Hypoallergenic soybean protein powder and preparation method thereof

Abstract

The invention provides hypoallergenic soybean protein powder and a preparation method thereof, and relates to the technical field of food processing. The preparation method of the hypoallergenic soybean protein powder comprises the following steps: preparing the papaya extract: crushing papaya, sieving, mixing with water, and carrying out ultrasonic treatment; carrying out solid-liquid separation, freeze-drying the solid, carrying out secondary sieving, then mixing with the separated liquid, and carrying out secondary freeze-drying, so as to obtain the pawpaw extract; after the soybeans germinate, extracting soybean protein; and mixing the papaya extract with soybean protein, controlling the pH value to be 6.0-9.0, stirring at 55-65 DEG C for 2-5 hours, separating, taking supernatant liquid, and drying. The prepared papaya extract endows the soybean powder with unique flavor, the preparation process is simple, and the requirements of vast consumers on high-quality soybean protein can be met.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to a low-allergenic soybean protein powder and a preparation method thereof. Background Art

[0002] Soybeans are rich in high-quality protein. Depending on the type, the protein content is between 20-36%. Soy protein contains 8 essential amino acids required by the human body, and its amino acid composition is close to that of animal protein. Currently, common soy protein products on the market include soy flour, soy protein concentrate, soy protein isolate, etc., which are mainly used in meat processing, plant beverages, baked food processing and health care product processing.

[0003] Soy protein is one of the few types of plant protein that can be used to replace animal protein due to its high nutritional value, easy preparation, wide source and low cost. It has become one of the important raw materials in the field of food processing. However, soybean is one of the eight types of allergenic foods recognized by the Food and Agriculture Organization of the United Nations. The incidence of soybean allergy in non-specific and specific populations is about 0.27%-1.9%, of which the incidence in infants and young children is about 0.4%. Clinical symptoms include rhinitis, rash, asthma and gastrointestinal discomfort, which can affect their healthy growth and development in severe cases. In order to prevent such allergic people from having adverse reactions when consuming soy milk, specific processing of soybean products can reduce their allergic properties.

[0004] With the rapid development of the national economy and food industry, the application of soy protein in infant food and other fields has been continuously expanded, and the incidence of soy allergy has been increasing. Therefore, reducing the allergenicity of soy protein has very important practical significance and broad market prospects.

[0005] Glycinin is the most abundant allergenic protein in soybeans, accounting for about 40% of the total protein in seeds. Enzymatic modification is a common method for processing soybean protein, which has the advantages of mild conditions and strong specificity. Proteases can catalyze the cleavage of peptide bonds in the primary structure of proteins to produce polypeptides. Most polypeptides have good solubility, emulsification and antioxidant properties. In addition, protease hydrolysis can destroy allergenic proteins in soybeans and reduce their allergenicity. Enzymatic modification has the characteristics of mild action conditions and easy control; strong specificity and few side reactions; good protection of the original functional properties of proteins; easy digestion and absorption of products, and biological activity; small toxic and side effects, and environmental friendliness. It has gradually become one of the mainstream methods of protein modification.

[0006] A Chinese patent (publication number CN110583787A, published on December 20, 2019) discloses a method for preparing low-allergenic soymilk, which relates to the field of soymilk beverage processing technology. The soymilk is made of the following raw materials in parts by weight: 70-100 parts of soybeans, 50-60 parts of compound fruit juice, 4-6 parts of fish oil, 6-10 parts of papaya, 2-3 parts of walnuts, 3-4 parts of lotus roots, 2-3 parts of soluble fiber, 1-2 parts of protease, 2-3 parts of glucose, 3-5 parts of lactic streptococci, and 1-3 parts of lactic acid bacteria. The invention prepares low-allergenic soymilk by enzymatic hydrolysis, but the corresponding effect is not tested, and it is impossible to determine whether its allergenicity can meet consumer demand.

[0007] A Chinese patent (publication number CN112385733A, publication date February 23, 2021) relates to a low-allergenic soy protein powder and a preparation method thereof, the method comprising: adding food-derived polyphenols to a soy protein aqueous solution, stirring evenly, adjusting the pH of the solution to alkaline, and reacting it in a dark place at room temperature for 24 hours to obtain a polyphenol-soy protein covalent complex solution; adding oligomeric reducing sugars to the polyphenol-soy protein covalent complex solution, stirring evenly, and obtaining a reaction solution; freeze-drying the reaction solution to obtain a reactant powder; placing the reactant powder under conditions of a temperature of 55-65°C and a relative humidity of 75% for reaction for 12-36 hours to obtain a low-allergenic soy protein powder. However, its allergenicity has only decreased by 45.7-61.3%, and still needs to be improved.

[0008] Based on this, developing a new method for preparing low-allergenic soy protein powder to further reduce the allergenicity of soy protein and meet the needs of consumers for high-quality soy protein powder is the research focus of researchers in this field. Summary of the invention

[0009] In view of the above problems, the present invention provides a low-allergenic soy protein powder and a preparation method thereof. The preparation method of papaya extract is optimized, the prepared papaya extract and the prepared soy protein are mixed, the supernatant is separated, and the low-allergenic soy protein is obtained by freeze-drying; the allergenicity of the product is significantly reduced.

[0010] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0011] In one aspect, the present invention provides a method for preparing hypoallergenic soy protein powder, comprising the following steps:

[0012] S1: preparing papaya extract: crushing and sieving papaya, mixing it with water, and ultrasonicating it; separating the solid from the liquid, freeze-drying the solid, sieving it again, and then mixing it with the separated liquid, and freeze-drying it again to obtain the papaya extract;

[0013] S2: Soybean protein is extracted after germination of soybeans;

[0014] S3: The papaya extract obtained in S1 is mixed with the soy protein obtained in S2, the pH value is 6.0-9.0, stirred at 55°C-65°C for 2-5h, separated, the upper clear liquid is taken and dried.

[0015] Preferably, in S1, the papaya needs to be dried before crushing;

[0016] Preferably, in S1, the sieving is through a 40-80 mesh sieve; further preferably, in S1, the sieving is through a 50 mesh sieve.

[0017] Preferably, in S1, the secondary screening is through a 80-120 mesh sieve; further preferably, in S1, the secondary screening is through a 100 mesh sieve.

[0018] Preferably, in S1, the temperature of the ultrasound is 30-45°C, and the time is 1-4h; further preferably, in S1, the temperature of the ultrasound is 35-45°C, and the time is 1.5-4h.

[0019] Preferably, the S2 specifically comprises the following steps:

[0020] Step 1: After washing and sterilizing the soybeans, soak them in water at a temperature of 25-30°C for 4-6 hours;

[0021] Step 2: The soaked soybeans are protected from light and allowed to germinate to obtain germinated soybeans;

[0022] Step 3: The germinated soybeans are dried, ground and defatted to obtain defatted soybean flour;

[0023] Step 4: After mixing defatted soy flour and solvent, centrifuge and remove supernatant to obtain soy protein.

[0024] Preferably, in step 1, the cleaning is performed with running water;

[0025] Preferably, the sterilization operation is: spraying soybeans with 0.5%-1.2% hydrogen peroxide.

[0026] Preferably, in step 1, the mass volume ratio of the soybeans to water is 1:4-8; further preferably, in step 1, the mass volume ratio of the soybeans to water is 1:4-6.

[0027] Preferably, in step 2, when the soybeans are placed in a germination box to germinate in the dark, the temperature is 25-35° C., the humidity is 80-90%, and the germination time is 3-5 days.

[0028] Preferably, in step 3, the drying is freeze-drying;

[0029] Preferably, in step 3, the specific operation of degreasing is:

[0030] The ground soybean powder is mixed with ethanol in a mass-to-volume ratio of 1:18-22 and defatted for 2-4 hours.

[0031] Further preferably, in step 3, the specific operation of degreasing is:

[0032] The ground soybean powder is mixed with ethanol in a mass-to-volume ratio of 1:19-21 and defatted for 2-3 hours.

[0033] Preferably, the ethanol is an ethanol solution with a volume fraction of 95%.

[0034] Preferably, in step 4, the solvent is a sodium bicarbonate solution;

[0035] Preferably, the pH of the sodium bicarbonate solution is 7.5-8.5; further preferably, the pH of the sodium bicarbonate solution is 8.0.

[0036] Preferably, the sodium bicarbonate solution functions to adjust pH.

[0037] Preferably, in step 4, the mixing is shaking.

[0038] Preferably, in step 4, the centrifugation parameters are: temperature 3-5°C, rotation speed 8000-12000g / min, time 5-15min.

[0039] Preferably, in S3, the papaya extract is 5-10wt% of the soy protein.

[0040] On the other hand, the present invention provides hypoallergenic soybean protein powder prepared by the above preparation method.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The present invention optimizes the preparation method of papaya extract and ensures that papain is active in enzymolysis of soy protein through specific extraction operations; and significantly reduces the allergenicity of soy protein through a specific ratio of papaya extract to soy protein;

[0043] 2. The present invention optimizes the preparation method of soybean protein and, through a specific germination operation, allows part of the soybean protein to be hydrolyzed under the action of its own endogenous protease, thereby significantly reducing the allergenicity of soybean protein;

[0044] 3. The present invention optimizes the preparation method of papaya extract and its subsequent operation to retain as much free sugar and flavor substances in papaya as possible. The mass percentage of free sugar in papaya extract is 13%, which mainly includes glucose (29%), galactose (24%) and galacturonic acid (44%), so that the prepared papaya extract gives soybean powder a unique flavor, and the preparation process is simple, meeting the needs of consumers for low-allergy, high-quality soybean protein. DETAILED DESCRIPTION

[0045] In order to make the technical means, creative features, purpose and effect of the present invention easy to understand, the present invention is further explained below in conjunction with specific embodiments, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without making creative work all belong to the protection scope of the present invention. It is worth noting that the raw materials used in the present invention are all common commercial products, and their sources are not specifically limited. The technology and scientific terms used in the embodiments have the meanings commonly understood by those of ordinary skill in the art to which the present invention belongs.

[0046] Example 1

[0047] A hypoallergenic soybean protein powder, the preparation method of which is as follows:

[0048] S1: Preparation of papaya extract: Dry and grind papaya and pass it through a 50-mesh sieve, add the obtained product into water, ultrasonicate in a 35-45°C water bath for 1.5-4h, centrifuge and take the upper clear liquid for later use, then directly freeze-dry the lower solid product, pass the freeze-dried product through a 100-mesh sieve again; then add the previous upper clear liquid, mix and freeze-dry again to obtain the papaya extract.

[0049] Among them, the function of the two sieving is to further remove impurities such as cellulose in the papaya extract; compared with the prior art, the extraction method of the papaya extract of the present invention retains as much free sugar and flavor substances in the papaya as possible on the basis of ensuring the activity of papain. The mass percentage of free sugar in the papaya extract is 13%, which mainly includes glucose (29%), galactose (24%) and galacturonic acid (44%).

[0050] S2: After the soybeans are germinated, soybean protein is extracted:

[0051] Step 1: Weigh a certain mass of fresh dry soybeans, wash them with running water, spray 1% hydrogen peroxide to kill pathogens attached to the surface of the seeds, rinse them, add 5 times the volume of tap water of the soybean mass, and soak them in a 37°C constant temperature incubator for 8 hours;

[0052] Step 2: Place the soybeans soaked in step 1 in a germination box with a germination temperature of 30°C, a humidity of 85%, and a germination time of 4 days.

[0053] Step 3: freeze-dry the obtained bean sprouts, grind them with liquid nitrogen, defatted them with 95% ethanol solution at a mass volume ratio of 1 / 20 (w / v) for 3 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, discarded the supernatant, and dried at 50°C to obtain defatted soybean powder. The defatted soybean powder was dissolved in a sodium bicarbonate solution (pH 8.0, 0.05mol) at a ratio of 1:10 (w / v) and extracted with shaking for 2 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, and the supernatant was taken for standby use to obtain soybean protein.

[0054] S3: Mix the papaya extract powder prepared above with the obtained soy protein in water, adjust the pH value to 8.5, and then stir at 60°C for 3 hours, and control the pH value to remain unchanged during the stirring process; separate the above solution to obtain the supernatant, and vacuum freeze-dry for 24 hours to obtain a moisture content of less than 5%. The powder obtained after drying is the hypoallergenic soy protein.

[0055] The indirect competitive ELISA method was used to measure the antigenicity of the soybean protein powder prepared by the method, which was reduced by 85%.

[0056] Comparative Example 1

[0057] A hypoallergenic soybean protein powder, the preparation method of which is as follows:

[0058] Compared with Example 1, the only difference is that the papaya extract prepared in S1 is replaced by papain in an amount of 50 U / g.

[0059] The remaining operations are the same as those in Example 1.

[0060] Comparative Example 2

[0061] A hypoallergenic soybean protein powder, the preparation method of which is as follows:

[0062] Compared with Example 1, the only difference is that the papaya extract prepared in S1 is replaced by an equal amount of papaya powder.

[0063] The remaining operations are the same as those in Example 1.

[0064] Comparative Example 3

[0065] A hypoallergenic soybean protein powder, the preparation method of which is as follows:

[0066] Compared with Example 1, the only difference is that S1 is different:

[0067] S1: Preparation of papaya extract: Dry and crush papaya, add the obtained product into water, ultrasonicate in a 35-45°C water bath for 1.5-4h, centrifuge and take the upper clear liquid for use, then directly freeze-dry the lower solid product; then add the previous upper clear liquid, mix and freeze-dry again to obtain papaya extract.

[0068] The remaining operations are the same as those in Example 1.

[0069] Comparative Example 4

[0070] A hypoallergenic soybean protein powder, the preparation method of which is as follows:

[0071] Compared with Example 1, the only difference is that S2 is different and the soybeans do not need to be sterilized:

[0072] After the soybeans are germinated, soybean protein is extracted:

[0073] Step 1: Weigh a certain amount of fresh dry soybeans, wash them with running water, add 5 times the volume of tap water of the soybeans, and soak them in a 37℃ constant temperature incubator for 8 hours;

[0074] Step 2: Place the soybeans soaked in step 1 in a germination box with a germination temperature of 30°C, a humidity of 75%, and a germination time of 4 days.

[0075] Step 3: freeze-dry the obtained bean sprouts, grind them with liquid nitrogen, defatted them with a 95% ethanol solution at a mass volume ratio of 1 / 20 (w / v) for 3 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, discarded the supernatant, and dried at 50°C to obtain defatted soybean powder. The defatted soybean powder was dissolved in a sodium bicarbonate solution (pH 8.0, 0.05mol) at a ratio of 1:10 (w / v) and extracted by shaking for 2 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, and the supernatant was taken for standby use to obtain soybean protein.

[0076] The remaining operations are the same as those in Example 1.

[0077] Comparative Example 5

[0078] A hypoallergenic soybean protein powder, the preparation method of which is as follows:

[0079] Compared with Example 1, the only difference is that S2 is different:

[0080] S2: After the soybeans are germinated, soybean protein is extracted:

[0081] Step 1: Weigh a certain mass of fresh dry soybeans, wash them with running water, spray 1% hydrogen peroxide to kill pathogens attached to the surface of the seeds, rinse them, add 5 times the volume of tap water of the soybean mass, and soak them in a 37°C constant temperature incubator for 8 hours;

[0082] Step 2: Place the soybeans soaked in step 1 in a germination box with a germination temperature of 45°C, a humidity of 85%, and a germination time of 4 days.

[0083] Step 3: freeze-dry the obtained bean sprouts, grind them with liquid nitrogen, defatted them with a 95% ethanol solution at a mass volume ratio of 1 / 20 (w / v) for 3 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, discarded the supernatant, and dried at 50°C to obtain defatted soybean powder. The defatted soybean powder was dissolved in a sodium bicarbonate solution (pH 8.0, 0.05mol) at a ratio of 1:10 (w / v) and extracted by shaking for 2 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, and the supernatant was taken for standby use to obtain soybean protein.

[0084] The remaining operations are the same as those in Example 1.

[0085] Comparative Example 6

[0086] A hypoallergenic soybean protein powder, the preparation method of which is as follows:

[0087] Compared with Example 1, the only difference is that S2 is different:

[0088] S2: After the soybeans are germinated, soybean protein is extracted:

[0089] Step 1: Weigh a certain mass of fresh dry soybeans, wash them with running water, spray 1% hydrogen peroxide to kill pathogens attached to the surface of the seeds, rinse them, add 5 times the volume of tap water of the soybean mass, and soak them in a 37°C constant temperature incubator for 8 hours;

[0090] Step 2: Place the soybeans soaked in step 1 in a germination box with a germination temperature of 30°C, a humidity of 85%, and a germination time of 4 days.

[0091] Step 3: freeze-dry the bean sprouts, grind them with liquid nitrogen, defatted them with acetone at a mass volume ratio of 1 / 20 (w / v) for 3 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, discarded the supernatant, evaporated the acetone in a fume hood and set aside to obtain defatted soybean powder. Dissolve the defatted soybean powder in a sodium bicarbonate solution (pH8.0, 0.05mol) at a ratio of 1:10 (w / v) and shake for extraction for 2 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, take the supernatant and set aside to obtain soybean protein.

[0092] The remaining operations are the same as those in Example 1.

[0093] Comparative Example 7

[0094] A hypoallergenic soybean protein powder, the preparation method of which is as follows:

[0095] Compared with Example 1, the only difference is that S2 is different:

[0096] S2: After the soybeans are germinated, soybean protein is extracted:

[0097] Step 1: Weigh a certain mass of fresh dry soybeans, wash them with running water, spray 1% hydrogen peroxide to kill pathogens attached to the surface of the seeds, rinse them, add 5 times the volume of tap water of the soybean mass, and soak them in a 37°C constant temperature incubator for 8 hours;

[0098] Step 2: Place the soybeans soaked in step 1 in a germination box with a germination temperature of 30°C, a humidity of 85%, and a germination time of 4 days.

[0099] Step 3: The obtained bean sprouts are freeze-dried, ground with liquid nitrogen, defatted at 1 / 20 (w / v) ethanol for 3 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, the supernatant is discarded, and dried at 50°C to obtain defatted soybean powder. The defatted soybean powder is dissolved in phosphate buffer (pH 8.0, 0.05mol) at a ratio of 1:10 (w / v) and extracted by shaking for 2 hours, then centrifuged at 4°C, 10000g / min for 10 minutes, and the supernatant is taken for standby use to obtain soybean protein.

[0100] The remaining operations are the same as those in Example 1.

[0101] The percentage reduction of antigenicity of the soybean protein powder prepared in Example 1 and Comparative Examples 1-7 is shown in Table 1:

[0102] Table 1. Antigenicity reduction rate of soybean protein powder

[0103] Group Antigenicity reduction rate of soybean protein powder / % Example 1 85 Comparative Example 1 60 Comparative Example 2 32 Comparative Example 3 53 Comparative Example 4 67 Comparative Example 5 61 Comparative Example 6 63 Comparative Example 7 68

[0104] From the data in Table 1, it can be seen that the percentage reduction in antigenicity of the soybean protein powder in Example 1 is significantly higher than that in Comparative Examples 1-7, indicating that the papaya extract obtained by the specific papaya extraction method of the present invention and the soybean protein powder prepared from the extracted soybean protein have significantly reduced allergenicity.

[0105] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing hypoallergenic soybean protein powder, characterized in that: The following steps are involved: S1: preparing papaya extract: crushing and sieving papaya, mixing it with water, and ultrasonicating it; separating the solid from the liquid, freeze-drying the solid, sieving it again, and then mixing it with the separated liquid, and freeze-drying it again to obtain the papaya extract; S2: After the soybeans are germinated, soybean protein is extracted; S3: The papaya extract obtained in S1 is mixed with the soy protein obtained in S2, the pH value is 6.0-9.0, stirred at 55°C-65°C for 2-5h, separated, the upper clear liquid is taken and dried.

2. The preparation method according to claim 1, characterized in that: In S1, the screening is through a 40-80 mesh sieve; the secondary screening is through a 80-120 mesh sieve; the temperature of the ultrasound is 30-45° C., and the time is 1-4 h.

3. The preparation method according to claim 1, characterized in that: The S2 specifically comprises the following steps: Step 1: After washing and sterilizing the soybeans, soak them in water at a temperature of 25-30°C for 4-6 hours; Step 2: The soaked soybeans are protected from light and allowed to germinate to obtain germinated soybeans; Step 3: The germinated soybeans are dried, ground and defatted to obtain defatted soybean flour; Step 4: After mixing defatted soy flour and solvent, centrifuge and remove supernatant to obtain soy protein.

4. The preparation method according to claim 3, characterized in that: In step 1, the operation of sterilizing and disinfecting soybeans is: spraying soybeans with 0.5%-1.2% hydrogen peroxide; the mass volume ratio of soybeans to water is 1:4-6.

5. The preparation method according to claim 3, characterized in that: In step 2, when the soybeans are germinated in the dark, the temperature is 25-35° C., the humidity is 80-90%, and the germination time is 3-5 days.

6. The preparation method according to claim 3, characterized in that: In step 3, the specific operation of degreasing is: The ground soybean powder is mixed with ethanol in a mass-to-volume ratio of 1:18-22 and defatted for 2-4 hours.

7. The preparation method according to claim 3, characterized in that: In step 4, the solvent is a sodium bicarbonate solution; the pH of the sodium bicarbonate solution is 7.5-8.

5.

8. The preparation method according to claim 3, characterized in that: In step 4, the defatted soy flour and the solvent are mixed for 1-3 hours; the centrifugal parameters are: temperature 3-5°C, rotation speed 8000-12000g / min, time 5-15min.

9. The preparation method according to claim 1, characterized in that: In S3, the papaya extract is 5-10wt% of the soy protein.

10. Hypoallergenic soybean protein powder prepared according to the preparation method according to any one of claims 1 to 9.