Soy protein peptide powder rich in organic acid and preparation method and application thereof

Abstract

The present invention discloses a soybean protein peptide powder rich in organic acid, and a preparation method and application thereof, and relates to the field of food processing. The preparation method is: after defatted soybeans are fermented with Aspergillus oryzae, they are matched with soybean protein isolate and a composite protease for enzymatic hydrolysis reaction, and after enzyme inactivation, separation, and concentration, vacuum freeze drying equipment is used for freeze drying to obtain soybean protein peptide powder. The defatted soybeans of the present application are fermented with Aspergillus oryzae to efficiently produce natural organic acids, and the enzymatic hydrolysis reaction with soybean protein isolate helps to increase the total nitrogen content. The product is rich in organic acids and has high contents of total nitrogen and small molecule protein peptides, and the fluctuations in the pH and flavor of protein peptide beverages are small. Natural organic acids help to improve the antiseptic effect of beverage products, so as to achieve the purpose of extending the shelf life and reducing the amount of exogenous preservatives added, and ensure food safety.

Description

Technical Field

[0001] The invention relates to the field of food processing, and in particular to a soybean protein peptide powder rich in organic acid, and a preparation method and application thereof. Background Art

[0002] Soy protein peptide refers to a mixture of oligopeptides made from soybeans or soybean protein, which is treated by enzyme hydrolysis or microbial fermentation, and then separated, refined, dried, and other processes. It also contains some free amino acids, sugars, cellulose and other substances. The relative molecular mass, peptide chain length and various physical and chemical properties of soybean peptides are determined by the selected enzymes, hydrolysis conditions and separation methods. Compared with traditional soybean protein, soybean protein peptides have the characteristics of no protein denaturation, no beany, easy to dissolve in water, good fluidity, no precipitation under acidic conditions, no coagulation under heating, and low antigenicity. In addition, the amino acid composition of soybean peptides is basically the same as that of soybean protein, and the essential amino acids are well balanced and rich in content. According to other studies, after the protein ingested by the human body is acted on by proteases in the intestines, a small part of it is absorbed by the intestines in the form of free amino acids, while most of the rest is absorbed in the form of small peptides. Therefore, compared with soybean protein, soybean peptides rich in small peptides are more conducive to human digestion and absorption. In addition, soy protein peptides have many advantages such as low allergenicity, promoting the absorption of trace elements, balancing the gastrointestinal microecology, promoting the growth of beneficial bacteria, enhancing immune function, and promoting human growth. Nowadays, they have been widely used as protein raw materials in various nutritional health products and ordinary foods.

[0003] As one of the sources of protein and small molecule peptides, soybean protein peptides are commonly found in protein peptide drinks, and together with a variety of other animal and plant protein peptide raw materials, they constitute the nutrient raw materials of the product. With the help of such raw materials, protein peptide drinks are deeply loved by consumers for their main functions of enhancing immunity, anti-fatigue, beauty and skin care, and have a wide sales market and customer base. In addition to protein peptide raw materials that mainly provide functional nutritional elements, protein peptide drinks on the market currently use fruit and vegetable juice (or its concentrated juice) as the main raw material to enhance the taste and flavor of the product, reduce the pH value of the product to extend the shelf life of the product and prevent product corruption. Some also add stabilizers, thickeners and other additives to maintain the product texture and optimize the drinking taste. In addition, some protein peptide drinks have the disadvantage of a short shelf life due to factors such as raw materials, processes, and cost restrictions. Preservatives such as potassium sorbate and sodium benzoate need to be added to ensure that the shelf life of the product can be maintained for more than 18 months, and some products will even extend the shelf life to 24 months.

[0004] At present, the food industry mainly uses chemically synthesized sorbic acid, benzoic acid and its salts as preservatives added to products due to shelf life requirements, legal and regulatory restrictions, and production cost considerations. However, chemically synthesized preservatives have received more and more attention and negative reports in recent years, causing consumers to pay more attention to and dislike their presence in food ingredients. In addition, protein peptide drinks are a kind of nutritious food with high added value, and their ingredients will be closely watched by consumers. Exogenously added chemically synthesized preservatives will have a serious impact on the cleanliness of the product ingredient list, thereby affecting consumers' desire to buy. Some organic acids such as lactic acid, citric acid, acetic acid, malic acid, etc. are also often used as natural preservatives. The exogenous addition of natural organic acids as preservatives may affect the taste and flavor of the product due to their strong sour taste. On the other hand, it will also complicate the product ingredient list, which will have an adverse effect on consumer purchases and repeat purchases.

[0005] In addition, the soybean peptide products widely used in the food market are generally weakly acidic or neutral (pH = 5.5 ~ 7.5). When added to protein peptide drinks with fruit and vegetable juice as the main raw material, the pH value of the product will cause an increase, which is not conducive to maintaining the acidic environment of the product. The most suitable environment for most microorganisms that cause spoilage of beverage products is weakly acidic to weakly alkaline. For example, the optimal growth pH of Escherichia coli is 6.5-7.5, the optimal growth pH of mold is 5.5-8.5, and the optimal growth pH of yeast is 4.5-6.5. The increase in product pH will cause product spoilage and shorten the shelf life. Summary of the invention

[0006] The present invention provides a soybean protein peptide powder rich in organic acid and a preparation method and application thereof, so as to increase the natural organic acid content in the soybean protein peptide powder. When used in preparing beverages, it helps to improve the antiseptic effect, and the total nitrogen content is relatively high, and the proportion of small molecule protein peptides is high.

[0007] In order to solve the above technical problems, one of the purposes of the present invention is to provide a method for preparing soybean protein peptide powder rich in organic acid, comprising the following steps:

[0008] (1) soaking defatted soybeans in water, draining the water, and then steaming the defatted soybeans to obtain steamed defatted soybeans;

[0009] (2) adding Aspergillus oryzae to the steamed defatted soybeans, wherein the Aspergillus oryzae accounts for 0.05% to 0.02% of the defatted soybeans by mass, and then performing a fermentation treatment to obtain a fermentation product;

[0010] (3) adding soy protein isolate to the fermentation product to obtain a mixture, wherein the mass ratio of the soy protein isolate to defatted soybean is (30-60):(40-70), and adding 2-3 times the mass of water to the mixture, stirring and shearing, to obtain a homogenized solution;

[0011] (4) adjusting the pH of the homogenate solution to 6.0-6.5, adding a composite protease at a mass fraction of 1%-3% of the homogenate solution, wherein the composite protease comprises an acidic protease, a neutral protease and a trypsin in a mass ratio of (3-5):(2-4):1, and performing an enzymatic hydrolysis reaction to obtain an enzymatic hydrolyzate;

[0012] (5) The enzymatic solution is inactivated, centrifuged, filtered, and then concentrated to a solid content of 30%-50%, followed by freeze drying using a vacuum freeze drying device, and then crushed to obtain soybean protein peptide powder.

[0013] The present application prepares soy protein peptide powder by using defatted soybeans and soy protein isolate as raw materials. The defatted soybeans are fermented by Aspergillus oryzae to efficiently produce abundant natural organic acids such as lactic acid, acetic acid, malic acid, citric acid, etc., and the pH value of the product is reduced. The soy protein isolate is used for enzymatic hydrolysis. During the enzymatic treatment, the composite protease can thoroughly hydrolyze the organic matter to ensure that the total nitrogen in the product is higher than 11.2%, and the proportion of small molecule protein peptides with a relative molecular mass of 189-10000 is higher than 60%. The product meets the key indicator requirements of the national standard GB31611, and the total acid content is higher than that of traditional soy protein peptide products on the market.

[0014] As a preferred solution, the defatted soybeans must meet the quality indicators of the first-level grading standards described in GB / T 13382-2008 "Edible Soybean Meal".

[0015] As a preferred solution, the defatted soybean has a protein content of 52%, a moisture content of 8%, and an ash content of 5.5%.

[0016] As a preferred embodiment, the protein content of the soy protein isolate is ≥90%.

[0017] As a preferred embodiment, the acidic protease is pepsin, and the neutral protease is subtilisin.

[0018] As a preferred embodiment, in step (1), the amount of water added is 1-1.5 times the mass of the defatted soybeans.

[0019] As a preferred embodiment, in step (1), the soaking time is 20-30 minutes.

[0020] As a preferred embodiment, in step (1), the steaming is performed at 115-125° C. for 15-25 minutes.

[0021] As a preferred solution, in step (2), the fermentation temperature is 27-33°C, the fermentation time is 38-42 hours, and the fermentation is stirred several times at intervals to avoid excessively high temperatures in some parts.

[0022] As a preferred embodiment, in step (2), the physical thickness during fermentation is less than 3 cm.

[0023] As a preferred embodiment, in step (2), the fermentation process is divided into four stages. The first stage is from the start of fermentation to the 16th to 17th hour, and the temperature is maintained at 31-33°C. The second stage is from the 23rd to 26th hour, and the temperature is maintained at 29-31°C. The third stage is from the 28th to 33th hour, and the temperature is maintained at 29-31°C. The fourth stage is from the end of fermentation to the end, and the temperature is maintained at 27-28.5°C. At the end of the first, second and third stages, the materials are stirred.

[0024] As a preferred embodiment, in step (3), the stirring shear rate is 8000-12000 r / min, and the time is 2-5 min.

[0025] As a preferred embodiment, in step (4), the pH is adjusted with a 0.5-2 mol / L hydrochloric acid solution.

[0026] As a preferred embodiment, in step (4), the enzymatic hydrolysis reaction temperature is 55-58°C, the time is 10-12 hours, and the enzymatic hydrolysis process is maintained with continuous oscillation.

[0027] As a preferred embodiment, in step (5), the enzyme is inactivated by boiling water bath for 10-15 minutes.

[0028] As a preferred embodiment, in step (5), the centrifugal speed is 7000-12000 r / min.

[0029] As a preferred embodiment, in step (5), the mesh size of the filter cloth used for filtration is 200 meshes.

[0030] As a preferred embodiment, in step (5), the concentration process temperature is controlled below 60°C, the concentration time is below 20 min, and the vacuum is evacuated to a vacuum degree of -0.1 MPa to -0.08 MPa.

[0031] As a preferred solution, in step (5), before vacuum freeze-drying, the product is pre-frozen to a central temperature below -20°C to improve the vacuum freeze-drying effect.

[0032] As a preferred embodiment, in step (5), the vacuum freeze drying temperature is -60°C to -40°C, the vacuum degree is 1-2 Pa, and the drying time is 20-24 hours.

[0033] The present application adopts vacuum freeze drying to treat the enzymatic hydrolysis product, which has a low drying temperature and high drying efficiency, and can avoid the destruction or decomposition of organic acids in the product due to high temperature treatment, thereby ensuring that the natural organic acid content in the product is high.

[0034] As a preferred solution, in step (5), the material processing time is controlled within 10 seconds during the pulverizing process to avoid excessively high equipment temperature or prolonged contact of the material with air, which may cause the material to absorb moisture.

[0035] In order to solve the above technical problems, the second object of the present invention is to provide a soybean protein peptide powder rich in organic acid.

[0036] In order to solve the above technical problems, the third object of the present invention provides a soybean protein peptide powder rich in organic acid for use in preparing protein peptide beverages.

[0037] As a preferred embodiment, the mass fraction of the soy protein peptide powder in the protein peptide beverage is 1wt%-10wt%.

[0038] The soy protein peptide powder prepared in the present application can be used in the preparation of protein peptide beverages. The pH of the soy protein peptide powder after dissolution is relatively low, which can reduce the fluctuation of the pH of the protein peptide beverage and prevent the pH of the product from rising to the optimal growth range of pathogenic bacteria or spoilage bacteria, so as to achieve the purpose of extending the shelf life of the product. The soy protein peptide contains rich natural organic acids such as lactic acid, acetic acid, citric acid, etc., which are produced by natural fermentation of defatted soybeans. There will be no sour and astringent stimulation when exogenous organic acids are added, and the effect on the flavor of the product itself is relatively small. Natural organic acids help to improve the antiseptic effect of beverage products, inhibit the proliferation of pathogenic bacteria in the product and the spoilage of the product, reduce the amount of exogenous preservatives added, and improve food safety.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. This application uses defatted soybeans that are fermented with Aspergillus oryzae to efficiently produce natural organic acids, and is combined with soy protein isolate for enzymatic hydrolysis. During the enzymatic treatment, the composite protease can completely hydrolyze the organic matter to ensure that the total nitrogen in the product is higher than 11.2%, and the proportion of small molecule protein peptides with a relative molecular mass of 189-10000 is higher than 60%. The total acid content of the product is higher than that of traditional soy protein peptide products on the market.

[0041] 2. The pH of the soy protein peptide powder after dissolution is relatively low, which can reduce the fluctuation of the pH of the protein peptide beverage, so as to achieve the purpose of extending the shelf life of the product. The soy protein peptide contains organic acids produced by natural fermentation of defatted soybeans, and there will be no sour and astringent feeling when exogenous organic acids are added, and the impact on the flavor of the product itself is relatively small. Natural organic acids help to improve the antiseptic effect of beverage products, reduce the amount of exogenous preservatives added, and improve food safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 : It is a statistical chart of lactic acid content of a soybean protein peptide powder rich in organic acid in the embodiments of the present invention and the comparative examples;

[0043] Figure 2 : It is a statistical chart of acetic acid content of a soybean protein peptide powder rich in organic acid in the examples of the present invention and the comparative examples;

[0044] Figure 3 : It is a statistical chart of the citric acid content of a soybean protein peptide powder rich in organic acid in the embodiments of the present invention and the comparative examples;

[0045] Figure 4 : It is a statistical chart of malic acid content of a soybean protein peptide powder rich in organic acid in the examples and comparative examples of the present invention;

[0046] Figure 5 : It is a statistical chart of the total acid content of a soybean protein peptide powder rich in organic acid in the embodiments of the present invention and the comparative examples;

[0047] Figure 6 : It is a statistical chart of the total nitrogen and small molecule peptide content of a soybean protein peptide powder rich in organic acid in the embodiments of the present invention and the comparative examples. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0050] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0051] As used herein:

[0052] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0053] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0054] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood to specifically invent all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, regardless of whether the range is invented separately. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0055] In these embodiments, unless otherwise specified, the parts and percentages are all by mass. "Parts by mass" refers to the basic unit of measurement representing the proportional relationship of the masses of multiple components, and 1 part can represent any unit mass. It should not be misunderstood that, unlike the mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0056] “And / or” is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0057] In order to further illustrate the present invention, the soybean protein peptide powder rich in organic acid provided by the present invention and its preparation method and application are described in detail in combination with the examples below, but they should not be understood as limiting the scope of protection of the present invention. The raw materials used in the following examples and comparative examples of the present application are all commercially available unless otherwise specified, and the same raw materials are used in parallel experiments.

[0058] Example 1

[0059] A method for preparing soybean protein peptide powder rich in organic acid comprises the following steps:

[0060] (1) Soaking defatted soybeans in 1.5 times the weight of normal temperature drinking water for 25 minutes, draining the water and placing them in a high pressure cooking pot, cooking them at 121° C. for 15 minutes, taking them out and cooling them to room temperature to obtain cooked defatted soybeans;

[0061] Among them, defatted soybeans meet the quality indicators of the first-level grading standard in GB / T 13382-2008 "Edible Soybean Meal", with a protein content of 52%, a moisture content of 8%, and an ash content of 5.5%;

[0062] (2) adding Aspergillus oryzae koji to the steamed defatted soybeans in a ratio of 1:0.0001 by mass, and stirring the mixture thoroughly to obtain a defatted soybean fermentation material; the number of Aspergillus oryzae koji spores is about ≥20 billion / g;

[0063] (3) Spreading the defatted soybean fermentation raw material on a tray with a thickness not exceeding 2 cm, and placing it in a fermentation cabinet for fermentation. The total fermentation time is 40 hours. The temperature is controlled at 33° C. at the beginning of fermentation. After fermentation for 17 hours, the tray is taken out and stirred thoroughly for fermentation, and then the fermentation is placed in a fermentation cabinet for another fermentation at 31° C. for 7 hours; the tray is taken out again and stirred thoroughly for fermentation, and then the fermentation is placed in a fermentation cabinet for fermentation at 30° C. for 7 hours; the tray is taken out again and stirred thoroughly for fermentation, and then the fermentation is placed in a fermentation cabinet for fermentation at 28° C. until the fermentation is completed, to obtain a fermentation product;

[0064] (4) The fermentation product was transferred to a clean conical flask, and soy protein isolate was added to obtain a mixture, wherein the mass ratio of defatted soybean to soy protein isolate was 54.2:45.8, and 2.5 times the total mass of normal temperature drinking water was added to the mixture, and the mixture was treated with a shearing machine at a speed of 10,000 r / min for 2 min to obtain a homogenized solution;

[0065] Among them, the protein content of soy protein isolate is ≥90%;

[0066] (5) adjusting the pH of the homogenate solution to 6.0 with a 1 mol / L hydrochloric acid solution, adding a composite protease at 1.5% of the mass of the homogenate solution, wherein the composite protease includes an acidic protease, a neutral protease and a trypsin in a mass ratio of 3:2:1, wherein the acidic protease is pepsin and the neutral protease is subtilisin, shaking well and performing enzymolysis at 56° C. for 11 h in a water bath shaker to obtain an enzymolysis solution;

[0067] (6) The enzymatic hydrolyzate was inactivated by boiling water for 15 min, centrifuged at 10,000 r / min, and the supernatant was filtered through a 200-mesh filter cloth and concentrated by a vacuum rotary evaporator at 55° C. in a water bath to a solid content of 35% to obtain a concentrated material;

[0068] (7) Spread the concentrated material on the tray of a vacuum freeze dryer with a thickness not exceeding 1 cm, and freeze-dry it at -60°C and 1.5 Pa vacuum for 22 h. After the material is taken out, it is processed into a uniform and fine powder using a pulverizer to obtain the finished product.

[0069] Example 2

[0070] A method for preparing soybean protein peptide powder rich in organic acid, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 1, except that in step (4), the mass ratio of defatted soybean to soybean protein isolate is 42.3:57.7.

[0071] Example 3

[0072] A method for preparing soybean protein peptide powder rich in organic acid, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 1, except that in step (2), the mass ratio of defatted soybean to Aspergillus oryzae koji is 1:0.00005.

[0073] Comparative Example 1

[0074] A method for preparing soybean protein peptide powder rich in organic acid, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 1, except that in step (7), the concentrated material is subjected to powder spraying treatment in a pressure spray drying tower, the air inlet temperature is controlled at 160°C, the fan frequency is 25MHz, the peristaltic pump speed is 35r / min, and the finished product after drying is collected.

[0075] Comparative Example 2

[0076] A method for preparing soybean protein peptide powder rich in organic acid comprises the following steps:

[0077] (1) mixing the soy protein isolate with 2.5 times the mass of normal temperature drinking water in a conical flask, and treating with a shearing machine at a speed of 10000 r / min for 2 min to obtain a homogenized solution; wherein the protein content of the soy protein isolate is ≥90%;

[0078] (2) adjusting the pH of the homogenate solution to 6.0 with a 1 mol / L hydrochloric acid solution, adding a composite protease at 1.5% of the mass of the homogenate solution, wherein the composite protease includes an acidic protease, a neutral protease and a trypsin in a mass ratio of 3:2:1, wherein the acidic protease is pepsin and the neutral protease is subtilisin, and after shaking, enzymolysis is performed at 56° C. for 11 hours in a water bath shaker to obtain an enzymolysis solution;

[0079] (3) The enzymatic hydrolyzate was inactivated by boiling water for 15 min, centrifuged at 10,000 r / min, and the supernatant was filtered through a 200-mesh filter cloth and concentrated by a vacuum rotary evaporator at 55° C. in a water bath to a solid content of 35% to obtain a concentrated material;

[0080] (4) Spread the concentrated material on the tray of a vacuum freeze dryer with a thickness not exceeding 1 cm, freeze-dry it at -60°C and 1.5 Pa vacuum for 22 h, and use a pulverizer to process the material into a uniform and fine powder to obtain the finished product.

[0081] Comparative Example 3

[0082] A method for preparing soybean protein peptide powder rich in organic acid, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 1, except that in step (4), the amount of soybean protein isolate added is 0.

[0083] Comparative Example 4

[0084] A method for preparing soybean protein peptide powder rich in organic acid, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 1, except that in step (2), Aspergillus oryzae koji is added to defatted soybeans at a mass ratio of 1:0.0001, and the mixture is fully stirred to obtain a defatted soybean fermentation material.

[0085] Comparative Example 5

[0086] A method for preparing soybean protein peptide powder rich in organic acid, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 1, except that in step (5), a 1 mol / L hydrochloric acid solution is used to adjust the pH of the homogenate solution to 3.5, an acidic protease is added at 1.5% of the mass of the homogenate solution, and the acidic protease is pepsin. After shaking, the mixture is enzymolyzed at 56° C. for 11 hours in a water bath shaker to obtain an enzymolysis solution.

[0087] Comparative Example 6

[0088] A method for preparing soybean protein peptide powder rich in organic acid comprises the following steps:

[0089] (1) Soaking defatted soybeans in 1.5 times the weight of normal temperature drinking water for 25 minutes, draining the water and placing them in a high pressure cooking pot, cooking them at 121° C. for 15 minutes, taking them out and cooling them to room temperature to obtain cooked defatted soybeans;

[0090] Among them, defatted soybeans meet the quality indicators of the first-level grading standard in GB / T 13382-2008 "Edible Soybean Meal", with a protein content of 52%, a moisture content of 8%, and an ash content of 5.5%;

[0091] (2) adding Aspergillus oryzae koji to the steamed defatted soybeans in a ratio of 1:0.0001 by mass, stirring the mixture thoroughly to obtain a defatted soybean fermentation material, wherein the number of Aspergillus oryzae koji spores is about ≥20 billion / g;

[0092] (3) Spreading the defatted soybean fermentation material on a tray with a thickness not exceeding 2 cm, placing it in a fermentation cabinet for fermentation, the total fermentation time is 40 hours, the temperature is controlled at 33° C. at the beginning of fermentation, taking out the tray after fermentation for 17 hours, stirring the fermentation material evenly, and then placing it in a fermentation cabinet for fermentation at 31° C. for another 7 hours; taking out the tray again, stirring the fermentation material evenly, and then placing it in a fermentation cabinet for fermentation at 30° C. for 7 hours; taking out the tray again, stirring the fermentation material evenly, and then placing it in a fermentation cabinet for fermentation at 28° C. until the fermentation is completed, to obtain a fermentation product;

[0093] (4) The fermentation product was transferred to a clean conical flask, and soy protein isolate was added to obtain a mixture, wherein the mass ratio of defatted soybean to soy protein isolate was 54.2:45.8, and 2.5 times the total mass of normal temperature drinking water was added to the mixture, and the mixture was treated with a shearing machine at a speed of 10,000 r / min for 2 min to obtain a homogenized solution;

[0094] Among them, the protein content of soy protein isolate is ≥90%;

[0095] (5) The homogenized solution was centrifuged at 10,000 r / min, and the supernatant was filtered through a 200-mesh filter cloth and concentrated using a vacuum rotary evaporator at 55° C. in a water bath to a solid content of 35% to obtain a concentrated material;

[0096] (6) Spread the concentrated material on the tray of a vacuum freeze dryer with a thickness not exceeding 1 cm, freeze-dry it at -60°C and 1.5 Pa vacuum for 22 h, and use a pulverizer to grind the material into a uniform and fine powder to obtain the finished product.

[0097] Comparative Example 7

[0098] A method for preparing soybean protein peptide powder rich in organic acid comprises the following steps:

[0099] (1) Soaking defatted soybeans in 1.5 times the weight of normal temperature drinking water for 25 minutes, draining the water and placing them in a high pressure cooking pot, cooking them at 121° C. for 15 minutes, taking them out and cooling them to room temperature to obtain cooked defatted soybeans;

[0100] Among them, defatted soybeans meet the quality indicators of the first-level grading standard in GB / T 13382-2008 "Edible Soybean Meal", with a protein content of 52%, a moisture content of 8%, and an ash content of 5.5%;

[0101] (2) adding Aspergillus oryzae koji to steamed defatted soybeans at a mass ratio of 1:0.0001 to defatted soybeans, adding soy protein isolate to steamed defatted soybeans at a mass ratio of 54.2:45.8 to defatted soybeans, and stirring well to obtain a fermented material, wherein the number of Aspergillus oryzae koji spores is about ≥20 billion / g, and the protein content of the soy protein isolate is ≥90%;

[0102] (3) Spread the fermentation material on a tray with a thickness not exceeding 2 cm, and place it in a fermentation cabinet for fermentation. The total fermentation time is 40 hours. The temperature is controlled at 33° C. at the beginning of fermentation. After fermentation for 17 hours, take out the tray and stir the fermentation material thoroughly, then place it in a fermentation cabinet for fermentation at 31° C. for another 7 hours; take out the tray again and stir the fermentation material thoroughly, then place it in a fermentation cabinet for fermentation at 30° C. for 7 hours; take out the tray again and stir the fermentation material thoroughly, then place it in a fermentation cabinet for fermentation at 28° C. until the fermentation is completed, to obtain a fermentation product;

[0103] (4) The fermentation product was transferred to a clean conical flask, 2.5 times the mass of normal temperature drinking water was added, and the product was treated with a shearing machine at a speed of 10,000 r / min for 2 min to obtain a homogenized solution;

[0104] (5) adjusting the pH of the homogenate solution to 6.0 with a 1 mol / L hydrochloric acid solution, adding a composite protease at 1.5% of the mass of the homogenate solution, wherein the composite protease includes an acidic protease, a neutral protease and a trypsin in a mass ratio of 3:2:1, wherein the acidic protease is pepsin and the neutral protease is subtilisin, shaking well and performing enzymolysis at 56° C. for 11 h in a water bath shaker to obtain an enzymolysis solution;

[0105] (6) The enzymatic hydrolyzate was inactivated by boiling water for 15 min, centrifuged at 10,000 r / min, and the supernatant was filtered through a 200-mesh filter cloth and concentrated by a vacuum rotary evaporator at 55° C. in a water bath to a solid content of 35% to obtain a concentrated material;

[0106] (7) Spread the concentrated material on the tray of a vacuum freeze dryer with a thickness not exceeding 1 cm, and freeze-dry it at -60°C and 1.5 Pa vacuum for 22 h. After the material is taken out, it is processed into a uniform and fine powder using a pulverizer to obtain the finished product.

[0107] Comparative Example 8

[0108] A method for preparing soybean protein peptide powder rich in organic acid, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 1, except that in step (5), a 1 mol / L hydrochloric acid solution is used to adjust the pH of the homogenate solution to 6.5, a neutral protease is added at 1.5% of the mass of the homogenate solution, and the neutral protease is Bacillus subtilis protease. After shaking, the mixture is enzymolyzed at 56° C. for 11 hours in a water bath shaker to obtain an enzymolysis solution.

[0109] Comparative Example 9

[0110] A method for preparing soybean protein peptide powder rich in organic acid, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 1, except that in step (2), Aspergillus oryzae koji is replaced by an equal amount of Aspergillus niger koji, which is purchased from Testobio Company with a product number of TS275096.

[0111] Product physical and chemical property testing

[0112] 1. The soy protein peptide powder prepared in the embodiment and the comparative example was subjected to lactic acid, acetic acid, citric acid, malic acid, total nitrogen and total acid determination. The detection standards for lactic acid, acetic acid, citric acid and malic acid are GB5009 / 157-2016 "National Food Safety Standard for Determination of Lactic Acid in Food", the detection standard for total nitrogen is GB 5009.5-2016 "National Food Safety Standard for Determination of Protein in Food", and the detection standard for total acid is GB 12456-2021 "National Food Safety Standard for Determination of Total Acid in Food". At the same time, according to Appendix A of GB 31645-2018 "National Food Safety Standard Collagen Peptide", the proportion of peptide segments with a molecular weight of 189-10000 was determined, and the test results are shown in Table 1 below.

[0113] 2. The soy protein peptide powder prepared in the example was diluted 50 times with water to form a uniform aqueous solution, and its pH was measured; at the same time, the soy protein peptide powder of the example was added to a protein peptide beverage at 2wt%, and a blank protein peptide beverage without adding soy protein peptide powder was used to measure the pH of the beverage. The test results are shown in Table 2 below.

[0114] Among them, the main auxiliary materials of protein peptide beverage include 45wt% pure water, 20wt% protein peptide raw materials, 30wt% fruit fat concentrate juice, 1wt% oligofructose, 1wt% xylitol, 0.5wt% olive fruit powder, 0.5wt% xanthan gum, 1wt% citric acid, 0.5wt% vitamin C, and 0.5wt% mogroside, among which water and fruit juice concentrate raw materials account for about 76%, among which fruit juice concentrate includes blueberry concentrate juice, cherry concentrate juice, apple concentrate juice, black plum concentrate juice, grape concentrate juice, lemon concentrate juice and cranberry concentrate juice with a mass ratio of 1:1:1:1:1:1:1, and protein peptide raw materials include 15wt% collagen peptides, 3wt% soy protein peptides and 2wt% bird's nest peptides.

[0115] Table 1 - Performance test results of soybean protein peptide powder in Examples 1-3 and Comparative Examples 1-9 of the present application

[0116]

[0117]

[0118] Table 2-pH of soybean protein peptide powder after dilution and application in protein peptide beverages in the examples and comparative examples of the present application

[0119]

[0120] As shown in Tables 1-2, Example 2 uses low-temperature vacuum drying to obtain soy protein peptide powder, and the drying temperature is as low as -60°C, while Comparative Example 1 uses spray drying, and the drying temperature is as high as 160°C. Compared with Example 2, the high-temperature drying of Comparative Example 1 causes a significant decrease in the organic acid content in the soy protein peptide powder. This is because organic acids will decompose in a high-temperature environment, causing the total acid content to drop sharply. When used in protein peptide beverages, the reduction in organic acid content leads to a decrease in the concentration of free hydrogen ions in the solution, which will increase its pH value to a weak acid or weak alkaline environment that microorganisms can adapt to survive, resulting in the beverage being easily spoiled and having a shortened shelf life, and easily affecting the taste of the beverage.

[0121] As shown in Tables 1-2, Example 2 uses fermented defatted soybeans and soy protein isolate as raw materials for enzymatic hydrolysis to prepare soy protein peptides. After fermentation and enzymatic hydrolysis, defatted soybeans can produce rich natural organic acids. The higher the organic acid content, the higher the free hydrogen ion concentration in the solution, and the lower the pH under the same total acid content, which can reduce the fluctuation of the pH of the beverage. At the same time, the enzymatic hydrolysis of soy protein isolate can increase the proportion of small molecule protein peptides and the total nitrogen content; while Comparative Example 2 uses soy protein isolate as raw material for enzymatic hydrolysis, and the organic acid content of the generated soy protein peptides is very small, and the pH under the same total acid content is relatively higher, which can easily cause large pH fluctuations in the beverage; Comparative Example 3 uses defatted soybeans as raw materials for fermentation and enzymatic hydrolysis, and the organic acid content of the generated soy protein peptides is increased, but the total nitrogen content is greatly reduced, and the proportion of small molecule protein peptides is greatly reduced.

[0122] As shown in Tables 1-2, the defatted soybeans in Comparative Example 4 were directly fermented without being steamed, while the defatted soybeans in Example 2 were fermented after being steamed. Steaming can provide a bactericidal effect, and is beneficial for gelatinizing starch and converting it into nutrients such as sugar and dextrin, which is beneficial for the absorption and utilization of microorganisms and improves the efficiency of fermentation acid production. Compared with Comparative Example 4, the prepared soybean protein peptide powder has more organic acid content and total nitrogen content, and a high proportion of small molecule protein peptides.

[0123] As shown in Tables 1-2, Example 1 uses a composite protease containing acidic protease, neutral protease and alkaline protease for enzymatic hydrolysis reaction, while Comparative Example 5 uses acidic protease for enzymatic hydrolysis reaction, and Comparative Example 8 uses neutral protease for enzymatic hydrolysis reaction. Compared with Example 2, the soy protein peptide prepared in Comparative Example 5 has a low organic acid content using a single acidic protease enzymatic hydrolysis reaction, and the soy protein peptide prepared in Comparative Example 8 has a low total nitrogen and organic acid content using a single neutral protease enzymatic hydrolysis reaction, and the proportion of small molecule protein peptides is also low.

[0124] As shown in Table 1-2, the defatted soybeans in Comparative Example 9 were fermented with Aspergillus niger. Compared with Example 2, the organic acid and total nitrogen contents of the soybean protein peptides prepared in Comparative Example 9 were lower, and the proportion of small molecule protein peptides was small.

[0125] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing soybean protein peptide powder rich in organic acid, characterized in that: The following steps are involved: (1) soaking defatted soybeans in water, draining the water, and then steaming the defatted soybeans to obtain steamed defatted soybeans; (2) adding Aspergillus oryzae to the steamed defatted soybeans, wherein the Aspergillus oryzae accounts for 0.05% to 0.02% of the defatted soybeans by mass, and then performing a fermentation treatment to obtain a fermentation product; (3) adding soy protein isolate to the fermentation product to obtain a mixture, wherein the mass ratio of the soy protein isolate to defatted soybean is (30-60):(40-70), and adding 2-3 times the mass of water to the mixture, stirring and shearing, to obtain a homogenized solution; (4) adjusting the pH of the homogenate solution to 6.0-6.5, adding a composite protease at a mass fraction of 1%-3% of the homogenate solution, wherein the composite protease comprises an acidic protease, a neutral protease and a trypsin in a mass ratio of (3-5):(2-4):1, and performing an enzymatic hydrolysis reaction to obtain an enzymatic hydrolyzate; (5) The enzymatic solution is inactivated, centrifuged, filtered, and then concentrated to a solid content of 30%-50%, followed by freeze drying using a vacuum freeze drying device, and then crushed to obtain soybean protein peptide powder.

2. The method for preparing the soybean protein peptide powder rich in organic acid as claimed in claim 1, characterized in that: In step (1), the amount of water added is 1-1.5 times the mass of the defatted soybeans; And / or, in step (1), the soaking time is 20-30 min; And / or, in step (1), steaming is performed at 115-125° C. for 15-25 min.

3. The method for preparing the soybean protein peptide powder rich in organic acid as claimed in claim 1, characterized in that: In step (2), the fermentation temperature is 27-33° C., the fermentation time is 38-42 hours, and the fermentation is performed several times at intervals; And / or, in step (2), the physical thickness during fermentation is less than 3 cm.

4. The method for preparing the soybean protein peptide powder rich in organic acid as claimed in claim 1, characterized in that: In step (2), the fermentation process is divided into four stages. The first stage is from the start of fermentation to the 16th to 17th hour, and the temperature is maintained at 31-33°C. The second stage is from the 23rd to 26th hour, and the temperature is maintained at 29-31°C. The third stage is from the 28th to 33th hour, and the temperature is maintained at 29-31°C. The fourth stage is from the end of fermentation to the end, and the temperature is maintained at 27-28.5°C. At the end of the first, second and third stages, the materials are stirred.

5. The method for preparing the soybean protein peptide powder rich in organic acid according to claim 1, characterized in that: In step (3), the stirring shear rate is 8000-12000 r / min, and the time is 2-5 min.

6. The method for preparing the soybean protein peptide powder rich in organic acid according to claim 1, characterized in that: In step (4), the pH is adjusted with a 0.5-2 mol / L hydrochloric acid solution; And / or, in step (4), the enzymatic hydrolysis reaction temperature is 55-58°C and the time is 10-12h.

7. The method for preparing the soybean protein peptide powder rich in organic acid according to claim 1, characterized in that: In step (5), the enzyme is inactivated by boiling water bath for 10-15 min; and / or, in step (5), the centrifugal speed is 7000-12000 r / min; And / or, in step (5), the mesh size of the filter cloth used for filtration is 200 mesh; And / or, in step (5), the concentration process temperature is controlled to be below 60° C., the concentration time is below 20 min, and the vacuum is evacuated to a vacuum degree of -0.1 MPa to -0.08 MPa; And / or, in step (5), the vacuum freeze drying temperature is -60°C to -40°C, the vacuum degree is 1-2 Pa, and the drying time is 20-24 hours.

8. A soybean protein peptide powder rich in organic acid prepared by the method for preparing soybean protein peptide powder rich in organic acid as claimed in any one of claims 1 to 7.

9. Use of the soy protein peptide powder rich in organic acid as claimed in claim 8 in preparing protein peptide beverages.

10. The use of the soy protein peptide powder rich in organic acid in the preparation of a protein peptide beverage according to claim 9, characterized in that: The mass fraction of the soybean protein peptide powder in the protein peptide beverage is 1wt%-10wt%.

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