CN115644453A

CN115644453A - Method for stabilizing DHA emulsion by soybean polypeptide-polyphenol antioxidant particles

Info

Publication number: CN115644453A
Application number: CN202211250326.0A
Authority: CN
Inventors: 丁俭; 吴天逸; 张欣怡; 王欣月; 林玲
Original assignee: Nanjing University of Finance and Economics
Current assignee: Nanjing University of Finance and Economics
Priority date: 2022-10-12
Filing date: 2022-10-12
Publication date: 2023-01-31

Abstract

The invention discloses a method for stabilizing DHA emulsion by soybean polypeptide-polyphenol antioxidant particles, which takes soybean polypeptide with wide application range and high nutritional value and polyphenol with strong antioxidant capacity, such as green tea extract EGCG, as emulsifier raw materials, prepares compound particles by an alkaline covalent method, takes fish oil and algae oil as oil phases, prepares nano DHA emulsion by shearing and high-pressure homogeneous emulsification processes, and disperses the emulsified DHA into small molecular droplets to obtain the nano DHA emulsion with good oxidation resistance, high stability and easy digestion and absorption.

Description

Method for stabilizing DHA emulsion by soybean polypeptide-polyphenol antioxidant particles

Technical Field

The invention belongs to the technical field of food processing, and particularly relates to a method for stabilizing DHA emulsion by soybean polypeptide-polyphenol antioxidant particles.

Background

The soybean protein has an amphiphilic structure, is easy to adsorb on an oil-water interface, is a high-efficiency protein emulsifier in a food system, is a common food protein raw material and has high nutritional value. However, the antioxidant capacity of soy protein is not strong, and these conditions limit the use of soy protein in food products. Researches show that under proper enzymolysis, the emulsifying capacity of the soybean protein is obviously improved, the molecular weight is reduced after enzymolysis, part of the structure is unfolded, hydrophobic groups are exposed, and the affinity and the adsorption capacity at an oil-water interface are improved. Meanwhile, the protein contains abundant polypeptide after enzymolysis, and has higher oxidation resistance. Therefore, compared with protein, the soybean polypeptide obtained by controllable enzymolysis of protease has more structural and functional advantages. In recent years, the molecular structure of the soybean protein is modified by methods such as grafting, covalence or polymerization, and the like, so that the soybean protein has important effects on improving the emulsibility, the oxidation resistance and the product quality, and the application of the soybean protein in the fields of new foods and biomedicines is widened. The preparation of the covalent complexes is mainly achieved by alkaline, free radical grafting and enzymatic methods. The enzyme method for preparing the compound has mild conditions, and the covalent compound shows strong free radical scavenging activity, but obvious browning can be caused in the reaction process, the reaction is not thorough, more intermediate products are obtained, and the relative cost is higher. The free radical grafting method has special requirements on polyphenol and protein structures, para-hydroxyl groups obtained from aromatic rings of polyphenol compounds are easily attacked by free radicals to influence the formation of covalent bonds, and the grafting rate is relatively low after the reaction time is long. The most important advantages of the alkaline method covalent bond are relative simplicity, mild reaction conditions and economy. The polyphenol with oxidation resistance is introduced into a protein structure, so that the biological activity and functional characteristics of the protein and the protein zymolyte can be obviously improved, and the polyphenol is a novel emulsifier which is concerned in the research and application of a food emulsion system.

DHA (docosahexaenoic acid), docosahexaenoic acid, commonly known as NAOHUANGJIN, is an unsaturated fatty acid very important to human body. With the enhancement of the awareness of people to prevent chronic diseases and to keep health, functional oil has become an important component of functional food raw materials. The functional oil is rich in omega-3 series polyunsaturated fatty acids, and has the effects of reducing the risk of heart disease, promoting growth and development, healing inflammation and the like, so that the functional oil is called as 'good fat'. In particular to deep sea fish oil and algae oil rich in docosahexaenoic acid (DHA), which are widely applied to the fields of infant formula products, dietary supplements, health care products and the like. But because the DHA molecule contains six unsaturated double bonds, the DHA molecule is extremely sensitive to metal ions, oxygen, light and heat, and is extremely easy to oxidize and degrade in the processing and preservation processes. The oxidation of functional oil not only causes food rancidity and physiological function loss, but also produces polymer or peroxide which can cause harm to human health, induce inflammatory reaction and various diseases and even cause cancer.

At present, researches in related fields mainly adopt modes such as soft capsules, powder, emulsion and liposome to improve the stability of functional grease, but solid protection modes such as powder have the problems of incompatibility, poor reconstitution property, low bioavailability and the like in liquid food application. The emulsion is used as an important protection system for stabilizing functional grease, and can make up the defects and promote mutual solubility of the grease. The emulsified DHA can be converted into small molecular droplets, can more easily cross the vascular barrier and can be absorbed by the digestive system. Experiments prove that the absorption effect of the emulsified DHA can be up to 9 times of that of the common capsule. When the functional grease is in the liquid environment of an emulsion system, the oxidation protection of the functional grease is more important, the oxidation of the grease in the emulsion mainly starts from an oil-water interface layer, and therefore the control of the interface oxidation of the emulsion is very important. The protein polypeptide and the polyphenol have good antioxidant property, and the two have antioxidant capacity of providing electrons, supplying hydrogen or chelating metal ions and the like through hydrophobic amino acid contained in the polypeptide and hydroxyl groups adjacent to each other in a polyphenol structure, so that a compound of the two has the potential of stabilizing an easily-oxidized functional grease emulsion system.

Disclosure of Invention

The invention aims to solve the problem of poor oxidation stability of DHA in an emulsion system, and provides a method for stabilizing DHA emulsion by using soybean polypeptide-polyphenol antioxidant particles.

The invention is realized by the following technical scheme:

the soybean polypeptide and the polyphenol are covalent under alkaline conditions, wherein the polyphenol is one of EGCG, ferulic acid, anthocyanin and the like.

Preferably, the mass ratio of the polyphenol to the soybean polypeptide is 1: 100, stirring is carried out for 24 hours at the pH value of 9.0, the pH value of the solution is adjusted to 7.0 after the reaction is finished, and then the covalent complex solution is dialyzed for 48 hours at the temperature of 4 ℃ to remove free polyphenol;

preferably, the dialysis aperture is 500Da, the vacuum degree of vacuum freeze drying is 5-20 Pa, the temperature is-40 to-60 ℃, and the time is 24-72 h;

preferably, the emulsifying system utilizes a covalent complex concentration of 4% as emulsifier, stabilizing the oil phase to 30% by high pressure homogenization;

preferably, the high-pressure homogenizing condition is 80-100MPa, the circulation homogenizing is carried out for 3 times, and the particle size of the emulsion is 200-400nm.

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention uses soybean polypeptide and polyphenol as raw materials, prepares novel EGCG/soybean polypeptide antioxidant particles in an alkaline covalent mode, realizes controllable preparation, and constructs stable DHAPickering emulsion with a novel antioxidant particle interface;

(2) The invention adopts a high-pressure homogenizing emulsion system to make up the defects of incompatibility, poor reconstitution property and low bioavailability of the oil in the application of liquid food. The emulsified DHA can be converted into small molecular droplets, so that the DHA can pass through a vascular barrier more easily and is absorbed by a digestive system;

(3) The preparation technology adopted by the invention is mature, the process is simple, and the method is suitable for industrial production.

Detailed Description

Example 1

(1) Soy polypeptides (SPHs, 1 g) were dissolved in deionized water (100 mL) and stirred at 4 ℃ for 24h to fully hydrate the solution, the pH of the solution was adjusted to 9.0, then 1% polyphenol (EGCG) was added, the pH of the mixed solution was maintained at 9.0, after 24h, the pH of the mixed solution was adjusted to 7.0, and then transferred to a dialysis bag (pretreated) with a molecular weight of 500 Da. Dialyzed at 4 ℃ for 48h to remove unbound polyphenols, then lyophilized. The lyophilized samples were stored at 4 ℃ for later use.

(2) Preparing the covalent compound in the step (1) into a solution with the concentration of 2%, and dispersing for 3min by using a high-speed disperser 10000r/min through high-pressure homogenizing to stabilize the oil phase to be 30% to obtain the DHA primary emulsion.

(3) And finally, circularly homogenizing the primary emulsion for 3 times under the condition of high-pressure homogenization of 80MPa to obtain the DHA nano emulsion.

Example 2

(1) Soy polypeptides (SPHs, 1 g) were dissolved in deionized water (100 mL) and stirred at 4 ℃ for 24h to fully hydrate the solution, the pH of the solution was adjusted to 9.0, then 1% ferulic acid was added, the pH was maintained at 9.0, after 24 hours, the pH of the mixed solution was adjusted to 7 and then transferred to a dialysis bag (pretreated) with a molecular weight of 500 Da. Dialyzed at 4 ℃ for 48h to remove unbound polyphenols, then lyophilized. The lyophilized samples were stored at 4 ℃ for later use.

(2) Preparing the covalent compound in the step (1) into a solution with the concentration of 3%, and dispersing for 3min by using a high-speed disperser 10000r/min through a high-pressure homogeneous stable oil phase with the concentration of 30% to obtain DHA primary emulsion.

Example 3

(1) Soy polypeptides (SPHs, 1 g) were dissolved in deionized water (100 mL) and stirred at 4 ℃ for 24h to fully hydrate the solution, the pH of the solution was adjusted to 9.0, then 1% polyphenol (EGCG) was added, the pH of the mixed solution was maintained at 9.0, after 24h, the pH of the mixed solution was adjusted to 7 and then transferred to a dialysis bag (pretreated) with a molecular weight of 500 Da. Dialyzed at 4 ℃ for 48h to remove unbound polyphenols, then lyophilized. The lyophilized samples were stored at 4 ℃ for later use.

(2) Preparing the covalent compound in the step (1) into a solution with the concentration of 4%, and dispersing for 3min by using a high-speed disperser 10000r/min through high-pressure homogenizing to stabilize the oil phase to be 30% to obtain the DHA primary emulsion.

(3) And finally, circularly homogenizing the primary emulsion for 3 times under the condition of high-pressure homogenization of 100MPa to obtain the DHA nano emulsion.

Claims

1. A method for stabilizing DHA emulsion by utilizing soybean polypeptide-polyphenol anti-oxidation particles is characterized in that soybean polypeptide-polyphenol covalent compounds are prepared by taking soybean polypeptide, EGCG, ferulic acid and other polyphenols as main raw materials in an alkaline covalent mode, the soybean polypeptide-polyphenol anti-oxidation particles are obtained after vacuum freeze drying, and the anti-oxidation type nano DHA emulsion is prepared by taking fish oil and algae oil rich in DHA as oil phases through shearing and high-pressure homogeneous emulsification processes.

2. The method for stabilizing DHA emulsion by using soybean polypeptide-polyphenol antioxidant particles as claimed in claim 1, wherein the preparation of soybean polypeptide comprises the following steps: extracting soybean protein from soybean, preparing protein solution with substrate concentration of 10% [ protein isolate: deionized water = 1: 10 (g/mL) ], stirring well, and fully hydrating for 12h under water bath condition of 55 ℃. The hydrated protein solution was preheated for 5min in a 90 ℃ water bath. Adjusting pH to 8.5 with 2mol/L NaOH, adding alkaline protease (Alcalase) into soybean protein isolate solution according to 2% (w/v), performing restriction enzyme hydrolysis to obtain soybean protein zymolyte, inactivating enzyme in 100 deg.C water for 15min, cooling, adjusting pH to 7.0 with 2mol/L HCl, centrifuging at 8000 Xg for 20min, and freeze drying supernatant to obtain soybean polypeptide sample.

3. The method for stabilizing DHA emulsion by utilizing soybean polypeptide-polyphenol anti-oxidation particles as claimed in claim 1, wherein the soybean polypeptide is covalently bonded with EGCG, ferulic acid and the like under alkaline covalent conditions, the mass ratio of polyphenol to soybean polypeptide is 1: 100, the pH is 9.0, stirring is carried out for 24h, the pH value of the solution is adjusted to 7.0 after the reaction is finished, then the covalent compound solution is dialyzed at 4 ℃ for 48h to remove free polyphenol, and vacuum freeze drying is carried out to obtain the soybean polypeptide-polyphenol anti-oxidation particles.

4. The method of claim 1, wherein the covalent complex is used at a concentration of 4% as an emulsifier to stabilize a 30% DHA emulsion by shearing and high pressure homogenization of the oil phase.

5. The method for stabilizing DHA emulsion through soybean polypeptide-polyphenol antioxidant particles as claimed in claim 1, wherein the shear rate of the high speed disperser is 10000r/min,3min, to obtain primary emulsion, and then the primary emulsion is subjected to high pressure homogenization cycle for 3 times, under the condition of 80-100MPa, to obtain DHA nano emulsion.