Method for increasing content of resistant starch in starch by using tea oil and oil tea cake polypeptide

Abstract

The invention discloses a method for increasing the content of resistant starch in starch by using tea oil and oil tea cake polypeptide. The method for increasing the content of the resistant starch in the starch by utilizing the tea oil and the oil tea cake polypeptide is simple in process, low in equipment requirement and easy to operate and control, and the prepared tea oil-oil tea cake polypeptide-starch compound is stable in quality. By utilizing the method disclosed by the invention, the content of resistant starch in starch such as wheat starch can be remarkably increased, and the prepared tea oil-oil tea cake polypeptide-starch compound also has an anti-oxidation effect, can be used for preparing slowly digestible foods such as slowly digestible bread, is beneficial to development of foods with high added value, improves the product quality, and is suitable for industrial production. The economic benefit is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and more specifically, relates to a method for increasing the content of resistant starch in starch by using tea oil and tea oil cake polypeptide. Background Art

[0002] As people's living standards improve, diseases related to nutrition metabolism, such as type 2 diabetes, are on the rise. Improving the dietary structure can reduce the incidence of diabetes, obesity, and cardiovascular and cerebrovascular diseases, alleviate and improve the clinical symptoms of diseases related to nutrition metabolism, and achieve the purpose of auxiliary treatment and prevention of diseases.

[0003] Starch is an important source of carbohydrate intake for humans. It exists in people's daily staple foods, such as rice, pasta, bread and other rice and flour products. It can provide energy for the human body and is an indispensable part of the human diet. Resistant starch (RS), also known as resistant starch and indigestible starch, refers to starch components that cannot be digested in the small intestine and partially fermented in the colon to produce a large amount of short-chain fatty acids. The short-chain fatty acids produced by it, such as acetic acid, propionic acid and butyric acid, can reduce cholesterol levels and the risk of colon or other cancers. In addition, resistant starch has a lower glycemic index and insulin response, is suitable for diabetic patients, helps maintain blood sugar stability, and regulates body weight and blood lipids. Therefore, if the resistant starch content in starchy foods can be increased, it will be more helpful in the prevention and regulation of nutritional metabolism-related diseases.

[0004] At present, there are many reports on methods for increasing the content of resistant starch in foods such as rice, which can be divided into two categories: physical and chemical treatment. Among them, physical treatment includes autoclave, ultrasound-microwave treatment and extrusion treatment, and chemical treatment includes enzymatic treatment, acid treatment and alcohol treatment. Although the content of resistant starch can be increased by physical or chemical treatment, the strict operating conditions, complex operating equipment, harsh reaction conditions and the introduction of certain chemical substances cause problems such as food safety and cumbersome operation. Vegetable oil and protein are widely present in food systems, which can form complexes with starch during food processing, or vegetable oil or protein can be added to starch to achieve the purpose of increasing the content of resistant starch and delaying the digestion of starch. There are also reports on methods for increasing the content of resistant starch in rice using soybean oil, vanilla oil, pepper oil, cashew oil, macadamia oil, coconut oil, peanut oil, sesame oil, sesame oil, olive oil, etc., among which the effect of using coconut oil with a high lauric acid content is better. However, this method is mainly for rice or brown rice, and the properties of rice or brown rice are different from starch, so this method cannot be applied to starch. Currently, there is no simple and effective method to increase the resistant starch content in starch.

[0005] Tea oil is a Chinese-specific edible woody plant oil extracted from tea seeds. It is rich in monounsaturated fatty acids such as oleic acid and active substances such as sterols and squalene. It has physiological health functions such as regulating blood lipids and lowering blood sugar. It is one of the high-quality edible oils recommended by the Food and Agriculture Organization. However, the lauric acid content in tea oil is not high, and there are no reports on methods for using tea oil to increase the content of resistant starch in starch, and its effect on the content of resistant starch is difficult to predict. Tea cake is a by-product of the tea industry. It is rich in protein and is an important raw material for the development of polypeptide products. The polypeptides produced by it have antioxidant, antibacterial and angiotensin converting enzyme activity inhibition effects, and have high biosafety. However, there are no reports on the use of tea oil and tea cake polypeptides to improve the resistance and antioxidant properties of starch foods, nor are there corresponding preparation methods. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the above-mentioned existing technologies and provide a method for increasing the content of resistant starch in starch by using tea oil and tea oil cake polypeptides and its application.

[0007] The first object of the present invention is to provide a method for increasing the content of resistant starch in starch by using tea oil and tea oil cake polypeptide.

[0008] The second object of the present invention is to provide an application of the method in preparing a tea oil-tea cake polypeptide-starch complex with increased resistant starch content.

[0009] The third object of the present invention is to provide a tea oil-tea cake polypeptide-starch complex prepared by the method.

[0010] The fourth object of the present invention is to provide the use of the tea oil-tea cake polypeptide-starch complex in the preparation of slowly digestible foods.

[0011] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0012] The present invention provides a method for increasing the content of resistant starch in starch by using tea oil and tea oil cake polypeptide, characterized in that it comprises the following steps:

[0013] S1. Mixing starch with water to obtain a starch suspension; completely gelatinizing the starch suspension to obtain a starch paste;

[0014] S2. Dissolve the camellia oil cake polypeptide in water to obtain a polypeptide solution; mix and homogenize the starch paste, vegetable oil and / or polypeptide solution; the amount of vegetable oil is 3% to 7% and the amount of camellia oil cake polypeptide is 3% to 7% as a percentage of the dry weight of starch;

[0015] S3. After homogenization, the obtained mixture is stirred at 45-55°C for 20-40 minutes, freeze-dried, and then crushed and sieved.

[0016] Specifically, step S1 is to mix starch and water in a mass ratio of 1:4 to 12 to obtain a starch suspension.

[0017] Optionally, the starch is wheat starch, corn starch or rice starch.

[0018] Preferably, the starch is wheat starch or corn starch.

[0019] More preferably, the starch is wheat starch, see Test Example 1.

[0020] Specifically, the complete gelatinization in step S1 is to treat the starch suspension in a water bath at 92 to 98° C. for 25 to 35 minutes.

[0021] Specifically, the complete gelatinization is to treat the starch suspension in a 95° C. water bath for 30 minutes.

[0022] In step S2, the amount of water used is not particularly limited, and any amount can be used. Optionally, the mass ratio of starch to water is 1:6 to 20 based on the dry mass of the starch used.

[0023] Specifically, the mass ratio of starch to water is 1:10.

[0024] Specifically, step S2 is to mix starch paste and polypeptide solution, or to mix starch paste, vegetable oil and polypeptide solution and homogenize them.

[0025] Specifically, the amount of vegetable oil used is 4% to 6%, and the amount of tea oil cake polypeptide used is 4% to 6%, calculated as a percentage of the dry weight of starch.

[0026] Preferably, the amount of vegetable oil is 5%, and the amount of camellia oleifera cake polypeptide is 5%, calculated as a percentage of the dry weight of starch.

[0027] Specifically, the vegetable oil is tea oil.

[0028] Specifically, the tea cake polypeptide is a tea cake polypeptide with a molecular weight of less than 3 kDa or a tea cake polypeptide with a molecular weight of 3 to 10 kDa.

[0029] Preferably, the tea oil cake polypeptide is a tea oil cake polypeptide with a molecular weight of less than 3 kDa.

[0030] Specifically, the preparation method of the tea cake polypeptide comprises the following steps:

[0031] S21. Extraction of camellia oleifera cake protein; defatted camellia oleifera cake and distilled water were mixed at a solid-liquid ratio of 1:25, the pH was adjusted to 9, and the extraction was performed under magnetic stirring at a speed of 600 rpm for 30 minutes, centrifuged for 20 minutes, and the supernatant was retained; the precipitate was repeatedly extracted, and the extraction was repeated 3 times according to the above steps, and the supernatants of the 3 extractions were combined; the pH was adjusted to the isoelectric point (pH=4), centrifuged for 20 minutes, and the precipitate was taken; the precipitate was washed with distilled water, the pH was adjusted to 7.0, and the precipitate was re-dissolved by stirring continuously, and the re-dissolved protein solution was freeze-dried at a cold trap temperature of -80°C and a vacuum degree of 1Pa for 48 hours to obtain camellia oleifera cake protein;

[0032] S22. The camellia oleifera cake protein obtained in S21 was dissolved to prepare a 4% protein solution, 5000U alkaline protease was added per gram (g) of substrate, and hydrolyzed at 45°C and pH 9 for 10 min to prepare camellia oleifera cake polypeptides; an ultrafiltration cup equipped with different ultrafiltration membranes (3kDa, 5kDa, 10kDa) was used to grade the enzymatic hydrolysate of the camellia oleifera cake protein, and the hydrolysate was divided into four components according to the molecular weight (MW): MW<3kDa, 3-5kDa, 5-10kDa and >10kDa; the four components were collected and concentrated, and freeze-dried at a cold trap temperature of -80°C and a vacuum degree of 1Pa for 48h to obtain the corresponding camellia oleifera cake polypeptides.

[0033] Specifically, during the extraction of tea oil cake protein, the reagent used to adjust the pH is sodium hydroxide solution.

[0034] Specifically, the polypeptide solution in step S2 is obtained by dissolving the camellia oleifera cake polypeptide in 92-98° C. water.

[0035] Specifically, the homogenization in step S2 is to cool the mixed starch solution to 50-60° C. and homogenize it at 8000-10000 rpm for at least 3 minutes at intervals of 1 minute.

[0036] Preferably, in step S3, the obtained mixture is stirred at 50° C. for 30 min.

[0037] Specifically, the freeze-drying temperature in step S3 is -85°C to -80°C, and the vacuum degree is 1Pa to 10Pa.

[0038] More specifically, the freeze-drying conditions in step S3 are freeze-drying for 72 hours at a cold trap temperature of -80°C and a vacuum degree of 1 Pa.

[0039] The present invention also claims to protect the use of the method in preparing starch with increased resistant starch content, that is, in preparing a tea oil-tea cake polypeptide-starch complex with increased resistant starch content.

[0040] The present invention also requests protection for the tea oil-tea cake polypeptide-starch complex prepared by the method; the resistant starch content in the obtained tea oil-tea cake polypeptide-starch complex is not only significantly increased relative to the native starch, but the obtained tea oil-tea cake polypeptide-starch complex also has certain antioxidant properties, and can be used to prepare foods with antioxidant effects.

[0041] The present invention also seeks to protect the use of the starch in preparing slowly digestible foods; the slowly digestible foods are foods with slow digestion and utilization rates and slow digestion characteristics; the slowly digestible foods also have antioxidant effects.

[0042] The slowly digestible foods include but are not limited to bread, noodles, steamed buns, biscuits, fried dough sticks, cakes, etc. By adding the starch of the present invention to the above foods, the digestion and utilization rate of the foods can be slowed down, and foods with slow digestion characteristics can be produced.

[0043] The present invention has the following beneficial effects:

[0044] The present invention provides a method for increasing the content of resistant starch in starch by using tea oil and tea cake polypeptides. The method of the present invention can significantly increase the content of resistant starch in starch such as wheat starch, and the method has a simple process, small requirements on equipment, easy operation and control, and the quality of the obtained product is stable. In addition, the tea oil-tea cake polypeptide-starch complex with increased resistant starch content prepared by the method of the present invention also has an antioxidant effect, and can be used to prepare slow-digestion foods such as slow-digestion bread. While improving product quality, it is conducive to the development of high-value-added foods and has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The results are the effects of tea oil cake polypeptides with different molecular weights on the DPPH free radical scavenging ability of the tea oil-tea oil cake polypeptide-wheat starch complex prepared by the method of the present invention.

[0046] Figure 2 The results are the effects of tea oil cake polypeptides with different molecular weights on the ABTS free radical scavenging ability of the tea oil-tea oil cake polypeptide-wheat starch complex prepared by the method of the present invention.

[0047] Figure 3 The results are the effects of tea oil cake polypeptides with different molecular weights on the reducing ability of the tea oil-tea oil cake polypeptide-wheat starch complex prepared by the method of the present invention.

[0048] Figure 4 The results are the effects of tea oil cake polypeptides with different molecular weights on the DPPH radical scavenging ability of the tea oil-tea oil cake polypeptide-corn starch complex prepared by the method of the present invention.

[0049] Figure 5 The results are the effects of tea oil cake polypeptides with different molecular weights on the ATBS free radical scavenging ability of the tea oil-tea oil cake polypeptide-corn starch complex prepared by the method of the present invention.

[0050] Figure 6 The results are the effects of tea oil cake polypeptides with different molecular weights on the reducing ability of the tea oil-tea oil cake polypeptide-corn starch complex prepared by the method of the present invention. DETAILED DESCRIPTION

[0051] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0052] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0053] Example 1 Method for increasing the content of resistant starch in wheat starch

[0054] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0055] 1. Preparation of Camellia oleifera cake polypeptide

[0056] (1) Extraction of camellia oleifera cake protein: defatted camellia oleifera cake and distilled water were mixed at a solid-liquid ratio of 1:25, sodium hydroxide was added to adjust the pH to 9, magnetic stirring was used for extraction at a speed of 600 rpm for 30 min, centrifuged for 20 min, the supernatant was retained, and the precipitate was repeatedly extracted; the precipitate was repeatedly extracted three times according to the above steps, the supernatants of the three extractions were combined, the pH was adjusted to the isoelectric point (pH 4), centrifuged for 20 min, and the precipitate was obtained; the precipitate was washed with distilled water, and then the pH was adjusted to 7.0 with sodium hydroxide, and the precipitate was re-dissolved by continuous stirring; the re-dissolved protein solution was freeze-dried at a cold trap temperature of -80°C and a vacuum degree of 1 Pa for 48 h to obtain camellia oleifera cake protein;

[0057] (2) The obtained camellia oleifera cake protein was dissolved to prepare a 4% protein solution, 5000U alkaline protease was added per gram (g) of substrate, and hydrolyzed at 45°C and pH 9 for 10 min to prepare camellia oleifera cake polypeptides; the enzymatic hydrolysate of the camellia oleifera cake protein was fractionated using an ultrafiltration cup equipped with different ultrafiltration membranes (3 kDa, 5 kDa, 10 kDa), and the hydrolysate was divided into four components according to molecular weight (MW): MW <3 kDa, 3-5 kDa, 5-10 kDa and >10 kDa; the four components were collected and concentrated, and freeze-dried at a cold trap temperature of -80°C and a vacuum degree of 1 Pa for 48 h to obtain the corresponding camellia oleifera cake polypeptides.

[0058] 2. Methods for increasing the content of resistant starch in wheat starch

[0059] (1) wheat starch is used as a raw material, starch and water are mixed in advance at a mass ratio of 1:8 to obtain a starch suspension; the starch suspension is treated in a water bath at 95° C. for 30 minutes to completely gelatinize the starch to obtain a starch paste for later use;

[0060] (2) Dissolving a 6% tea cake polypeptide with a molecular weight of 3 to 5 kDa in water at 95°C in advance, based on the percentage of the dry mass of wheat starch used, to obtain a polypeptide solution; mixing starch paste, tea oil with an addition amount of 5% (based on the percentage of the dry mass of wheat starch used) and the polypeptide solution, and adding water so that the constant concentrations of starch, tea oil and polypeptide are 10.0 g / 100 g, 0.5 g / 100 g and 0.6 g / 100 g, respectively;

[0061] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0062] Example 2 Method for increasing the content of resistant starch in corn starch

[0063] In this embodiment, corn starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0064] (1) corn starch is used as a raw material, starch and water are mixed in a mass ratio of 1:8 in advance to obtain a starch suspension; the starch suspension is treated in a water bath at 95° C. for 30 minutes to completely gelatinize the starch to obtain a starch paste for later use;

[0065] (2) Dissolving a 6% tea cake polypeptide with a molecular weight of 3-5 kDa in water at 95° C. in advance, based on the percentage of the dry mass of corn starch used, in 95° C. water to obtain a polypeptide solution; mixing starch paste, tea oil with an addition amount of 5% (based on the percentage of the dry mass of wheat starch used) and the polypeptide solution, and adding water to obtain constant concentrations of starch, tea oil and polypeptide of 10.0 g / 100 g, 0.5 g / 100 g and 0.6 g / 100 g, respectively;

[0066] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0067] Example 3 Method for increasing the content of resistant starch in rice starch

[0068] In this embodiment, rice starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0069] (1) using rice starch as a raw material, preliminarily mixing starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0070] (2) dissolving a 6% tea cake polypeptide with a molecular weight of 3 to 5 kDa in water at 95° C. in advance, based on the percentage of the dry mass of rice starch used, to obtain a polypeptide solution; mixing starch paste, tea oil with an addition amount of 5% (based on the percentage of the dry mass of wheat starch used) and the polypeptide solution, and adding water so that the constant concentrations of starch, tea oil and polypeptide are 10.0 g / 100 g, 0.5 g / 100 g and 0.6 g / 100 g, respectively;

[0071] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0072] Example 4 Method for increasing the content of resistant starch in wheat starch

[0073] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0074] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0075] (2) In terms of percentage of the dry mass of wheat starch used, a 6% tea oil cake polypeptide with a molecular weight of 3 to 5 kDa was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, 3% tea oil and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, tea oil and polypeptide 10.0 g / 100 g, 0.3 g / 100 g and 0.6 g / 100 g, respectively;

[0076] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0077] Example 5 Method for increasing the content of resistant starch in wheat starch

[0078] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0079] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0080] (2) In terms of percentage of the dry mass of wheat starch used, a 6% tea cake polypeptide with a molecular weight of 3-5 kDa was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, 7% tea oil and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, tea oil and polypeptide 10.0 g / 100 g, 0.7 g / 100 g and 0.6 g / 100 g, respectively;

[0081] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0082] Example 6 Method for increasing the content of resistant starch in wheat starch

[0083] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0084] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0085] (2) In terms of percentage of the dry mass of wheat starch used, a 4% tea oil cake polypeptide with a molecular weight of 3 to 5 kDa was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, 3% tea oil and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, tea oil and polypeptide 10.0 g / 100 g, 0.3 g / 100 g and 0.4 g / 100 g, respectively;

[0086] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0087] Example 7 Method for increasing the content of resistant starch in wheat starch

[0088] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0089] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0090] (2) In terms of percentage of the dry mass of wheat starch used, a 5% tea oil cake polypeptide with a molecular weight of 3 to 5 kDa was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, 3% tea oil and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, tea oil and polypeptide 10.0 g / 100 g, 0.3 g / 100 g and 0.5 g / 100 g, respectively;

[0091] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0092] Example 8 Method for increasing the content of resistant starch in wheat starch

[0093] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0094] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0095] (2) In terms of percentage of the dry mass of wheat starch used, a 5% tea cake polypeptide with a molecular weight of less than 3 kDa was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, 7% tea oil and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, tea oil and polypeptide 10.0 g / 100 g, 0.7 g / 100 g and 0.5 g / 100 g, respectively;

[0096] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0097] Example 9 Method for increasing the content of resistant starch in wheat starch

[0098] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0099] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0100] (2) In terms of percentage of the dry mass of wheat starch used, a 5% tea cake polypeptide with a molecular weight of 5 to 10 kDa was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, 5% tea oil and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, tea oil and polypeptide 10.0 g / 100 g, 0.7 g / 100 g and 0.5 g / 100 g, respectively;

[0101] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0102] Example 10 Method for increasing the content of resistant starch in wheat starch

[0103] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0104] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0105] (2) In terms of percentage of the dry mass of wheat starch used, a camellia oil cake polypeptide with a molecular weight of >10 kDa and an addition amount of 5% was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, camellia oil with an addition amount of 5% and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, camellia oil and polypeptide 10.0 g / 100 g, 0.7 g / 100 g and 0.5 g / 100 g, respectively;

[0106] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0107] Example 11 Method for increasing the content of resistant starch in wheat starch

[0108] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0109] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0110] (2) In terms of percentage of the dry mass of wheat starch used, a camellia oil cake polypeptide with a molecular weight of less than 3 kDa and an addition amount of 4% was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, camellia oil with an addition amount of 5% and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, camellia oil and polypeptide 10.0 g / 100 g, 0.5 g / 100 g and 0.4 g / 100 g, respectively;

[0111] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 30 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0112] Example 12 Method for increasing the content of resistant starch in wheat starch

[0113] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0114] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0115] (2) In terms of percentage of the dry mass of wheat starch used, a camellia oil cake polypeptide with a molecular weight of less than 3 kDa and an addition amount of 4% was pre-dissolved in 95°C water to obtain a polypeptide solution; starch paste, camellia oil with an addition amount of 5% and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, camellia oil and polypeptide 10.0 g / 100 g, 0.5 g / 100 g and 0.4 g / 100 g, respectively;

[0116] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 40 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0117] Example 13 Method for increasing the content of resistant starch in wheat starch

[0118] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0119] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0120] (2) In terms of percentage of the dry mass of wheat starch used, a camellia oleifera cake polypeptide with a molecular weight of less than 3 kDa and an addition amount of 4% was pre-dissolved in 95° C. water to obtain a polypeptide solution; starch paste, peanut oil with an addition amount of 5% and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, peanut oil and polypeptide 10.0 g / 100 g, 0.5 g / 100 g and 0.4 g / 100 g, respectively;

[0121] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0122] Example 14 Method for increasing the content of resistant starch in wheat starch

[0123] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0124] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0125] (2) In terms of percentage of the dry mass of wheat starch used, a camellia oleifera cake polypeptide with a molecular weight of less than 3 kDa and an addition amount of 4% was pre-dissolved in 95° C. water to obtain a polypeptide solution; starch paste, soybean oil with an addition amount of 5% and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, soybean oil and polypeptide 10.0 g / 100 g, 0.5 g / 100 g and 0.4 g / 100 g, respectively;

[0126] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0127] Example 15 Method for increasing the content of resistant starch in wheat starch

[0128] In this embodiment, wheat starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0129] (1) mixing wheat starch and water in a mass ratio of 1:8 to obtain a starch suspension; treating the starch suspension in a 95° C. water bath for 30 min to completely gelatinize the starch to obtain a starch paste for later use;

[0130] (2) In terms of percentage of the dry mass of wheat starch used, a 4% tea cake polypeptide with a molecular weight of less than 3 kDa was pre-dissolved in 95° C. water to obtain a polypeptide solution; starch paste, 5% corn oil and the polypeptide solution were mixed, and water was added to make the constant concentrations of starch, corn oil and polypeptide 10.0 g / 100 g, 0.5 g / 100 g and 0.4 g / 100 g, respectively;

[0131] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0132] Example 16 Method for increasing the content of resistant starch in corn starch

[0133] In this embodiment, corn starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0134] (1) corn starch and water are mixed in a mass ratio of 1:8 to obtain a starch suspension; the starch suspension is treated in a water bath at 95° C. for 30 minutes to completely gelatinize the starch to obtain a starch paste for later use;

[0135] (2) Dissolving a 6% tea oil cake polypeptide with a molecular weight of less than 3 kDa in water at 95° C. in advance, based on the percentage of the dry mass of corn starch used, to obtain a polypeptide solution; mixing starch paste, 5% tea oil and the polypeptide solution, and adding water so that the constant concentrations of starch, tea oil and polypeptide are 10.0 g / 100 g, 0.5 g / 100 g and 0.6 g / 100 g, respectively;

[0136] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0137] Example 17 Method for increasing the content of resistant starch in corn starch

[0138] In this embodiment, corn starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0139] (1) corn starch and water are mixed in a mass ratio of 1:8 to obtain a starch suspension; the starch suspension is treated in a water bath at 95° C. for 30 minutes to completely gelatinize the starch to obtain a starch paste for later use;

[0140] (2) Dissolving a 6% tea oil cake polypeptide with a molecular weight of 5 to 10 kDa in water at 95° C. in advance, based on the percentage of the dry mass of corn starch used, to obtain a polypeptide solution; mixing starch paste, 5% tea oil and the polypeptide solution, and adding water to obtain constant concentrations of starch, tea oil and polypeptide of 10.0 g / 100 g, 0.5 g / 100 g and 0.6 g / 100 g, respectively;

[0141] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0142] Example 18 Method for increasing the content of resistant starch in corn starch

[0143] In this embodiment, corn starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0144] (1) corn starch and water are mixed in a mass ratio of 1:8 to obtain a starch suspension; the starch suspension is treated in a water bath at 95° C. for 30 minutes to completely gelatinize the starch to obtain a starch paste for later use;

[0145] (2) Dissolving a 6% tea cake polypeptide with a molecular weight of >10 kDa in water at 95°C in advance, based on the percentage of the dry mass of corn starch used, to obtain a polypeptide solution; mixing starch paste, 5% tea oil and the polypeptide solution, and adding water to obtain constant concentrations of starch, tea oil and polypeptide of 10.0 g / 100 g, 0.5 g / 100 g and 0.6 g / 100 g, respectively;

[0146] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0147] Example 19 Method for increasing the content of resistant starch in corn starch

[0148] In this embodiment, corn starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0149] (1) corn starch and water are mixed in a mass ratio of 1:8 to obtain a starch suspension; the starch suspension is treated in a water bath at 95° C. for 30 minutes to completely gelatinize the starch to obtain a starch paste for later use;

[0150] (2) Dissolving a 6% tea cake polypeptide with a molecular weight of less than 3 kDa in water at 95° C. in advance, based on the percentage of the dry mass of corn starch used, to obtain a polypeptide solution; mixing starch paste, 5% peanut oil and the polypeptide solution, and adding water to obtain constant concentrations of starch, peanut oil and polypeptide of 10.0 g / 100 g, 0.5 g / 100 g and 0.6 g / 100 g, respectively;

[0151] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0152] Example 20 Method for increasing the content of resistant starch in corn starch

[0153] In this embodiment, corn starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0154] (1) corn starch and water are mixed in a mass ratio of 1:8 to obtain a starch suspension; the starch suspension is treated in a water bath at 95° C. for 30 minutes to completely gelatinize the starch to obtain a starch paste for later use;

[0155] (2) Dissolving a 6% tea cake polypeptide with a molecular weight of less than 3 kDa in water at 95° C. in advance, based on the percentage of the dry mass of corn starch used, to obtain a polypeptide solution; mixing starch paste, 5% soybean oil and the polypeptide solution, and adding water so that the constant concentrations of starch, soybean oil and polypeptide are 10.0 g / 100 g, 0.5 g / 100 g and 0.6 g / 100 g, respectively;

[0156] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0157] Example 21 Method for increasing the content of resistant starch in corn starch

[0158] In this embodiment, corn starch is used as raw material starch to increase its resistant starch content, and the specific process is as follows:

[0159] (1) corn starch and water are mixed in a mass ratio of 1:8 to obtain a starch suspension; the starch suspension is treated in a water bath at 95° C. for 30 minutes to completely gelatinize the starch to obtain a starch paste for later use;

[0160] (2) Dissolving a 6% tea cake polypeptide with a molecular weight of less than 3 kDa in water at 95° C. in advance, based on the percentage of the dry mass of corn starch used, to obtain a polypeptide solution; mixing starch paste, corn oil with a 5% addition amount, and the polypeptide solution, and adding water so that the constant concentrations of starch, corn oil, and polypeptide are 10.0 g / 100 g, 0.5 g / 100 g, and 0.6 g / 100 g, respectively;

[0161] (3) The mixed starch solution was cooled to 60°C and homogenized at 10,000 rpm for 3 min at intervals of 1 min. After homogenization, the resulting mixture was stirred at 50°C for 20 min and then freeze-dried for 72 h at a cold trap temperature of -80°C and a vacuum degree of 1 Pa. After freeze-drying, the mixture was crushed and passed through a 100-mesh standard sieve.

[0162] Example 22 Method for increasing the content of resistant starch in wheat starch

[0163] In this example, wheat starch is used as raw material starch to increase its resistant starch content. The specific process is the same as in Example 1, except that no camellia oleifera cake polypeptide is added in this example.

[0164] Example 23 Method for increasing the content of resistant starch in corn starch

[0165] In this example, corn starch is used as raw material starch to increase its resistant starch content. The specific process is the same as in Example 2, except that no camellia oleifera cake polypeptide is added in this example.

[0166] Example 24 Method for increasing the content of resistant starch in rice starch

[0167] In this example, rice starch is used as raw material starch to increase its resistant starch content. The specific process is the same as in Example 3, except that no camellia oleifera cake polypeptide is added in this example.

[0168] Example 25 Method for increasing the content of resistant starch in wheat starch

[0169] In this example, wheat starch is used as raw material starch to increase its resistant starch content. The specific process is the same as in Example 1, except that no tea oil is added in this example and the tea cake polypeptide used is a tea cake polypeptide with a molecular weight of <3 kDa.

[0170] Example 26 Method for increasing the content of resistant starch in wheat starch

[0171] The specific process of this example is the same as that of Example 25, except that the camellia oleifera cake polypeptide used in this example is a camellia oleifera cake polypeptide with a molecular weight of 3 to 5 kDa.

[0172] Example 27 Method for increasing the content of resistant starch in wheat starch

[0173] The specific process of this example is the same as that of Example 25, except that the camellia oleifera cake polypeptide used in this example is a camellia oleifera cake polypeptide with a molecular weight of 5 to 10 kDa.

[0174] Example 28 Method for increasing the content of resistant starch in wheat starch

[0175] The specific process of this example is the same as that of Example 25, except that the camellia oleifera cake polypeptide used in this example is a camellia oleifera cake polypeptide with a molecular weight > 10 kDa.

[0176] Test Example 1

[0177] The present invention measured the digestibility of the tea oil-tea cake polypeptide-starch complex with increased resistant starch content prepared in Examples 1 to 28 and three native starches (wheat, corn, and rice starch), specifically according to the following steps:

[0178] The in vitro digestibility of the samples was determined by an in vitro simulation method. Accurately weigh 200 mg of starch sample in a small beaker, add 20 mL of sodium acetate buffer solution (pH 5.2, 0.1 M), mix well, place in a 37°C magnetic stirring water bath and stir for 30 min, then add 5 mL of mixed enzyme solution containing porcine pancreatic enzyme and glucoamylase (290 U / mL porcine pancreatic α-amylase and 15 U / mL amyloglucosidase), mix well, place in a 37°C water bath and continue magnetic stirring reaction; take out 250 μL of enzymatic hydrolyzate at 0, 20 min, and 120 min respectively, and place in 66% ethanol solution to terminate enzymolysis; glucose release from starch was determined by glucose oxidase / peroxidase method (GOPOD); according to digestion time, starch can be divided into fast digestible starch (RDS, starch digestion time <20 min), slowly digestible starch (SDS, 20 min < starch digestion time <120 min) and resistant starch (RS, starch digestion time >120 min), and the calculation formula is as follows:

[0179] RDS(%)=(G 20 -G 0 ×0.9) / TS;

[0180] RDS(%)=(G 120 -G 20 ×0.9) / TS;

[0181] RS (%) = 1-RDS-SDS;

[0182] Where TS is the total starch mass (g); G 0 , G 20 and G 120are the amounts of glucose released at 0, 20 and 120 min after the mixed enzyme addition reaction; 0.9 is the glucose conversion parameter; all experiments were repeated three times independently and the results are expressed as mean ± standard deviation; SPSS18.0 software was used to perform significance analysis of the data through Tukey test, with p = 0.05 as the test level, and p < 0.05 indicating that the difference is statistically significant.

[0183] The experimental results of the digestibility characteristics of the tea oil-tea cake polypeptide-starch complex with increased resistant starch content prepared in Examples 1 to 28 are shown in Table 1:

[0184] Table 1 In vitro digestibility of tea oil-tea cake polypeptide-starch complex

[0185]

[0186]

[0187] *Different letters in the same column of data in the table indicate significant differences between the data (p<0.05).

[0188] As shown in Table 1, adding tea oil and tea cake polypeptide to wheat, rice or corn starch (Examples 1 to 3) significantly reduced the low digestibility starch content (RDS and SDS) of the starch and significantly increased the resistant starch (RS) content. In addition, by comparing Examples 1, 2 and 3, it can be seen that the type of starch has a significant effect on the digestibility characteristics (resistant starch content) of the tea oil-tea cake polypeptide-starch complex obtained. Under the same other conditions, the tea oil-tea cake polypeptide-starch complex prepared by wheat starch has the strongest digestibility.

[0189] Comparison of Examples 11, 13, 14, and 15 shows that the type of vegetable oil used has a significant effect on the digestion characteristics of wheat starch. When the vegetable oil used is tea oil, the tea oil-tea cake polypeptide-starch complex prepared has the strongest digestion resistance. The same conclusion can be obtained by comparing Examples 16, 19, 20, and 21 in which the starch type is corn starch.

[0190] By comparing Examples 1, 4, and 5, it can be seen that the amount of tea oil added has an effect on the digestibility of starch; when the amount of tea oil added is 3%, its resistant starch content is significantly lower than that of the other two groups; and when the amount of tea oil added exceeds 5%, the effect on its digestibility is not significant.

[0191] By comparing Examples 4, 6, and 7, it can be seen that the amount of camellia oleifera cake polypeptide added has a certain effect on the digestion characteristics of starch; when the amount of polypeptide added is 4%, the content of fast-digestible starch and resistant starch is significantly different from that of the other two groups; and when the amount of polypeptide added exceeds 5%, the difference in the content of fast-digestible starch and resistant starch is not significant.

[0192] Comparison of Examples 5, 8, 9, and 10 shows that the molecular weight of the polypeptide has a significant effect on the digestion characteristics of wheat starch; when the molecular weight of the polypeptide used is <3 kDa, the tea oil-tea cake polypeptide-starch complex has the strongest digestion resistance, and the content of low-digestible starch is less than 50%. At the same time, comparison of Examples 2, 16, 17, and 18, in which the starch type is corn starch, shows that when the molecular weight of the polypeptide used is <3 kDa, the content of low-digestible starch is the lowest; indicating that no matter what kind of starch, the tea cake polypeptide with a molecular weight <3 kDa has the greatest impact on its digestion resistance.

[0193] By comparing Examples 6, 11, and 12, it can be seen that the length of the stirring time of the mixture affects the digestion characteristics of starch; when the stirring time is 20 minutes, the stirring time is shorter, and the content of low-digestible starch is lower than that of the longer stirring time; when the stirring time exceeds 30 minutes, the difference in the rapidly digestible starch and resistant starch is not significant.

[0194] By comparing Examples 1, 2, 3 with 22, 23, 24, it can be seen that the digestibility of different types of starch, when tea oil and tea oil cake polypeptide are added simultaneously, varies more significantly than starch added with tea oil alone, and the resistant starch content of starch is more significantly increased.

[0195] By comparing Examples 5, 8, 9, 10 with 25, 26, 27, and 28, it can be seen that regardless of the molecular weight of the polypeptide, the effect of adding tea oil and tea oil cake polypeptide at the same time on the digestion characteristics of wheat starch is greater than adding only tea oil cake polypeptide, the fast-digestible starch of starch is significantly reduced, and the resistant starch content is more significantly increased.

[0196] Test Example 2

[0197] The present invention also measures the antioxidant properties of the wheat tea oil-tea cake polypeptide-starch complex prepared in Examples 5, 8, 9, and 10 and the corn tea oil-tea cake polypeptide-starch complex prepared in Examples 2, 16, 17, and 18.

[0198] 1. Test methods

[0199] (1) DPPH free radical scavenging rate

[0200] Prepare 0.1 μmol / mL DPPH stock solution with anhydrous ethanol for use; weigh an appropriate amount of starch-tea oil-polypeptide complex to prepare sample solutions of different concentrations (0, 0.5, 1, 1.5, 2, 2.5 mg / mL), add 3.0 mL of DPPH solution to 1.0 mL of sample solution; mix well and react at room temperature (25°C) in the dark for 30 minutes, and measure the absorbance at a wavelength of 517 nm; the DPPH free radical scavenging rate of the sample is:

[0201] WDPPH =(1-(A i -A j ) / A0)×100%

[0202] W is the DPPH free radical scavenging rate, A 0 is the absorbance without sample, A i is the absorbance of the sample and DPPH solution, A j is the absorbance of the sample solution.

[0203] (2) ABTS free radical scavenging rate

[0204] Prepare an ABTS cation radical working solution with an absorbance of 0.70±0.02 at a wavelength of 734 nm. Mix 1.0 mL of sample solutions of different concentrations (0, 0.5, 1, 1.5, 2, 2.5 mg / mL) and 4.0 mL of ABTS working solution, and react at room temperature in the dark for 6 minutes. Measure the absorbance at a wavelength of 734 nm. The ABTS radical scavenging rate of the sample is:

[0205] W ABTS =(1-(A i -A j ) / A0)×100%

[0206] W is the ABTS free radical scavenging rate, A 0 is the absorbance without sample, A i is the absorbance of the sample and ABTS solution, A j is the absorbance of the sample solution.

[0207] (3) Determination of reducing power

[0208] Add 1.0 mL of sample solutions of different concentrations (0, 0.5, 1, 1.5, 2, 2.5 mg / mL) to phosphate buffer and potassium ferricyanide solution, react in a constant temperature water bath at 50°C for 20 min, add 1.5 mL of trichloroacetic acid solution, centrifuge for 10 min, take 2.5 mL of supernatant, add 0.5 mL of ferric chloride solution and 2.0 mL, and measure the absorbance at a wavelength of 700 nm; the absorbance value indicates the strength of the sample's reducing ability.

[0209] 2. Experimental results

[0210] The effects of tea oil cake polypeptides with different molecular weights on the DPPH free radical scavenging ability, ABTS free radical scavenging ability and reducing ability of the tea oil-tea oil cake polypeptide-wheat starch complex prepared by the method of the present invention are shown in the following order: Figures 1 to 3The effects of tea oil cake polypeptides with different molecular weights on the DPPH free radical scavenging ability, ABTS free radical scavenging ability and reducing ability of the tea oil-tea oil cake polypeptide-corn starch complex prepared by the method of the present invention are shown in the following order: Figures 4 to 6 shown.

[0211] The difference between Examples 5, 8, 9 and 10 is that the types of polypeptides added (polypeptide molecular weights) are different. Figures 1 to 3 It can be seen that within the mass concentration range of 0-2.5 mg / mL, with the increase of sample concentration, the scavenging rate of tea oil-tea cake polypeptide-wheat starch complex for DPPH free radicals and ATBS free radicals and its own reducing ability increase accordingly. When reaching a certain mass concentration, the changes gradually tend to be stable, but the sample concentration is different when the free radical scavenging rate or reducing ability begins to tend to be flat. The maximum free radical scavenging rate or reducing ability of resistant starch prepared by polypeptides of different molecular weights is different. Among them, the antioxidant ability of resistant starch prepared by tea cake polypeptide with a molecular weight of <3 kDa is relatively the strongest, and the antioxidant ability of the molecular weight>10 kDa is relatively weak, and the antioxidant ability of the other two molecular weight polypeptides is close.

[0212] When the starch type is corn starch, the antioxidant capacity of the tea oil-tea cake polypeptide-corn starch complex prepared by tea oil cake polypeptides with different molecular weights is as follows Figures 4 to 6 As shown. Figures 4 to 6 It can be seen that, except for the free radical scavenging ability and reducing ability, which are different from the resistant starch formed by wheat starch, the change pattern with concentration and the comparison of the antioxidant ability of polypeptides with different molecular weights are consistent with the resistant starch formed by wheat starch. From the above results, it can be seen that the order of influence of the molecular weight of tea oil cake polypeptide on the antioxidant ability of the prepared tea oil-tea oil cake polypeptide-starch complex is: (MW<3kDa)>(MW=3~5kDa)>(MW=5~10kDa)>(MW>10kDa), that is, the higher the resistant starch content, the stronger the antioxidant ability. Therefore, when it is added to food, the higher the addition amount, the greater the impact on the antioxidant property of the food.

[0213] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for increasing the content of resistant starch in starch by using tea oil and tea cake polypeptide, characterized in that: The following steps are involved: S1. Mixing starch with water to obtain a starch suspension; completely gelatinizing the starch suspension to obtain a starch paste; S2. Dissolve the camellia oil cake polypeptide in water to obtain a polypeptide solution; mix and homogenize the starch paste, vegetable oil and / or polypeptide solution; the amount of vegetable oil is 3% to 7% and the amount of camellia oil cake polypeptide is 3% to 7% as a percentage of the dry weight of starch; S3. After homogenization, the obtained mixture is stirred at 45-55°C for 20-40 minutes, freeze-dried, and then crushed and sieved.

2. The method according to claim 1, characterized in that: The complete gelatinization in step S1 is to treat the starch suspension in a water bath at 92 to 98° C. for 25 to 35 minutes.

3. The method according to claim 1, characterized in that: The tea cake polypeptide is a tea cake polypeptide with a molecular weight less than 3 kDa or a tea cake polypeptide with a molecular weight of 3-10 kDa.

4. The method according to claim 1, characterized in that: The polypeptide solution in step S2 is obtained by dissolving the camellia oleifera cake polypeptide in 92-98° C. water.

5. The method according to claim 1, characterized in that: The homogenization in step S2 is to cool the mixed starch solution to 50-60° C. and homogenize it at 8000-10000 rpm for at least 3 minutes at intervals of 1 minute.

6. The method according to claim 1, characterized in that: The starch is wheat starch, corn starch or rice starch.

7. The method according to claim 1, characterized in that: The vegetable oil is tea oil.

8. Use of the method according to any one of claims 1 to 7 in the preparation of a tea oil-tea cake polypeptide-starch complex with increased resistant starch content.

9. The tea oil-tea cake polypeptide-starch complex prepared by the method according to any one of claims 1 to 7.

10. Use of the tea oil-tea cake polypeptide-starch complex according to claim 9 in the preparation of slowly digestible foods.

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