A method for synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies

Abstract

The present invention discloses a method for synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies, which comprises the following steps: raw material pretreatment; subjecting soybeans to activation with weakly alkaline water and washing with deionized water, incubating in a nano-metal suspension, and then continuing to incubate in a culture solution to complete the cultivation of endogenous proteases; pulping and filtering to obtain soy milk; adjusting the pH value and temperature of the obtained soy milk, and performing three enzyme dissociations to obtain peptide-rich soy milk; heating the obtained peptide-rich soy milk, then cooling and centrifuging, where the upper cream is soybean oil bodies and the lower liquid phase is low-fat peptide-rich soy milk. The present invention uses activation with weakly alkaline water-incubation in a nano-metal suspension-cultivation in a culture solution to stimulate and cultivate the endogenous proteases in soybean seeds, and adopts the pH-temperature synergistic offset technology to enzymatically dissociate soybean protein and oil body protein using different endogenous proteases, realizing the synchronous preparation of low-fat peptide-rich soy milk and soybean oil bodies.

Description

Technical Field

[0001] The present invention relates to the technical field of soybean processing, and particularly relates to a method for synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies. Background Art

[0002] Soybeans are rich in nutrients such as protein, fat, vitamins, soy isoflavones, and minerals, and do not contain lactose and cholesterol, with high nutritional and health care value, and are known as the "king of beans". The soy milk prepared from soybeans is a traditional plant protein beverage in China and has the broadest mass base in China.

[0003] Soy milk is prepared from high-quality soybeans through processes such as impurity removal (peeling), soaking, hot blanching and rinsing, hot grinding and extraction, separation, heat treatment and deodorization, high-pressure homogenization, packaging, and sterilization. It makes full use of plant protein resources, applies plant protein, improves protein efficiency and biological value, contains various vitamins and minerals, and has high nutritional value. It has a strong, mellow, and smooth taste without being greasy, and regular consumption is beneficial. It is a healthy and nutritious soy milk beverage. According to analysis, soy milk contains rich nutritional components, especially rich in protein and relatively more trace element magnesium. In addition, it also contains vitamin B l 、B 2 etc., and is a relatively good nutritional food. However, most of the soy milk prepared by the existing processes is full-fat soy milk, which has a high oil content. It not only cannot meet the needs of some special consumers for low-fat beverages, but also is prone to problems such as oil floating and acidification that affect the quality of soy milk. In addition, the soy milk prepared by the existing processes is rich in macromolecular proteins, and the digestion and absorption rate in the human body is relatively slow, which cannot fully meet the consumption needs of children, the elderly, and adults with relatively weak digestive ability. In recent years, there have been individual technologies for preparing peptide-rich soy milk disclosed, all of which use expensive commercial proteases to enzymatically hydrolyze soy proteins, resulting in high costs.

[0004] Soybean oil bodies are natural emulsified oil droplet particles, with particle sizes mainly distributed in the range of 200nm - 500nm. They have a core composed of triglycerides, and their outer shell is composed of a single-layer membrane structure of phospholipids and oil body membrane proteins. The oil body membrane proteins are mainly composed of three molecular weight oleosins, namely 24kDa, 18kDa, and 16kDa. In addition, soybean oil bodies also contain vitamin E and sterols, which indicates that soybean oil bodies are natural emulsified oil droplet particles rich in oil-soluble functional small molecules and have the potential to become new types of oil products.

[0005] Patent CN113615810A discloses a method for synchronously preparing low-fat soymilk and soybean cream. First, soybeans are washed, soaked, ground, and defatted to obtain soymilk; then the pH value is adjusted, heated and incubated to activate the endogenous protease P34 in the soymilk; then heat-treated, and finally centrifuged to obtain low-fat soymilk and soybean cream of oil body emulsion. To dissociate the soybean oil body protein in the soymilk, the endogenous protease used is P34 enzyme. However, P34 enzyme can only enzymatically dissociate the soybean oil body protein in the soymilk, and has almost no enzymatic dissociation ability for the more abundant globulin and conglobulin in the soymilk, and the content of bioactive peptides in the soymilk is low. Summary of the Invention

[0006] In view of the above-mentioned prior art, the object of the present invention is to provide a method for synchronously preparing low-fat peptide-rich soymilk and soybean oil bodies.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides a method for synchronously preparing low-fat peptide-rich soymilk and soybean oil bodies, comprising the following steps:

[0009] S01 Raw material pretreatment: The soybean raw material is rinsed with tap water - soaked in a weak acid aqueous solution - washed with deionized water and then air-dried naturally to obtain pretreated soybeans;

[0010] S02 Cultivation of endogenous protease: The pretreated soybeans obtained in S01 are stimulated with weak alkaline water and washed with deionized water, then incubated in a nano-metal suspension, and then placed in a culture solution for further cultivation to complete the cultivation of endogenous protease;

[0011] S03 Preparation of soymilk: Deionized water is added to the soybeans after the cultivation of endogenous protease in S02 for pulping, and the obtained slurry after filtration is soymilk;

[0012] S04 Preparation of peptide-rich soymilk: Adjust the pH value and temperature of the soymilk obtained in S03, perform the first enzymatic dissociation, then adjust the pH value and temperature of the soymilk, perform the second enzymatic dissociation, and then adjust the pH value and temperature of the soymilk, perform the third enzymatic dissociation, and the obtained soymilk is peptide-rich soymilk;

[0013] S05 Synchronously preparing low-fat peptide-rich soymilk and soybean oil bodies: Heat the peptide-rich soymilk obtained in S04, then cool it, and centrifuge it to obtain the upper cream as soybean oil bodies and the lower liquid phase as low-fat peptide-rich soymilk.

[0014] Preferably, in step S01, the weak acid aqueous solution is an acetic acid solution prepared by mixing acetic acid and deionized water in a mass ratio of (0.5 - 1.0):100, the temperature of the weak acid aqueous solution soaking is 20 - 25 °C, and the soaking time is 30 - 60 minutes. The purpose of soaking in the weak acid aqueous solution is to perform preliminary sterilization and disinfection on the surface of soybean seeds.

[0015] Preferably, in step S02, the weakly alkaline water is an aqueous sodium bicarbonate solution prepared by mixing sodium bicarbonate and deionized water in a mass ratio of (0.1 - 0.5):100. The activation of the weakly alkaline water is to soak the pretreated soybeans in the aqueous sodium bicarbonate solution at 45 - 55°C for 20 - 50 minutes. The purpose of activating the weakly alkaline water is to stimulate the soybeans seeds to absorb water quickly, providing a basis for improving the efficiency of various biochemical reactions inside the soybeans.

[0016] Preferably, in step S02, the nano - metal suspension is a nano - iron suspension with a concentration of 25 - 200 mg / L. The incubation time in the nano - metal suspension is 20 - 60 minutes, and the temperature is room temperature.

[0017] The function of the nano - metal suspension is to accelerate the biosynthesis rate of various proteases in soybeans themselves, stimulate the seeds to produce more types and larger quantities of endogenous proteases, and significantly enhance the activity of each protease through the cultivation of soybeans. The types, quantities, activities of various enzymes, and the effect of enzyme - dissociation of soybean proteins produced are all higher than those of the prior art.

[0018] More preferably, the nano - iron suspension is prepared by dispersing nano - iron in distilled water and ultrasonicating it for 20 - 40 minutes at a power of 100 - 300 W and a frequency of 20 - 40 kHz. The particle size of nano - iron is 20 - 100 nm.

[0019] Preferably, in step S02, the cultivation solution is an aqueous sodium bicarbonate solution prepared by mixing sodium bicarbonate and deionized water in a mass ratio of (0.2 - 1.0):100. The cultivation time in the cultivation solution is 10 - 30 hours, and the temperature is 18 - 23°C. Various proteases can be further activated in the cultivation solution, significantly improving their catalytic activity.

[0020] Preferably, in step S03, the mass of deionized water added is 6 - 11 times that of the soybeans, the pulping time is 1 - 3 minutes, and the pulping speed is 10000 - 18000 r / min.

[0021] Preferably, in step S04, the pH value of the first enzyme - dissociation is 2 - 4, the temperature is 20 - 35°C, and the time is 1 - 3 hours; the pH value of the second enzyme - dissociation is 4.5 - 6.5, the temperature is 40 - 55°C, and the time is 3 - 6 hours; the pH value of the third enzyme - dissociation is 7.5 - 9.5, the temperature is 30 - 40°C, and the time is 1 - 3 hours.

[0022] Preferably, in step S05, the temperature for heating the peptide-rich soymilk is 90 - 100 °C, the time is 10 - 30 minutes, the cooling temperature is 50 - 90 °C, the centrifugation speed is 5000 - 8000 r / min, and the centrifugation time is 10 - 30 minutes.

[0023] The second aspect of the present invention provides low-fat peptide-rich soymilk and soybean oil bodies prepared by the above method.

[0024] Soybean seeds contain a variety of endogenous proteases, which have been widely studied in the research of plant physiology, biochemistry and plant science, but there are few studies in the field of soybean food processing. Different endogenous proteases in soybeans have different optimal enzyme dissociation temperatures and pH values (acidic, weakly acidic, alkaline), and they can only efficiently play their role in hydrolyzing different soybean proteins and oil body proteins under the synergy of their optimal enzyme dissociation temperature and optimal pH conditions.

[0025] The endogenous proteases used in the present invention include: ① Aspartic endopeptidase, which has strong enzyme activity in an acidic environment (pH 2 - 4), and can dissociate soybean globulin into small peptides under the condition of its optimal enzyme dissociation temperature of 20 - 35 °C; ② P34, cysteine protease, serine carboxypeptidase, glutamate decarboxylase, etc., these enzymes have strong activity in a weakly acidic environment (pH 4.5 - 6.5), and can dissociate protease inhibitors such as soybean oil body protein, soybean lipoxygenase and protease inhibitors into small peptides under the condition of their optimal enzyme dissociation temperature of 40 - 55 °C; ③ Glutamine endopeptidase and aspartic aminopeptidase have strong activity in an alkaline environment (pH 7.5 - 9.5), and can dissociate enzymes such as soybean oil body protein and soybean conglycinin into small peptides under the condition of their optimal enzyme dissociation temperature of 30 - 40 °C.

[0026] The cultivation of soybean seeds by alkaline water excitation and nano-metal suspension in the present invention can significantly increase the number of various endogenous proteases including P34 inside soybean seeds, and significantly enhance the activity of various proteases. It can not only achieve the purpose of efficiently dissociating soybean oil body protein by P34 and improving the extraction rate of soybean oil bodies, but also fully exert the enzyme dissociation activity of other various endogenous proteases through pH offset and temperature regulation, so as to significantly reduce the lipid content in soymilk and significantly increase the small peptide content in soymilk.

[0027] The beneficial effects of the present invention:

[0028] The present invention uses the endogenous protease cultivated from soybean seeds themselves to enzymatically dissociate soybean protein and oleosome protein, and synchronously prepares low-fat peptide-rich soy milk and soybean oleosomes. Compared with the prior art, the present invention uses weak alkaline water excitation - nano-metal suspension incubation - culture solution cultivation to stimulate and cultivate the endogenous protease in soybean seeds themselves, and uses the pH-temperature synergistic offset technology to enzymatically dissociate soybean protein and oleosome protein with different endogenous proteases, realizing the synchronous preparation of low-fat peptide-rich soy milk and soybean oleosomes.

[0029] Compared with the prior art, the low-fat peptide-rich soy milk prepared by the present invention has a high content of small molecule bioactive peptides, a low lipid content, is easy to digest and absorb, and does not require the purchase of expensive commercial proteases, with low cost and energy saving and consumption reduction.

[0030] The nano-iron used in the present invention has a purity of ≥99.9%, and will not cause the residue of other heavy metal impurities. The iron content in the soy milk or oleosomes of the present invention complies with the national food safety standard GB 5009.90—2016. Brief Description of the Drawings

[0031] Figure 1 : Comparison of the activities of endogenous proteases in the soy milk of Example 1 and Comparative Examples 1-3;

[0032] Figure 2 : Physical pictures of the low-fat peptide-rich soy milk and oleosomes prepared in Example 1. Detailed Description of the Invention

[0033] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0034] As described in the background art, based on this, the present invention provides a method for synchronously preparing low-fat peptide-rich soy milk and soybean oleosomes, including the following steps:

[0035] S01 Raw material pretreatment: The soybean raw material is rinsed with tap water - soaked in a weak acid aqueous solution - washed with deionized water and then naturally air-dried to obtain pretreated soybeans; the raw material is soybean seeds with plump, complete, non-moldy, non-rotten, and non-pest-infested grains; the weak acid aqueous solution is an acetic acid solution prepared by mixing acetic acid and deionized water in a mass ratio of (0.5-1.0:100), the temperature of the weak acid aqueous solution soaking is 20-25°C, and the soaking time is 30-60 minutes;

[0036] Cultivation of S02 endogenous protease: The pretreated soybeans obtained in S01 are stimulated with weakly alkaline water and washed with deionized water, then incubated at room temperature in a nano-metal suspension, and then further cultivated in a cultivation solution to complete the cultivation of endogenous protease; the weakly alkaline water is a sodium bicarbonate aqueous solution prepared by mixing sodium bicarbonate and deionized water in a mass ratio of (0.1 - 0.5):100, and the stimulation with weakly alkaline water is to soak the pretreated soybean seeds in the sodium bicarbonate aqueous solution at 45 - 55°C for 20 - 50 minutes; the nano-metal suspension is a nano-iron suspension with a concentration of 25 - 200 mg / L, and the nano-iron suspension is prepared by ultrasonic treatment with an ultrasonic generator at a power of 100 - 300 W and a frequency of 20 - 40 kHz for 20 - 40 minutes. The incubation time in the nano-metal suspension is 20 - 60 minutes; the cultivation solution is a sodium bicarbonate aqueous solution prepared by mixing sodium bicarbonate and deionized water in a mass ratio of (0.2 - 1.0):100, and the cultivation time in the cultivation solution is 10 - 30 hours at a temperature of 18 - 23°C;

[0037] S03 Preparation of soymilk: Deionized water is added to the soybeans after the cultivation of S02 endogenous protease is completed and ground, and the obtained slurry after filtration is soymilk; the mass of the added deionized water is 6 - 11 times that of the soybeans, the grinding time is 1 - 3 minutes, and the grinding speed is 10000 - 18000 r / min;

[0038] S04 Preparation of peptide-rich soymilk: The pH value of the soymilk obtained in S03 is adjusted to 2 - 4 with a food-grade citric acid solution, the temperature of the soymilk is adjusted to 20 - 35°C, and the first enzymatic dissociation is carried out for 1 - 3 hours. Then, the pH value of the soymilk is adjusted to 4.5 - 6.5 with a food-grade sodium hydroxide solution, the temperature is adjusted to 40 - 55°C, and the second enzymatic dissociation is carried out for 3 - 6 hours. Then, the pH value of the soymilk is adjusted to 7.5 - 9.5 with a food-grade sodium hydroxide solution, the temperature is adjusted to 30 - 40°C, and the third enzymatic dissociation is carried out for 1 - 3 hours. The obtained soymilk is peptide-rich soymilk;

[0039] S05 Simultaneous preparation of low-fat peptide-rich soy milk and oil bodies: The peptide-rich soymilk obtained in S04 is heated at 90 - 100°C for 10 - 30 minutes, then cooled to 50 - 90°C, and centrifuged at 5000 - 8000 r / min for 10 - 30 minutes. The upper cream obtained is soybean oil bodies, and the lower liquid phase is low-fat peptide-rich soy milk.

[0040] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with specific embodiments.

[0041] The test materials used in the embodiments of the present invention are all conventional test materials in the art and can be obtained through commercial channels. The nano-iron used in the following examples and comparative examples of the present invention was purchased from Aladdin Biochemical Technology Co., Ltd., with a particle size of 100 nm and a purity of 99.9%.

[0042] Example 1:

[0043] S01 Raw material pretreatment: Select the soybeans harvested in the current year with plump, complete, non-moldy, non-rotten, and pest-free seeds as raw materials. After washing the soybean raw materials with tap water, immerse the soybean seeds in an acetic acid solution prepared by mixing acetic acid and deionized water at a mass ratio of 0.5:100, soak at 23°C for 40 minutes, wash with deionized water, and air-dry naturally to obtain pretreated soybeans;

[0044] S02 Cultivation of endogenous protease: Mix sodium bicarbonate and deionized water at a mass ratio of 0.5:100 to prepare an aqueous sodium bicarbonate solution. Place the pretreated soybeans obtained in S01 in the aqueous sodium bicarbonate solution at 50°C and stir and soak for 30 minutes to stimulate the endogenous protease; immediately wash the soybean seeds excited by the weakly alkaline water with deionized water, drain the water, and incubate in a 50 mg / L nano-iron suspension (prepared by dispersing nano-iron in distilled water and ultrasonically treating it for 25 minutes at a power of 200 W and a frequency of 40 kHz, with a nano-iron particle size of 100 nm and a purity of 99.9%) at room temperature for 30 minutes, and then incubate in a cultivation solution (an aqueous sodium bicarbonate solution prepared by mixing sodium bicarbonate and deionized water at a mass ratio of 0.2:100) at 20°C for 20 hours to complete the cultivation of endogenous protease;

[0045] S03 Preparation of soymilk: Put the soybeans that have completed the cultivation of endogenous protease in S02 into a high-speed tissue homogenizer, add 9 times the mass of the soybeans of 4°C deionized water to make soymilk, beat at 18,000 r / min for 3 minutes, and the filtered slurry is soymilk, and the soymilk is weakly alkaline;

[0046] S04 Preparation of peptide-rich soymilk: Adjust the pH value of the soymilk obtained in step S03 to 3 with a 50% mass fraction of food-grade citric acid solution, adjust the temperature of the soymilk to 35°C for the first enzymatic dissociation for 3 hours, then adjust the pH value of the soymilk to 6.0 with a 2% food-grade sodium hydroxide solution, adjust the temperature of the soymilk to 45°C and continue the second enzymatic dissociation for 3 hours, and finally adjust the pH of the soymilk to 8.0 with a 2% food-grade sodium hydroxide solution, adjust the temperature of the soymilk to 40°C and continue the third enzymatic dissociation for 3 hours, and the obtained soymilk is peptide-rich soymilk.

[0047] S05 Synchronously prepare low-fat peptide-rich soymilk and oil bodies: Heat the peptide-rich soymilk obtained in S04 in a water bath at 100 °C for 20 minutes, then cool it to 90 °C and centrifuge at 6000 r / min for 30 min. Collect the upper cream as soybean oil bodies and the lower liquid phase as low-fat peptide-rich soymilk.

[0048] Comparative Example 1:

[0049] S01 Raw material pretreatment: Select the soybeans harvested in the current year with plump, complete, non-moldy, non-rotten, and pest-free seeds as raw materials. After rinsing the soybean raw materials with tap water, immerse the soybean seeds in deionized water and soak them at 23 °C for 8 hours to obtain pretreated soybeans;

[0050] S02 Prepare soymilk: Put the pretreated soybeans in S01 into a high-speed tissue grinder, add 9 times the mass of deionized water at 4 °C to the soybeans and beat them into a slurry. Beat the slurry at 18000 r / min for 3 minutes, and the obtained slurry after filtration is soymilk;

[0051] S03 Endogenous protease cultivation: Adjust the pH of the soymilk obtained in S02 to 6.0 with 50% food-grade citric acid solution, adjust the temperature to 45 °C, and carry out endogenous protease cultivation and enzyme dissociation of the soymilk for 90 minutes;

[0052] S04 Synchronously prepare soymilk and oil bodies: Heat the soymilk after completing endogenous protease cultivation and enzyme dissociation in S03 in a water bath at 100 °C for 20 minutes, then cool it to 90 °C and centrifuge at 6000 r / min for 30 min. Collect the upper cream as soybean oil bodies and the lower liquid phase as soymilk.

[0053] Comparative Example 2:

[0054] S01 Raw material pretreatment: Select the soybeans harvested in the current year with plump, complete, non-moldy, non-rotten, and pest-free seeds as raw materials. After rinsing the soybean raw materials with tap water, immerse the soybean seeds in an acetic acid solution prepared by mixing acetic acid and deionized water at a mass ratio of 0.5:100, soak them at 23 °C for 40 minutes, wash them with deionized water and air-dry them naturally to obtain pretreated soybeans;

[0055] S02 Endogenous protease cultivation: Mix sodium bicarbonate and deionized water at a mass ratio of 0.5:100 to prepare an aqueous sodium bicarbonate solution. Place the pretreated soybeans obtained in S01 in the aqueous sodium bicarbonate solution at 50 °C and stir and soak them for 30 minutes to activate the endogenous protease; Immediately wash the soybean seeds excited by weak alkaline water with deionized water, drain the water, and put them into a culture solution (an aqueous sodium bicarbonate solution prepared by mixing sodium bicarbonate and deionized water at a mass ratio of 0.2:100) and continue to cultivate at 20 °C for 20 hours to complete the endogenous protease cultivation;

[0056] S03 Preparation of soymilk: The soybeans that have completed the cultivation of endogenous protease in S02 are put into a high-speed tissue homogenizer, and deionized water at 4°C with a mass 9 times that of the soybeans is added for pulping. Pulping is carried out at 18,000 r / min for 3 minutes. The obtained slurry after filtration is soymilk, and the soymilk is weakly alkaline;

[0057] S04 Preparation of peptide-rich soymilk: The pH value of the soymilk obtained in step S03 is adjusted to 3 with a 50% (mass fraction) food-grade citric acid solution, and the temperature of the soymilk is adjusted to 35°C for the first enzymatic dissociation for 3 hours. Then, the pH value of the soymilk is adjusted to 6.0 with a 2% food-grade sodium hydroxide solution, and the temperature of the soymilk is adjusted to 45°C to continue the second enzymatic dissociation for 3 hours. Finally, the pH of the soymilk is adjusted to 8.0 with a 2% food-grade sodium hydroxide solution, and the temperature of the soymilk is adjusted to 40°C to continue the third enzymatic dissociation for 3 hours. The obtained soymilk is peptide-rich soymilk.

[0058] S05 Simultaneous preparation of low-fat peptide-rich soy milk and oil bodies: The peptide-rich soymilk obtained in S04 is subjected to a water bath at 100°C for 20 minutes, then cooled to 90°C and centrifuged at 6000 r / min for 30 min. The upper cream is collected as soybean oil bodies, and the lower liquid phase is low-fat peptide-rich soy milk.

[0059] In Comparative Example 2 compared with Example 1, no nano-iron suspension was used for incubation in step S02.

[0060] Comparative Example 3:

[0061] S01 Raw material pretreatment: Select the soybeans harvested in the current year with plump, complete, non-moldy, non-rotten, and pest-free seeds as raw materials. After the soybeans are washed with tap water, the soybean seeds are immersed in an acetic acid solution prepared by mixing acetic acid and deionized water at a mass ratio of 0.5:100, soaked at 23°C for 40 minutes, washed with deionized water, and air-dried naturally to obtain pretreated soybeans;

[0062] S02 Cultivation of endogenous protease: The pretreated soybeans obtained in S01 are put into a 50 mg / L nano-iron suspension (prepared by dispersing nano-iron in distilled water and ultrasonically treating it for 25 minutes with a 200 W power and 40 kHz frequency ultrasonic generator, with a nano-iron particle size of 100 nm and a purity of 99.9%). After incubating at room temperature for 30 minutes, they are then put into a culture solution (a sodium bicarbonate aqueous solution prepared by mixing sodium bicarbonate and deionized water at a mass ratio of 0.2:100) and cultivated at 20°C for another 20 hours to complete the cultivation of endogenous protease;

[0063] S03 Preparation of soymilk: The soybeans that have completed the cultivation of endogenous protease in S02 are put into a high-speed tissue homogenizer, and deionized water at 4°C with a mass 9 times that of the soybeans is added for pulping. Pulping is carried out at 18,000 r / min for 3 minutes. The obtained slurry after filtration is soymilk, and the soymilk is weakly alkaline;

[0064] S04 Preparation of peptide-rich soymilk: Adjust the pH value of the soymilk obtained in step S03 to 3 with a 50% (mass fraction) food-grade citric acid solution, adjust the temperature of the soymilk to 35°C and perform the first enzymatic dissociation for 3 hours. Then, adjust the pH value of the soymilk to 6.0 with a 2% food-grade sodium hydroxide solution, adjust the temperature of the soymilk to 45°C and continue the second enzymatic dissociation for 3 hours. Finally, adjust the pH of the soymilk to 8.0 with a 2% food-grade sodium hydroxide solution, adjust the temperature of the soymilk to 40°C and continue the third enzymatic dissociation for 3 hours. The obtained soymilk is peptide-rich soymilk.

[0065] S05 Simultaneous preparation of low-fat peptide-rich soymilk and oil bodies: Subject the peptide-rich soymilk obtained in S04 to a water bath at 100°C for 20 minutes, then cool it to 90°C and centrifuge at 6000 r / min for 30 min. Collect the upper cream as soybean oil bodies and the lower liquid phase as low-fat peptide-rich soymilk.

[0066] Compared with Example 1, in Comparative Example 3, sodium bicarbonate aqueous solution was not used to soak the soybeans in step S02.

[0067] Comparative Example 4:

[0068] S01 Raw material pretreatment: Select the soybeans harvested in the current year with plump, complete, non-moldy, non-rotten, and pest-free seeds as raw materials. After washing the soybean raw materials with tap water, immerse the soybean seeds in an acetic acid solution prepared by mixing acetic acid and deionized water at a mass ratio of 0.5:100, soak at 23°C for 40 minutes, wash with deionized water and air-dry naturally to obtain pretreated soybeans;

[0069] S02 Cultivation of endogenous protease: Mix sodium bicarbonate and deionized water at a mass ratio of 0.5:100 to prepare a sodium bicarbonate aqueous solution. Place the pretreated soybeans obtained in S01 in the sodium bicarbonate aqueous solution at 50°C and stir and soak for 30 minutes to stimulate the endogenous protease. Immediately wash the soybean seeds excited by the weakly alkaline water with deionized water, drain the water, and incubate in a 50 mg / L nano-iron suspension (prepared by dispersing nano-iron in distilled water and ultrasonically treating it for 25 minutes at a power of 200 W and a frequency of 40 kHz. The nano-iron particle size is 100 nm and the purity is 99.9%) at room temperature for 30 minutes, and then incubate in a cultivation solution (a sodium bicarbonate aqueous solution prepared by mixing sodium bicarbonate and deionized water at a mass ratio of 0.2:100) at 20°C for 20 hours to complete the cultivation of endogenous protease;

[0070] S03 Preparation of soymilk: Put the soybeans after completing the cultivation of endogenous protease in S02 into a high-speed tissue homogenizer, add 9 times the mass of the soybeans of 4°C deionized water and beat the pulp for 3 minutes at 18000 r / min. The obtained slurry after filtration is soymilk, and the soymilk is weakly alkaline;

[0071] S04 Preparation of peptide-rich soymilk: Adjust the pH value of the soymilk obtained in step S03 to 3 with a 50% food-grade citric acid solution by mass, adjust the temperature of the soymilk to 35 °C, and perform enzymatic dissociation for 3 hours. The resulting soymilk is peptide-rich soymilk.

[0072] S05 Simultaneous preparation of low-fat peptide-rich soy milk and oil bodies: Heat the peptide-rich soymilk obtained in S04 in a water bath at 100 °C for 20 minutes, then cool it to 90 °C and centrifuge at 6000 r / min for 30 min. Collect the upper cream as soybean oil bodies and the lower liquid phase as low-fat peptide-rich soy milk.

[0073] In Comparative Example 4 compared with Example 1, only the first enzymatic dissociation in Example 1 was performed in step S04.

[0074] Comparative Example 5:

[0075] S01 Raw material pretreatment: Select the soybeans harvested in the current year with plump, complete, non-moldy, non-rotten, and pest-free seeds as raw materials. After washing the soybeans with tap water, immerse the soybean seeds in an acetic acid solution prepared by mixing acetic acid and deionized water at a mass ratio of 0.5:100, soak at 23 °C for 40 minutes, wash with deionized water, and air dry naturally to obtain pretreated soybeans.

[0076] S02 Cultivation of endogenous protease: Mix sodium bicarbonate and deionized water at a mass ratio of 0.5:100 to prepare an aqueous sodium bicarbonate solution. Place the pretreated soybeans obtained in S01 in the aqueous sodium bicarbonate solution at 50 °C, stir and soak for 30 minutes to stimulate the endogenous protease. Immediately wash the soybean seeds excited by the weakly alkaline water with deionized water, drain the water, and incubate in a 50 mg / L nano-iron suspension (prepared by dispersing nano-iron in distilled water and ultrasonicating for 25 minutes at a power of 200 W and a frequency of 40 kHz. The nano-iron has a particle size of 100 nm and a purity of 99.9%) at room temperature for 30 minutes, and then incubate in a cultivation solution (an aqueous sodium bicarbonate solution prepared by mixing sodium bicarbonate and deionized water at a mass ratio of 0.2:100) at 20 °C for 20 hours to complete the cultivation of endogenous protease.

[0077] S03 Preparation of soymilk: Put the soybeans after completing the cultivation of endogenous protease in S02 into a high-speed tissue homogenizer, add 9 times the mass of the soybeans of 4 °C deionized water to make slurry, beat at 18000 r / min for 3 minutes, and the resulting slurry after filtration is soymilk, and the soymilk is weakly alkaline.

[0078] S04 Preparation of peptide-rich soymilk: Adjust the pH value of the soymilk obtained in step S03 to 6.0 with a 50% food-grade citric acid solution by mass, adjust the temperature of the soymilk to 45 °C, and perform enzymatic dissociation for 3 hours. The resulting soymilk is peptide-rich soymilk.

[0079] S05 Synchronously prepare low-fat peptide-rich soy milk and oil bodies: Heat the peptide-rich soy milk obtained in S04 in a water bath at 100 °C for 20 minutes, then cool it to 90 °C and centrifuge at 6000 r / min for 30 min. Collect the upper cream as soy oil bodies and the lower liquid phase as low-fat peptide-rich soy milk.

[0080] Compared with Example 1, in Comparative Example 5, only the second enzyme dissociation in Example 1 was carried out in step S04.

[0081] Comparative Example 6:

[0082] S01 Raw material pretreatment: Select the soybeans harvested in the current year with plump, complete, non-moldy, non-rotten, and pest-free seeds as raw materials. After rinsing the soybeans with tap water, immerse the soybean seeds in an acetic acid solution prepared by mixing acetic acid and deionized water at a mass ratio of 0.5:100, soak at 23 °C for 40 minutes, wash with deionized water and air dry naturally to obtain pretreated soybeans.

[0083] S02 Cultivate endogenous protease: Mix sodium bicarbonate and deionized water at a mass ratio of 0.5:100 to prepare an aqueous sodium bicarbonate solution. Place the pretreated soybeans obtained in S01 in the aqueous sodium bicarbonate solution at 50 °C and stir and soak for 30 minutes to stimulate the endogenous protease. Immediately wash the soybean seeds excited by the weakly alkaline water with deionized water, drain the water, and incubate in a 50 mg / L nano-iron suspension (prepared by dispersing nano-iron in distilled water and ultrasonicating at a power of 200 W and a frequency of 40 kHz for 25 minutes, with a nano-iron particle size of 100 nm and a purity of 99.9%) at room temperature for 30 minutes, and then incubate in a culture solution (an aqueous sodium bicarbonate solution prepared by mixing sodium bicarbonate and deionized water at a mass ratio of 0.2:100) at 20 °C for 20 hours to complete the cultivation of endogenous protease.

[0084] S03 Prepare soy milk: Put the soybeans after completing the cultivation of endogenous protease in S02 into a high-speed tissue homogenizer, add 9 times the mass of the soybeans of 4 °C deionized water to make pulp, beat at 18000 r / min for 3 minutes, and the obtained slurry after filtration is soy milk, and the soy milk is weakly alkaline.

[0085] S04 Prepare peptide-rich soy milk: Adjust the pH of the soy milk obtained in step S03 to 8.0 with a 2% food-grade sodium hydroxide solution by mass, adjust the temperature of the soy milk to 40 °C and carry out enzyme dissociation for 3 hours, and the obtained soy milk is peptide-rich soy milk.

[0086] S05 Synchronously prepare low-fat peptide-rich soy milk and oil bodies: Heat the peptide-rich soy milk obtained in S04 in a water bath at 100 °C for 20 minutes, then cool it to 90 °C and centrifuge at 6000 r / min for 30 min. Collect the upper cream as soy oil bodies and the lower liquid phase as low-fat peptide-rich soy milk.

[0087] Comparative Example 6 was compared with Example 1. In step S04, only the third enzymatic dissociation in Example 1 was performed.

[0088] Comparative Example 7:

[0089] S01 Raw material pretreatment: Select the soybeans harvested in the current year with plump, complete, non-moldy, non-rotten, and pest-free seeds as raw materials. After rinsing the soybean raw materials with tap water, immerse the soybean seeds in an acetic acid solution prepared by mixing acetic acid and deionized water at a mass ratio of 0.5:100, soak at 23 °C for 40 minutes, wash with deionized water and air-dry naturally to obtain pretreated soybeans;

[0090] S02 Cultivation of endogenous protease: Mix sodium bicarbonate and deionized water at a mass ratio of 0.5:100 to prepare an aqueous sodium bicarbonate solution. Place the pretreated soybeans obtained in S01 in the aqueous sodium bicarbonate solution at 50 °C, stir and soak for 30 minutes to activate the endogenous protease; Immediately wash the soybean seeds excited by the weakly alkaline water with deionized water, drain the water, and incubate in a 50 mg / L nano-iron suspension (prepared by dispersing nano-iron in distilled water and ultrasonicating for 25 minutes at a power of 200 W and a frequency of 40 kHz, with a nano-iron particle size of 100 nm and a purity of 99.9%) at room temperature for 30 minutes, and then incubate in a cultivation solution (an aqueous sodium bicarbonate solution prepared by mixing sodium bicarbonate and deionized water at a mass ratio of 0.2:100) at 20 °C for 20 hours to complete the cultivation of endogenous protease;

[0091] S03 Preparation of soymilk: Put the soybeans after completing the cultivation of endogenous protease in S02 into a high-speed tissue homogenizer, add 9 times the mass of the soybeans of 4 °C deionized water to make soymilk, beat at 18000 r / min for 3 minutes, and the filtrate is soymilk, and the soymilk is weakly alkaline;

[0092] S04 Simultaneous preparation of low-fat peptide-rich soy milk and oil bodies: Heat the peptide-rich soymilk obtained in S04 in a water bath at 100 °C for 20 minutes, then cool to 90 °C, centrifuge at 6000 r / min for 30 min, collect the upper cream as soybean oil bodies, and the lower liquid phase as low-fat peptide-rich soy milk.

[0093] Comparative Example 7 was compared with Example 1. The three enzymatic dissociations in step S04 of Example 1 were not carried out.

[0094] Test Example

[0095] 1. The total activity of endogenous protease in the soymilk of Example 1 and Comparative Examples 1-3 was measured. The measurement method refers to the method used in "Study on the Enrichment of Peptides in Wheat Germ by Microwave Combined with Metal Ions" (Guo Yuanxin et al., Food Industry Science and Technology 2023, 44(1): 217-223). The results are as Figure 1As shown, the total activity of endogenous protease in the soymilk of Example 1 was significantly higher than that of Comparative Examples 1-3. The results indicate that the cultivation method of the endogenous protease of the present invention can significantly enhance the activity of soybean endogenous protease.

[0096] 2. After the synchronous preparation of soymilk and oil bodies was completed, the mass m of the collected oil bodies was measured using an electronic balance. The total mass of the oil bodies contained in the soymilk before centrifugation was M. The separation rate of soybean oil bodies in Example 1 and Comparative Examples 1-7 was calculated according to the following formula, and the results are shown in Table 1.

[0097]

[0098] Table 1 Comparison of oil body separation rates

[0099] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Separation rate / % 52.76 37.68 41.53 42.19 39.12 42.03 40.41 27.97

[0100] The results in Table 1 show that the oil body separation rate of Example 1 was significantly higher than that of Comparative Examples 1-7. The higher the oil body separation rate, the higher the yield of oil bodies and the lower the oil content in the soymilk. The oil body content in the soymilk prepared by the present invention was only about 4%, so its separation rate had no significant impact on the yield of soymilk.

[0101] 3. The soybean peptide content and fat content of the soymilk prepared in Example 1 and Comparative Examples 1-7 were measured respectively. The method for measuring the soybean peptide content referred to the method adopted in "Study on the Enrichment of Peptides in Wheat Germ by Microwave Combined with Metal Ions" (Guo Yuanxin et al., Science and Technology of Food Industry 2023, 44(1): 217-223), and the method for measuring the fat content adopted the method of GB 5009.6-2016. The measurement results are shown in Table 2.

[0102] Table 2 Comparison of peptide content in soymilk

[0103] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Peptide content / (mg / g) 370.96 119.54 220.85 233.76 136.37 121.68 133.13 90.33 Lipid content (%) 0.93 1.47 2.03 2.06 1.97 1.66 1.89 3.36

[0104] The results show that the peptide content in the soymilk of Example 1 was significantly higher than that of Comparative Examples 1-7. On the contrary, the fat content in the soymilk of Example 1 was significantly lower than that of Comparative Examples 1-7. And step S04 in Example 1 had a synergistic promoting effect on the three enzymatic dissociations of soybean protein and oil body protein.

[0105] The present invention uses the endogenous protease cultivated from the soybean seeds themselves to enzymatically dissociate soybean protein and oil body protein, reducing the fat content in the soymilk, increasing the peptide content in the soymilk, and simultaneously achieving the purpose of synchronously preparing soybean oil bodies.

[0106] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies, characterized in that, it includes the following steps: S01 Raw material pretreatment: The soybean raw material is rinsed with tap water, soaked in a weak acid aqueous solution, washed with deionized water, and then naturally air-dried to obtain pretreated soybeans; S02 Cultivation of endogenous protease: The pretreated soybeans obtained in S01 are stimulated with weak alkaline water and washed with deionized water, incubated in a nano-metal suspension, and then placed in a culture solution for further cultivation to complete the cultivation of endogenous protease; S03 Preparation of soy milk: Deionized water is added to the soybeans that have completed the cultivation of endogenous protease in S02 for pulping, and the obtained slurry after filtration is soy milk; S04 Preparation of peptide-rich soy milk: Adjust the pH value and temperature of the soy milk obtained in S03, perform the first enzymatic dissociation, then adjust the pH value and temperature of the soy milk, perform the second enzymatic dissociation, and then adjust the pH value and temperature of the soy milk, perform the third enzymatic dissociation, and the obtained soy milk is peptide-rich soy milk; S05 Synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies: Heat the peptide-rich soy milk obtained in S04, then cool it and centrifuge it. The upper cream layer is soybean oil bodies, and the lower liquid phase is low-fat peptide-rich soy milk; In step S02, the culture solution is a sodium bicarbonate aqueous solution prepared by mixing sodium bicarbonate and deionized water in a mass ratio of (0.2-1.0):

100. The cultivation time in the culture solution is 10-30 hours, and the temperature is 18-23°C; In step S04, the pH value of the first enzymatic dissociation is 2-4, the temperature is 20-35°C, and the time is 1-3 hours; the pH value of the second enzymatic dissociation is 4.5-6.5, the temperature is 40-55°C, and the time is 3-6 hours; the pH value of the third enzymatic dissociation is 7.5-9.5, the temperature is 30-40°C, and the time is 1-3 hours.

2. The method for synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies according to claim 1, characterized in that, in step S01, the weak acid aqueous solution is an acetic acid solution prepared by mixing acetic acid and deionized water in a mass ratio of (0.5-1.0):

100. The temperature of soaking in the weak acid aqueous solution is 20-25°C, and the soaking time is 30-60 minutes.

3. The method for synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies according to claim 1, characterized in that, in step S02, the weak alkaline water is a sodium bicarbonate aqueous solution prepared by mixing sodium bicarbonate and deionized water in a mass ratio of (0.1-0.5):

100. The weak alkaline water stimulation is to soak the pretreated soybeans in a sodium bicarbonate aqueous solution at 45-55°C for 20-50 minutes.

4. The method for synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies according to claim 1, characterized in that, in step S02, the nano-metal suspension is a nano-iron suspension with a concentration of 25-200 mg / L. The incubation time in the nano-metal suspension is 20-60 minutes, and the temperature is room temperature.

5. The method for synchronously preparing low-fat peptide-rich soy milk and soybean oil bodies according to claim 4, characterized in that, The nano-iron suspension is prepared by dispersing nano-iron in distilled water and ultrasonicating for 20 - 40 minutes at a power of 100 - 300 W and a frequency of 20 - 40 kHz. The particle size of the nano-iron is 20 - 100 nm.

6. The method for simultaneously preparing low-fat peptide-rich soymilk and soybean oil bodies according to claim 1, characterized in that, in step S03, the mass of deionized water added is 6 - 11 times that of soybeans, the pulping time is 1 - 3 minutes, and the pulping rotation speed is 10000 - 18000 r / min.

7. The method for simultaneously preparing low-fat peptide-rich soymilk and soybean oil bodies according to claim 1, characterized in that, in step S05, the temperature for heating the peptide-rich soymilk is 90 - 100 °C, the time is 10 - 30 minutes, the cooling temperature is 50 - 90 °C, the centrifugation rotation speed is 5000 - 8000 r / min, and the centrifugation time is 10 - 30 minutes.

8. Low-fat peptide-rich soymilk and soybean oil bodies prepared by the method according to any one of claims 1 - 7.

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