Method for improving gas-liquid interface property of yeast protein

Abstract

The invention belongs to the technical field of yeast protein processing, and particularly relates to a method for improving the gas-liquid interface property of yeast protein. The method comprises the following steps: dispersing yeast protein in water to obtain a yeast protein dispersion liquid; adjusting the temperature and the pH value of the yeast protein dispersion liquid, stabilizing for a period of time, then carrying out restriction enzyme hydrolysis, and centrifuging after enzyme deactivation to obtain supernate. The surface tension of the yeast protein obtained by the method is reduced, the foaming ability and the foam stability are remarkably improved, and bubbles generated by whipping are small and uniform. And the method is green and efficient, and is beneficial to full utilization of high-quality protein resources.

Description

Technical Field

[0001] The present invention relates to the technical field of yeast protein processing, and in particular to a method for improving the gas-liquid interface properties of yeast protein. Background Art

[0002] Yeast protein is a type of single-cell protein and a high-efficiency protein source. It has been developed and used in the food industry in recent years. Yeast protein is not only rich in protein but also of good quality. Most yeast proteins are rich in free amino acids, and the content of lysine, methionine and cysteine ​​is similar to that of fish meal. It has a complete amino acid composition, and the content of essential amino acids for the human body (such as lysine) is also high. It has the advantages of wide sources, high production efficiency, and easy industrial large-scale production. In addition, yeast protein also contains a variety of enzymes, rich vitamins and some unknown growth factors, which are beneficial to the digestion and absorption of organic matter. Substances such as β-glucan in the yeast cell wall can also enhance the body's immunity. Therefore, yeast protein has been developed and utilized and has gradually become a good substitute for conventional plant protein and feed.

[0003] Improving the interfacial properties of yeast protein plays an important role in enhancing its application in the food industry and biotechnology, including improving the nutritional absorption, processing performance and biological activity of protein. The gas-liquid interfacial properties of existing yeast protein are poor, which is manifested in its high surface tension, limited foaming ability, poor foam stability, and large and unevenly distributed stable foam size. Summary of the invention

[0004] The present invention provides a method for improving the gas-liquid interface properties of yeast protein to solve the above technical problems existing in the prior art.

[0005] According to a first aspect of the present invention, the present invention provides a method for improving the gas-liquid interface properties of yeast protein based on restricted enzymatic hydrolysis, wherein the method comprises dispersing yeast protein in water to obtain a yeast protein dispersion; adjusting the temperature and pH value of the yeast protein dispersion, stabilizing it for a period of time, then performing restricted enzymatic hydrolysis, inactivating the enzyme, and centrifuging to obtain the supernatant.

[0006] The present invention experiments found that the yeast protein obtained by the restricted enzymolysis of the present invention has a reduced surface tension, a significantly improved foaming ability and foam stability, and small and uniform foaming produced by whipping. The method is green and efficient, and is conducive to the full utilization of high-quality protein resources.

[0007] Furthermore, the hydrolase added in the restriction enzyme hydrolysis is one or more of alkaline protease, neutral protease, papain, trypsin, flavor protease, and composite protease. By selecting the appropriate type of hydrolase, it is more conducive to changing the structure of yeast protein, improving its foaming ability and foam stability, thereby optimizing the processing performance, nutritional value and taste of the food. Preferably, the hydrolase added in the restriction enzyme hydrolysis is trypsin, papain, and composite protease.

[0008] Furthermore, the mass of the hydrolase added by the restriction enzyme hydrolysis is 0.05%-4.00% of the mass of the yeast protein. By limiting the mass of the hydrolase added by the restriction enzyme hydrolysis to a reasonable range, it is more conducive to improving its foaming ability and foam stability.

[0009] Optionally, the mass of the hydrolase added by the restriction enzyme hydrolysis can be 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5% or 4.00% of the yeast protein mass, and of course, it can also be other values ​​within the above range, which are not limited here. Preferably, it is 1-3%. In some specific embodiments, the mass of the hydrolase added by the restriction enzyme hydrolysis is 2% of the yeast protein mass.

[0010] Furthermore, the restriction enzyme hydrolysis time is 15-60min.

[0011] Optionally, the enzymolysis time of the restriction enzyme hydrolysis can be 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min or 60min, etc., and certainly can be other values ​​within the above range, which are not limited here. Preferably, it is 20-40min. In some specific embodiments, the enzymolysis time of the restriction enzyme hydrolysis is 30min.

[0012] Furthermore, the mass concentration of the yeast protein dispersion is 4%-8%. By controlling the mass concentration of the yeast protein dispersion within a reasonable range, it is beneficial for the yeast protein to fully contact and act with the restriction hydrolase.

[0013] Optionally, the mass concentration of the yeast protein dispersion can be 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5% or 8%, etc., and of course, it can also be other values ​​within the above range, which are not limited here, preferably 5-7%. In some specific embodiments, the mass concentration of the yeast protein dispersion is 6%.

[0014] Furthermore, the pH value of the yeast protein dispersion is adjusted to 6.5-8.6, the temperature is 37-55° C., and the yeast protein dispersion is stabilized in a magnetic stirring water bath for 10-30 minutes. By adjusting the pH value and temperature of the yeast protein dispersion within a reasonable range, it is beneficial to increase the activity of the protease, thereby improving the reaction efficiency.

[0015] Furthermore, the enzyme inactivation condition is heating at 90-100°C for 5-18 minutes. By limiting the temperature and time of enzyme inactivation within a reasonable range, the enzymatic reaction can be stopped in time to prevent the protein or peptide from being further enzymatically hydrolyzed, and most of the microorganisms in the enzymatic solution can be killed to ensure the safety of the enzymatic solution.

[0016] In some specific embodiments, the enzyme inactivation condition is heating at 95° C. for 15 min.

[0017] Furthermore, the centrifugal speed is 5000-10000 r / min, and the time is 8-20 min. By limiting the centrifugal speed and time within a reasonable range, it is beneficial to the efficient separation of yeast protein.

[0018] In some specific embodiments, the centrifugal speed is 6000 r / min and the time is 10 min.

[0019] Furthermore, the surface tension of the yeast protein obtained after treatment by the method is 30-40 mN / m, the foaming ability is 100-150%, the foaming stability is 85-97%, and the surface hydrophobicity index H 0 It is 25-55.

[0020] Beneficial effects of the present invention: The method for improving the gas-liquid interface properties of yeast protein is green and efficient, which is conducive to the full utilization of high-quality protein resources. The surface tension of the obtained yeast protein is reduced, the foaming ability and foam stability are significantly improved, and the foam generated by whipping is small and uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 Surface tension diagram of yeast protein obtained in Examples 1-6 of the present invention.

[0023] Figure 2The diagram shows the foaming ability and foam stability of yeast protein prepared in Examples 1-6 of the present invention.

[0024] Figure 3 Surface hydrophobicity graphs of yeast proteins prepared in Examples 1-6 of the present invention.

[0025] Figure 4 The microstructure diagram of the yeast protein stabilized foam prepared in Examples 1-6 of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1 This embodiment provides a method for improving the gas-liquid interface properties of yeast protein based on restriction enzyme hydrolysis, comprising the following steps: (1) Disperse yeast protein in deionized water to obtain a yeast protein dispersion with a mass concentration of 6%, heat and adjust the temperature to 37°C and the pH to 8.00±0.02, and stabilize the dispersion for 15 min.

[0028] (2) Add trypsin at a concentration of 2% by weight of yeast protein to the yeast protein dispersion of step (1) for restriction enzyme hydrolysis for 30 minutes.

[0029] (3) After the enzymatic hydrolysis is completed, heat in a 95°C water bath for 15 min to inactivate the enzyme, cool to room temperature, centrifuge at 6000 rpm for 10 min, and collect the supernatant.

[0030] Example 2 This example provides a method for improving the gas-liquid interface properties of yeast protein based on restriction enzyme hydrolysis, which is different from Example 1 in that: In step (1), the yeast protein dispersion is heated to 55° C. and the pH value is adjusted to 8.5±0.02. In step (2), alkaline protease is added as the enzyme. The remaining conditions and steps are the same as those in Example 1.

[0031] Example 3 This example provides a method for improving the gas-liquid interface properties of yeast protein based on restriction enzyme hydrolysis, which is different from Example 1 in that: In step (1), the yeast protein dispersion is heated to 50° C. and the pH value is adjusted to 7.00±0.02. In step (2), papain is added as the enzyme. The remaining conditions and steps are the same as those in Example 1.

[0032] Example 4 This example provides a method for improving the gas-liquid interface properties of yeast protein based on restriction enzyme hydrolysis, which is different from Example 1 in that: In step (1), the yeast protein dispersion is heated to 45° C. and the pH value is adjusted to 7.00±0.02. In step (2), the enzyme added is neutral protease. The remaining conditions and steps are the same as those in Example 1.

[0033] Example 5 This example provides a method for improving the gas-liquid interface properties of yeast protein based on restriction enzyme hydrolysis, which is different from Example 1 in that: In step (1), the yeast protein dispersion is heated to 50° C. and the pH value is adjusted to 7.00±0.02. In step (2), the added enzyme is a composite protease. The remaining conditions and steps are the same as those in Example 1.

[0034] Example 6 This example provides a method for improving the gas-liquid interface properties of yeast protein based on restriction enzyme hydrolysis, which is different from Example 1 in that: In step (1), the yeast protein dispersion is heated to 50° C. and the pH value is adjusted to 6.50±0.02. In step (2), papain is added as the enzyme. The remaining conditions and steps are the same as those in Example 1.

[0035] Test example The untreated yeast protein dispersion sample obtained in step (1) of Example 1 was used as a control sample.

[0036] The adsorption of samples at the air-water interface was detected using the interfacial tension meter in hanging mode. At 25 ± 0.1 °C, the densities of air and sample were 0.001185 g / cm 3 and about 1.001 g / cm 3 , the interfacial tension between ultrapure water and air is 72±0.1mN / m. Take 10ml yeast protein sample and high-speed shear it at 10000r / min for 2min, record the volume after beating as V 0 After standing for 15 min, measure the foam volume again and record it as V 15min .

[0037] Foaming ability .

[0038] Foam stability .

[0039] 8 mL of each sample was mixed with 20 μL of Nile blue dye solution (0.01%) and sheared at 10000 r / min for 2 min. Then, 50 μL of foam was placed on a concave confocal microscope slide and the foam microstructure was quickly observed using a laser confocal microscope under a 10x lens condition and a helium-neon laser (He / Ne) at 633 nm for excitation.

[0040] The 8-ANS fluorescent probe method was used to determine the surface hydrophobicity. First, 8-ANS was dissolved in water to a concentration of 8.0 mM. Shake and let stand. The fluorescence intensity was measured on a fluorescence photometer, with the emission wavelength and excitation wavelength being 470 nm and 390 nm, respectively. A curve was drawn with the fluorescence intensity versus protein concentration, and the starting slope of the curve was defined as the surface hydrophobicity index (H) of the sample being tested. 0 ).

[0041] Depend on Figure 1 It can be seen that compared with the untreated yeast protein dispersion sample (surface tension of 41.53-36.89 mN / m), the yeast protein dispersion sample treated by the method of the present invention has a lower surface tension (39.64-30.84 mN / m), among which the surface tension of Example 2 is the smallest.

[0042] Depend on Figure 2 It can be seen that compared with the untreated yeast protein dispersion sample, the yeast protein dispersion sample treated by the method of the present invention has significantly improved foaming ability and foam stability, with a foaming ability of 101.33-138.67% and a foaming stability of 85.83-96.72%, among which Example 1 has the best comprehensive foaming ability and foam stability.

[0043] Depend on Figure 3 It can be seen that compared with the untreated yeast protein dispersion sample, the surface hydrophobicity of the yeast protein dispersion sample treated by the method of the present invention is significantly improved, and the surface hydrophobicity index H 0 The hydrophobicity of Example 5 is the best at 25.663-54.399.

[0044] Depend on Figure 4 It can be seen that, compared with the untreated yeast protein dispersion sample, the foam size stabilized by the yeast protein dispersion sample treated by the method of the present invention is significantly reduced, and the foam distribution is more uniform, among which the foam size and distribution state of Example 1 are the best.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the gas-liquid interface properties of yeast protein, characterized in that: The method comprises the following steps: dispersing yeast protein in water to obtain a yeast protein dispersion; adjusting the temperature and pH value of the yeast protein dispersion, stabilizing it for a period of time, hydrolyzing it with a restriction enzyme, killing the enzyme, centrifuging and obtaining the supernatant.

2. The method according to claim 1, characterized in that The hydrolase added in the restriction enzyme hydrolysis is one or more of alkaline protease, neutral protease, papain, trypsin, flavor protease and composite protease.

3. The method according to claim 1 or 2, characterized in that: The mass of the hydrolase added in the restriction enzyme hydrolysis is 0.05%-4.00% of the mass of the yeast protein.

4. The method according to any one of claims 1 to 3, characterized in that: The restriction enzyme hydrolysis time is 15-60min.

5. The method according to claim 1, characterized in that The mass concentration of the yeast protein dispersion is 4%-8%.

6. The method according to claim 1 or 5, characterized in that: The pH value of the yeast protein dispersion is adjusted to 6.5-8.

6.

7. The method according to any one of claims 1, 5 and 6, characterized in that: The temperature of the yeast protein dispersion is adjusted to 37-55° C. and stabilized for 10-30 minutes.

8. The method according to any one of claims 1 to 7, characterized in that: The enzyme inactivation condition is heating at 90-100° C. for 5-18 min.

9. The method according to any one of claims 1 to 8, characterized in that: The centrifugal speed is 5000-10000 r / min, and the time is 8-20 min.

10. The method according to any one of claims 1 to 9, characterized in that: The surface tension of the yeast protein obtained after being treated by the method is 30-40 mN / m, the foaming ability is 100-150%, the foaming stability is 85-97%, and the surface hydrophobicity index H0 is 25-55.

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