CN115088784A

CN115088784A - Natural aggregation method and extraction method of sesame protein

Info

Publication number: CN115088784A
Application number: CN202210764237.1A
Authority: CN
Inventors: 胡帅; 李信; 周巾英; 欧阳玲花; 祝水兰; 何家林; 袁林峰
Original assignee: Agricultural Institute Of Agriculture Jiangxi Province
Current assignee: Agricultural Institute Of Agriculture Jiangxi Province
Priority date: 2022-06-29
Filing date: 2022-06-29
Publication date: 2022-09-23
Anticipated expiration: 2042-06-29
Also published as: CN115088784B

Abstract

The invention belongs to the technical field of agricultural product processing, and particularly relates to a natural aggregation method and an extraction method of sesame protein. The natural aggregation method of the sesame protein provided by the invention comprises two steps of water soaking and germination, during the germination process, protease in sesame is continuously activated, phytic acid is continuously decomposed, a self-stored protein structure is developed, protein modification is further carried out, rearrangement aggregation is promoted among the protein, starch, phenols and other substances through hydrophobic interaction, and then the aggregated protein with high molecular weight is produced. The aggregated protein in the germinated sesame has more excellent functional properties than the original protein contained in the non-germinated sesame. Compared with the existing mechanical processing and thermal processing, the invention has the characteristics of low energy consumption, low cost, naturalness, environmental friendliness and the like, and is suitable for large-scale and industrialized production.

Description

Natural aggregation method and extraction method of sesame protein

Technical Field

The invention belongs to the technical field of agricultural product processing, and particularly relates to a natural aggregation method and an extraction method of sesame protein.

Background

Sesame is one of the main oil crops in China, contains a large amount of grease and also contains abundant protein, and after the sesame is extracted by an organic solvent or mechanically pressed, the protein content in sesame meal is about 50 percent, so that the sesame is a good protein source which is not fully utilized. The utilization of proteins in food products depends mainly on their functional properties, solubility is a prerequisite for the use of proteins in food systems, emulsifying properties and foaming properties play an important role in stabilizing colloidal system foods (ice cream, soy milk) and dispersion system foods (cakes, bread), respectively. Among them, protein aggregation is considered as one of the main mechanisms for improving the functional properties of proteins, and is mainly realized through mechanical action or thermal action, but such an implementation mode has high energy consumption and high cost, and is difficult to apply to large-scale production. Therefore, the method for improving the functional properties of the protein with low energy consumption and low cost has important significance for development and utilization of the sesame protein.

Disclosure of Invention

In view of the above, the present invention aims to provide a novel method for improving the functional properties of sesame protein, which is capable of improving various functional properties of sesame protein by controlling the conditions of germination and protein extraction of sesame without using mechanical or thermal action to naturally aggregate protein in sesame.

The purpose of the invention is realized by the following technical scheme:

in one aspect, the invention provides a natural aggregation method of sesame protein, comprising the following steps:

mixing sesame with water at the temperature of 25-30 ℃, and soaking for 8-10 hours at the temperature of 25-30 ℃;

spreading the soaked sesame on a wet medium, standing for 68-72 h at 25-30 ℃ under the condition of keeping out of the sun with the humidity of 90-95%, and drying.

Optionally, the ratio of the mass of the sesame to the volume of the water is 1: 5, the proportion relation is g/mL.

Optionally, spraying water at 25-30 ℃ to the sesame every 8h in the standing process.

Optionally, the temperature of the drying step is 40-50 ℃.

Optionally, the water content of the dried sesame is 4-7%.

Optionally, the sesame is black sesame and/or white sesame with a germination rate of more than 90% according to the requirements of GB/T5520-2011 grain and oil test for seed germination.

The invention also provides a sesame processed product prepared by the method.

Preferably, the protease activity in the sesame processed product is 0.371 to 0.461, more preferably 0.445 to 0.461, as expressed by absorbance at 345nm of azocasein as a substrate. Compared with sesame raw materials, the processed sesame product disclosed by the invention has the advantages that the protease content is activated to 200-300%, and the phytic acid content is reduced to 80-90%.

On the other hand, the invention provides a sesame protein extraction method, which comprises the following steps:

degreasing the processed sesame;

soaking the degreased sesame in an alkaline aqueous solution with the pH value of 10.00-10.20, carrying out solid-liquid separation, collecting a liquid phase, adjusting the pH value of the liquid phase to 4.00-4.20, and collecting a precipitate.

Optionally, the stirring is continuously carried out in the soaking process, and the stirring speed is 200-300 rpm.

Optionally, the soaking time is 2-3 h.

Optionally, the degreasing treatment is to soak the sesame processed product in n-hexane for degreasing for 8-10 h, and the degreasing is repeated for at least 2 times.

Optionally, the ratio of the mass of the sesame processed product to the volume of the n-hexane is 1: 4, the proportion relation is g/mL.

Optionally, the extraction method further comprises, after the defatting treatment, collecting the solid phase, drying, pulverizing, and sieving with a 40-mesh sieve to obtain defatted sesame.

Optionally, the extraction method further comprises dissolving the precipitate in distilled water, and freeze-drying to obtain sesame protein.

The invention also provides sesame protein extracted by the extraction method.

Preferably, the molecular weight of the sesame protein is greater than 180 kDa.

Preferably, the sesame protein has a purity of greater than 50%.

Compared with the prior art, the technical scheme of the invention has the following advantages:

1. the natural aggregation method of the sesame protein provided by the invention comprises two steps of water soaking and germination. The inventor also surprisingly discovers that protease in the sesame is continuously activated and phytic acid is continuously decomposed during the germination process, so that the self-storage protein structure is unfolded, protein modification is further carried out, rearrangement and aggregation are carried out between the protein and substances such as protein, starch, phenols and the like through hydrophobic interaction, and aggregated protein with high molecular weight is generated. Compared with the original protein contained in the unmalted sesame, the aggregated protein in the germinated sesame has more excellent functional properties, such as the solubility is improved by 191.305-862.801%, the foamability is improved by 58.05-273.27%, the emulsibility is improved by 170.70-184.47%, the particle size is improved by 25.93-35.63%, the surface hydrophobicity is improved by 263.42-673.83%, the sulfhydryl content is improved by 57.45-324.16%, the polyphenol content is improved by 356.13-721.89%, and the antioxidant activity is improved by 26.88-40.23% after in vitro gastrointestinal digestion simulation.

And germination is a very mild processing mode, only proper temperature and humidity are needed to be provided, and compared with the existing mechanical processing and thermal processing, the natural aggregation method of the sesame protein provided by the invention has the characteristics of low energy consumption, low cost, nature, environmental friendliness and the like, and is suitable for large-scale and industrial production.

2. The extraction method of the sesame protein provided by the invention comprises the steps of sequentially carrying out degreasing, alkali extraction and acid precipitation on germinated sesame, and controlling the process conditions of the alkali extraction and acid precipitation steps to obtain the high-functional-activity aggregated protein (the molecular weight is more than 180 kDa). The extraction method has the advantages of simple and convenient operation, short process flow, environmental friendliness and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain the existing drawings from the drawings without creative efforts.

FIG. 1 is a flow chart of the sesame protein extraction method provided by the present invention.

FIG. 2 is a reductive electrophoresis pattern of protein isolates obtained in examples 1 and 2 of the present invention;

wherein, M represents a standard protein molecular weight; BR stands for ungerminated black sesame; BG for germinated black sesame (example 1); WR represents unmalted white sesame; WG stands for germinated white sesame (example 2).

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.

The examples do not indicate specific experimental procedures or conditions, and can be performed according to the procedures or conditions of the conventional experimental procedures described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.

The embodiment of the invention provides a natural aggregation method of sesame protein, which comprises the following steps:

mixing sesame with water at the temperature of 25-30 ℃, and soaking for 8-10 hours at constant temperature under the condition of 25-30 ℃;

spreading the soaked sesame on a wet medium, placing for 68-72 hours under the dark condition that the temperature is 25-30 ℃ and the humidity is 90-95%, spraying water at 25-30 ℃ to the sesame every 8 hours in the placing process, and drying the sesame at the temperature of 40-50 ℃ until the water content is 4-7% to obtain the dried sesame.

Wherein the ratio of the mass of the sesame to the volume of the water is 1: 5, the proportion relation is g/mL.

Wherein, the sesame is black sesame and/or white sesame with the germination rate more than 90 percent according to the specification in GB/T5520-2011 grain and oil test seed germination test.

The embodiment of the invention also provides a sesame processed product prepared by the method.

Preferably, the protease activity in the sesame processed product is 0.371 to 0.461, more preferably 0.445 to 0.461, as expressed by absorbance at 345nm of azocasein as a substrate. Compared with sesame raw materials, the sesame processed product disclosed by the invention has the advantages that the protease content is activated to 200-300%, and the phytic acid content is reduced to 80-90%.

The embodiment of the invention also provides a sesame protein extraction method, which comprises the following steps:

soaking the sesame processed product in n-hexane for degreasing for 8-10 h, repeatedly degreasing for at least 2 times, crushing a solid phase after degreasing, and sieving the solid phase with a 40-mesh sieve to obtain degreased sesame;

and (2) soaking the degreased sesame in an alkaline aqueous solution with the pH value of 10.00-10.20 for 2-3 h, continuously stirring in the soaking process, carrying out solid-liquid separation at the stirring speed of 200-300 rpm, collecting the liquid phase, adjusting the pH value of the liquid phase to 4.00-4.20, collecting the precipitate, dissolving the precipitate in distilled water, and freeze-drying to obtain the sesame protein.

Wherein the ratio of the mass of the sesame processed product to the volume of the n-hexane is 1: 4, the proportion relation is g/mL.

The embodiment of the invention also provides sesame protein extracted by the extraction method.

The sesame protein has molecular weight of more than 180kDa and purity of more than 50%.

The present invention will be described in further detail with reference to examples.

Example 1

(1) Selecting and removing impurities of black sesame seeds: mature and plump sesame raw materials are selected by a color selector, unqualified black sesame and impurities are removed, and the germination rate of the black sesame is determined to be 95% by adopting a method in GB/T5520-2011 grain and oil inspection seed germination test.

(2) Soaking black sesame: weighing 200g of black sesame after impurity removal in a glass container, adding 1000mL of preheated clear water at 30 ℃, slightly stirring to fully soak the black sesame, and placing the container in a thermostat at 30 ℃ for soaking for 8 hours.

(3) Germination of black sesame seeds: draining water of soaked black sesame by using gauze, uniformly spreading the black sesame on wet double-layer filter paper, spreading the black sesame on the wet double-layer filter paper, carrying out germination treatment in a light-proof climate incubator with the temperature of 30 ℃ and the humidity of 95%, spraying 50mL of clear water at 30 ℃ every 8h, taking out black sesame buds after germination for 70h, drying the black sesame buds in an oven at 40 ℃ for 14h until the water content is 4.81%, and finishing the germination process.

(4) Degreasing black sesame: slightly crushing dried black sesame by using a crusher, weighing 50g of germinated black sesame powder raw material, adding 200mL of n-hexane, degreasing for 8h at the rotation speed of 200rpm through magnetic stirring, pouring out the n-hexane, filtering by using filter paper, repeating the operation twice, and naturally drying for 12h in a fume hood to constant weight. The obtained defatted germinated black sesame was further finely pulverized by a pulverizer and then sieved through a 40-mesh sieve.

(5) Protein isolate preparation: dispersing defatted germinated black sesame powder in distilled water by alkali extraction and acid precipitation, dissolving with 2M NaOH to adjust pH to 10.10, magnetically stirring at 200rpm for 3h to dissolve protein, centrifuging at 5000g for 30min, and collecting supernatant. The pH of the supernatant was adjusted to 4.02 with 2M HCl solution for protein precipitation, and the supernatant was left to stand at room temperature for 0.5h and then centrifuged at 5000g for 30 min. Dissolving the protein precipitate in distilled water, and lyophilizing for 48 hr to obtain germinated semen Sesami Niger protein isolate with purity of 50.18%.

As shown in FIG. 2, the germinated black sesame protein isolate obtained in this example had a significantly reduced low molecular weight protein band and a significant high molecular weight protein (greater than 180kDa) band, indicating that the proteins were aggregated.

Example 2

(1) Selecting white sesame seeds and removing impurities: mature and full white sesame raw materials are selected by a winnowing machine, unqualified white sesame and impurities are removed, and the germination rate of the white sesame is determined to be 92% by adopting a method in GB/T5520-2011 grain and oil inspection seed germination test.

(2) Soaking white sesame seeds: weighing 200g of white sesame after impurity removal in a glass container, adding 1000mL of preheated clear water at 30 ℃, slightly stirring to fully soak the sesame, and placing the container in a thermostat at 30 ℃ for soaking for 8 h.

(3) Germination of white sesame seeds: draining water of the soaked white sesame seeds by using gauze, uniformly spreading the white sesame seeds on wet double-layer filter paper, spreading the white sesame seeds with the thickness of 2 mm in a dark climate incubator with the temperature of 30 ℃ and the humidity of 95%, spraying 50mL of clear water at 30 ℃ every 8h, taking out white sesame seeds after germination for 72h, drying the white sesame seeds in an oven with the temperature of 40 ℃ for 16h until the water content is 6.82%, and finishing the germination process.

(4) Degreasing white sesame seeds: slightly crushing the dried white sesame seeds by using a crusher, weighing 50g of germinated white sesame seed powder raw material, adding 200mL of n-hexane, degreasing for 8h at the rotation speed of 200rpm through magnetic stirring, pouring out the n-hexane, filtering by using filter paper, repeating the operation twice, and naturally drying for 12h in a fume hood to constant weight. The obtained defatted germinated white sesame was finely pulverized by a pulverizer and passed through a 40-mesh sieve.

(5) Protein isolate preparation: dispersing defatted germinated white sesame powder in distilled water by alkali extraction and acid precipitation, dissolving with 2M NaOH to adjust pH to 10.07, magnetically stirring at 200rpm for 3h to dissolve protein, centrifuging at 5000g for 30min, and collecting supernatant. The pH of the supernatant was adjusted to 4.05 with 2M HCl solution for protein precipitation, and the supernatant was allowed to stand at room temperature for 0.5h and then centrifuged at 5000g for 30 min. Dissolving the protein precipitate in distilled water, and freeze drying for 48 hr to obtain the germinated white sesame protein isolate with purity of 56.45%.

As shown in FIG. 2, the low molecular weight protein band of the germinated white sesame protein isolate obtained in this example was significantly reduced, and the high molecular weight protein (greater than 180kDa) band was significantly observed, indicating that the protein was aggregated.

Comparative example 1

The same as in example 1 is repeated except for the following points.

Step (2) and step (3) in example 1 were omitted.

Comparative example 2

The same as example 2 was repeated except for the following.

Step (2) and step (3) in example 2 were omitted.

Experimental example 1

The phytic acid content and protease activity of sesame before and after germination were measured, respectively, and the results are shown in table 1.

TABLE 1

As shown in Table 1, the phytic acid content in the germinated black sesame was 25.77mg/g, which was 12.79% lower than that in the non-germinated black sesame, and the protease activity in the germinated black sesame was 0.453% higher than that in the non-germinated black sesame by 198.03%. The phytic acid content of the germinated white sesame is 22.29mg/g, which is reduced by 20.42% compared with the ungerminated white sesame, and the protease activity of the germinated white sesame is 0.377% which is improved by 120.47% compared with the ungerminated white sesame.

Experimental example 2

The solubility (pH 7), foaming property, emulsifying property, particle size, surface hydrophobicity, mercapto content, polyphenol content and antioxidant activity of the sesame protein isolates obtained in examples 1-2 and comparative examples 1-2 were measured, respectively, and the results are shown in table 2.

TABLE 2

As shown in table 2, the solubility of the germinated black sesame protein isolate obtained in example 1 at pH 7 was 80.49%, which is an improvement of 862.80% over the black sesame protein isolate obtained in comparative example 1; the foamability is 46.36%, which is improved by 273.27%; the emulsibility is 83.15m ² The per gram is improved by 184.47 percent; the particle size is 157.37nm, which is increased by 35.63%; the sulfhydryl content (protein structure development mark) is 73.75 mu mol/g, which is increased by 57.45%; the surface hydrophobicity is 8.28, which is improved by 673.83%; the polyphenol content is 13.89mg GAE/g, which is improved by 721.89%; the antioxidant activity measured by Oxygen Radical Absorbance Capacity (ORAC) method is 809.28 μ M TE, which is increased by 40.23%. The solubility of the germinated white sesamin isolate obtained in example 2 at pH 7 was 29.48%, which is an improvement of 191.30% over the white sesamin isolate obtained in comparative example 2; the foamability is 46.94%, which is improved by 58.05%; the emulsifiability is 43.23m ² The per gram is improved by 170.70 percent; the particle size is 201.40, which is increased by 25.93%; the sulfydryl content (protein structure development sign) is 57.05 mu mol/g, which is improved by 324.16%; the surface hydrophobicity is 13.81, which is improved by 263.42%; the polyphenol content is 9.67mg GAE/g, which is improved by 356.13%; the antioxidant activity measured by Oxygen Radical Absorbance Capacity (ORAC) method is 737.54 μ M TE, which is increased by 26.88%.

Table 1 and table 2 fully illustrate with reference to fig. 2 that, in the germination process, phytic acid in sesame is degraded and endogenous protease is activated, so that sesame storage protein is developed and modified, and the modified protein undergoes rearrangement aggregation due to hydrophobic interaction, so that the molecular weight and particle size of the sesame protein are increased, that is, the sesame protein aggregates, and finally the solubility, foamability, emulsibility and oxidation resistance of the sesame protein are improved.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications derived therefrom are intended to be within the scope of the invention.

Claims

1. A natural aggregation method of sesame protein is characterized by comprising the following steps:

mixing sesame with water at 25-30 ℃, and soaking for 8-10 h at 25-30 ℃;

and flatly spreading the soaked sesame on a wet medium, standing for 68-72 hours under the dark condition that the temperature is 25-30 ℃ and the humidity is 90-95%, and then drying.

2. The method for natural aggregation of sesame protein according to claim 1, wherein the temperature of the drying step is 40 to 50 ℃; and/or the water content in the dried sesame is 4-7%.

3. The method for naturally aggregating sesame protein according to claim 1 or 2, wherein the sesame is black sesame and/or white sesame, and the germination rate is more than 90%.

4. A processed sesame product produced by the method according to any one of claims 1 to 3;

preferably, the protease activity in the sesame processed product is 0.371 to 0.461, more preferably 0.445 to 0.461, as expressed by absorbance at 345nm of azocasein as a substrate.

5. The extraction method of the sesame protein is characterized by comprising the following steps:

defatting the processed sesame according to claim 4;

6. The extraction method of sesame protein according to claim 5, characterized in that stirring is continuously carried out during the soaking process, wherein the stirring speed is 200-300 rpm; and/or the soaking time is 2-3 h.

7. The method for extracting sesame protein according to claim 5, wherein the degreasing treatment is carried out by immersing the processed sesame in n-hexane to degrease for 8 to 10 hours, and repeating the degreasing at least 2 times.

8. The method for extracting sesame protein according to claim 5, further comprising, after the defatting treatment, collecting a solid phase, drying, pulverizing, and sieving with a 40-mesh sieve to obtain defatted sesame.

9. The method for extracting sesame protein according to claim 5, further comprising dissolving the precipitate in distilled water, and freeze-drying to obtain sesame protein.

10. A sesame protein which is obtained by extraction by the extraction method according to any one of claims 5 to 9; preferably, the molecular weight of the sesame protein is greater than 180 kDa.