Preparation method and application of oat protein-pectin-proanthocyanidin complex

Abstract

The application belongs to the technical field of food processing, and particularly relates to an oat protein-pectin-proanthocyanidin compound and a preparation method thereof. The oat protein is mixed with water, and an alkali liquor is added to adjust the pH to obtain a protein material solution for medium grinding. Then, pectin is added to the ground protein material solution, and proanthocyanidin powder is added after the pH is adjusted, and secondary medium grinding is performed to obtain an oat protein-pectin-proanthocyanidin solution. Then, hydrochloric acid is slowly added to adjust the pH to 6.8-7.0. Finally, the protein solution is centrifuged, and the supernatant is spray dried to obtain the oat protein-pectin-proanthocyanidin compound. The oat protein-pectin-proanthocyanidin compound prepared by the method is a brand-new protein system, and solves the problems of poor dispersibility, nutritional defects and poor emulsifying property of oat protein, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to an oat protein-pectin-proanthocyanidin complex and a preparation method thereof. Background Art

[0002] The proportion of plant protein in the global diet is increasing year by year. Compared to animal protein, plant protein offers advantages such as greater accessibility, low carbon footprint, environmental friendliness, and nutritional and health benefits, making it a popular ingredient in new health foods. Oats are abundant and high in protein, with a biological value of 74.5-79.6% and a high digestibility.

[0003] Pectin is a large, natural polysaccharide derived from plants and a key component of plant cell walls. Its complex structure, diverse functions, and wide range of applications are evident. Pectin molecules with different structures exhibit distinct functional properties, which in turn determine their diverse industrial applications. The degree of esterification of pectin refers to the ratio of methyl-esterified galacturonic acid units to the total galacturonic acid units in the pectin. Pectins with varying degrees of esterification exhibit distinct properties.

[0004] Proanthocyanidins are a general term for a large class of polyphenolic compounds that are widely present in plants. They can help eliminate free radicals in the body and are widely added to plant protein-based foods because of their antioxidant, anti-inflammatory and risk-reducing effects. Summary of the Invention

[0005] After extensive research, the present invention proposes combining oat protein, pectin, and proanthocyanidins to form a complex. The interaction between proanthocyanidins and plant proteins facilitates the formation of a product with improved emulsification properties, higher bioavailability, and antioxidant capacity. Thus, the present invention provides an oat protein-pectin-proanthocyanidin complex and a method for its preparation, specifically employing the following technical solutions:

[0006] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0007] S1: mixing oat protein and water uniformly, then adding alkali solution to adjust the pH to 12.0-12.2 to obtain an oat protein solution, and grinding the obtained protein solution with a medium mill;

[0008] S2: adding the pre-dissolved pectin solution to the protein solution obtained in step S1, adding hydrochloric acid to lower the pH to 10.0-10.2, and then adding proanthocyanidin powder and performing secondary media milling;

[0009] S3: adding hydrochloric acid dropwise to the aqueous solution of the protein-pectin-proanthocyanidin complex obtained in step S2 to adjust the pH to 6.8-7.0;

[0010] S4: centrifuging the protein-pectin-proanthocyanidin solution obtained in step S3, removing the precipitate, and spray drying to obtain an oat-pectin-proanthocyanidin complex.

[0011] In one embodiment of the present invention, the alkali solution is a 10 M sodium hydroxide solution; the hydrochloric acid is a 1.2-1.5 M hydrochloric acid solution. In one embodiment, a citric acid solution of the same concentration can also be used instead of the hydrochloric acid solution.

[0012] Among them, in the above preparation process, the pH of the system is adjusted to 12-12.2 by adding alkaline solution. When the pH is too low, the protein cannot be fully unfolded and the modification effect will be greatly weakened; if the pH is too high, the protein is easily hydrolyzed into peptides, thereby destroying the nutritional integrity of the protein and causing bitterness. In addition, too much alkali will also cause the final salt content of the product to be too high; then 1.2-1.5 M hydrochloric acid is added to adjust the pH. Too high a hydrochloric acid concentration will cause the system to be locally over-acidic during the adjustment process, resulting in protein precipitation. A too low concentration will increase the amount of hydrochloric acid solution used and increase the water content of the system; the final pH of the system is 6.8-7.0. This is because maintaining the pH of the protein solution at neutral at this time is conducive to maintaining the stability of the properties of the composite plant protein. A too acidic concentration will cause the protein to precipitate again, and a too alkaline concentration will limit the application scenarios of the protein.

[0013] The pectin used in the present invention has an esterification degree of 60-75%; preferably, the pectin has an esterification degree of 62.46% and a molecular weight of 70.4 kDa.

[0014] As a further preferred embodiment, in step S1 of the preparation method of the present invention, the ratio (mass-to-volume ratio, m / V) of plant protein (oat protein) to water is (5-10):100, preferably 1:10. Testing has shown that a lower water-to-protein ratio can result in low production efficiency, while a higher ratio can compromise processing effectiveness.

[0015] As a further preferred embodiment, the medium beads used in the preparation method of the present invention for the medium grinding are 0.6 mm in diameter. According to tests, medium beads with diameters that are too large or too small will result in poor grinding effects.

[0016] As a further preferred embodiment, the preferred degree of esterification of pectin in the preparation method of the present invention is 60-75%. According to tests, a low degree of esterification of pectin results in a low improvement in emulsification performance, while pectin with a high degree of esterification is difficult to obtain.

[0017] As a further preferred embodiment, the preferred mass ratio of oat protein to beet pectin in the preparation method of the present invention is 10:1. When pectin is introduced, the plant protein forms a complex structure with the pectin molecules when the pH returns to neutral. This structure helps the protein maintain good water solubility at neutral pH.

[0018] As a further preferred embodiment, in the preparation method of the present invention, the mass ratio of oat protein: pectin: proanthocyanidins is 100: (10-12): (3-3.5). Proanthocyanidins are sensitive to pH. Before adding proanthocyanidins, the pH of the system should be ensured to be 10-10.2 to ensure that the proanthocyanidins are not decomposed in a strong alkaline environment.

[0019] The particle size of the composite plant protein-pectin-proanthocyanidin complex solution obtained in step S4 of the preparation method of the present invention is 300 nm-450 nm.

[0020] The present invention also provides a composite plant protein prepared by the above-mentioned preparation method. Compared with natural plant protein, the composite plant protein prepared by the present invention has a solubility of ≥95%, an emulsification property improved by approximately 199%, and significantly enhanced functional properties, greatly expanding its application scenarios.

[0021] In summary, the method of the present invention regulates the conformational changes of plant proteins through alkaline activation, and adds pectin to prevent the refolding of plant proteins in a neutral environment to a certain extent. Then, proanthocyanidin powder is added to the system to form a new oat protein-pectin-proanthocyanidin composite system with antioxidant capacity.

[0022] The beneficial effects of the present invention are:

[0023] This invention utilizes a combination of chemical and physical modification, using oat protein as the raw material. Through a process involving alkali activation, low-temperature grinding, and acid neutralization, the expanded oat protein is produced. Pectin solution and proanthocyanidin powder are then added in stages to the expanded oat protein, creating an oat protein-pectin-proanthocyanidin complex. Compared to the raw protein (oat protein), the oat protein-pectin-proanthocyanidin complex produced in this invention exhibits a solubility exceeding 95% and approximately two-fold improvement in emulsification. This process framework addresses the challenges of oat protein's poor solubility and functional properties, significantly broadening the scope and scope of plant protein product development and achieving the requirements for industrial production. DETAILED DESCRIPTION

[0024] The following will be combined with various embodiments to clearly and completely describe the concept, specific structure and technical effects of the present invention to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments and features in the embodiments of this application can be combined with each other unless there is a conflict. Example 1

[0025] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0026] (1) Alkali-activated protein: 1 kg of commercial oat protein was added to 10 L of distilled water in a stirring tank and mixed evenly to obtain a protein solution with a concentration of 10% (w / v). 10 M sodium hydroxide solution was added to the solution to maintain the pH of the protein solution at 12.0.

[0027] (2) Media milling: The protein solution prepared in step (1) was subjected to media milling. The milling parameters were as follows: 0.6 mm media beads, 75% media filling rate, 1200 rpm agitator speed, 7°C media chamber temperature, and 1.5 h milling time.

[0028] (3) Adding pectin: Add 103.21 g of pre-dissolved beet pectin with an esterification degree of 62.46% to the protein solution after medium grinding in step (2) and stir evenly;

[0029] (4) Adding proanthocyanidins: Slowly add 1.2 M hydrochloric acid solution to the oat protein-beet pectin composite system of step (3) to adjust the pH to 10.0, then add 30.19 g of proanthocyanidin powder and mix well;

[0030] (5) Secondary media grinding: The oat protein-beet pectin-proanthocyanidin composite system of step (4) was subjected to secondary media grinding. The grinding parameters were as follows: the media beads were 0.6 mm media beads, the media filling rate was 75%, the stirrer speed was 1200 rpm, the medium chamber temperature was 7 °C, and the grinding time was 30 min.

[0031] (6) Acid neutralization: slowly add 1.2 M hydrochloric acid to the oat protein-pectin-proanthocyanidin complex obtained in step (5) to adjust the pH to 7.0;

[0032] (7) Spray drying: The complex solution obtained in step (6) was centrifuged at 4800 g for 20 min, and the supernatant was spray dried at 48 Hz, an inlet air temperature of 165°C, and an outlet air temperature of 78°C. 1085.50 g of oat protein-beet pectin-proanthocyanidin complex powder was obtained, with a protein solubility of 95.2%. Example 2

[0033] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0034] (1) Alkali-activated protein: 1 kg of commercial oat protein was added to 10 L of distilled water in a stirring tank and mixed evenly to obtain a protein solution with a concentration of 10% (w / v). 10 M sodium hydroxide solution was added to the solution to maintain the pH of the protein solution at 12.0.

[0035] (2) Media milling: The protein solution prepared in step (1) was subjected to media milling. The milling parameters were as follows: 0.6 mm media beads, 75% media filling rate, 1200 rpm agitator speed, 7°C media chamber temperature, and 1.5 h milling time.

[0036] (3) Adding pectin: Add 102.54 g of pre-dissolved beet pectin with an esterification degree of 72.56% to the protein solution after medium grinding in step (2) and stir evenly;

[0037] (4) Adding proanthocyanidins: Slowly add 1.2 M hydrochloric acid solution to the oat protein-beet pectin composite system of step (3) to adjust the pH to 10.0, then add 30.45 g of proanthocyanidin powder and mix well;

[0038] (5) Secondary media grinding: The oat protein-beet pectin-proanthocyanidin composite system of step (4) was subjected to secondary media grinding. The grinding parameters were as follows: the media beads were 0.6 mm media beads, the media filling rate was 75%, the stirrer speed was 1200 rpm, the medium chamber temperature was 7 °C, and the grinding time was 30 min.

[0039] (6) Acid neutralization: slowly add 1.2 M hydrochloric acid to the oat protein-pectin-proanthocyanidin complex obtained in step (5) to adjust the pH to 6.9;

[0040] (7) Spray drying: The complex solution obtained in step (6) was centrifuged at 4800 g for 20 min, and the supernatant was spray dried at 50 Hz, an inlet air temperature of 165°C, and an outlet air temperature of 75°C. 1103.99 g of oat protein-beet pectin-proanthocyanidin complex powder was obtained, with a protein solubility of 97.10%. Example 3

[0041] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0042] (1) Alkali-activated protein: 800 g of commercial oat protein was added to 10 L of distilled water in a stirring tank and mixed evenly to obtain a protein solution with a concentration of 8% (w / v). 10 M sodium hydroxide solution was added to the solution to maintain the pH of the protein solution at 12.0.

[0043] (2) Media milling: The protein solution prepared in step (1) was subjected to media milling. The milling parameters were as follows: 0.6 mm media beads, 75% media filling rate, 1200 rpm agitator speed, 7°C media chamber temperature, and 1.5 h milling time.

[0044] (3) Adding pectin: Add 80.25 g of pre-dissolved beet pectin with an esterification degree of 62.46% to the protein solution after medium grinding in step (2) and stir evenly;

[0045] (4) Adding proanthocyanidins: Slowly add 1.2 M hydrochloric acid solution to the oat protein-beet pectin composite system of step (3) to adjust the pH to 10.0, then add 25.12 g of proanthocyanidin powder and mix well;

[0046] (5) Secondary media grinding: The oat protein-beet pectin-proanthocyanidin composite system of step (4) was subjected to secondary media grinding. The grinding parameters were as follows: the media beads were 0.6 mm media beads, the media filling rate was 75%, the stirrer speed was 1200 rpm, the medium chamber temperature was 7 °C, and the grinding time was 30 min.

[0047] (6) Acid neutralization: slowly add 1.2 M hydrochloric acid to the oat protein-pectin-proanthocyanidin complex obtained in step (5) to adjust the pH to 7.0;

[0048] (7) Spray drying: The complex solution obtained in step (6) was centrifuged at 4800 g for 20 min, and the supernatant was spray dried at 50 Hz, an inlet air temperature of 170°C, and an outlet air temperature of 80°C. 896.57 g of oat protein-beet pectin-proanthocyanidin complex powder was obtained, with a protein solubility of 98.90%. Example 4

[0049] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0050] (1) Alkali-activated protein: 800 g of commercial oat protein was added to 10 L of distilled water in a stirring tank and mixed evenly to obtain a protein solution with a concentration of 8% (w / v). 10 M sodium hydroxide solution was added to the solution to maintain the pH of the protein solution at 12.2.

[0051] (2) Media milling: The protein solution prepared in step (1) was subjected to media milling. The milling parameters were as follows: 0.6 mm media beads, 75% media filling rate, 1200 rpm agitator speed, 7°C media chamber temperature, and 1.5 h milling time.

[0052] (3) Adding pectin: Add 80.51 g of pre-dissolved beet pectin with an esterification degree of 72.56% to the protein solution after medium grinding in step (2) and stir evenly;

[0053] (4) Adding proanthocyanidins: Slowly add 1.4 M hydrochloric acid solution to the oat protein-beet pectin composite system of step (3) to adjust the pH to 10.0, then add 26.22 g of proanthocyanidin powder and mix well;

[0054] (5) Secondary media grinding: The oat protein-beet pectin-proanthocyanidin composite system of step (4) was subjected to secondary media grinding. The grinding parameters were as follows: the media beads were 0.6 mm media beads, the media filling rate was 75%, the stirrer speed was 1200 rpm, the medium chamber temperature was 9 °C, and the grinding time was 30 min.

[0055] (6) Acid neutralization: slowly add 1.4 M hydrochloric acid to the oat protein-pectin-proanthocyanidin complex obtained in step (5) to adjust the pH to 7.0;

[0056] (7) Spray drying: The complex solution obtained in step (6) was centrifuged at 4800 g for 20 min, and the supernatant was spray dried at 50 Hz, an inlet air temperature of 160°C, and an outlet air temperature of 75°C. 867.61 g of oat protein-beet pectin-proanthocyanidin complex powder was obtained, with a protein solubility of 95.11%.

[0057] Comparative Example 1:

[0058] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0059] (1) Mixing: 1 kg of commercial oat protein was added to 10 L of distilled water and mixed evenly in a mixing tank to obtain a protein solution with a concentration of 10% (w / v);

[0060] (2) Adding pectin and proanthocyanidins: Add 102.51 g of pre-dissolved beet pectin with an esterification degree of 62.46% and 30.29 g of proanthocyanidin powder to the protein solution of step (1) and mix well;

[0061] (3) Media milling: The oat protein-beet pectin-proanthocyanidin composite system prepared in step (2) was subjected to secondary media milling. The milling parameters were as follows: 0.6 mm media beads, 75% media filling rate, 1200 rpm agitator speed, 7°C medium chamber temperature, and 2 h milling time.

[0062] (4) Spray drying: The complex solution obtained in step (3) was centrifuged at 4800 g for 20 min, and the supernatant was spray dried at 50 Hz, an inlet air temperature of 160°C, and an outlet air temperature of 75°C. 386.40 g of oat protein-beet pectin-proanthocyanidin complex powder was obtained, with a protein solubility of 25.36%.

[0063] Comparative Example 2:

[0064] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0065] (1) Alkali-activated protein: 1 kg of commercial oat protein was added to 10 L of distilled water in a stirring tank and mixed evenly to obtain a protein solution with a concentration of 10% (w / v). 10 M sodium hydroxide solution was added to the solution to maintain the pH of the protein solution at 12.2.

[0066] (2) Media milling: The protein solution prepared in step (1) was subjected to media milling. The milling parameters were as follows: 1.8 mm media beads, 75% media filling rate, 800 rpm agitator speed, 7°C media chamber temperature, and 1.5 h milling time.

[0067] (3) Adding pectin: Add 105.3 g of pre-dissolved beet pectin with an esterification degree of 37.13% to the protein solution after medium grinding in step (2) and stir evenly;

[0068] (4) Adding proanthocyanidins: Slowly add 1.2 M hydrochloric acid solution to the oat protein-beet pectin composite system of step (3) to adjust the pH to 10.0, then add 33.21 g of proanthocyanidin powder and mix well;

[0069] (5) Secondary media grinding: The oat protein-beet pectin-proanthocyanidin composite system of step (4) was subjected to secondary media grinding. The grinding parameters were as follows: the media beads were 0.6 mm media beads, the media filling rate was 75%, the stirrer speed was 800 rpm, the medium chamber temperature was 7 °C, and the grinding time was 30 min.

[0070] (6) Acid neutralization: slowly add 1.2 M hydrochloric acid to the oat protein-pectin-proanthocyanidin complex obtained in step (5) to adjust the pH to 7.0;

[0071] (7) Spray drying: The complex solution obtained in step (6) was centrifuged at 4800 g for 20 min, and the supernatant was spray dried at 45 Hz, an inlet air temperature of 160°C, and an outlet air temperature of 75°C. 694.91 g of oat protein-beet pectin-proanthocyanidin complex powder was obtained, with a protein solubility of 55.64%.

[0072] Comparative Example 3:

[0073] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0074] (1) Alkali-activated protein: 800 g of commercial oat protein was added to 10 L of distilled water in a stirring tank and mixed evenly to obtain a protein solution with a concentration of 8% (w / v). 10 M sodium hydroxide solution was added to the solution to maintain the pH of the protein solution at 12.2.

[0075] (2) Adding pectin: Add 84.51 g of pre-dissolved beet pectin with a degree of esterification of 37.13% to the protein solution of step (1) and stir evenly;

[0076] (3) Adding proanthocyanidins: Slowly add 1.4 M hydrochloric acid solution to the oat protein-beet pectin composite system of step (2) to adjust the pH to 10.0, then add 25.22 g of proanthocyanidin powder and mix well;

[0077] (4) Acid neutralization: slowly add 1.4 M hydrochloric acid to the oat protein-pectin-proanthocyanidin complex obtained in step (3) to adjust the pH to 6.9;

[0078] (5) Spray drying: The complex solution obtained in step (4) was centrifuged at 4800 g for 20 min, and the supernatant was spray dried at 50 Hz, an inlet air temperature of 160°C, and an outlet air temperature of 80°C. 359.41 g of oat protein-beet pectin-proanthocyanidin complex powder was obtained, with a protein solubility of 31.21%.

[0079] Comparative Example 4:

[0080] A method for preparing an oat protein-pectin-proanthocyanidin complex comprises the following steps:

[0081] (1) Alkali-activated protein: 1 kg of commercial oat protein was added to 10 L of distilled water in a stirring tank and mixed evenly to obtain a protein solution with a concentration of 10% (w / v). 10 M sodium hydroxide solution was added to the solution to maintain the pH of the protein solution at 12.2.

[0082] (2) Media milling: The protein solution prepared in step (1) was subjected to media milling. The milling parameters were as follows: 0.6 mm media beads, 75% media filling rate, 800 rpm agitator speed, 7°C media chamber temperature, and 1.5 h milling time.

[0083] (3) Adding pectin: Add 214.22 g of pre-dissolved beet pectin to the protein solution after medium grinding in step (2) and stir evenly;

[0084] (4) Adding proanthocyanidins: Slowly add 1.2 M hydrochloric acid solution to the oat protein-beet pectin composite system of step (3) to adjust the pH to 10.0, then add 60.89 g of proanthocyanidin powder and mix well;

[0085] (5) Secondary media grinding: The oat protein-beet pectin-proanthocyanidin composite system of step (4) was subjected to secondary media grinding. The grinding parameters were as follows: the media beads were 0.6 mm media beads, the media filling rate was 75%, the stirrer speed was 800 rpm, the medium chamber temperature was 7 °C, and the grinding time was 30 min.

[0086] (6) Acid neutralization: slowly add 1.2 M hydrochloric acid to the oat protein-pectin-proanthocyanidin complex obtained in step (5) to adjust the pH to 7.0;

[0087] (7) Spray drying: The complex solution obtained in step (6) was centrifuged at 4800 g for 20 min, and the supernatant was spray dried at 50 Hz, an inlet air temperature of 165°C, and an outlet air temperature of 75°C. 987.51 g of oat protein-beet pectin-proanthocyanidin complex powder was obtained, with a protein solubility of 71.24%.

[0088] Test example:

[0089] In this example, the solubility, emulsification and foaming properties of the composites prepared in Examples 1-4 and Comparative Examples 1-4 were measured and analyzed. The specific process is as follows:

[0090] (1) Determination of solubility of the complex: Kjeldahl method. The experimental process refers to GB 5009.5-2016.

[0091] (2) Determination of emulsification and emulsion stability of the complex:

[0092] The emulsification and emulsion stability were determined by turbidimetry. 16 mL of the complex solution was added to 4 mL of soybean oil and immediately dispersed using a disperser to obtain an emulsion. 50 μL of the emulsion was then accurately measured at a distance of 0.5 cm from the bottom of the container and dispersed in 10 mL of 0.1% SDS (w / v). The mixture was vortexed and the absorbance values ​​of the emulsion at 0 min and 10 min were measured at a wavelength of 500 nm, respectively. 10 . Emulsifying activity index (EAI, m 2 / g) and emulsion stability index (ESI, min) to express emulsification; the calculation formula is as follows:

[0093] ;

[0094] Where: DF represents the dilution factor, C represents the protein concentration (g / mL), φ represents the optical path (1 cm), and θ represents the volume fraction of oil (v / v)

[0095] ;

[0096] Where: A0 represents the absorbance value at 0 min; A10 represents the absorbance value after 10 min; Δt represents the time difference

[0097] The above measurement results are shown in Table 1:

[0098] Table 1 Results of composite performance test

[0099]

[0100] In summary, the method of the present invention mixes oat protein with water and adds alkali solution to obtain a protein solution with a pH of 12-12.2 for medium grinding; then pectin is added to the ground protein solution, and after adjusting the pH to 10.0-10.2, proanthocyanidin powder is added for secondary medium grinding to obtain an oat protein-pectin-proanthocyanidin solution; then 1.2-1.5 M hydrochloric acid is slowly added to adjust the pH to 6.8-7.0; finally, the protein solution is centrifuged and the supernatant is spray-dried to obtain an oat protein-pectin-proanthocyanidin complex. The method of the present invention regulates the conformational change of oat protein by alkali activation combined with medium grinding treatment, then adds pectin molecules thereto to prevent it from refolding under neutral conditions, and finally adds proanthocyanidins with antioxidant capacity thereto, so that the plant protein is compounded with pectin and proanthocyanidins into a new molecular system, and the protein solubility and emulsification of the obtained complex are greatly improved. The solubility was increased by up to 5.24 times, and the emulsification was increased by approximately 1.99 times, significantly enhancing the functional properties of oat protein. The resulting complex has solubility and emulsification properties that are almost comparable to whey protein isolate, and its application prospects are very broad.

[0101] Although the present invention has been described in considerable detail and with particularity with respect to several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but rather should be construed as providing a broad possible interpretation of these claims in view of the prior art by reference to the appended claims, thereby effectively encompassing the intended scope of the invention. In addition, the invention has been described above in terms of embodiments foreseen by the inventors for the purpose of providing a useful description, and those insubstantial modifications of the invention that are not currently foreseen may still represent equivalent modifications of the invention.

Claims

1. A method for preparing an oat protein-pectin-proanthocyanidin complex, characterized by: The following steps are involved: S1: Oat protein and water are uniformly mixed, and then an alkali solution is added to adjust the pH to 12.0-12.2 to obtain an oat protein solution, and the obtained protein solution is subjected to a medium mill grinding. The medium mill grinding parameters are as follows: medium beads are 0.6 mm medium beads, the medium filling rate is 75%, the stirrer speed is 1200 rpm, the medium chamber temperature is less than 10°C, and the grinding time is 1.5 hours; S2: The pre-dissolved pectin solution was added dropwise to the protein solution obtained in step S1, and 1.2-1.5M hydrochloric acid was added dropwise to lower the pH to 10.0-10.2, and then proanthocyanidin powder was added thereto and subjected to secondary media mill grinding. The media mill grinding parameters were as follows: 0.6 mm media beads, media filling rate 75%, stirrer speed 1200 rpm, media chamber temperature below 10 °C, grinding time 30 min; S3: Add 1.2-1.5 M hydrochloric acid dropwise to the aqueous solution of the protein-pectin-proanthocyanidin complex obtained in step S2 to lower the pH to 6.8-7.0; S4: centrifuging the protein-pectin-proanthocyanidin solution obtained in step S3, removing the precipitate, and spray drying to obtain an oat-pectin-proanthocyanidin complex; The mass ratio of oat protein: pectin: proanthocyanidin is 100: (10-12): (3-3.5); the esterification degree of the pectin is 60-75%, and the mass volume ratio of oat protein to water is (5-10):

100.

2. The method for preparing the oat protein-pectin-proanthocyanidin complex according to claim 1, wherein: The mass volume ratio of the oat protein to water is 1:

10.

3. The method for preparing the oat protein-pectin-proanthocyanidin complex according to claim 1, wherein: The pectin is beet pectin with an esterification degree of 62.46% and a molecular weight of 70.4 kDa.

4. The method for preparing the oat protein-pectin-proanthocyanidin complex according to claim 1, wherein: In step S4, the centrifugal speed is 4800 rpm and the centrifugal time is 20 min.

5. The method for preparing the oat protein-pectin-proanthocyanidin complex according to claim 1, wherein: In step S4, spray drying is performed using a mist drying tower atomizer, and the specific process parameters are as follows: frequency is 45 Hz-50 Hz, inlet air temperature is 160°C-175°C, and outlet air temperature is 75°C-85°C.

6. An oat protein-pectin-proanthocyanidin complex, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the oat protein-pectin-proanthocyanidin complex according to claim 6 in the preparation of food and health food.

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