Yeast protein composite particle as well as preparation method and application thereof

Abstract

The invention relates to a yeast protein composite particle as well as a preparation method and application thereof. According to the yeast protein composite particle, within the wavelength range of 1600 cm <-1 >-1700 cm <-1 > of an infrared spectrum, an alpha-spiral secondary structure accounts for 16%-18%, a beta-folded secondary structure accounts for 20%-27%, a beta-corner secondary structure accounts for 42%-47%, and an irregular crimped secondary structure accounts for 14%-17%; the sum of the ratio of the alpha-spiral secondary structure, the beta-folded secondary structure, the beta-corner secondary structure and the irregular curled secondary structure is 100%. The yeast peculiar smell in the flavor (smell and taste) of the yeast protein composite particle is obviously reduced or eliminated, the protein content is not influenced, and the yeast protein composite particle has a wide application scene.

Description

Technical Field

[0001] The invention belongs to the field of yeast protein processing, and in particular relates to a yeast protein composite particle, a preparation method and use thereof. Background Art

[0002] As per capita protein demand and global protein consumption increase year by year, traditional protein (meat, eggs or fish) is in short supply, and the development of sustainable alternative protein becomes necessary. Plant protein mainly comes from soybeans and has a distinct beany smell. Microbial protein (such as yeast protein) has the advantages of high productivity and low environmental pollution. Yeast protein is rich in a complete amino acid group, but it also has an unpleasant yeast smell brought by fermentation, which affects its flavor and taste.

[0003] There is a need in the art to develop a yeast protein whose yeast odor is weakened or eliminated, and which achieves better taste and flavor effects while preserving protein nutrition. Summary of the invention

[0004] In view of the shortcomings of the prior art, one of the purposes of the present invention is to provide a yeast protein composite particle, wherein the yeast protein composite particle has an infrared spectrum of 1600cm -1 ~1700cm -1 Within the wavelength range, α-helix accounts for 16-18%, β-pleated secondary structure accounts for 20-27%, β-turn secondary structure accounts for 42-47%, and random coil secondary structure accounts for 14-17%, and the sum of the α-helix secondary structure, β-pleated secondary structure, β-turn secondary structure and random coil secondary structure is 100%.

[0005] Compared with the yeast protein in the prior art (such as yeast protein F80), the yeast protein composite particles provided in the present application have a higher amide I band (1600cm -1 ~1700cm -1 The proportion of β-folded secondary structure within the wavelength range of 200 nm (nm) is lower, and the yeast odor in its flavor (smell and taste) is significantly reduced or eliminated. The reason may be due to changes in the protein structure, especially the reduction of the proportion of β-folded structure in the secondary structure of the protein, and the increase of the proportion of α-helix, β-turn structure and irregular coil structure, which exposes more hydrophobic groups, which can better bind to the source substances of yeast odor, reduce or eliminate their release, and reduce or eliminate them in the flavor. The yeast protein composite particles provided by the present application have no obvious odor and have a wide range of applications.

[0006] Preferably, the yeast protein composite particles are formed by agglomeration of yeast protein molecular particles.

[0007] Preferably, the particle size of the yeast protein molecule particles is less than or equal to 230 nm, for example, 225 nm, 220 nm, 213 nm, 205 nm, 195 nm, 188 nm, 183 nm, 167 nm, 150 nm, 135 nm, etc., preferably 190-230 nm.

[0008] Compared with large-sized yeast protein molecular particles, smaller-sized yeast protein molecular particles can expose more hydrophobic groups and absorb more sources of yeast protein odor. At the same time, they have less granularity and a smoother taste when eaten.

[0009] Preferably, the protein content of the yeast protein composite particles is ≥ 70 wt%, such as 72 wt%, 77 wt%, 83 wt%, 88 wt%, 95 wt%, etc.

[0010] In addition to protein molecules, the yeast protein composite particles generally contain amino acids, polypeptides, vitamins and / or minerals, most of which are derived from the composition of the yeast itself.

[0011] Preferably, the indole content of the yeast protein composite particles is ≤1.5 μg / kg, such as 1.4 μg / kg, 1.2 μg / kg, 1.0 μg / kg, 0.8 μg / kg, 0.6 μg / kg, 0.4 μg / kg, 0.2 μg / kg, 0.0 μg / kg, etc. The 0.0 μg / kg means that the yeast protein composite particles do not contain indole.

[0012] Preferably, the o-cresol content of the yeast protein composite particles is ≤8.5 μg / kg, for example, 8.4 μg / kg, 8.1 μg / kg, 7.8 μg / kg, 7.3 μg / kg, 7.0 μg / kg, 6.6 μg / kg, 6.3 μg / kg, 5.8 μg / kg, 5.5 μg / kg, 5.0 μg / kg, 4.5 μg / kg, 4.2 μg / kg, 3.8 μg / kg, 3.2 μg / kg, etc.

[0013] Preferably, the yeast protein composite particles have a 3,7-dimethyl-7-octenol content of ≤1.5 μg / kg, such as 1.4 μg / kg, 1.2 μg / kg, 1.0 μg / kg, 0.8 μg / kg, 0.6 μg / kg, 0.5 μg / kg, 0.4 μg / kg, 0.3 μg / kg, 0.2 μg / kg, 0.0 μg / kg, etc. The 0.0 μg / kg means that the yeast protein composite particles do not contain 3,7-dimethyl-7-octenol.

[0014] It should be noted that the contents of indole, o-phenol and 3,7-dimethyl-7-octenol in the yeast protein composite particles are the contents of headspace gas measured by solid phase microextraction, and the measurement conditions are:

[0015] The yeast protein composite particles and water were mixed to prepare a dispersion in a ratio of 1:10, and the dispersion was placed in a 20 mL SPME injection sample bottle, heated in a 45°C water bath for 20 min, and headspace extraction was performed at 45°C for 40 min using a 65 μm DBC / PDMS fiber. After the extraction was completed, desorption was performed at a GC-MS injection port at 250°C for 5 min.

[0016] In the assay conditions, a 5 μM 0.01 mg / mL methanol solution of 2-methyl-3-heptanone can also be added as an internal standard to accurately quantify the flavor substances.

[0017] The second object of the present application is to provide a method for preparing the yeast protein composite particles as described in the first object, comprising the following steps:

[0018] (1) Using yeast protein dispersion as raw material, adding citric acid thereto, performing acid treatment, separating protein, and obtaining an acid-treated sample;

[0019] (2) dispersing the acid-treated sample in water, then adding sodium bicarbonate thereto, performing alkali treatment, separating the protein, and obtaining an alkali-treated sample;

[0020] (3) dispersing the alkali-treated sample in water and subjecting it to ultrasonic treatment to obtain a yeast protein composite particle dispersion;

[0021] Preferably, step (4) is performed after step (3):

[0022] (4) Drying the yeast protein composite particle dispersion to obtain yeast protein composite particle powder.

[0023] In the preparation method of the present application, acid treatment can help depolymerize proteins and cause preliminary changes in the secondary structure of proteins; alkali treatment can neutralize the acidic environment to pH 6-8; ultrasonic treatment can use cavitation effect and thermal effect to further stretch the secondary structure of proteins, exposing more hydrophilic groups and / or hydrophobic groups, so that it can improve the binding ability of yeast odor source substances with protein molecules. On the other hand, acid treatment, alkali treatment and ultrasonic treatment can synergistically treat yeast protein (raw material) and also reduce the particle size of yeast protein composite particles, reduce its edible granularity, and make it taste delicate.

[0024] It should be noted that the yeast protein dispersion described in the present application can be a solution obtained by collecting the bacterial raw materials after culturing, fermenting and centrifuging yeast (exemplary examples include Saccharomyces cerevisiae, etc.), breaking the yeast cells and removing the cell wall fragments; it can also be a sample in which a solid (such as powder) product of yeast protein is dispersed in water.

[0025] The solid (such as powder) product of the yeast protein can be purchased commercially, or can be obtained by collecting bacterial raw materials after cultivation, fermentation, centrifugation, breaking yeast cells, removing cell wall fragments, precipitating protein, and drying.

[0026] Preferably, the solid content of the yeast protein dispersion is 8-12%, such as 9%, 10%, 11%, etc. The solid content of the yeast protein dispersion measured is recorded as the yeast protein effective matter.

[0027] The solid content is usually determined by a drying method (constant weight method).

[0028] Preferably, the mass ratio of the citric acid to the yeast protein effective substance is 1:1-1:8, such as 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, etc., preferably 1:1-1:5.

[0029] Preferably, the acid treatment time is 0.5 to 8 h, for example, 0.7 h, 1 h, 1.3 h, 1.6 h, 2 h, 2.4 h, 3 h, 3.8 h, 4.5 h, 5.8 h, 6 h, 7 h, etc., preferably 0.5 to 4 h.

[0030] Preferably, the temperature of the acid treatment is 45-55°C, such as 46°C, 47°C, 49°C, 53°C, etc.

[0031] Preferably, the mass ratio of the sodium bicarbonate to the yeast protein effective substance is 1:1-1:8, such as 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, etc., preferably 1:1-1:5.

[0032] Preferably, the alkali treatment time is 0.1 to 3 h, for example, 0.27 h, 0.4 h, 0.6 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2.4 h 2.8 h, etc., preferably 0.25 to 2 h.

[0033] Preferably, the temperature of the alkali treatment is 45-55°C, such as 46°C, 47°C, 49°C, 53°C, etc.

[0034] Preferably, the power of the ultrasonic treatment is 800-1500 W, for example, 1000 W, 1100 W, 1200 W, 1300 W, 1400 W, etc.; the temperature of the ultrasonic treatment is 45-55° C., for example, 46° C., 47° C., 49° C., 51° C., 43° C., etc.

[0035] Preferably, the ultrasonic treatment time is 10 to 60 min, for example, 12 min, 15 min, 18 min, 25 min, 28 min, 36 min, 39 min, 45 min, 53 min, 59 min, etc.

[0036] In the preparation method of the yeast protein composite particles described in the present application, the appropriate amount of citric acid and sodium bicarbonate added can cause a certain degree of change in the secondary structure of the protein. If the amount added is too large, it is easy to cause protein denaturation and reduce protein nutrition. If the amount added is too small, the degree of secondary structure development is low, and it is necessary to increase the subsequent ultrasonic treatment power or time; if the ultrasonic power and time are too large, it will also increase the possibility of protein denaturation and reduce protein nutrition, while if the ultrasonic power and time are too small, it may affect the degree of opening of the secondary structure of the protein, and more citric acid needs to be added.

[0037] Preferably, the drying comprises spray drying or freeze drying.

[0038] Preferably, the inlet temperature of the spray drying is 120-200°C (e.g., 125°C, 130°C, 135°C, 150°C, 160°C, 170°C, 190°C, etc.), the outlet temperature is 60-85°C (e.g., 65°C, 70°C, 75°C, 80°C, 83°C, etc.), and the air flow rate is 30-40m 3 / h(e.g. 32m 3 / h、35m 3 / h、37m 3 / h、39m 3 / h, etc.), the sample injection flow rate is 0.100~0.120L / h (for example, 0.101L / h, 0.106L / h, 0.114L / h, 0.118L / h, etc.).

[0039] Appropriate spray drying conditions can further improve the delicate taste of yeast protein composite particles, probably because appropriate drying conditions can reduce their particle size and reduce the granular feel when eaten.

[0040] Preferably, the freeze-drying temperature is -70 to -90°C (e.g., -72°C, -77°C, -80°C, -85°C, -88°C, etc.), the vacuum degree is ≤20Pa, and the freeze-drying time is 40 to 50h (e.g., 42h, 45h, 48h, etc.).

[0041] The third object of the present application is to provide a use of the yeast protein composite particles as described in the first object, wherein the yeast protein composite particles are used to prepare any one of health products, food additives, and pharmaceutical carriers.

[0042] Preferably, the yeast protein composite particles are used to prepare any one of a protein supplement, a food flavoring agent, a beverage clarifier, a capsule wall material, and a meat product preservative.

[0043] Compared with the prior art, this application has the following beneficial effects:

[0044] (1) The yeast-protein composite particles provided in the present application have a significantly reduced or eliminated yeast odor in their flavor (smell and taste) without affecting their protein content, and have a wide range of application scenarios;

[0045] (2) The preparation method of yeast protein composite particles provided in the present application has simple steps, convenient operation and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The electronic tongue result diagrams of Examples 1-6 and Comparative Examples 1-2 are given;

[0047] Figure 2 SEM images of yeast protein composite particle powders of Examples 1-6 and Comparative Examples 1-2 are given; wherein in the SEM images corresponding to each example, the scale length of the upper image is 20 μm, and the scale length of the lower image is 1 μm;

[0048] Figure 3 The infrared spectrum of the yeast protein composite particle powder of Example 1 is given. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further explained below in conjunction with specific implementation methods. However, it should be noted that the specific implementation methods are only a specific implementation and explanation of the essence of the technical solution of the present invention, and should not be understood as a limitation on the protection scope of the present invention.

[0050] The reagents and instruments used in the examples can all be purchased from commercial products, and the detection methods are conventional methods well known in the art.

[0051] Example 1

[0052] A method for preparing yeast protein composite particles comprises the following steps:

[0053] (1) Yeast protein powder F80 and distilled water are dissolved in a ratio of 1:10 (m:v), citric acid is added and dissolved in a mass ratio of 1:3 (m:m) to yeast protein powder, and then placed in an environment at a temperature of 50°C for reaction for 3 hours to perform acid treatment; after the reaction is completed, centrifuge at 4°C and 8000r / min for 6 minutes, repeat 3 times, obtain a precipitate, which is a protein, and obtain an acid-treated sample;

[0054] (2) The acid-treated sample and distilled water are dissolved in a ratio of 1:10 (m:v), sodium bicarbonate is added and dissolved in a mass ratio of 1:3 (m:m) to yeast protein powder, and then placed in an environment at a temperature of 50°C for reaction for 1 hour to perform alkali treatment; after the reaction is completed, centrifuge at 4°C and 8000 r / min for 6 minutes, repeat 3 times, obtain a precipitate, which is a protein, and obtain an alkali-treated sample;

[0055] (3) The alkali-treated sample and distilled water were dissolved in a ratio of 1:10 (m:v), and then the mixed solution was treated with 1200W ultrasonic waves at 50°C for 30 minutes for ultrasonic treatment; after the reaction was completed, the mixture was centrifuged at 4°C and 8000r / min for 6 minutes, and the reaction was repeated 3 times to obtain a precipitate, which was the protein, and thus an ultrasonically treated sample was obtained;

[0056] (4) The ultrasonically treated sample and distilled water are dissolved in a protein mixture at a ratio of 1:10 (m:v), and then the protein mixture is placed in a freeze dryer for freeze drying to obtain yeast protein composite particle powder.

[0057] Example 2

[0058] A method for preparing yeast protein composite particles, which differs from Example 1 only in that step (4) is replaced by spray drying: the protein mixture of the ultrasonically treated sample and distilled water in a ratio of 1:5 (m:v) is spray dried (inlet temperature 140°C, outlet 80-85°C, air flow rate 35m 3 / h, sample injection flow rate 0.105L / h) to obtain yeast protein composite particle powder.

[0059] Example 3

[0060] A method for preparing yeast protein composite particles, which is different from Example 1 only in that the mass ratio of citric acid to yeast protein powder is adjusted to 1:1 (m:m), and the mass ratio of sodium bicarbonate to yeast protein powder is adjusted to 1:1 (m:m).

[0061] Example 4

[0062] A method for preparing yeast protein composite particles, which differs from Example 3 only in that step (4) is replaced by spray drying: the protein mixture of the ultrasonically treated sample and distilled water in a ratio of 1:5 (m:v) is spray dried (inlet temperature 120°C, outlet 66-70°C, air flow rate 35m 3 / h, sample injection flow rate 0.105L / h) to obtain yeast protein composite particle powder.

[0063] Example 5

[0064] A method for preparing yeast protein composite particles, which is different from Example 1 only in that the mass ratio of citric acid to yeast protein powder is adjusted to 1:5 (m:m), and the mass ratio of sodium bicarbonate to yeast protein powder is adjusted to 1:5 (m:m).

[0065] Example 6

[0066] A method for preparing yeast protein composite particles, which differs from Example 5 only in that step (4) is replaced by spray drying: the protein mixture in which the ultrasonically treated sample and distilled water are fully dissolved in a ratio of 1:5 (m:v) is spray dried (inlet temperature 200°C, outlet temperature 98-102°C, air flow rate 35m 3 / h, sample injection flow rate 0.105L / h) to obtain yeast protein composite particle powder.

[0067] Comparative Example 1

[0068] A method for preparing yeast protein composite particles, which differs from Example 1 only in that the ultrasonic treatment step is not performed, comprises the following steps:

[0069] (1) Yeast protein powder F80 and distilled water are dissolved in a ratio of 1:10 (m:v), citric acid is added and dissolved in a mass ratio of 1:3 (m:m) to yeast protein powder, and then placed in an environment at a temperature of 50°C for reaction for 3 hours to perform acid treatment; after the reaction is completed, centrifuge at 4°C and 8000r / min for 6 minutes, repeat 3 times, obtain a precipitate, which is a protein, and obtain an acid-treated sample;

[0070] (2) The acid-treated sample and distilled water are dissolved in a ratio of 1:10 (m:v), sodium bicarbonate is added and dissolved in a mass ratio of 1:3 (m:m) to yeast protein powder, and then placed in an environment at a temperature of 50°C for reaction for 1 hour to perform alkali treatment; after the reaction is completed, centrifuge at 4°C and 8000 r / min for 6 minutes, repeat 3 times, obtain a precipitate, which is a protein, and obtain an alkali-treated sample;

[0071] (3) The alkali-treated sample and distilled water are dissolved in a protein mixture at a ratio of 1:10 (m:v), and then the protein mixture is placed in a freeze dryer for freeze drying to obtain yeast protein powder.

[0072] Comparative Example 2

[0073] Yeast protein powder F80 (commercially available from Angel Yeast) was used as comparative example 2.

[0074] Performance Test:

[0075] (1) Sensory evaluation:

[0076] Determination method: Weigh 10g of each powder sample of Examples 1 to 4 and Comparative Examples 1 and 2, and place them in a clean transparent glass cup, add 100mL of pure water, stir to obtain a sample solution, and invite 10 sensory evaluators to evaluate and score the sample solution. The scoring standard is: 10mL of F80 yeast protein solution containing 0%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, and 20% is used as the standard solution, and 10 points, 9 points, 8 points, 7 points, 6 points, 5 points, 4 points, 3 points, 2 points, 1 point, and 0 points are given respectively. The scores of the 10 sensory evaluators are averaged, and the scoring results are shown in Table 1.

[0077] (2) Electronic tongue detection:

[0078] Determination method: 10g sample and 100mL deionized water were added to a 250mL beaker. The mixture was stirred and extracted at room temperature for 10min, and then filtered through two layers of filter paper. The filtrate was analyzed by an electronic tongue (SA402B electronic tongue from Insent Company); the determination results are shown in Figure 1 , Figure 1 The electronic tongue result diagrams of Examples 1-6 and Comparative Examples 1-2 are given.

[0079] (3) SEM scanning

[0080] Determination method: Observe the microscopic morphology of the dried sample at an accelerating voltage of 1.5 kV and a scale of 20 μm and 1 μm. Before measurement, a high-performance ion sputtering instrument (Suo Sai Cressington 108) was used to coat the dried sample with a gold coating; the measurement results are shown in Table 1. Figure 2 SEM images of the yeast protein composite particle powders of Examples 1-6 and Comparative Examples 1 and 2 are given. The particle sizes of the yeast protein composite particles are shown in Table 1.

[0081] (4) Infrared spectroscopy

[0082] Determination method: 1 mg of dried YP sample was mixed with 100 mg of KBr, which was then thoroughly ground and formed into sheets. The sample was spectrally scanned by a Fourier transform infrared spectrometer (Thermo Fisher Nicolet iS50) with a scanning band of 4000-500 cm -1 , the scanning frequency is 64. The measurement results are shown in Table 1. Figure 3 The infrared spectrum of the yeast protein composite particle powder of Example 1 is given. -1 ~1700cm -1 The peak area of ​​the amide I band within the wavelength range of is calculated to obtain the proportions of the α-helix secondary structure, the β-fold secondary structure, the β-turn secondary structure and the random coil secondary structure. The results of the secondary structure proportions of the yeast protein composite particle powders of Examples 1, 2, 3, 4 and Comparative Examples 1 and 2 are shown in Table 1.

[0083] (5) Headspace solid phase microextraction

[0084] Determination method: The yeast protein composite particle powder of Examples 1, 2, 3, 4 and Comparative Examples 1 and 2 was mixed with water in a ratio of 1:10 to prepare a dispersion, the dispersion was placed in a 20 mL SPME injection sample bottle, heated in a 45°C water bath for 20 min, and headspace extracted at 45°C for 40 min using a 65 μm DBC / PDMS fiber. After the extraction was completed, the dispersion was desorbed at a GC-MS (Agilent 7890B) injection port at 250°C for 5 min. The contents of indole, o-cresol and 3,7-dimethyl-7-octenol were counted, and the results are shown in Table 1.

[0085] Table 1

[0086]

[0087] As can be seen from Table 1, the sensory scores of the yeast protein composite particles provided in Examples 1 to 6 of the present application are all above 8.2, the product has excellent aroma and taste, and no obvious granularity, which are higher than the yeast protein and yeast protein powder Y80 that have only been treated with acid and alkali; the particle size of the yeast protein composite particles provided in Examples 1 to 6 of the present application is all below 230nm, which may be the reason for the lack of obvious granularity; the secondary structures of the yeast protein composite particles provided in Examples 1 to 6 of the present application are α-helix, β-fold, β-turn and random coil. The secondary structures all meet the requirements of the infrared spectrum wavelength range of 1600cm-1 to 1700cm-1, with α-helix secondary structure accounting for 16-18%, β-fold secondary structure accounting for 20-27%, β-turn secondary structure accounting for 42-47%, and irregular coil secondary structure accounting for 14-17%. The indole content is ≤1.5μg / kg, the o-cresol content is ≤8.5μg / kg, and the 3,7-dimethyl-7-octenol content is ≤1.5μg / kg. This may be the reason why there is no obvious yeast smell.

[0088] Example 7

[0089] A method for preparing yeast protein composite particles comprises the following steps:

[0090] (1) Yeast protein powder F80 and distilled water are dissolved in a ratio of 1:10 (m:v), citric acid is added and dissolved in a mass ratio of 1:8 (m:m) to yeast protein powder, and then placed in an environment at a temperature of 50°C for reaction for 8 hours to perform acid treatment; after the reaction is completed, centrifuge at 4°C and 8000 r / min for 6 minutes, repeat 3 times, obtain a precipitate, which is a protein, and obtain an acid-treated sample;

[0091] (2) The acid-treated sample and distilled water are dissolved in a ratio of 1:10 (m:v), sodium bicarbonate is added and dissolved in a mass ratio of 1:8 (m:m) to yeast protein powder, and then placed in an environment at a temperature of 50°C for reaction for 3 hours to perform alkali treatment; after the reaction is completed, centrifuge at 4°C and 8000 r / min for 6 minutes, repeat 3 times, obtain a precipitate, which is a protein, and obtain an alkali-treated sample;

[0092] (3) The alkali-treated sample and distilled water were dissolved in a ratio of 1:10 (m:v), and then the mixed solution was treated with 1200W ultrasonic waves at 50°C for 30 minutes for ultrasonic treatment; after the reaction was completed, the mixture was centrifuged at 4°C and 8000r / min for 6 minutes, and the reaction was repeated 3 times to obtain a precipitate, which was the protein, and thus an ultrasonically treated sample was obtained;

[0093] (4) The ultrasonically treated sample and distilled water are dissolved in a protein mixture at a ratio of 1:10 (m:v), and then the protein mixture is placed in a freeze dryer for freeze drying to obtain yeast protein composite particle powder.

[0094] According to the sensory evaluation method of performance test (1), the score of yeast protein composite particle powder was 7.85.

[0095] 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A yeast protein composite particle, characterized in that: The yeast protein composite particles have an infrared spectrum of 1600 cm -1 ~1700cm -1 Within the wavelength range, the α-helix secondary structure accounts for 16-18%, the β-pleat secondary structure accounts for 20-27%, the β-turn secondary structure accounts for 42-47%, and the random coil secondary structure accounts for 14-17%, and the sum of the α-helix, β-pleat, β-turn and random coil secondary structures is 100%.

2. The yeast protein composite particle according to claim 1, characterized in that The yeast protein composite particles are formed by agglomeration of yeast protein molecular particles; Preferably, the particle size of the yeast protein molecular particles is less than or equal to 230 nm, preferably 190 to 230 nm.

3. The yeast protein composite particle according to claim 1 or 2, characterized in that: The protein content of the yeast protein composite particles is ≥70wt%.

4. The yeast protein composite particle according to any one of claims 1 to 3, characterized in that: The indole content of the yeast protein composite particles is ≤1.5 μg / kg; Preferably, the o-cresol content of the yeast protein composite particles is ≤8.5 μg / kg; Preferably, the yeast protein composite particles have a 3,7-dimethyl-7-octenol content of ≤1.5 μg / kg.

5. A method for preparing yeast protein composite particles according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) Using yeast protein dispersion as raw material, adding citric acid thereto, performing acid treatment, separating protein, and obtaining an acid-treated sample; (2) dispersing the acid-treated sample in water, then adding sodium bicarbonate thereto, performing alkali treatment, separating the protein, and obtaining an alkali-treated sample; (3) dispersing the alkali-treated sample in water and subjecting it to ultrasonic treatment to obtain a yeast protein composite particle dispersion; Preferably, step (4) is performed after step (3): (4) Drying the yeast protein composite particle dispersion to obtain yeast protein composite particle powder.

6. The preparation method according to claim 5, characterized in that: The solid content of the yeast protein dispersion is 8-12%; The solid content of the yeast protein dispersion measured for solid content is recorded as yeast protein effective matter.

7. The preparation method according to claim 5 or 6, characterized in that: The mass ratio of the citric acid to the yeast protein effective substance is 1:1 to 1:8, preferably 1:1 to 1:5; Preferably, the acid treatment time is 0.5 to 8 hours, preferably 0.5 to 4 hours; Preferably, the temperature of the acid treatment is 45 to 55°C; Preferably, the mass ratio of the sodium bicarbonate to the yeast protein effective substance is 1:1 to 1:8, preferably 1:1 to 1:5; Preferably, the alkali treatment time is 0.1 to 3 hours, preferably 0.25 to 2 hours; Preferably, the temperature of the alkali treatment is 45-55°C.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The power of the ultrasonic treatment is 800-1500W; the temperature of the ultrasonic treatment is 45-55°C; Preferably, the ultrasonic treatment time is 10 to 60 minutes.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The drying comprises spray drying or freeze drying; Preferably, the inlet temperature of the spray drying is 120-200°C, the outlet temperature is 60-85°C, and the air flow rate is 30-40m 3 / h, injection flow rate 0.100~0.120L / h; Preferably, the freeze-drying temperature is -70 to -90°C, the vacuum degree is ≤20Pa, and the freeze-drying time is 40 to 50 hours.

10. Use of the yeast protein composite particles according to any one of claims 1 to 4, characterized in that: The yeast protein composite particles are used to prepare any one of health products, food additives, and drug carriers; Preferably, the yeast protein composite particles are used to prepare any one of a protein supplement, a food flavoring agent, a beverage clarifier, a capsule wall material, and a meat product preservative.

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