Micro-hydrolyzed yeast protein and preparation method thereof

Abstract

The invention belongs to the technical field of yeast protein processing, and discloses a micro-hydrolyzed yeast protein preparation method, which comprises: dissolving with purified water, carrying out heating treatment, removing floating oil, and adsorbing with beta-cyclodextrin; the preparation method comprises the following steps: firstly, performing enzymolysis by using trypsin and flavourzyme in sequence, strictly controlling the addition amount of enzyme and the enzymolysis time, and performing spray drying after enzyme deactivation to obtain the micro-hydrolyzed yeast protein, and discloses the micro-hydrolyzed yeast protein prepared by the method. The preparation method is simple, and the taste and flavor of the obtained product are remarkably improved while the nutritional function of the yeast protein is reserved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of yeast protein processing, and particularly relates to a micro-hydrolyzed yeast protein and a preparation method thereof. BACKGROUND

[0002] Yeast protein has a wide application prospect in the fields of food and health care products due to its high nutritional value (rich in essential amino acids, vitamins and minerals) and sustainable production characteristics. The production efficiency and energy conversion rate of yeast protein are high, and the preparation process is mature. In recent years, as a sustainable source of microbial protein, the application of yeast protein in the food industry has gradually increased. However, yeast protein has problems such as rough taste and poor solubility, which limits its application in high-end food (such as protein drinks, dairy product substitutes and nutritional supplements).

[0003] At present, there are certain limitations in the traditional methods for improving the taste of yeast protein, such as physical treatment methods (such as high-pressure homogenization and ultrasonic treatment): which can partially improve solubility, but the damage to protein structure is limited, and the taste improvement is not obvious; chemical modification methods (such as acid-base treatment and glycosylation reaction): which may introduce chemical residue risks and have complex processes; enzymatic hydrolysis: which can effectively degrade macromolecular proteins, but traditional enzymatic hydrolysis usually uses a single enzyme for deep hydrolysis, which can partially solve the problems of taste and solubility, but may cause excessive hydrolysis, and the bitterness and fishy smell may be aggravated, thereby affecting its application. SUMMARY

[0004] The first technical problem to be solved by the present application is to provide a micro-hydrolyzed yeast protein preparation method, which overcomes the defects of the prior art and significantly improves the smoothness and taste of yeast protein while retaining its nutritional function.

[0005] The second technical problem to be solved by the present application is to provide a micro-hydrolyzed yeast protein prepared by the above method.

[0006] To solve the above technical problems, the technical solution of the present application is:

[0007] A micro-hydrolyzed yeast protein preparation method, comprising the following steps:

[0008] S1. Add purified water to the yeast protein in a mass ratio of 1:5-7, mix thoroughly to configure a yeast protein slurry, adjust the pH value of the slurry to 6.8-7.2, and treat it in a water bath at 90-100℃ for 10-20 min to make the yeast protein structure loose;

[0009] S2. After cooling the liquid obtained in step S1 to 37°C, skim off the surface oil, then add 2% to 3% of yeast protein adsorbent (β-cyclodextrin), stir evenly and let stand for 20 minutes, filter out the adsorbent (β-cyclodextrin) through a 200-mesh filter, add 0.5% to 1.5% of yeast protein trypsin (enzyme activity 800,000 U / g), mix thoroughly and enzymatically hydrolyze for 10 to 60 minutes. Trypsin acts as an endopeptidase responsible for cutting large yeast protein segments into smaller segments.

[0010] S3. Heat the liquid obtained in step S2 to 50°C, then add 0.5% to 1.5% of yeast protein content of flavor protease (enzyme activity 150,000 U / g), and continue enzymatic hydrolysis for 10 min to 60 min. The flavor protease mainly reduces bitterness and balances the overall flavor by forming bitter peptides through enzymatic hydrolysis, and further enzymatically hydrolyzes yeast protein.

[0011] S4. After the reaction in step S3 is completed, heat to 90℃~100℃ to inactivate the enzyme for 10 min~15 min, and then spray dry to obtain microhydrolyzed yeast protein powder.

[0012] Preferably, in step S1, the mass ratio of yeast protein to purified water is 1:6, the pH of the solution is adjusted to 7.0, and the solution is incubated in a water bath at 95°C for 15 minutes.

[0013] Preferably, in step S2, the amount of β-cyclodextrin added is 2.5% of the yeast protein mass, the amount of trypsin added is 1% of the yeast protein mass, and the enzymatic hydrolysis time is 30 min.

[0014] Preferably, in step S3, the amount of flavor protease added is 1% of yeast protein, and the enzymatic hydrolysis time is 30 min.

[0015] Preferably, in step S4, the enzyme inactivation temperature is 95°C and the enzyme inactivation time is 13 min; the spray drying conditions are: inlet air temperature of 170°C, outlet air temperature of about 85°C, and injection flow rate of 800 mL / h.

[0016] A microhydrolyzed yeast protein is a microhydrolyzed yeast protein prepared by the above method.

[0017] Due to the adoption of the above technical solution, the beneficial effects achieved by this invention are:

[0018] The micro-hydrolyzed yeast protein powder prepared by this invention has undergone deodorization, intramolecular cleavage, and bitterness removal flavor optimization, resulting in a lower molecular weight. Therefore, its solubility and stability after dissolving in water are significantly improved, the particle size is significantly reduced, the smoothness is significantly improved, and the taste is significantly improved. Moreover, the nutritional components are still retained, which can meet its application in high-end foods (such as protein drinks, dairy substitutes, and nutritional supplements). Attached Figure Description

[0019] Figure 1 This is a diagram showing the state of the micro-hydrolyzed yeast protein and the yeast protein before enzymatic hydrolysis of the present invention, dissolved in water at a concentration of 5% and left to stand for 0 minutes.

[0020] Figure 2 This is a diagram showing the state of the micro-hydrolyzed yeast protein and the unhydrolyzed yeast protein of the present invention after standing in water at a concentration of 5% for 5 minutes.

[0021] Figure 3 This is a particle size distribution diagram of yeast proteins before enzymatic hydrolysis.

[0022] Figure 4 This is a particle size distribution diagram of the microhydrolyzed yeast protein in Example 3.

[0023] Figure 5 This is a comparison chart of the yield of micro-hydrolyzed yeast protein in Examples 1-4. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to embodiments:

[0025] The yeast protein used in the following examples is model F75, purchased from Angel Yeast Co., Ltd.; food-grade β-cyclodextrin was purchased from Zibo Qianhui Biotechnology Co., Ltd.; trypsin was purchased from Shandong Qiannuo Biotechnology Co., Ltd.; and flavor protease was purchased from Novozymes (China) Biotechnology Co., Ltd.

[0026] Example 1:

[0027] S1. Add 5000 g of purified water to 1000 g of yeast protein, mix thoroughly to prepare a yeast protein solution, adjust the pH of the solution to 6.8, and treat in a 90℃ water bath for 20 min.

[0028] S2. After cooling the liquid obtained in step S1 to 37°C, skim off the surface oil, then add 20 g of β-cyclodextrin, stir evenly and let stand for 20 minutes, filter out the adsorbent (β-cyclodextrin) through a 200-mesh filter; then add 5 g of trypsin (enzyme activity 800,000 U / g), mix thoroughly and enzymatically hydrolyze for 30 minutes.

[0029] S3. Heat the liquid obtained in step S2 to 50°C, then add 5 g of flavor protease (enzyme activity 150,000 U / g) and continue enzymatic hydrolysis for 30 min.

[0030] S4. After the reaction in step S3 was completed, the temperature was raised to 90℃ for 15 min to inactivate the enzyme, followed by spray drying (inlet air temperature 170℃, outlet air temperature approximately 85℃, injection flow rate 800 mL / h) to obtain microhydrolyzed yeast protein powder. A total of 861 g was obtained, with a product yield of 86.1% (see...). Figure 5 ).

[0031] Example 2:

[0032] S1. Add 7000 g of purified water to 1000 g of yeast protein, mix thoroughly to prepare a yeast protein solution, adjust the pH of the solution to 7.2, and treat in a 100℃ water bath for 10 min.

[0033] S2. After cooling the liquid obtained in step S1 to 37°C, skim off the surface oil, then add 30 g of β-cyclodextrin, stir evenly and let stand for 20 minutes, filter out the adsorbent (β-cyclodextrin) through a 200-mesh filter; then add 15 g of trypsin (enzyme activity 800,000 U / g), mix thoroughly and enzymatically hydrolyze for 60 min.

[0034] S3. Heat the liquid obtained in step S2 to 50°C, then add 15 g of flavor protease (enzyme activity 800,000 U / g) and continue enzymatic hydrolysis for 60 min;

[0035] S4. After the reaction in step S3 was completed, the temperature was raised to 100℃ for 10 min to inactivate the enzyme, followed by spray drying (inlet air temperature 170℃, outlet air temperature approximately 85℃, injection flow rate 800 mL / h) to obtain microhydrolyzed yeast protein powder. A total of 792 g was obtained, with a product yield of 79.2% (see...). Figure 5 ).

[0036] Example 3:

[0037] S1. Add 6000 g of purified water to 1000 g of yeast protein, mix thoroughly to prepare a yeast protein solution, adjust the pH of the solution to 7.0, and treat in a 95℃ water bath for 15 min.

[0038] S2. After cooling the liquid obtained in step S1 to 37°C, skim off the surface oil, then add 25 g of β-cyclodextrin, stir well and let stand for 20 minutes, then filter out the adsorbent (β-cyclodextrin) through a 200-mesh filter; then add 10 g of trypsin (enzyme activity 800,000 U / g), mix thoroughly and enzymatically hydrolyze for 30 minutes.

[0039] S3. Heat the liquid obtained in step S2 to 50°C, then add 10 g of flavor protease (enzyme activity 150,000 U / g) and continue enzymatic hydrolysis for 30 min;

[0040] S4. After the reaction in step S3 was completed, the temperature was raised to 95℃ for 13 min to inactivate the enzyme, followed by spray drying (inlet air temperature 170℃, outlet air temperature approximately 85℃, injection flow rate 800 mL / h) to obtain microhydrolyzed yeast protein powder. A total of 855 g was obtained, with a product yield of 85.5% (see...). Figure 5 ).

[0041] Example 4:

[0042] S1. Add 6000 g of purified water to 1000 g of yeast protein, mix thoroughly to prepare a yeast protein solution, adjust the pH of the solution to 7.0, and treat in a 95℃ water bath for 15 min.

[0043] S2. After cooling the liquid obtained in step S1 to 37°C, skim off the surface oil, then add 25 g of β-cyclodextrin, stir evenly and let stand for 20 minutes, filter out the adsorbent (β-cyclodextrin) through a 200-mesh filter; then add 10 g of trypsin (enzyme activity 800,000 U / g), mix thoroughly and enzymatically hydrolyze for 10 min.

[0044] S3. Heat the liquid obtained in step S2 to 50°C, then add 10 g of flavor protease (enzyme activity 150,000 U / g) and continue enzymatic hydrolysis for 10 min;

[0045] S4. After the reaction in step S3 was completed, the temperature was raised to 95℃ for 13 min to inactivate the enzyme, followed by final spray drying (inlet air temperature 170℃, outlet air temperature approximately 85℃, injection flow rate 800 mL / h) to obtain microhydrolyzed yeast protein powder. A total of 872 g was obtained, with a product yield of 87.2% (see...). Figure 1 ).

[0046] Product testing methods, results, and analysis:

[0047] 1. Determination of the degree of hydrolysis of original yeast protein and micro-hydrolyzed yeast protein obtained in Examples 1-4

[0048] The formaldehyde titration method was used for determination. Take 10 mL of the micro-hydrolyzed yeast protein solution after the reaction, place it in a 250 mL Erlenmeyer flask, add 60 mL of CO2-free distilled water, and shake well. Titrate with 0.1 mol / L NaOH standard solution to pH 7.0, add 10 mL of formaldehyde solution (pH=9.2), shake well, and titrate the pH of the solution with NaOH standard solution to 9.2. Record the volume of NaOH standard solution consumed, V1 (mL). Then take 10 mL of unhydrolyzed yeast protein solution of the same concentration and perform a blank test using the same method to obtain the volume of NaOH solution consumed, V2 (mL). Calculate the degree of hydrolysis (DH) of the micro-hydrolyzed yeast protein solution after the reaction using the following formula:

[0049]

[0050] Wherein, M—molar concentration of NaOH standard solution, mol / L; V1—volume of NaOH standard solution consumed in titrating the sample, mL; V2—volume of NaOH standard solution consumed in titrating the blank, mL; C—mass concentration of yeast feed, g / mL; m—protein content in yeast feed, %; v—volume of enzymatic hydrolysate used for formaldehyde titration, 10 mL; I—total number of peptide bonds in yeast protein, taken as 8.38 mmol / g for yeast protein. The results are shown in Table 1.

[0051] Determination of water solubility of yeast protein in Examples 1-4

[0052] Take 10 mg of sample and place it in a 50 mL beaker. Add 10 mL of purified water, stir magnetically for 1 h, and then centrifuge at 4500 r / min for 15 min. Determine the protein concentration using a BCA kit. The water solubility index is the percentage of protein in the supernatant to the total protein. The results are shown in Table 1. Figure 2 and Figure 1 .

[0053] Yeast protein emulsifying properties determination in Examples 1-4

[0054] The emulsifying property (EAI) of yeast protein was determined spectrophotometrically. 64 mL of water and 16 mL of oil were weighed into a 250 mL beaker, and 1 g of protein sample was added. After emulsification at 15000 r / min for 3 min using a high-speed shear press, 100 μL of the emulsion was immediately taken from the bottom of the solution and added to 10 mL of 0.1% SDS solution (diluted 100 times). The mixture was thoroughly mixed, and the absorbance (A) was measured at 500 nm. The emulsifying property (EAI) of yeast protein was calculated using the following formula:

[0055]

[0056] Where A is the measured absorbance; N is the dilution factor (100); and C is the protein concentration, g / mL. — represents the proportion of the oil phase in the emulsion (0.25). The results are shown in Table 1.

[0057] Table 1 shows the detection results of various indicators of the original yeast protein in Examples 1-4.

[0058]

[0059] As shown in Table 1, the appearance color of yeast protein darkened to some extent after microhydrolysis treatment, changing from off-white to light yellow. This is because heat denaturation causes the protein to unfold, increasing the contact area with water. With the increase of enzyme dosage and the extension of enzymatic hydrolysis time, the degree of yeast protein hydrolysis continues to deepen. The protein molecules are gradually cleaved by the enzyme, exposing more of their hydrophilic groups, enhancing their interaction with water molecules, and gradually increasing their water solubility. The emulsifying properties of microhydrolyzed yeast protein also gradually improve under the influence of increased solubility.

[0060] Depend on Figure 2 and Figure 3 It can be seen that the precipitation rate of yeast protein before hydrolysis is significantly faster than that after hydrolysis. Therefore, it is proven that the solubility stability of yeast protein is greatly improved after micro-hydrolysis treatment, which indirectly proves that the water solubility of the micro-hydrolyzed yeast protein of this invention is significantly improved compared with the original yeast protein.

[0061] 2. Determination of water-holding and oil-holding properties of microhydrolyzed yeast protein and proto-yeast protein in Example 3.

[0062] Water retention: Accurately weigh the centrifuge tube (m), weigh W1 g (approximately 0.2 g) of sample and place it in a 10 mL centrifuge tube. Add 5 mL of deionized water and mix thoroughly. Let stand for 2 h, centrifuge at 4500 rpm for 10 min, then discard the supernatant and weigh the sample and the total weight of the centrifuge tube (W2). Repeat the process three times for each sample and take the average value. The results are shown in Table 2.

[0063] Oil-holding capacity: Accurately weigh the centrifuge tube (m), weigh W1 g (approximately 0.2 g) of sample and place it in a 10 mL centrifuge tube. Add 5 mL of soybean oil and mix thoroughly. Let stand for 2 hours, centrifuge at 4500 rpm for 10 minutes, discard the supernatant, and weigh the sample and the total weight of the centrifuge tube (W2). Repeat this process three times for each sample and take the average value. The formula for calculating water-holding capacity / oil-holding capacity is:

[0064]

[0065] Where: W1 - sample mass, g; W2 - total mass of precipitate and centrifuge tube, g; m - centrifuge tube mass, g. The results are shown in Table 2.

[0066] Table 2 shows the results of water-holding and oil-holding capacity tests for microhydrolyzed yeast protein and protoy yeast protein in Example 3.

[0067]

[0068] As shown in Table 2, the water-holding capacity and oil-holding capacity of micro-hydrolyzed yeast protein are both increased compared with those of the original yeast protein. This is because after the yeast protein is hydrolyzed, the molecular weight decreases, the specific surface area increases, and the hydrophilic groups are exposed more.

[0069] 3. Determination of the foaming properties and foam stability of microhydrolyzed yeast protein and proto-yeast protein in Example 3.

[0070] Prepare a 1% concentration solution. Accurately measure V mL (approximately 40 mL) of the sample solution into a measuring cup. Disperse the solution using a high-shear stirrer at 15000 rpm for 1 min to generate foam. Record the initial foam volume V1. After standing for 30 min, record the foam volume as V30. The formulas for calculating the foaming property (FC) and foaming stability (FS) of the sample are as follows:

[0071]

[0072] Where: V - liquid volume before homogenization, mL; V1 - initial foam volume, mL; V30 - foam volume after standing for 30 min, mL. The results are shown in Table 3.

[0073] Table 3 shows the results of foaming properties and foam stability tests for microhydrolyzed yeast protein and protoy yeast protein in Example 3.

[0074]

[0075] Table 3 shows that micro-hydrolysis of yeast proteins increases foaming ability but decreases foam stability. This is because hydrolysis of yeast proteins reduces molecular size, increasing solubility and dispersibility, thus increasing foaming ability, while decreasing interfacial film stability leads to decreased foam stability.

[0076] 4. Determination of particle size of microhydrolyzed yeast protein and proto-yeast protein in Example 3

[0077] The particle size distribution of yeast protein was determined using an HL3100 laser particle size analyzer. Deionized water was used as the dispersion solvent. An appropriate amount of sample was weighed and added to an appropriate amount of deionized water. The mixture was sonicated and stirred for 5 minutes to ensure uniform dispersion. The dispersed sample was then added dropwise to the instrument until the concentration reached the instrument's detection concentration. The instrument was then activated for data acquisition and analysis. The particle size distribution diagrams of the original yeast protein powder and the micro-hydrolyzed yeast protein powder from Example 3 are shown below. Figure 4 and Figure 3 .

[0078] Depend on Figure 4 andFigure 5 Comparison shows that after micro-hydrolysis, the overall particle size of yeast proteins decreased, with the largest particle size distribution changing from 4.9941 μm to 1.9775 μm; from ​ It can be seen that as the amount of enzyme added increases and the enzymatic hydrolysis time is extended, the degree of yeast protein hydrolysis continues to deepen, and the particle size of micro-hydrolyzed yeast protein gradually decreases, which aggravates the problem of micro-hydrolyzed yeast protein powder flying. Therefore, the yield of micro-hydrolyzed yeast protein powder is the lowest in Example 2.

[0079] 5. Sensory evaluation of microhydrolyzed yeast protein in Examples 1-4:

[0080] The sensory evaluation of the finished products in the following examples is as follows: 15 professional evaluators evaluated the smoothness, bitterness, and umami of the microhydrolyzed yeast protein. The evaluation result for each product is the average of the total scores given by the 15 professional evaluators. The evaluation indicators and standards are shown in Table 4, and the evaluation results are shown in Table 5.

[0081] Table 4 shows the sensory evaluation indicators and standards.

[0082]

[0083] Table 5 shows the sensory evaluation results of the products in Examples 1-4.

[0084]

[0085] As shown in Table 5, compared with Example 1, the amounts of trypsin and flavor protease were increased in Example 3. Therefore, the smoothness of the yeast protein after enzymatic hydrolysis was significantly increased, and the bitterness and umami flavor were also increased to some extent. As shown in Examples 1 and 4, both the amount of enzyme added and the hydrolysis time have a significant impact on the degree of hydrolysis of yeast protein. As shown in Example 2, although a greater degree of hydrolysis is more conducive to smoothness, it also has a greater impact on bitterness and umami flavor. Therefore, after comprehensive evaluation, Example 3 is the optimal process condition.

[0086] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for preparing a micro-hydrolyzed yeast protein, characterized by: It comprises the following steps: S1. Add purified water to the yeast protein in a mass ratio of 1:5-7, mix well to prepare a yeast protein slurry, adjust the pH of the slurry to 6.8-7.2, and treat in a water bath at 90-100℃ for 10-20 min; S2. After cooling the slurry obtained in step S1 to 37℃, remove the surface oil, then add 2%-3% β-cyclodextrin by mass of the yeast protein, stir well, stand for 20 min, filter out the β-cyclodextrin with a 200-mesh screen, add 0.5%-1.5% trypsin by mass of the yeast protein, mix well, and enzymatically hydrolyze for 10-60 min; S3. Warm the slurry obtained in step S2 to 50℃, then add 0.5%-1.5% flavor protease by mass of the yeast protein, and continue to enzymatically hydrolyze for 10-60 min; S4. After the reaction in step S3 is completed, warm to 90-100℃ to inactivate the enzyme for 10-15 min, then spray dry to obtain the micro-hydrolyzed yeast protein powder.

2. The method for preparing microbially hydrolyzed yeast protein as described in claim 1, characterized in that: In step S1, the mass ratio of the yeast protein to purified water is 1:6, the pH of the slurry is adjusted to 7.0, and the treatment is carried out in a water bath at 95℃ for 15 min.

3. The method for preparing microbially hydrolyzed yeast protein as described in claim 1, characterized in that: In step S2, the amount of β-cyclodextrin added is 2.5% by mass of the yeast protein, the amount of trypsin added is 1% by mass of the yeast protein, and the enzymatic hydrolysis time is 30 min.

4. The method for preparing microbially hydrolyzed yeast protein as described in claim 1, characterized in that: In step S3, the amount of flavor protease added is 1% by mass of the yeast protein, and the enzymatic hydrolysis time is 30 min.

5. The method for preparing microbially hydrolyzed yeast protein as described in claim 1, characterized in that: In step S4, the inactivation temperature is 95℃, the inactivation time is 13 min, the spray drying conditions are: the inlet air temperature is 170℃, the outlet air temperature is about 85℃, and the sample flow rate is 800 mL / h.

6. A micro-hydrolyzed yeast protein, characterized by: The micro-hydrolyzed yeast protein prepared by the method of claim 1.

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