Optimized preparation method and application of oat protein-tea polyphenol complex

Abstract

The invention discloses an optimized preparation method and application of an avenin-tea polyphenol complex, belongs to the technical field of food, and solves the technical problems of poor solubility of avenin and insufficient stability of the complex. The solution is as follows: firstly, respectively weighing avenin and tea polyphenol powder and dispersing in a phosphate buffer solution; secondly, mixing the oat protein solution and the tea polyphenol solution in equal volume, fully stirring, and adjusting the pH value of the oat protein-tea polyphenol mixed solution to 9; thirdly, heating the oat protein-tea polyphenol mixed solution in a water bath; and finally, transferring into a dialysis bag, dialyzing for 72 hours, freeze-drying and storing to obtain the oat protein-tea polyphenol complex which is used for preparing a raw material for food or cosmetic processing. The oat protein and the tea polyphenol are combined through a specific technology, along with the increase of the grafting rate of the polyphenol, the physicochemical properties of the oat protein are improved, the loading capacity of the vegetable oil is improved, and the emulsion stability and the oxidation resistance are also greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of food technology, and specifically relates to an optimized preparation method and application of an oat protein-tea polyphenol complex. Background Art

[0002] Oat protein has outstanding nutritional properties, is rich in various amino acids, and is hypoallergenic, so it is especially suitable for people who are allergic to protein. In addition, it is rich in protein, has good digestion and absorption rate, and contains antioxidants. In addition, the thermal stability and acid-base stability of oat protein are good within a certain range, and it has broad application prospects in the fields of food, cosmetics, etc.

[0003] Tea polyphenols is the general term for polyphenols in tea leaves. Its main chemical components are catechins, flavonoids, anthocyanins and phenolic acids, among which catechin compounds account for the majority. Tea polyphenols have significant antioxidant effects, can strongly remove free radicals in the body, reduce oxidative damage, and are effective in preventing chronic diseases such as cardiovascular disease, cancer, and diabetes. Its antioxidant capacity far exceeds that of vitamin C and vitamin E. At the same time, it also has many functions such as anti-radiation, anti-aging, liver protection, and prevention of dental caries, and has many benefits for human health.

[0004] In traditional food processing, proteins and polyphenols often exist independently. With the deepening of research, people have found that proteins and tea polyphenols can form complexes through various interactions. These interactions include hydrogen bonds, hydrophobic interactions, electrostatic interactions, etc. The formation of protein-tea polyphenol complexes can not only change the physical and chemical properties of proteins and polyphenols, but also affect their biological activities and functional properties. After the combination of protein and polyphenols, the antioxidant capacity of protein can be improved and its scavenging effect on free radicals can be enhanced. At the same time, polyphenols can also improve their solubility and stability in water by combining with proteins, so as to better exert their biological activity. On this basis, after complexation, the ability of protein to load vegetable oil is improved, and low-content protein can achieve excellent emulsification effect. In addition, protein-polyphenol complexes can also improve the sensory properties of food such as taste, texture and color, and improve the quality of food.

[0005] In the prior art, oat protein has poor solubility, and the stability of the protein-polyphenol complex is often a difficult problem to solve. During storage, it is easy to stratify and deteriorate, thus affecting its use value and product quality. Summary of the invention

[0006] The main purpose of the present invention is to overcome the deficiencies in the prior art, solve the technical problems of poor solubility of oat protein and insufficient stability of the protein-polyphenol complex, and provide an optimized preparation method and application of an oat protein-tea polyphenol complex. Oat protein is combined with tea polyphenols through a specific process. As the polyphenol grafting rate increases, the physicochemical properties of oat protein are improved, the vegetable oil loading capacity is increased, and the emulsion stability and antioxidant properties are also greatly improved.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solution: an optimized preparation method of oat protein-tea polyphenols complex, comprising the following steps: S1. Accurately weigh oat protein powder in a beaker, add phosphate buffer with a volume molar concentration of 0.1 mol / L, stir thoroughly until dissolved, prepare an oat protein solution with a concentration of 1% to 2%, adjust the pH value of the oat protein solution to 9, and reserve it for use in the next step; S2. Accurately weigh tea polyphenol powder into a beaker, add phosphate buffer with a volume molar concentration of 0.1 mol / L, stir thoroughly until dissolved, and prepare a tea polyphenol solution with a concentration of 0.1% to 2%, which will be used in the next step; S3, taking equal volumes of the oat protein solution prepared in step S1 and the tea polyphenol solution prepared in step S2, mixing them to prepare a mass ratio of oat protein to tea polyphenol of 10:1, stirring them thoroughly until dissolved, and then using a sodium hydroxide solution with a molar concentration of 1 mol / L to adjust the pH value of the oat protein-tea polyphenol mixed solution to 9, and leaving it for use in the next step; S4, heating the oat protein-tea polyphenols mixed solution prepared in step S3 in a water bath for 8h~12h, with the water bath heating temperature being 25°C~75°C; S5. Transfer the mixed solution after water bath heating in step S4 to a dialysis bag and dialyze for 72 hours, then freeze-dry and store to obtain oat protein-tea polyphenols complex.

[0008] Furthermore, in step S4, the mixed solution is heated in a water bath for 8 hours, and the water bath heating temperature is 50°C.

[0009] The present invention adopts temperature control technology, and oat protein and tea polyphenols undergo complexation reaction under medium and low temperature conditions, which has a positive improvement effect on the physical and chemical properties of oat protein, so that the emulsification activity of oat protein is significantly improved. This improvement makes oat protein perform better in loading vegetable oil, and very small protein content can form quite stable emulsion droplets, which has high economic benefits; at the same time, because tea polyphenols themselves have excellent antioxidant capacity, after it is complexed with oat protein, the stability of the prepared emulsion is greatly improved, and the improvement of this stability is specifically manifested in that the effective storage period of the emulsion is significantly extended.

[0010] An application of the oat protein-tea polyphenols complex prepared by the above-mentioned optimized preparation method comprises the following steps: S1. Weigh 0.2 g of oat protein-tea polyphenols complex, dissolve it in 90 mL of pure water at a temperature of 25°C to 75°C, and stir it thoroughly with a magnetic stirrer until it is dissolved to obtain an oat protein-tea polyphenols complex aqueous solution for use in the next step; S2, measuring 10 mL of linseed oil, adding the linseed oil dropwise into the aqueous solution of the oat protein-tea polyphenols complex prepared in step S1, using an ultra-high-speed stirrer for high-speed shearing at a speed of 10000 rpm and a stirring time of 3 min to obtain a crude emulsion; S3, high-pressure homogenization: Add the crude emulsion prepared in step S2 into a high-pressure homogenizer, set the pressure to 600 bar, and perform at least 3 cycles to obtain an oat protein-tea polyphenol emulsion for preparing raw materials for food or cosmetics processing.

[0011] Furthermore, in step S2, the temperature at which the oat protein-tea polyphenols complex is dissolved in pure water is 50°C.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The present invention improves the physicochemical properties of oat protein by optimizing the temperature of the complex reaction on the basis of the prior art, greatly reduces the protein content required for a higher emulsification effect, improves the protein utilization rate, and makes the application of oat protein more economical; after the oat protein is emulsified, the droplet size is reduced, the free radical scavenging ability of tea polyphenols gives the complex a better antioxidant effect, the oat protein emulsion is more stable, the shelf life of the emulsion is greatly extended, and the oat protein can be widely used in the fields of food, cosmetics, etc.

[0013] In summary, the process of the present invention is simple and efficient, and the operation is simple. The oat protein-tea polyphenol complex with significantly improved solubility, emulsification and antioxidant properties can be prepared at low cost and high efficiency without any pretreatment of the oat protein. The emulsion protein prepared using the complex requires a small content and has excellent stability. The vegetable oil can be loaded at a lower content and more effectively, and the prepared emulsion is more stable and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a comparison chart of the solubility of untreated oat protein and the oat protein-tea polyphenol complex prepared in Examples 1 to 3; Figure 2 A comparison chart of polyphenol grafting rates of oat protein-tea polyphenol complexes prepared in Examples 1 to 3; Figure 3 This is a comparison chart of the protein emulsification activity of untreated oat protein and the oat protein-tea polyphenol complex prepared in Examples 1 to 3; Figure 4 This is a comparison chart of the antioxidant capacity of untreated oat protein and the oat protein-tea polyphenol complex prepared in Examples 1 to 3. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Example 1

[0016] An optimized preparation method of oat protein-tea polyphenols complex comprises the following steps: S1. Accurately weigh 1g of oat protein powder into a beaker, add 100mL of phosphate buffer (pH=7) with a volume molar concentration of 0.1mol / L, use a magnetic stirrer to fully stir until dissolved, and prepare a 1% oat protein solution. Use a sodium hydroxide solution with a volume molar concentration of 1mol / L to adjust the pH value of the oat protein solution to 9, and save it for use in the next step; S2. Accurately weigh 0.1 g of tea polyphenol powder into a beaker, add 100 mL of phosphate buffer (pH = 7) with a volume molar concentration of 0.1 mol / L, use a magnetic stirrer to fully stir until dissolved, and prepare a tea polyphenol solution with a concentration of 0.1%, which will be used in the next step; S3, taking equal volumes of the oat protein solution prepared in step S1 and the tea polyphenol solution prepared in step S2, mixing them to prepare a mass ratio of oat protein to tea polyphenol of 10:1, stirring them thoroughly until dissolved, and then using a sodium hydroxide solution with a molar concentration of 1 mol / L to adjust the pH value of the oat protein-tea polyphenol mixed solution to 9, and leaving it for use in the next step; S4, heating the oat protein-tea polyphenols mixed solution prepared in step S3 in a water bath for 8 hours at a water bath heating temperature of 25° C.; S5. Boil the dialysis bag (molecular weight cutoff value is 3500Da) in boiling water for 10 minutes, then transfer the mixed solution heated in a water bath in step S4 to the dialysis bag and dialyze for 72 hours, changing the water every 6 hours to ensure sufficient dialysis, and finally pre-freeze the dialysate and vacuum freeze-dry it for 42 hours before storing to obtain oat protein-tea polyphenols complex.

[0017] The application of the oat protein-tea polyphenols complex prepared by the optimized preparation method described in Example 1 comprises the following steps: S1. Weigh 0.2 g of oat protein-tea polyphenols complex, dissolve it in 90 mL of pure water at 25°C, and stir it thoroughly with a magnetic stirrer until it is dissolved to obtain an oat protein-tea polyphenols complex aqueous solution for use in the next step; S2, measuring 10 mL of linseed oil, adding the linseed oil dropwise into the aqueous solution of the oat protein-tea polyphenols complex prepared in step S1, using an ultra-high-speed stirrer for high-speed shearing at a speed of 10000 rpm and a stirring time of 3 min to obtain a crude emulsion; S3, high-pressure homogenization: Add the crude emulsion prepared in step S2 into a high-pressure homogenizer, set the pressure to 600 bar, and perform at least 3 cycles to obtain an oat protein-tea polyphenol emulsion for preparing raw materials for food or cosmetics processing. Example 2

[0018] An optimized preparation method of oat protein-tea polyphenols complex comprises the following steps: S1. Accurately weigh 1g of oat protein powder into a beaker, add 100mL of phosphate buffer (pH=7) with a volume molar concentration of 0.1mol / L, use a magnetic stirrer to fully stir until dissolved, and prepare a 1% oat protein solution. Use a sodium hydroxide solution with a volume molar concentration of 1mol / L to adjust the pH value of the oat protein solution to 9, and save it for use in the next step; S2. Accurately weigh 0.1 g of tea polyphenol powder into a beaker, add 100 mL of phosphate buffer (pH = 7) with a volume molar concentration of 0.1 mol / L, use a magnetic stirrer to fully stir until dissolved, and prepare a tea polyphenol solution with a concentration of 0.1%, which will be used in the next step; S3, taking equal volumes of the oat protein solution prepared in step S1 and the tea polyphenol solution prepared in step S2, mixing them to prepare a mass ratio of oat protein to tea polyphenol of 10:1, stirring them thoroughly until dissolved, and then using a sodium hydroxide solution with a molar concentration of 1 mol / L to adjust the pH value of the oat protein-tea polyphenol mixed solution to 9, and leaving it for use in the next step; S4, heating the oat protein-tea polyphenols mixed solution prepared in step S3 in a water bath for 8 hours at a water bath heating temperature of 50° C.; S5. Boil the dialysis bag (molecular weight cutoff value is 3500Da) in boiling water for 10 minutes, then transfer the mixed solution heated in a water bath in step S4 to the dialysis bag and dialyze for 72 hours, changing the water every 6 hours to ensure sufficient dialysis, and finally pre-freeze the dialysate and vacuum freeze-dry it for 42 hours before storing to obtain oat protein-tea polyphenols complex.

[0019] The use of the oat protein-tea polyphenols complex prepared by the optimized preparation method described in Example 2 comprises the following steps: S1. Weigh 0.2 g of oat protein-tea polyphenols complex, dissolve it in 90 mL of pure water at 50° C., stir it thoroughly with a magnetic stirrer until it is dissolved, and obtain an oat protein-tea polyphenols complex aqueous solution for use in the next step; S2, measuring 10 mL of linseed oil, adding the linseed oil dropwise into the aqueous solution of the oat protein-tea polyphenols complex prepared in step S1, using an ultra-high-speed stirrer for high-speed shearing at a speed of 10000 rpm and a stirring time of 3 min to obtain a crude emulsion; S3, high-pressure homogenization: Add the crude emulsion prepared in step S2 into a high-pressure homogenizer, set the pressure to 600 bar, and perform at least 3 cycles to obtain an oat protein-tea polyphenol emulsion for preparing raw materials for food or cosmetics processing. Example 3

[0020] An optimized preparation method of oat protein-tea polyphenols complex comprises the following steps: S1. Accurately weigh 1g of oat protein powder into a beaker, add 100mL of phosphate buffer (pH=7) with a volume molar concentration of 0.1mol / L, use a magnetic stirrer to fully stir until dissolved, and prepare a 1% oat protein solution. Use a sodium hydroxide solution with a volume molar concentration of 1mol / L to adjust the pH value of the oat protein solution to 9, and save it for use in the next step; S2. Accurately weigh 0.1 g of tea polyphenol powder into a beaker, add 100 mL of phosphate buffer (pH = 7) with a volume molar concentration of 0.1 mol / L, use a magnetic stirrer to fully stir until dissolved, and prepare a tea polyphenol solution with a concentration of 0.1%, which will be used in the next step; S3, taking equal volumes of the oat protein solution prepared in step S1 and the tea polyphenol solution prepared in step S2, mixing them to prepare a mass ratio of oat protein to tea polyphenol of 10:1, stirring them thoroughly until dissolved, and then using a sodium hydroxide solution with a molar concentration of 1 mol / L to adjust the pH value of the oat protein-tea polyphenol mixed solution to 9, and leaving it for use in the next step; S4, heating the oat protein-tea polyphenols mixed solution prepared in step S3 in a water bath for 8 hours at a water bath heating temperature of 75° C.; S5. Boil the dialysis bag (molecular weight cutoff value is 3500Da) in boiling water for 10 minutes, then transfer the mixed solution heated in a water bath in step S4 to the dialysis bag and dialyze for 72 hours, changing the water every 6 hours to ensure sufficient dialysis, and finally pre-freeze the dialysate and vacuum freeze-dry it for 42 hours before storing to obtain oat protein-tea polyphenols complex.

[0021] The use of the oat protein-tea polyphenols complex prepared by the optimized preparation method described in Example 3 comprises the following steps: S1. Weigh 0.2 g of oat protein-tea polyphenols complex, dissolve it in 90 mL of pure water at 75°C, and stir it thoroughly with a magnetic stirrer until it is dissolved to obtain an oat protein-tea polyphenols complex aqueous solution for use in the next step; S2, measuring 10 mL of linseed oil, adding the linseed oil dropwise into the aqueous solution of the oat protein-tea polyphenols complex prepared in step S1, using an ultra-high-speed stirrer for high-speed shearing at a speed of 10000 rpm and a stirring time of 3 min to obtain a crude emulsion; S3, high-pressure homogenization: Add the crude emulsion prepared in step S2 into a high-pressure homogenizer, set the pressure to 600 bar, and perform at least 3 cycles to obtain an oat protein-tea polyphenol emulsion for preparing raw materials for food or cosmetics processing.

[0022] The performance of the untreated oat protein was compared with that of the oat protein-tea polyphenol complex prepared in Examples 1 to 3, as follows: 1. The solubility of untreated oat protein and the oat protein-tea polyphenol complex prepared in Examples 1 to 3 was characterized to obtain the solubility change of oat protein before and after compounding. Figure 1 It can be seen that the solubility of oat protein in Examples 1 to 3 before and after compounding is significantly improved, among which Example 2 has the highest solubility, which indicates that Example 2 exhibits better solubility under neutral conditions; 2. The polyphenol grafting rate of the oat protein-tea polyphenol complex prepared in Examples 1 to 3 was characterized by Figure 2 It can be seen that the polyphenol grafting rate of the oat protein-tea polyphenol complex prepared in Example 2 is much higher than that of Example 1, and the polyphenol grafting rate of the oat protein-tea polyphenol complex prepared in Example 3 is lower than that of Example 2, which indicates that under the environment of Example 2, the ratio of successful complexation of tea polyphenols is higher; 3. The emulsifying properties of untreated oat protein and the oat protein-tea polyphenol complex prepared in Examples 1 to 3 were characterized to obtain the changes in the protein emulsifying activity of oat protein before and after it was compounded with tea polyphenols. Figure 3 It can be seen that the emulsifying activities of Examples 1 to 3 are all significantly improved, among which the emulsifying activity of Example 3 is less improved, and the emulsifying activity improvements of Examples 1 and 2 are relatively close, which indicates that Examples 1 and 2 exhibit better emulsifying activities, followed by Example 3; 4. The ABTS free radical scavenging ability of untreated oat protein and the oat protein-tea polyphenol complex prepared in Examples 1 to 3 was characterized to obtain the changes in the antioxidant capacity before and after the oat protein and tea polyphenol complex were combined. Figure 4 It can be seen that the ABTS free radical scavenging rates of Examples 1 to 3 are significantly improved compared to the untreated oat protein, among which Example 2 has the strongest antioxidant capacity, followed by Example 1.

[0023] In order to prepare oat protein with high solubility in neutral aqueous solution to enhance its emulsification quality, tea polyphenols are natural and healthy, antibacterial and antioxidant. The oat protein-tea polyphenols complex solves the solubility problem and meets the characteristics of improved emulsification activity and strong antioxidant capacity. Among them, Example 2 has the best effect.

[0024] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An optimized preparation method of oat protein-tea polyphenols complex, characterized in that: The following steps are involved: S1. Accurately weigh oat protein powder in a beaker, add phosphate buffer with a volume molar concentration of 0.1 mol / L, stir thoroughly until dissolved, prepare an oat protein solution with a concentration of 1% to 2%, adjust the pH value of the oat protein solution to 9, and reserve it for use in the next step; S2. Accurately weigh tea polyphenol powder into a beaker, add phosphate buffer with a volume molar concentration of 0.1 mol / L, stir thoroughly until dissolved, and prepare a tea polyphenol solution with a concentration of 0.1% to 2%, which will be used in the next step; S3, taking equal volumes of the oat protein solution prepared in step S1 and the tea polyphenol solution prepared in step S2, mixing them to prepare a mass ratio of oat protein to tea polyphenol of 10:1, stirring them thoroughly until dissolved, and then using a sodium hydroxide solution with a molar concentration of 1 mol / L to adjust the pH value of the oat protein-tea polyphenol mixed solution to 9, and leaving it for use in the next step; S4, heating the oat protein-tea polyphenols mixed solution prepared in step S3 in a water bath for 8h~12h, with the water bath heating temperature being 25°C~75°C; S5. Transfer the mixed solution after water bath heating in step S4 to a dialysis bag and dialyze for 72 hours, then freeze-dry and store to obtain oat protein-tea polyphenols complex.

2. The optimized preparation method of an oat protein-tea polyphenol complex according to claim 1, characterized in that: In step S4, the mixed solution is heated in a water bath for 8 hours, and the water bath heating temperature is 50°C.

3. An application of the oat protein-tea polyphenols complex prepared by the optimized preparation method according to claim 1, characterized in that: The following steps are involved: S1. Weigh 0.2 g of oat protein-tea polyphenols complex, dissolve it in 90 mL of pure water at a temperature of 25°C to 75°C, and stir it thoroughly with a magnetic stirrer until it is dissolved to obtain an oat protein-tea polyphenols complex aqueous solution for use in the next step; S2, measuring 10 mL of linseed oil, adding the linseed oil dropwise into the aqueous solution of the oat protein-tea polyphenols complex prepared in step S1, using an ultra-high-speed stirrer for high-speed shearing at a speed of 10000 rpm and a stirring time of 3 min to obtain a crude emulsion; S3, high-pressure homogenization: Add the crude emulsion prepared in step S2 into a high-pressure homogenizer, set the pressure to 600 bar, and perform at least 3 cycles to obtain an oat protein-tea polyphenol emulsion for preparing raw materials for food or cosmetics processing.

4. The use according to claim 3, characterized in that: In step S2, the temperature at which the oat protein-tea polyphenols complex is dissolved in pure water is 50°C.

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