Yeast enzymatic hydrolysate with high emulsifying property, yeast protein, yeast protein sodium salt product and preparation and application thereof

Abstract

The invention belongs to the field of food, and particularly relates to a yeast enzymatic hydrolysate, a yeast protein and a yeast protein sodium salt product with high emulsifying performance as well as preparation and application of the yeast enzymatic hydrolysate and the yeast protein sodium salt product. The emulsifying activity of the yeast enzymatic hydrolysate is greater than or equal to 25.0 m / g, and the emulsifying stability is greater than or equal to 77.0%; the emulsifying activity of the yeast protein is greater than or equal to 70.0 m / g, and the emulsifying stability is greater than or equal to 175.0%; the emulsifying activity of the yeast protein is greater than or equal to 70.0 m / g, and the emulsifying stability is greater than or equal to 175.0%. According to the preparation method disclosed by the invention, the yeast is subjected to composite enzymolysis through the alkaline protease, the flavourzyme, the glucanase, the mannase and the glutamine transaminase and then is subjected to ionization reaction with the sodium hydroxide to obtain the yeast protein sodium salt product, and the yeast protein sodium salt product has relatively high emulsifying activity and also has relatively good color and flavor; the sodium caseinate can be used as a natural emulsifier, and the problems of limited sodium caseinate yield, unstable supply and high price are solved.

Description

[0001] This application claims priority to the earlier application No. 202511667412.5 filed with the China National Intellectual Property Administration on November 13, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention belongs to the food field, specifically relating to a yeast hydrolysate with high emulsifying properties, yeast protein, yeast protein sodium salt products, and their preparation and application. Background Technology

[0003] Emulsifiers used in the food industry are mainly produced through chemical synthesis or semi-synthetic methods. Although there are many types and strong functionalities, in recent years, with the rise of clean labeling, the food industry has gradually begun to use natural emulsifiers to replace synthetic emulsifiers. However, natural emulsifiers, such as sodium caseinate, suffer from limited production, unstable supply, and high prices.

[0004] Yeast protein refers to microbial protein products made from yeast through processes such as cultivation, fermentation, enzymatic hydrolysis, extraction, and purification. Currently, yeast protein has poor emulsifying properties, so yeast protein derivatives, such as sodium yeast protein, have not been used in the food industry as natural yeast emulsifiers.

[0005] Patent CN120694333A discloses a method for preparing a yeast protein and polysaccharide complex. By compounding yeast protein with other exogenous polysaccharides (xanthan gum, carrageenan, pectin, konjac gum), the emulsifying activity and water absorption properties of the yeast protein obtained by this method mainly depend on the polysaccharide structure, rather than the yeast protein itself having good emulsifying activity. Summary of the Invention

[0006] The problem with the existing technology is that sodium caseinate is often used as an emulsifier, but its supply is unstable and its cost is high.

[0007] To address the aforementioned problems in the existing technology, this invention provides yeast enzymatic hydrolysate with high emulsifying performance, yeast protein, yeast protein sodium salt products, and their preparation and application.

[0008] The specific technical solution is as follows: Technical Solution 1: A yeast hydrolysate with high emulsifying properties, characterized in that the emulsifying activity of the yeast hydrolysate is ≥25.0 m² / g and the emulsifying stability is ≥77.0%.

[0009] Technical Solution 2: The yeast hydrolysate according to Technical Solution 1, characterized in that the emulsifying activity of the yeast hydrolysate is 25.0-70.0 m² / g, and the emulsifying stability is 77.0-160.0%. Preferably, the yeast hydrolysate is prepared by a method comprising the following steps: (1) Autolysis of high-protein brewing yeast to obtain autosol; (2) The solution obtained in step (1) is enzymatically hydrolyzed to obtain an enzymatic hydrolysate, wherein the enzymes used in the enzymatic hydrolysis include two or more combinations of alkaline protease, flavor protease, glucanase, mannanase and transglutaminase. (3) The enzyme hydrolysate obtained in step (2) is inactivated and homogenized to obtain the yeast hydrolysate.

[0010] Technical Solution 3: The yeast hydrolysate according to Technical Solution 2 is characterized in that the enzymes used in the hydrolysis are composed of alkaline protease, flavor protease, glucanase, mannanase and transglutaminase.

[0011] Preferably, based on the dry matter weight of the self-solution, the amount of alkaline protease added is 0.10-1.00 wt%, and / or the amount of flavor protease added is 0.10-1.00 wt%, and / or the amount of dextranase added is 0.10-1.00 wt%, and / or the amount of mannanase added is 0.10-1.00 wt%, and / or the amount of transglutaminase added is 0.10-1.00 wt%. More preferably, the alkaline protease activity is 500,000-700,000 U / g, and / or the flavor protease activity is 30,000-70,000 U / g, the dextranase activity is 250,000-350,000 U / mL, and / or the mannanase activity is 50,000-150,000 U / g, and / or the transglutaminase activity is 50,000-150,000 U / g.

[0012] Technical Solution 4: The yeast hydrolysate according to Technical Solution 2 or 3, characterized in that the protein content of the high-protein brewer's yeast is 45-75%, preferably 65-75%, and more preferably, the high-protein yeast is obtained by brewer's yeast ( Saccharomyces cerevisiae FX-2 was prepared.

[0013] Technical Solution 5: A method for preparing yeast enzymatic hydrolysate according to any one of technical solutions 1-4, characterized in that it includes the following steps: (1) The yeast was autolyzed to obtain an autosol solution; (2) The solution obtained in step (1) is enzymatically hydrolyzed to obtain an enzymatic hydrolysate, wherein the enzymes used in the enzymatic hydrolysis include two or more combinations selected from the group consisting of alkaline protease, flavor protease, glucanase, mannanase and transglutaminase. (3) The enzyme hydrolysate obtained in step (2) is inactivated and homogenized to obtain the yeast hydrolysate.

[0014] Technical Solution 6: The preparation method according to Technical Solution 5 is characterized in that the autolysis temperature is 55~60℃ and / or the autolysis time is 4~6h. Preferably, the enzymatic hydrolysis temperature is 55-65℃, and / or the enzymatic hydrolysis time is 15-20 h, and / or the enzymatic hydrolysis pH is 6.5-6.8. Preferably, the enzyme inactivation temperature is 85-90°C and / or the enzyme inactivation time is 5-10 min.

[0015] Preferably, the homogenization method is microjet homogenization, wherein the pressure of microjet homogenization is greater than or equal to 1000 bar and / or the temperature is 60~70°C, and more preferably, the pressure of microjet homogenization is 1000-1500 bar and / or the homogenization temperature is 65~70°C.

[0016] Technical Solution 7: The preparation method according to Technical Solution 5 or 6 is characterized in that, before autolysis, it further includes mixing high-protein yeast and water to obtain a mixed solution, preferably, the yeast concentration in the mixed solution is 15~20wt% on a dry matter basis.

[0017] Technical Solution 8: A yeast protein with high emulsifying properties, characterized in that it is prepared by separating and purifying the yeast enzymatic hydrolysate according to any one of Technical Solutions 1-4, wherein the emulsifying activity of the yeast protein is ≥70.0 m² / g and the emulsifying stability is ≥175.0%.

[0018] Technical Solution 9: The yeast protein according to Technical Solution 8 is characterized in that the emulsifying activity of the yeast protein is 70.0-120.0 m² / g and the emulsifying stability is 175.0-290.0%.

[0019] Technical Solution 10: A method for preparing yeast protein as described in Technical Solution 8 or 9, characterized in that it includes the following steps: separating and purifying the yeast enzymatic hydrolysate as described in any one of Technical Solutions 1-4 to obtain yeast protein with high emulsifying properties.

[0020] Technical Solution 11: A yeast protein sodium salt product with high emulsifying performance, characterized in that it is prepared by ionizing and purifying the yeast hydrolysate as described in any one of Technical Solutions 1-4, wherein the emulsifying activity of the yeast protein sodium salt product is ≥125m² / g and the emulsifying stability is ≥300.0%.

[0021] Technical Solution 12: The yeast protein sodium salt product according to Technical Solution 11 is characterized in that the emulsifying activity of the yeast protein sodium salt product is 125-142m² / g and the emulsifying stability is 300.0-400.0%.

[0022] Technical Solution 13: The yeast protein sodium salt product according to Technical Solution 11 or 12 is characterized in that, during the ionization reaction, the pH of the yeast hydrolysate is adjusted to 7.1~7.5 using sodium hydroxide, and then kept at a temperature of 60~65℃ for 2-5 hours, wherein the pH of the yeast hydrolysate is always controlled to be 7.1~7.5 during the heat preservation process.

[0023] Technical Solution 14: A method for preparing a yeast protein sodium salt product according to any one of technical solutions 11-13, characterized in that it includes the following steps: subjecting the yeast enzymatic hydrolysate according to any one of technical solutions 1-4 to ionization reaction and separation and purification to obtain a yeast protein sodium salt product with high emulsification performance.

[0024] Technical Solution 15: The yeast protein product according to Technical Solution 8 or 9 or the yeast protein sodium salt product according to any one of Technical Solutions 11-13, characterized in that the separation and purification method is ultrafiltration membrane filtration, wherein the molecular weight cutoff of the ultrafiltration membrane is ≥1000 Da, preferably, the molecular weight cutoff of the ultrafiltration membrane is greater than or equal to 1000 Da and less than 30000 Da.

[0025] Technical Solution 16: The yeast protein product according to any one of Technical Solutions 8, 9, or 15, or the yeast protein sodium salt product according to any one of Technical Solutions 11-13, or the product according to Technical Solution 15, is characterized in that, after separation and purification, it further includes sterilization, concentration, and spray drying. Preferably, the sterilization temperature is 135-137°C and / or the sterilization time is 1-5 seconds. More preferably, before sterilization, the retentate obtained after separation and purification is mixed with water to obtain a mixed solution with a dry matter content of 5-8 wt%. Preferably, the dry matter content of the concentrate is 20-25 wt% based on its weight. Preferably, the inlet air temperature of the spray dryer is 165~170℃, and the outlet air temperature of the spray dryer is 65~70℃.

[0026] Technical Solution 17: The use of yeast hydrolysate as described in any one of Technical Solutions 1-4, or yeast protein as described in any one of Technical Solutions 8, 9, 15 or 16, or yeast protein sodium salt product as described in any one of Technical Solutions 11-13, 15 or 16 in the preparation of emulsifiers.

[0027] Technical Solution 18: The application of the yeast hydrolysate of any one of Technical Solutions 1-4, or the yeast protein of any one of Technical Solutions 8, 9, 15 or 16, or the yeast protein sodium salt product of any one of Technical Solutions 11-13, 15 or 16 in the preparation of food.

[0028] Beneficial effects of this invention: (1) In this invention, yeast is subjected to compound enzymatic hydrolysis by alkaline protease, flavor protease, glucanase, mannanase and transglutaminase to obtain yeast hydrolysate with high emulsifying activity and high emulsifying stability; after separation, purification and drying of yeast hydrolysate, yeast protein with high emulsifying activity and high emulsifying stability is obtained.

[0029] (2) The invention involves the combined enzymatic hydrolysis of yeast with alkaline protease, flavor protease, glucanase, mannanase and transglutaminase to obtain a yeast hydrolysate with high emulsifying activity and high emulsifying stability; the yeast hydrolysate is then subjected to an ionization reaction with sodium hydroxide and combined with a separation and purification process to obtain a yeast protein sodium salt product. The yeast protein sodium salt product has high emulsifying activity, as well as good color and flavor, and can be used as a natural emulsifier, thus solving the problems of limited production, unstable supply and high price of sodium caseinate.

[0030] Information on microbial strains The brewing yeast used in this invention ( Saccharomyces cerevisiae FX-2 was deposited on August 1, 2016, at the China Center for Type Culture Collection (CCTCC), accession number CCTCC NO: M2016418, address: Wuhan University, No. 299 Bayi Road, Wuchang District, Wuhan, Hubei Province, 430072, China; telephone: (027)-68752319. This strain has been described in the patent with publication number CN108220175A and application number 201611141122.8. Detailed Implementation

[0031] To better understand the above technical solutions, the technical solutions of the present invention will be clearly and completely explained below in conjunction with specific embodiments. It should be noted that the content of the specific embodiments is only a specific implementation and explanation of the technical solutions of the present invention, and should not be construed as a limitation on the scope of protection of the present invention.

[0032] Terminology Explanation Sodium Yeast Protein Salt Product: Yeast hydrolysate is obtained by enzymatic hydrolysis of yeast. Yeast hydrolysate contains a variety of organic molecules, such as amino acids, short peptides, and organic acids. These molecules often have carboxyl (-COOH) functional groups. When yeast hydrolysate is reacted with sodium hydroxide under certain conditions, the carboxyl (-COOH) groups in the yeast hydrolysate undergo a neutralization reaction with the sodium hydroxide to generate sodium salt, which is the sodium yeast protein salt product.

[0033] High-protein yeast: Yeast with a protein content of 45% or more obtained by culturing yeast strains. For example, the high-protein yeast of this application can be obtained by batch fermentation or continuous fermentation of yeast strains using one or more of sugarcane molasses, hydrolyzed sugar or beet molasses as fermentation carbon source. Its protein content can be 45-75%, preferably 65-75%.

[0034] In some embodiments, the type of yeast strain used in preparing the high-protein yeast is not particularly limited; it can be commercially available or obtained by any method, specifically *Saccharomyces cerevisiae* FX-2, with accession number CCTCCNO: M2016418. Furthermore, the culture conditions required to obtain the high-protein yeast are not particularly limited; as long as the protein content of the high-protein yeast obtained by any method reaches 45% or higher, it can be used in this invention.

[0035] Preferably, in some embodiments, the high-protein yeast can be prepared by a method comprising the following steps: (1) Yeast seed culture was obtained by performing primary and secondary seed cultures. (2) The yeast seed liquid was centrifuged, washed and enriched to obtain yeast seeds; (3) The yeast seed obtained in step (2) is inoculated into a mixture containing water and phosphorus source for fermentation culture to obtain yeast fermentation broth; (4) After solid-liquid separation and washing of the fermentation broth obtained in step (3), high-protein yeast is collected.

[0036] Preferably, in step (1), the primary seed culture includes the following steps: inoculating the strain into the primary culture medium for primary culture; more preferably, the primary culture temperature is 28-32℃, and / or the primary culture pH is 5.0-5.5, and / or the primary culture time is 15-25h; even more preferably, based on the total weight of the primary culture medium, the primary culture medium includes 1-2wt% yeast extract, 2-3wt% peptone and 2-3wt% glucose, with the remainder being water.

[0037] Preferably, in step (1), the secondary seed culture includes the following steps: inoculating the seed liquid from the primary culture into the secondary culture medium for secondary culture; more preferably, the secondary culture temperature is 28-32℃, and / or the secondary culture pH is 5.0-5.5, and / or the secondary culture time is 15-25h; even more preferably, based on the total weight of the secondary culture medium, the secondary culture medium includes 2-3wt% glucose, 2-3wt% yeast extract, 0.1-0.2wt% potassium dihydrogen phosphate and 0.1-0.2wt% dipotassium hydrogen phosphate.

[0038] Preferably, in step (3), the aeration ratio during fermentation is 1.6-2.5 VVM, the dissolved oxygen volume is 45-70%, the physiological state of the cells is monitored online in real time, and the feed rate is adjusted according to the real-time monitored physiological parameters. The physiological parameters include carbon dioxide release rate (CER), oxygen uptake rate (OUR), and respiratory quotient (RQ). The fermentation control process does not require the addition of inorganic salts, acids, alkalis, and trace elements other than feed. More preferably, in step (3), during the fermentation process, the physiological parameters RQ, CER and OUR are monitored online in real time by a biological exhaust gas analyzer. The online parameter RQ value is kept to fluctuate slightly between 1.0 and 1.2. When RQ is greater than 1.2, the flow acceleration rate of molasses and ammonia is reduced simultaneously to reduce the RQ value. When RQ is less than 1.0, the flow acceleration rate of molasses and ammonia is increased simultaneously to increase the RQ value. More preferably, during the entire regulation process, the flow rate of molasses is controlled within the range of 10-50 mL / min, the flow rate of nitrogen source is controlled within the range of 1-5 mL / min, and the pH is controlled within the range of 4.2-6.5 throughout the fermentation process. More preferably, in step (3), the fermentation temperature is 25-35℃, and / or the fermentation time is 10-20h, and / or the pH of the fermentation is 4.0-7.0. Even more preferably, in step (3), the amount of phosphorus source added is 0.1-0.5% by weight of water.

[0039] More preferably, the method for preparing high-protein yeast further includes: pretreatment of fermentation raw materials: removing residue and precipitating molasses, separating it and preparing a solution with a total sugar content of 25-35%; preferably, the pretreatment of fermentation raw materials further includes adding water to a nitrogen source to prepare a solution with a concentration of 20-25%.

[0040] In some specific embodiments, the present invention provides a yeast enzymatic hydrolysate with high emulsifying properties, wherein the emulsifying activity of the yeast enzymatic hydrolysate is 25.0-70.0 m² / g, and the emulsifying stability is 77.0-160.0%. Preferably, the emulsifying activity of the yeast hydrolysate can be 25.0, 26.0, 27.0, 28.0, 29.0, 30.0, 31.0, 32.0, 33.0, 34.0, 35.0, 36.0, 37.0, 38.0, 39.0, 40.0, 41.0, 42.0, 43.0, 44.0, 45.0, 46.0, 47.0, 48.0, 49.0, 50.0, or 51. The emulsifying activity of the yeast hydrolysate is 0, 52.0, 53.0, 54.0, 55.0, 56.0, 57.0, 58.0, 59.0, 60.0, 61.0, 62.0, 63.0, 64.0, 65.0, 66.0, 67.0, 68.0, 69.0, or 70.0, or within a numerical range consisting of any two of the above specific values ​​as endpoints, wherein the unit of each of the above values ​​is m² / g.

[0041] The emulsification stability of the yeast hydrolysate can be 77.0, 78.0, 79.0, 80.0, 81.0, 82.0, 83.0, 84.0, 85.0, 86.0, 87.0, 88.0, 89.0, 90.0, 91.0, 92.0, 93.0, 94.0, 95.0, 96.0, 97.0, 98.0, 99.0, 100.0, 1 01.0, 102.0, 103.0, 104.0, 105.0, 106.0, 107.0, 108.0, 109.0, 110.0, 111.0, 112.0, 113.0, 114.0, 115.0, 116.0, 117.0, 118.0, 119.0, 120.0, 121.0, 122.0, 123.0 124.0, 125.0, 126.0, 127.0, 128.0, 129.0, 130.0, 131.0, 132.0, 133.0, 134.0, 135.0, 136.0, 137.0, 138.0, 139.0, 140.0, 141.0, 142.0, 143.0, 144.0, 145.0, 146.0 The emulsification stability of the yeast hydrolysate is defined as 147.0, 148.0, 149.0, 150.0, 151.0, 152.0, 153.0, 154.0, 155.0, 156.0, 157.0, 158.0, 159.0, or 160.0, or within a numerical range defined by any two of the above specific values ​​as endpoints, where the units of each of the above values ​​are 1.

[0042] In some specific embodiments, the yeast hydrolysate is prepared by a method comprising the following steps: (1) Autolysis of high-protein brewing yeast to obtain autosol; (2) The solution obtained in step (1) is enzymatically hydrolyzed to obtain an enzymatic hydrolysate, wherein the enzymes used in the enzymatic hydrolysis include two or more combinations selected from the group consisting of alkaline protease, flavor protease, glucanase, mannanase and transglutaminase. (3) The enzyme hydrolysate obtained in step (2) is inactivated and homogenized to obtain the yeast hydrolysate.

[0043] More preferably, based on the dry matter weight of the self-solution, the amount of alkaline protease added is 0.10-1.00 wt%, and / or the amount of flavor protease added is 0.10-1.00 wt%, and / or the amount of dextranase added is 0.10-1.00 wt%, and / or the amount of mannanase added is 0.10-1.00 wt%, and / or the amount of transglutaminase added is 0.10-1.00 wt%.

[0044] More preferably, the amount of alkaline protease added, based on the dry matter weight of the self-solution, can be 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, or 0. 30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.8 3, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1.00, or the amount of alkaline protease added within the numerical range formed by any two of the above specific values ​​as endpoints, where the units of the above values ​​are .

[0045] More preferably, the amount of flavor protease added, based on the dry matter weight of the self-solution, can be 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, or 0. 30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.8 3, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1.00, or the amount of flavor protease added within the numerical range formed by any two of the above specific values ​​as endpoints, where the units of the above values ​​are .

[0046] More preferably, the amount of dextranase added, based on the dry matter weight of the self-solution, can be 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81 The amount of dextranase added is 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or 1.00, or within a numerical range consisting of any two of the above specific values ​​as endpoints.

[0047] More preferably, the amount of mannanase added, based on the dry matter weight of the self-solution, can be 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, or 0. 30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.8 3, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1.00, or the amount of mannanase added within the range of any two of the above specific values ​​as endpoints, where the units of the above values ​​are .

[0048] More preferably, the amount of transglutaminase added, based on the dry matter weight of the self-solution, can be 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83 The amount of transglutaminase added is 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or 1.00, or within the range of any two of the above specific values ​​as endpoints. The units of the above values ​​are _____.

[0049] More preferably, the alkaline protease includes the alkaline protease with enzyme number EC 3.4.21.14. It should be noted that the source of the alkaline protease used in this invention is not particularly limited, and its source can be arbitrary, such as commercially available or prepared by conventional methods. As long as the alkaline protease obtained by commercial purchase or prepared by conventional methods includes the alkaline protease with enzyme number EC 3.4.21.14, preferably with an enzyme activity of 500,000-700,000 U / g, it can be used in this invention.

[0050] More preferably, the dextranase includes the dextranase with enzyme number EC 3.2.1.71; it should be noted that the source of the dextranase used in this invention is not particularly limited, and its source can be arbitrary, such as commercially available or prepared by conventional methods, as long as the commercially available or conventionally prepared dextranase includes the dextranase with enzyme number EC 3.2.1.71, preferably with an enzyme activity of 250,000-350,000 U / g, it can be used in this invention; More preferably, the mannanase includes mannanase with enzyme number EC 3.2.1.78. It should be noted that the source of the mannanase used in this invention is not particularly limited, and its source can be arbitrary. For example, it can be commercially available or prepared by conventional methods. As long as the mannanase obtained by commercial purchase or prepared by conventional methods includes mannanase with enzyme number EC 3.2.1.78, preferably, the enzyme activity is 50,000-150,000 U / g, it can be used in this invention.

[0051] More preferably, the glutamine transaminase includes glutamine transaminase with enzyme number EC 2.3.2.13. It should be noted that the source of the glutamine transaminase used in this invention is not particularly limited, and its source can be arbitrary, such as commercially available or prepared by conventional methods. As long as the glutamine transaminase obtained by commercial purchase or prepared by conventional methods includes glutamine transaminase with enzyme number EC 2.3.2.13, preferably, the enzyme activity is 50,000-150,000 U / g, it can be used in this invention.

[0052] More preferably, the source of the flavor protease used in this invention is not particularly limited. It can be any source, such as commercially available protease or protease prepared by conventional methods. As long as the enzyme activity of the commercially available or protease prepared by conventional methods is 30,000 to 70,000 U / g, it can be used in this invention.

[0053] In some specific embodiments, the present invention provides a yeast protein with high emulsifying properties, wherein the yeast protein has an emulsifying activity of 70.0-120.0 m² / g and an emulsifying stability of 175.0-290.0%.

[0054] Preferably, the emulsifying activity of the yeast protein can be 77.0, 78.0, 79.0, 80.0, 81.0, 82.0, 83.0, 84.0, 85.0, 86.0, 87.0, 88.0, 89.0, 90.0, 91.0, 92.0, 93.0, 94.0, 95.0, 96.0, 97.0, 98.0, 99.0, 100.0, 101.0, 102.0, or 103.0. The emulsifying activity of the yeast protein is defined as m² / g, or 104.0, 105.0, 106.0, 107.0, 108.0, 109.0, 110.0, 111.0, 112.0, 113.0, 114.0, 115.0, 116.0, 117.0, 118.0, 119.0, or 120.0, or within a numerical range defined by any two of the above specific values ​​as endpoints.

[0055] The emulsification stability of the yeast protein can be 175.0, 176.0, 177.0, 178.0, 179.0, 180.0, 181.0, 182.0, 183.0, 184.0, 185.0, 186.0, 187.0, 188.0, 189.0, 190.0, 191.0, 192.0, 193.0, 194.0, 195.0, 196.0, 197.0. 198.0, 199.0, 200.0, 201.0, 202.0, 203.0, 204.0, 205.0, 206.0, 207.0, 208.0, 209.0, 210.0, 211.0, 212.0, 213.0, 214.0, 215.0, 216.0, 217.0, 218.0, 219.0, 220.0, 221.0, 222.0, 223 0, 224.0, 225.0, 226.0, 227.0, 228.0, 229.0, 230.0, 231.0, 232.0, 233.0, 234.0, 235.0, 236.0, 237.0, 238.0, 239.0, 240.0, 241.0, 242.0, 243.0, 244.0, 245.0, 246.0, 247.0, 248.0 The emulsifying stability of the yeast protein is defined as 249.0, 250.0, 251.0, 252.0, 253.0, 254.0, 255.0, 256.0, 257.0, 258.0, 259.0, 260.0, 270.0, 275.0, 280.0, 285.0, or 290.0, or within a numerical range defined by any two of the above specific values ​​as endpoints, where the units of the above values ​​are:

[0056] Preferably, in preparing the yeast protein, the separation and purification method is to use ultrafiltration membrane filtration, wherein the molecular weight cutoff of the ultrafiltration membrane is ≥1000 Da. More preferably, the molecular weight cutoff of the ultrafiltration membrane is greater than or equal to 1000 Da and less than 30000 Da. More preferably, the molecular weight cutoff of the ultrafiltration membrane can be 1000 Da, 2000 Da, 3000 Da, 4000 Da, 5000 Da, 6000 Da, 7000 Da, 8000 Da, 9000 Da, 10000 Da, 20000 Da, or 30000 Da, or the molecular weight cutoff of the ultrafiltration membrane used is within the numerical range formed by any two of the above specific values ​​as endpoints.

[0057] In some specific embodiments, the present invention provides a yeast protein sodium salt product with high emulsifying performance, wherein the emulsifying activity of the yeast protein sodium salt product is 125-142 m² / g. More preferably, the emulsifying activity of the yeast protein sodium salt product may be 125.0, 126.0, 127.0, 128.0, 129.0, 130.0, 131.0, 132.0, 133.0, 134.0, 135.0, 136.0, 137.0, 138.0, 139.0, 140.0, 141.0 or 142.0, or the emulsifying activity of the yeast protein sodium salt product within the numerical range formed by any two of the above specific values ​​as endpoints. The unit of each of the above values ​​is m² / g.

[0058] The emulsification stability of the yeast protein sodium salt product is 300.0-400.0%, more preferably, the emulsification stability of the yeast protein sodium salt product can be 300.0, 301.0, 302.0, 303.0, 304.0, 305.0, 306.0, 307.0, 308.0, 309.0, 310.0, 311.0, 312.0, 313.0, 314.0, 315.0, 316.0, 317.0, 318.0, 319.0, or 320.0. 321.0, 322.0, 323.0, 324.0, 325.0, 326.0, 327.0, 328.0, 329.0, 330.0, 331.0, 332.0, 333.0, 334.0, 335.0, 336.0, 337.0, 338.0, 339.0, 340.0, 341.0, 342.0, 343.0, 344.0, 345.0, 346.0, 347.0, 348.0, 349.0, 350. 0, 351.0, 352.0, 353.0, 354.0, 355.0, 356.0, 357.0, 358.0, 359.0, 360.0, 361.0, 362.0, 363.0, 364.0, 365.0, 366.0, 367.0, 368.0, 369.0, 370.0, 371.0, 372.0, 373.0, 374.0, 375.0, 376.0, 377.0, 378.0, 379.0, 38 The emulsification stability of the yeast protein sodium salt product is 0.0, 381.0, 382.0, 383.0, 384.0, 385.0, 386.0, 387.0, 388.0, 389.0, 390.0, 391.0, 392.0, 393.0, 394.0, 395.0, 396.0, 397.0, 398.0, 399.0, or 400.0, or within the numerical range formed by any two of the above specific values ​​as endpoints, wherein the units of the above values ​​are .

[0059] Preferably, in some specific embodiments, when preparing the yeast protein sodium salt product, during the ionization reaction process, the pH of the yeast hydrolysate is adjusted to 7.1~7.5 using sodium hydroxide (preferably, the pH of the yeast hydrolysate adjusted using sodium hydroxide can be 7.1, 7.2, 7.3, 7.4 or 7.5, or, or within the pH range formed by any two of the above specific values ​​as endpoints), and then kept at a temperature of 60~65℃ for 2-5 hours. During the incubation process, the pH of the yeast hydrolysate is consistently controlled to 7.1~7.5 (preferably, the pH of the yeast hydrolysate is consistently controlled to 7.1, 7.2, 7.3, 7.4 or 7.5, or, within the pH range formed by any two of the above specific values ​​as endpoints).

[0060] To better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0061] Unless otherwise stated, all raw materials / reagents / instruments used in the embodiments of this invention are conventional commercially available products. Information on the sources of experimental materials used in this invention is shown in Table 1.

[0062]

[0063] The specific method for determining the protein content of high-protein yeast cells in this embodiment is shown below: The protein content was determined according to GB 5009.5-2016, the method for determination of protein in food. The specific operation was as follows: 1g of sample was taken, and under the action of a mixed catalyst (0.4g copper sulfate pentahydrate + 6g potassium sulfate), 20mL of concentrated sulfuric acid was added for digestion, followed by distillation. The nitrogen in the product was absorbed with boric acid, and then titrated with 0.1mol / L hydrochloric acid. The data were read, and the nitrogen content was calculated. The protein coefficient was N (nitrogen content) × 6.25 to calculate the protein content.

[0064] Example 1.1: Preparation method of yeast protein with high emulsifying properties (1) Preparation of high-protein Saccharomyces cerevisiae cells: (1.1) Preparation of fermentation nutrient source: Remove insoluble matter from molasses raw material to obtain molasses supernatant, dilute the supernatant to a mass fraction of 30%, and then sterilize it in an autoclave at 121℃ for 20 min for sterilization; at the same time, use sterile water to dilute ammonia water to a nitrogen source with an ammonia nitrogen concentration of 20%; (1.2) Seed yeast culture: For primary seed culture, one loopful of Saccharomyces cerevisiae FX-2 was inoculated into 200 ml of primary culture medium using a sterile inoculation loop and cultured at 30°C and 220 rpm for 18 hours to obtain the primary seed culture. The primary culture medium, by weight, consisted of 1 wt% yeast extract, 2 wt% peptone, and 2 wt% glucose, with a pH of 5.0-5.5, and the remainder being water. The pH was maintained at 5.0-5.5 throughout the primary culture process. For secondary seed culture, the seed culture from the primary culture was inoculated into 1L of secondary culture medium at 10% of the secondary culture medium volume. After culturing at 30℃ and 200rpm for 18h, the *Saccharomyces cerevisiae* FX-2 seed culture was obtained. The secondary culture medium consisted of 2wt% glucose, 2wt% yeast extract, 0.1wt% potassium dihydrogen phosphate, and 0.1wt% dipotassium hydrogen phosphate, with the remainder being water. The pH was maintained at 5.0-5.5 throughout the secondary culture process. (1.3) Seed enrichment: After centrifuging the Saccharomyces FX-2 seed liquid obtained in step (1.2), the cell precipitate was retained. The cell precipitate was washed three times with deionized water with low calcium and magnesium ion content to enrich the Saccharomyces FX-2 seed. The wet weight of Saccharomyces FX-2 was 400 g / L. (1.4) Fermentation culture: 45L of fermentation bottom water and 0.2% monoammonium phosphate (by weight of fermentation bottom water) were added to a 100L fermenter and sterilized at 121℃ for 20min. The brewing yeast FX-2 seed obtained in step (1.3) was inoculated into the fermenter at a volume inoculation rate of 10%. The temperature was controlled at 30℃, and the fermentation was carried out at atmospheric pressure with an aeration ratio of 1.667VVM. The dissolved oxygen volume was controlled at 50% by adjusting the rotation speed. During fermentation, physiological parameters RQ, CER, and OUR were monitored online in real time using a biological exhaust gas analyzer. The online parameter RQ value was kept within a small fluctuation range of 1.0-1.2. When RQ was greater than 1.2, the flow rate of molasses and ammonia was simultaneously reduced to decrease the RQ value. When RQ was less than 1.0, the flow rate of molasses and ammonia was simultaneously increased to increase the RQ value. Throughout the entire regulation process, the flow rate of molasses was controlled within the range of 10-50 mL / min, the flow rate of nitrogen source was controlled within the range of 1-5 mL / min, and the pH was controlled within the range of 4.2-6.5 throughout the fermentation process. (1.5) Fermentation broth separation: After 12 hours of fermentation, the bacterial phase was harvested by centrifuging at 5000 rpm and 15℃ for 10 min using a Beckman centrifuge. The bacterial phase was then washed with deionized water and the washing was repeated once to harvest high-protein yeast cells. The protein content of the high-protein yeast cells was 67.2 wt% based on the dry matter weight.

[0065] (2) Autolysis: The high-protein Saccharomyces cerevisiae cells obtained in step (1) were prepared into a solution containing 15 wt% dry matter using deionized water and kept at 55°C for 6 h for autolysis to obtain autolysis solution.

[0066] (3) Enzymatic hydrolysis: The pH of the solution obtained in step (2) was adjusted to 6.6 using sodium hydroxide. Based on the dry matter weight of the solution, 0.10 wt% alkaline protease, 0.15 wt% flavor protease, 0.16 wt% glucanase, 0.12 wt% mannanase and 0.20 wt% transglutaminase were added to the solution. The solution was then incubated at 60°C for 18 h for enzymatic hydrolysis to obtain the hydrolysate.

[0067] (4) Inactivation of enzyme: The enzyme hydrolysate obtained in step (3) is kept at 90°C for 5 minutes to inactivate the enzyme, and the enzyme hydrolysate after inactivation is obtained.

[0068] (5) Microfluidic treatment: The enzyme hydrolysate obtained in step (4) is subjected to microfluidic treatment at 1200 bar and 65°C to further break down and homogenize the macromolecular substances in the enzyme hydrolysate to obtain yeast hydrolysate.

[0069] (6) Membrane filtration: The yeast hydrolysate obtained in step (5) is separated and purified using an ultrafiltration membrane with a molecular weight cutoff of 1KD, and the filtrate rich in macromolecular components with a molecular weight >1KD is retained. (7) Sterilization: The retentate obtained in step (6) is prepared into a mixed solution using deionized water and then instantaneously sterilized at 137°C for 5 seconds. The dry matter content of the mixed solution is 6 wt% by weight.

[0070] (8) Concentration: The sterilized mixed solution obtained in step (7) is concentrated using a rising film evaporator to obtain a concentrated solution, wherein the dry matter content of the concentrated solution is 25%wt based on the weight of the concentrated solution.

[0071] (9) Spray drying: The concentrate obtained in step (8) is spray dried to obtain yeast protein with high emulsification performance and a moisture content of 2.98%. The inlet air temperature of the spray drying is 165℃ and the outlet air temperature is 70℃.

[0072] Example 1.2: Preparation method of yeast protein with high emulsifying properties (1) The method for preparing high-protein Saccharomyces cerevisiae cells is the same as the method in step (1) of Example 1.1.

[0073] (2) Autolysis: The high-protein Saccharomyces cerevisiae cells obtained in step (1) were prepared into a 15 wt% solution using deionized water and then incubated at 60°C for 6 hours to undergo autolysis, thus obtaining the autolysis solution; (3) Enzymatic hydrolysis: The pH of the solution obtained in step (2) was adjusted to 6.6 using sodium hydroxide. Based on the dry matter weight of the solution, 0.1 wt% alkaline protease, 0.2 wt% flavor protease, 0.16 wt% glucanase, 0.12 wt% mannanase and 0.30 wt% transglutaminase were added to the solution. The solution was then incubated at 60°C for 16 h for enzymatic hydrolysis to obtain the hydrolysate. (4) Inactivation of enzyme: The enzyme hydrolysate obtained in step (3) is kept at 90°C for 5 minutes to inactivate the enzyme, and an enzyme hydrolysate after inactivation is obtained. (5) Microfluidic treatment: The enzyme hydrolysate obtained in step (4) is subjected to microfluidic treatment at 1200 bar and 65°C to further break down and homogenize the macromolecular substances in the enzyme hydrolysate to obtain yeast hydrolysate. (6) Membrane filtration: The yeast hydrolysate obtained in step (5) is separated and purified using an ultrafiltration membrane with a molecular weight cutoff of 1KD, and the filtrate rich in macromolecular components with a molecular weight >1KD is retained. (7) Sterilization: The retentate obtained in step (6) is prepared into a mixed solution using deionized water and then instantaneously sterilized at 137°C for 5 seconds. The dry matter content of the mixed solution is 6 wt% by weight. (8) Concentration: The sterilized mixed solution obtained in step (7) is concentrated to obtain a concentrated solution, wherein the dry matter content of the concentrated solution is 25 wt% by weight; (9) Spray drying: The concentrate obtained in step (8) is spray dried to obtain yeast protein with high emulsification performance and a moisture content of 2.89 wt%. The inlet air temperature of the spray drying is 165 ℃ and the outlet air temperature is 70 ℃.

[0074] Example 1.3: Preparation method of yeast protein with high emulsifying properties (1) The method for preparing high-protein Saccharomyces cerevisiae cells is the same as the method in step (1) of Example 1.1.

[0075] (2) Autolysis: The high-protein Saccharomyces cerevisiae cells obtained in step (1) were prepared into a 15 wt% solution using deionized water and then incubated at 60°C for 5 h to perform autolysis, thus obtaining the autolysis solution; (3) Enzymatic hydrolysis: The pH of the solution obtained in step (2) was adjusted to 6.7 using sodium hydroxide. Based on the dry matter weight of the solution, 0.15wt% alkaline protease, 0.20wt% flavor protease, 0.20wt% glucanase, 0.18wt% mannanase and 0.20wt% transglutaminase were added to the solution. The solution was then incubated at 60℃ for 16h for enzymatic hydrolysis to obtain the hydrolysate. (4) Inactivation of enzyme: The enzyme hydrolysate obtained in step (3) is kept at 90°C for 5 minutes to inactivate the enzyme, and an enzyme hydrolysate after inactivation is obtained. (5) Microfluidic treatment: The enzyme hydrolysate obtained in step (4) is subjected to microfluidic treatment at 1200 bar and 65°C to further break down and homogenize the macromolecular substances in the enzyme hydrolysate to obtain yeast hydrolysate. (6) Membrane filtration: The yeast hydrolysate obtained in step (5) is separated and purified using an ultrafiltration membrane with a molecular weight cutoff of 1KD, and the filtrate rich in macromolecular components with a molecular weight >1KD is retained. (7) Sterilization: The retentate obtained in step (6) is prepared into a mixed solution using deionized water and then instantaneously sterilized at 137°C for 5 seconds. The dry matter content of the mixed solution is 6 wt% by weight. (8) Concentration: The sterilized mixed solution obtained in step (7) is concentrated to obtain a concentrated solution, wherein the dry matter content of the concentrated solution is 25 wt% by weight; (9) Spray drying: The concentrate obtained in step (8) is spray dried to obtain yeast protein with high emulsification performance and a moisture content of 2.87 wt%. The inlet air temperature of the spray drying is 165 ℃ and the outlet air temperature is 70 ℃.

[0076] Example 1.4: Preparation method of yeast protein with high emulsifying properties (1) The method for preparing high-protein Saccharomyces cerevisiae cells is the same as the method in step (1) of Example 1.1.

[0077] (2) Autolysis: The high-protein Saccharomyces cerevisiae cells obtained in step (1) were prepared into a 15 wt% solution using deionized water and then incubated at 60°C for 5 h to perform autolysis, thus obtaining the autolysis solution; (3) Enzymatic hydrolysis: The pH of the solution obtained in step (2) was adjusted to 6.7 using sodium hydroxide. Based on the dry matter weight of the solution, 0.15wt% alkaline protease, 0.20wt% flavor protease, 0.16wt% glucanase, 0.12wt% mannanase and 0.20wt% transglutaminase were added to the solution. The solution was then incubated at 60℃ for 16h for enzymatic hydrolysis to obtain the hydrolysate. (4) Inactivation of enzyme: The enzyme hydrolysate obtained in step (3) is kept at 90°C for 5 minutes to inactivate the enzyme, and an enzyme hydrolysate after inactivation is obtained. (5) Microfluidic treatment: The enzyme hydrolysate obtained in step (4) is subjected to microfluidic treatment at 1200 bar and 65°C to further break down and homogenize the macromolecular substances in the enzyme hydrolysate to obtain yeast hydrolysate. (6) Membrane filtration: The yeast hydrolysate obtained in step (5) is separated and purified using an ultrafiltration membrane with a molecular weight cutoff of 1KD, and the filtrate rich in macromolecular components with a molecular weight >1KD is retained. (7) Sterilization: The retentate obtained in step (6) is prepared into a mixed solution using deionized water and then instantaneously sterilized at 137°C for 5 seconds. The dry matter content of the mixed solution is 6 wt% by weight. (8) Concentration: The sterilized mixed solution obtained in step (7) is concentrated to obtain a concentrated solution, wherein the dry matter content of the concentrated solution is 25 wt% by weight; (9) Spray drying: The concentrate obtained in step (8) is spray dried to obtain yeast protein with high emulsification performance and a moisture content of 2.88 wt%. The inlet air temperature of the spray drying is 165 ℃ and the outlet air temperature is 70 ℃.

[0078] Example 1.5: Preparation method of yeast protein with high emulsifying properties (1) The method for preparing high-protein Saccharomyces cerevisiae cells is the same as the method in step (1) of Example 1.1.

[0079] (2) Autolysis: The high-protein Saccharomyces cerevisiae cells obtained in step (1) were prepared into a 15 wt% solution using deionized water and then incubated at 60°C for 5 h to perform autolysis, thus obtaining the autolysis solution; (3) Enzymatic hydrolysis: The pH of the solution obtained in step (2) was adjusted to 6.6 using sodium hydroxide. Based on the dry matter weight of the solution, 0.20 wt% alkaline protease, 0.20 wt% flavor protease, 0.20 wt% glucanase, 0.12 wt% mannanase and 0.10 wt% transglutaminase were added to the solution. The solution was then incubated at 60°C for 16 h for enzymatic hydrolysis to obtain the hydrolysate. (4) Inactivation of enzyme: The enzyme hydrolysate obtained in step (3) is kept at 90°C for 5 minutes to inactivate the enzyme, and an enzyme hydrolysate after inactivation is obtained. (5) Microfluidic treatment: The enzyme hydrolysate obtained in step (4) is subjected to microfluidic treatment at 1200 bar and 65°C to further break down and homogenize the macromolecular substances in the enzyme hydrolysate to obtain yeast hydrolysate. (6) Membrane filtration: The yeast hydrolysate obtained in step (5) is separated and purified using an ultrafiltration membrane with a molecular weight cutoff of 1KD, and the filtrate rich in macromolecular components with a molecular weight >1KD is retained. (7) Sterilization: The retentate obtained in step (6) is prepared into a mixed solution using deionized water and then instantaneously sterilized at 137°C for 5 seconds. The dry matter content of the mixed solution is 6 wt% by weight. (8) Concentration: The sterilized mixed solution obtained in step (7) is concentrated to obtain a concentrated solution, wherein the dry matter content of the concentrated solution is 25 wt% by weight; (9) Spray drying: The concentrated liquid obtained in step (8) is spray dried to obtain yeast protein with high emulsification performance, with a moisture content of 3.01 wt%. The inlet air temperature of the spray drying is 165 ℃ and the outlet air temperature is 70 ℃.

[0080] Comparative Example 1.1 The difference from Example 1.3 is that in step (3), only 0.15wt% alkaline protease is added to the solution and then incubated at 60°C for 16h to carry out enzymatic hydrolysis to obtain the hydrolysate.

[0081] Comparative Example 1.2 The difference from Example 1.3 is that in step (6), the yeast hydrolysate obtained in step (4) is separated and purified using an ultrafiltration membrane with a molecular weight cutoff of 30KD, and the cutoff solution is rich in macromolecular components with a molecular weight >30KD.

[0082] Technical Effect Evaluation 1 (1) The yeast hydrolysate obtained in step (5) of Examples 1.1 to 1.5 and the yeast protein obtained in step (9) of Examples 1.1 to 1.5 were subjected to the determination of emulsifying activity index (EAI) and emulsifying stability index (ESI). The specific method for testing emulsifying activity and emulsifying stability is as follows: The yeast hydrolysate obtained in step (5) or the yeast protein obtained in step (9) is used as the test sample. The test sample is prepared into a 0.5% w / v test sample solution (v represents the volume of deionized water in mL and w represents the weight of the test sample in g) with deionized water. Then, 1 mL of soybean oil and 3 mL of the test sample solution are mixed and homogenized at 10000 rpm for 10 min. Before homogenization, 50 μL of emulsion is drawn from the bottom of the tube and the emulsion is diluted with 0.1% w / v SDS solution to 5 μL. The emulsion was diluted to 5 mL and vortexed for 3 s as the pre-homogenization sample. After homogenization for 10 min, 50 μL of emulsion was aspirated from the bottom of the tube as the post-homogenization sample. This emulsion was diluted with 0.1% w / v SDS solution to 5 mL and vortexed for 3 s as the post-homogenization sample. The absorbance of both the pre-homogenization and post-homogenization samples was then measured at 500 nm using a UV-1200 spectrophotometer. The absorbance of the 0.1% w / v SDS solution at 500 nm was used as a blank control. Then, the emulsion activity index (EAI) and emulsion stability index (ESI) were calculated using Formulas 1 and 2 below:

[0083] Where EAI represents the emulsified area per gram of protein, in m². 2 / g; c is the protein content in g per mL of the sample solution to be tested, in g / mL; Φ is the volume fraction of the oil phase, which accounts for 1 / 4 in this experiment; DF is the dilution factor, which is 100 times in this experiment; A0 is the absorbance of the sample before homogenization.

[0084] The method for detecting the protein content in the sample solution to be tested is as follows: the first method, "Kjeldahl method" (wherein the protein conversion factor is taken as 6.25 according to the "Other Foods" category in Appendix C of the standard), is used for detection according to the "National Food Safety Standard GB5009.5 Determination of Protein in Food".

[0085]

[0086] Where A0 is the absorbance of the sample before homogenization, A 10 The absorbance of the homogenized sample is denoted as .

[0087] The results of measuring the emulsifying activity index (EAI) and emulsifying stability index (ESI) of the yeast hydrolysates obtained in step (5) of Examples 1.1 to 1.5, and the yeast proteins obtained in step (9) of Examples 1.1 to 1.5 are shown in Tables 2 and 3 below:

[0088]

[0089] As shown in Tables 2 and 3, the emulsifying activity index of the yeast hydrolysate obtained in step (5) of Examples 1.1 to 1.5 is as high as 26.6 m² / g or more, specifically 26.6-51.2 m² / g, and the emulsifying stability is as high as 77.4% or more, specifically 77.4-148.9%. The emulsifying activity index of the yeast protein obtained in step (9) of Examples 1.1 to 1.5 is as high as 70.5 m² / g or more, specifically 70.5-89.6 m² / g, and the emulsifying stability is as high as 179.7% or more, specifically 179.7-286.2%. The results indicate that both single enzymatic hydrolysis and excessively high molecular weight cutoff reduce the emulsifying activity and emulsifying stability of the hydrolysate and yeast protein.

[0090] Example 2.1: Preparation method of yeast protein sodium salt product with high emulsifying properties Steps (1) to (5) in this embodiment are the same as in embodiment 1.5.

[0091] (6) Ionization treatment: After adjusting the pH of the yeast hydrolysate obtained in step (5) to 7.1 using food-grade sodium hydroxide, it is kept at 65°C for 3 hours. During the incubation process, the pH of the yeast hydrolysate is always controlled to be 7.1. (7) Membrane filtration: The yeast hydrolysate obtained in step (5) is separated and purified using an ultrafiltration membrane with a molecular weight cutoff of 1KD, and the retentate is rich in macromolecular components with a molecular weight >1KD. (8) Sterilization: The retentate obtained in step (6) is prepared into a mixed solution using deionized water and then instantaneously sterilized at 137°C for 5 seconds. The dry matter content of the mixed solution is 6 wt% by weight. (9) Concentration: The sterilized mixed solution obtained in step (6) is concentrated to obtain a concentrated solution, wherein the dry matter content of the concentrated solution is 25 wt% by weight; (10) Spray drying: The concentrated liquid obtained in step (7) is spray dried to obtain a yeast protein sodium salt product with high emulsification performance and a moisture content of 3.21 wt%. The inlet air temperature of the spray drying is 165 ℃ and the outlet air temperature is 70 ℃.

[0092] Example 2.2: Preparation method of yeast protein sodium salt product with high emulsifying properties Steps (1) to (5) in this embodiment are the same as in embodiment 1.5.

[0093] (6) Ionization treatment: After adjusting the pH of the yeast hydrolysate obtained in step (5) to 7.2 using food-grade sodium hydroxide, it is kept at 65°C for 4 hours. During the incubation process, the pH of the yeast hydrolysate is always controlled to be 7.2. (7) Membrane filtration: The yeast hydrolysate obtained in step (5) is separated and purified using an ultrafiltration membrane with a molecular weight cutoff of 1KD, and the retentate is rich in macromolecular components with a molecular weight >1KD. (8) Sterilization: The retentate obtained in step (6) is prepared into a mixed solution using deionized water and then instantaneously sterilized at 137°C for 5 seconds. The dry matter content of the mixed solution is 6 wt% by weight. (9) Concentration: The sterilized mixed solution obtained in step (6) is concentrated to obtain a concentrated solution, wherein the dry matter content of the concentrated solution is 25 wt% by weight; (10) Spray drying: The concentrated liquid obtained in step (7) is spray dried to obtain a yeast protein sodium salt product with high emulsification performance and a moisture content of 2.84 wt%. The inlet air temperature of the spray drying is 165 ℃ and the outlet air temperature is 70 ℃.

[0094] Comparative Example 2.1: Preparation method of yeast protein sodium salt product The difference from Example 2.1 is that in step (6), during the ionization treatment, the pH of the yeast hydrolysate obtained in step (5) is adjusted to 7.0 using food-grade sodium hydroxide, and then kept at 65°C for 4 hours. During the heat preservation process, the pH of the yeast hydrolysate is always controlled to be 7.0.

[0095] Technical Effect Evaluation 2 (1) The yeast protein sodium salt products obtained in Examples 2.1-2.2 and Comparative Example 2.1 were used as test samples to determine the emulsifying activity index (EAI) and the emulsifying stability index (ESI). The test methods for emulsifying activity and emulsifying stability were the same as those in Technical Effect Evaluation 1. The specific results are shown in Table 4 below:

[0096] As shown in Table 4, the emulsifying activity index of the yeast protein sodium salt products obtained in Examples 2.1-2.2 is as high as 130.2 m² / g or higher, specifically 130.2-141.1 m² / g, and the emulsifying stability is as high as 305.1% or higher, specifically 305.1-337.6%. These are significantly higher than those in Comparative Example 2.1. Therefore, the yeast protein sodium salt products provided by this invention have high emulsifying activity and emulsifying stability indices, making them suitable as natural emulsifiers and possessing the potential to replace sodium caseinate.

[0097] (2) Sensory evaluation was conducted on the yeast protein sodium salt products obtained in Examples 2.1-2.2 and Comparative Example 2.1. The specific method of sensory evaluation was as follows: the color of the yeast protein sodium salt products (no need to be prepared) obtained in Examples 2.1-2.2 and Comparative Example 2.1 was evaluated. The specific sensory evaluation standards are shown in Table 5 below, and the specific sensory evaluation results are shown in Table 6 below. 2g of the yeast protein sodium salt products obtained in Examples 2.1-2.2 and Comparative Example 2.1 were taken and mixed with 8g of water, and then sensory evaluation of yeast flavor, fineness, bitterness, astringency and umami was conducted. The specific sensory evaluation standards are shown in Table 5 below, and the specific sensory evaluation results are shown in Table 6 below.

[0098]

[0099]

[0100] The results showed that the yeast protein sodium salt products of Examples 2.1 and 2.2 had high emulsifying activity and emulsifying stability, as well as high fineness. This indicates that by ionizing the yeast hydrolysate under specific pH conditions, a yeast protein sodium salt product with high emulsifying activity and emulsifying stability and high fineness can be obtained. Furthermore, a higher degree of ionization treatment also helps to reduce the yeast flavor.

[0101] The above embodiments are only for further explanation and understanding of the technical solution of the present invention, and are not intended to limit the present invention. Any improvements made by those skilled in the art on this basis that do not highlight substantive features or make significant progress should fall within the protection scope of the present invention.

Claims

1. A yeast hydrolysate with high emulsifying properties, characterized in that, The yeast hydrolysate has an emulsifying activity of ≥25.0 m² / g and an emulsifying stability of ≥77.0%.

2. The yeast hydrolysate according to claim 1, characterized in that, The yeast hydrolysate was prepared by a method comprising the following steps: (1) Autolyze high-protein yeast to obtain an autosol solution; (2) The solution obtained in step (1) is enzymatically hydrolyzed to obtain an enzymatic hydrolysate, wherein the enzymes used in the enzymatic hydrolysis include alkaline protease, flavor protease, glucanase, mannanase and transglutaminase. (3) The enzyme hydrolysate obtained in step (2) is inactivated and homogenized to obtain the yeast hydrolysate.

3. The yeast hydrolysate according to claim 2, characterized in that, Based on the dry matter weight of the self-solution, the amount of alkaline protease added is 0.10-1.00 wt%, and / or the amount of flavor protease added is 0.10-1.00 wt%, and / or the amount of dextranase added is 0.10-1.00 wt%, and / or the amount of mannanase added is 0.10-1.00 wt%, and / or the amount of transglutaminase added is 0.10-1.00 wt%.

4. The yeast hydrolysate according to claim 2, characterized in that, The protein content of the high-protein yeast is 45-75%.

5. A method for preparing yeast hydrolysate according to any one of claims 1-4, characterized in that, It includes the following steps: (1) The yeast was autolyzed to obtain an autosol solution; (2) The solution obtained in step (1) is enzymatically hydrolyzed to obtain an enzymatic hydrolysate, wherein the enzymes used in the enzymatic hydrolysis include two or more combinations selected from the group consisting of alkaline protease, flavor protease, glucanase, mannanase and transglutaminase. (3) The enzyme hydrolysate obtained in step (2) is inactivated and homogenized to obtain the yeast hydrolysate.

6. The preparation method according to claim 5, characterized in that, The autolysis temperature is 55~60℃ and / or the autolysis time is 4~6h.

7. The preparation method according to claim 5, characterized in that, The enzymatic hydrolysis temperature is 55-65℃, and / or the enzymatic hydrolysis time is 15-20h, and / or the enzymatic hydrolysis pH is 6.5-6.

8.

8. A yeast protein with high emulsifying properties, characterized in that, The yeast enzymatic hydrolysate according to any one of claims 1-4 is prepared by separating and purifying it, wherein the yeast protein has an emulsifying activity ≥70.0 m² / g and an emulsifying stability ≥175.0%.

9. The yeast protein according to claim 8, characterized in that, The yeast protein has an emulsifying activity of 70.0-120.0 m² / g and an emulsifying stability of 175.0-290.0%.

10. A method for preparing yeast protein according to claim 8 or 9, characterized in that, The method includes the following steps: separating and purifying the yeast hydrolysate according to any one of claims 1-4 to obtain yeast protein with high emulsifying properties.

11. A yeast protein sodium salt product with high emulsifying properties, characterized in that, The product is prepared by ionizing and purifying the yeast hydrolysate according to any one of claims 1-4, wherein the emulsifying activity of the yeast protein sodium salt product is ≥125m² / g and the emulsifying stability is ≥300.0%.

12. The yeast protein sodium salt product according to claim 11, characterized in that, The emulsifying activity of the yeast protein sodium salt product is 125-142 m² / g, and the emulsifying stability is 300.0-400.0%.

13. The yeast protein sodium salt product according to claim 11, characterized in that, During the ionization reaction, the pH of the yeast hydrolysate is adjusted to 7.1-7.5 using sodium hydroxide, and then kept at 60-65℃ for 2-5 hours. During the incubation process, the pH of the yeast hydrolysate is maintained at 7.1-7.

5.

14. A method for preparing the yeast protein sodium salt product according to any one of claims 11-13, characterized in that, The method includes the following steps: subjecting the yeast hydrolysate according to any one of claims 1-4 to ionization reaction and separation and purification to obtain a yeast protein sodium salt product with high emulsifying properties.

15. The yeast protein product according to claim 8 or 9, or the yeast protein sodium salt product according to any one of claims 11-13, characterized in that, The separation and purification method is to use ultrafiltration membrane filtration, wherein the molecular weight cutoff of the ultrafiltration membrane is ≥1000 Da.

16. The yeast protein product according to claim 8 or 9, or the yeast protein sodium salt product according to any one of claims 11-13, characterized in that, After separation and purification, the process also includes sterilization, concentration, and spray drying.

17. The use of the yeast hydrolysate of any one of claims 1-4, or the yeast protein of any one of claims 8, 9, 15, or 16, or the yeast protein sodium salt product of any one of claims 11-13, 15, or 16 in the preparation of an emulsifier.

18. The use of the yeast hydrolysate of any one of claims 1-4, or the yeast protein of any one of claims 8, 9, 15, or 16, or the yeast protein sodium salt product of any one of claims 11-13, 15, or 16 in the preparation of food.

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