the mixed solution is subjected to absorbance measurement at the wavelength of 734 nm. Meanwhile, the absorbance was measured by the same procedure using 0.15mL of absolute ethanol as a blank. ABTS +. clearance was calculated as follows:

in the following examples, the Fe of a polypeptide is determined according to the method of Stookey et al (Stookey et al, Analytical Chemistry,1970,42(7):779-²⁺Ion chelating ability. Specifically, 100. mu.l of the polypeptide solution was mixed with 1ml of distilled water and 1ml of 50ppm Fe²⁺The ions were mixed and incubated at room temperature for 30min, then 900. mu.l of 11.3% TCA solution was added, followed by centrifugation at 10000rpm for 10 min. Transfer 100. mu.l of supernatant to a centrifuge tube and add 1ml of deionized water, 800. mu.l10% ammonium acetate solution and 200. mu.l of indicator (75mg of Ferrozine in 25ml of deionized water) were mixed and incubated at room temperature for 5min, after which the absorbance was measured at 562 nm.

In the following examples, the Cu content of polypeptides was determined according to the method of Saiga et al (Saiga et al, Journal of Agricultural and Food Chemistry,51 (12)), 3661-²⁺Ion chelating ability. Specifically, 100. mu.l, 0.1. mu.g/. mu.l of CuSO was added₄A solution in 50mM sodium acetate buffer (pH 6.0) was mixed with 25. mu.l of a solution of 4mM catechol violet in 40mM sodium acetate buffer (pH 6.0), kept at room temperature for 30min, and then the absorbance at 632nm was measured. The copper chelating capacity is proportional to the decrease in absorbance at 632nm and can therefore be calculated as follows:

preparation of guar active peptide

As shown in fig. 1, the preparation method of guar active peptide comprises the following steps: (1) adding guar protein into water, uniformly oscillating to prepare a suspension, (2) selecting protease for hydrolyzing the suspension, adjusting the pH value of the suspension according to the acid-base adaptability of the selected protease, then adding a proper amount of protease, and hydrolyzing for 1-12h in a constant-temperature water environment at 30-50 ℃ to obtain a mixed water solution; (3) heating the mixed aqueous solution after hydrolysis to inactivate the protease therein, and (4) removing the solid residue in the mixed aqueous solution to obtain the guar active peptide.

In the step (1), guar protein is extracted from guar or guar meal, preferably guar meal which is a byproduct of guar gum production is used to fully utilize guar, during extraction, an alkali extraction and acid precipitation method is used, the property that guar protein generates soluble substances in an alkaline solution and generates precipitates in an acidic solution is utilized, alkali extraction is performed, and acid precipitation is performed to achieve the purpose of purifying or separating guar protein in guar meal. In addition, deionized water from which impurities in ionic form have been removed is selected for the preparation of the suspension to reduce the influence of impurities in the water on the preparation process. Meanwhile, the guar protein content is 2.5-15% of the water content.

In step (2), a suitable protease is selected, preferably a protease with enzyme activity of 100-. In the preparation process, single protease can be selected for hydrolysis, and multiple proteases can be selected for hydrolysis in a composite manner. After selecting proper protease, determining the acid-base adaptability of the protease, namely the optimal acid-base environment of the protease, and adaptively adjusting the pH value of the suspension to make the pH value of the suspension be in the range of 3-9, wherein the pH value of the suspension corresponding to the acid protease is 3.0-6.0, the pH value of the suspension corresponding to the neutral protease is 6.0-8.0, and the pH value of the suspension corresponding to the alkaline protease is 7.0-9.0. Then, taking out a proper amount of protease according to the enzyme activity and the content of the guar protein in the suspension, adding the protease into the suspension, and hydrolyzing for 1-12h at the constant temperature of 30-50 ℃ to obtain a mixed aqueous solution, wherein the protease is ensured to be capable of completely hydrolyzing the guar protein in the suspension; wherein, the optimum temperature of the protease reaction is mostly between 30 ℃ and 50 ℃, and the hydrolysis time of 1 h to 12h also ensures the complete progress of the hydrolysis reaction.

In step (3), the optimum reaction temperature of the enzyme is usually between 30 ℃ and 50 ℃, and when the temperature is higher or lower than the optimum reaction temperature, the activity is greatly reduced, and when the temperature is far higher than the optimum reaction temperature, the enzyme is inactivated. In the preparation process, the mixed water solution after hydrolysis is boiled in boiling water bath for 10min to inactivate enzyme completely.

In the step (4), removing solid residues in the mixed aqueous solution in the step (3) by centrifugation or filtration, and obtaining the guar active peptide solution in the form of supernatant or filtrate.

Further, the above preparation method further comprises the step (5): and (4) drying the supernatant or the filtrate obtained in the step (4) to obtain the guar active peptide powder. Preferably, in this embodiment, the drying method is preferably spray drying or direct air freeze drying.

The guar active peptide obtained by the above steps has antioxidant activity, Angiotensin Converting Enzyme (ACE) inhibitory activity and/or metal ion chelating activity.

Example 1 Effect of protease type on guar active peptide yield and Activity

In order to investigate the effect of different proteases on the activity of guar active peptides in the preparation method disclosed in this example, the following 5 experiments were performed using animal-derived pepsin and trypsin, plant-derived actinidin, and microbial-derived flavor protease and compound protease:

uniformly shaking guar protein in deionized water to prepare 5 parts of 5% suspension, adjusting the pH value of the suspension to be shown in table 1 by using 1mol/L HCl or NaOH respectively, then adding 1000U/g of corresponding protease, and shaking and hydrolyzing the protease on a constant-temperature water bath shaker at the corresponding temperature for 6 hours respectively as shown in table 1. After the reaction was completed, the mixed aqueous solution was boiled in a boiling water bath for 10min to inactivate the enzyme, and centrifuged at 10000rpm for 10 min. In the above experiment, the reaction temperature and pH were respectively optimum reaction environments for the respective proteases. After the reaction was completed, the activities of the obtained guar active peptides were measured, respectively, wherein the variable data and the measured data of 5 experiments are shown in table 1:

TABLE 1 Effect of protease species on yield and inhibitory Activity of guar active peptides

¹Shows the determination of ACE inhibitory activity, Fe (II) chelation rate and Cu (II) chelation rate at a polypeptide concentration of 1mg/ml

²Represents the determination of ABTS. degree.0.2 mg/ml polypeptide concentration⁺Scavenging activity

By comprehensively comparing the data in table 1, it can be seen that,in-polypeptide yield, ABTS of microbial-derived flavourzyme and complex protease⁺The data on the scavenging activity, the Fe (II) chelating rate (%) and the Cu (II) chelating rate (%) are better than those of animal-derived pepsin, trypsin and plant-derived actinidin as a whole, so that when the protease is selected, the protease derived from microorganisms is preferably selected.

Example 2 Effect of added protease content on yield and inhibitory Activity of guar active peptides

As can be seen from table 1, compared to other proteases, the guar active peptide prepared by selecting pepsin or actinidin has the best ACE inhibitory activity, and in order to further investigate the influence of the enzyme dosage on the yield and inhibitory activity of the guar active peptide, the following 5 experiments were also performed in this example using pepsin and actinidin, respectively:

shaking guar protein in deionized water to uniformly prepare 10 parts of 5% suspension, adjusting the pH of the suspension to 3.0 by using 1mol/L HCl, adding pepsin with the enzyme activity of 100, 200, 500, 1000 and 2000U/g respectively, and shaking the mixture on a constant-temperature water bath shaker at 37 ℃ for 6 hours. After the reaction was completed, the suspension was boiled in a boiling water bath for 10min to inactivate the enzyme, and centrifuged at 10000rpm for 10 min. The centrifuged supernatant was taken to determine the polypeptide content and the ACE inhibitory activity, and the results are shown in table 2. The results in the table are the mean ± SD of three experiments.

TABLE 2 Effect of enzyme dosage on the yield and inhibitory Activity of guar active peptides

Representative ACE inhibition was determined at 1mg/ml polypeptide concentration

As can be seen from Table 2, the yield of the guar active peptide gradually increases and the ACE inhibition rate also increases with the increase of the enzyme addition amount, but when the enzyme addition amount is increased from 1000U/g to 2000U/g, the yield of the guar active peptide and the ACE inhibition rate do not change greatly and are reduced to a certain extent. Therefore, a combined consideration of an enzyme dosage of preferably 1000U/g is used for the preparation of guar ACE inhibitory peptides.

Example 3 Effect of suspension concentration on guar active peptide yield

Guar protein was shaken well in deionized water to prepare two suspensions each with a concentration of 2.5%, 5%, 7.5%, 10%, 12.5% and 15% (w/v), the suspension was adjusted to pH 3.0 with 1mol/L HCl, then 1000U/g pepsin and 1000U/g actinidin were added, respectively, and shaken for 6h at 37 ℃ on a constant temperature water bath shaker. After the reaction was completed, the suspension was boiled in a boiling water bath for 10min to inactivate the enzyme, and centrifuged at 10000rpm for 10 min. The centrifuged supernatant was taken to determine the polypeptide content and the ACE inhibitory activity, and the results are shown in table 3. The results in the table are the mean ± SD of three experiments.

TABLE 3 Effect of suspension concentration on guar active peptide yield and ACE inhibitory Activity

Determination of ACE inhibition at 1mg/ml polypeptide concentration

Table 3 shows that the polypeptide yield and ACE inhibitory activity gradually decreased with increasing suspension concentration. At substrate concentrations between 5.0% and 10.0%, the polypeptide yield and ACE inhibition do not vary much with substrate concentration. Considering that too low a concentration would reduce the efficiency of the reaction, a concentration of 10.0% of the suspension is preferred for the preparation of guar ACE inhibiting peptides.

Example 4 Effect of hydrolysis time

Guar protein was shaken well in deionized water to prepare 2 parts of 10% strength suspension, the pH of the suspension was adjusted to 3.0 with 1mol/L HCl, 1000U/g pepsin and 1000U/g actinidin were added, respectively, and shaken at 37 ℃ on a constant temperature water bath shaker. Samples were taken at 0.5, 1,2, 4, 6, 8 and 12h respectively, the samples were boiled in a boiling water bath for 10min to inactivate the enzyme and centrifuged at 10000rpm for 10 min. The centrifuged supernatant was taken to determine the polypeptide content and ACE inhibitory activity, and the results are shown in table 4. The results in the table are the mean ± SD of three experiments.

TABLE 4 Effect of hydrolysis time on guar active peptide yield and ACE inhibitory Activity

Determination of ACE inhibition at 1mg/ml polypeptide concentration

Table 4 shows that the polypeptide yield and ACE inhibitory activity gradually increased with the hydrolysis time. When the hydrolysis time reaches 6h, the hydrolysis time is continuously prolonged, the increase range of the polypeptide yield and the ACE inhibitory activity is reduced, and no obvious change is caused. Thus, considering the time cost of the reaction in combination, the hydrolysis time for the preparation of the ACE inhibiting peptides of guar is preferably 6 h.

Example 5 Complex proteases formulation of guar ACE inhibitory peptides

Uniformly oscillating guar protein in deionized water to prepare 5 parts of 10% suspension, adjusting the pH of the suspension to 3.0 by using 1mol/L HCl, adding 1000U/g of pepsin, and oscillating and hydrolyzing the mixture for 6 hours at 37 ℃ on a constant-temperature water bath oscillator; then, the pH was adjusted to the optimum pH for the protease to be complexed (as shown in Table 1), respectively, 1000U/g flavourzyme, complex protease, trypsin or actinidin was added and hydrolysis continued for 2h at the optimum temperature for the indicated enzymes (as shown in Table 1). After hydrolysis was complete, the sample was boiled for 10min, followed by centrifugation at 10000rpm for 10 min. The supernatant was taken to determine the polypeptide content and the ACE inhibitory activity, and the results are shown in Table 5. The results in the table are the mean ± SD of three experiments.

TABLE 5 Effect of Complex enzyme hydrolysis on yield and inhibitory Activity of ACE inhibitory peptide from guar

Determination of ACE inhibition in 0.1mg/ml polypeptide concentration

As shown in Table 5, the polypeptide yield was improved when pepsin was combined with other proteases, as compared with pepsin single enzyme hydrolysis; from the aspect of ACE inhibitory activity, after the pepsin and the flavourzyme are compounded, the ACE inhibitory rate is reduced, no obvious inhibitory activity is detected at the concentration of 0.1mg/ml, after the pepsin and the flavourzyme are compounded, the ACE inhibitory activity is slightly increased, and after the pepsin and the trypsase are compounded, the ACE inhibitory activity is obviously increased. Thus, the guar ACE inhibitory peptides can be prepared using pepsin in combination with actinidin.

Example 6 preparation of guar ACE inhibitory peptide powder

The guar ACE inhibitory peptide solution prepared by compounding pepsin and actinidin the above embodiment and the guar ACE inhibitory peptide solution prepared by pepsin are respectively prepared into powder by vacuum freeze drying. The powder was redissolved and the ACE-consistent activity of the polypeptide before and after drying was compared, with the results shown in table 6. The results in the table are the mean ± SD of three experiments.

TABLE 6 inhibitory Activity of guar ACE inhibitory peptide before and after vacuum Freeze drying

The results show that the vacuum freeze-drying process has no obvious influence on the ACE inhibitory activity. Therefore, for convenient storage, the polypeptides prepared by the above experiments can be prepared into powder.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The preparation method of the guar active peptide is characterized by comprising the following steps:

(1) dispersion and dissolution of guar protein: adding guar protein into water, stirring and dispersing to prepare suspension, wherein the content of the guar protein is 2.5-12.5% of the water content;

(2) enzymolysis: adjusting the pH value of the suspension in the step (1) to 3-6, adding protease with the activity of 500-1000U/g according to the content of the guar protein, and hydrolyzing at constant temperature of 30-50 ℃ for 6-12h to obtain a mixed water solution; the protease is selected from pepsin, actinidin or composite protease formed by mixing pepsin and actinidin;

(3) heating and enzyme deactivation: heating the mixed aqueous solution in the step (2) to inactivate the protease in the mixed aqueous solution;

(4) impurity removal: and (4) removing solid residues in the mixed aqueous solution in the step (3) to obtain the guar active peptide solution.

2. The preparation method of the guar active peptide according to claim 1, wherein the guar protein in the step (1) is extracted from guar or guar meal, and the extraction method is an alkali extraction and acid precipitation method.

3. The preparation method of the guar active peptide according to claim 2, wherein in the step (2), NaOH or HCl solution is selected to adjust the pH value, and the concentration of the NaOH or HCl solution is 0.5-4 mol/L.

4. The method for preparing guar active peptide according to claim 1 or 2, wherein in step (1), guar protein is added to water at a content of 10% of the water content.

5. The method for preparing guar active peptide according to claim 1 or 2, wherein in step (2), the time for isothermal hydrolysis is 6 h.

6. The method for preparing guar active peptide according to claim 1 or 2, further comprising step (5): and (3) drying the guar active peptide solution obtained in the step (4) by adopting a spray drying method or a vacuum freeze drying method to obtain guar active peptide powder.

7. A guar active peptide produced by the method for producing a guar active peptide according to any one of claims 1 to 6, wherein the guar active peptide is used as a functional feed or food material.