Views: 0 Author: Site Editor Publish Time: 2023-02-15 Origin: Site
Walnut peptide is a small molecular structure, which removes oil, and the small molecule is more easily absorbed and utilized by the body. Walnut peptide is rich in glutamic acid, which is the only amino acid that participates in brain metabolism. It will increase the content of acetylcholine in the brain and make the cerebral cortex The activity of nerve cells is vigorous, promotes the metabolism of brain tissue, and restores the function of brain cells.
For mental workers, office workers, and those who often use the brain, it can quickly restore brain vitality, enhance thinking agility, effectively prevent memory loss, and improve brain vitality. Small molecule walnut peptides can improve immunity, sleep and sleep, and promote intestinal digestion. , to help nutrient absorption play a positive role.
The preparation of biologically active peptides from plants mainly includes chemical methods, enzymatic hydrolysis methods, and fermentation methods. Among them, the chemical method refers to the method of breaking the peptide chains connecting amino acids with chemical reagents under specific temperature conditions to make protein molecules form small molecular peptides, including acid hydrolysis and alkali hydrolysis. Although the cost of acid hydrolysis is low, it will completely destroy tryptophan, make part of methionine disappear, and convert amides (glutamine, asparagine) into amino acids; alkaline hydrolysis has the advantages of low cost and high recovery rate of tryptophan. But there are problems such as unstable product quality. Although the chemical method has the advantages of easy operation, low cost, etc.
Advantages, but its extraction rate is low, the reaction process is not easy to control, the environmental pollution is relatively serious and the economic benefit is low, so it is not suitable for the production of modern industrialized walnut peptide. At present, enzymatic hydrolysis and fermentation are mostly used to prepare bioactive peptides from walnut dregs.
Due to the advantages of protease with specificity, high efficiency, mild reaction conditions, easy control of reaction process and low nutritional loss, no harmful substances produced, enzymatic method is widely used in the preparation of walnut peptides. In order to meet the demand of industrial production, the choice of protease is especially important (wide source, low price, etc.), and the proteases commonly used for the preparation of walnut peptides are pepsin, trypsin, alkaline protease, papain, neutral protease, etc. The same protein can be hydrolyzed by different proteases, but the hydrolysis effect has some differences. Even if the same protein is hydrolyzed by the same protease, the hydrolysis effect varies under different reaction conditions and degree of hydrolysis, which is mainly caused by the different hydrolysis sites and enzyme activity of proteases, and also influenced by the enzymatic conditions, such as pH, reaction time, temperature, material-liquid ratio, enzyme-substrate concentration ratio, etc. It is very important to study and regulate the enzymatic conditions for the preparation of walnut peptides. The study and regulation of enzymatic conditions are very important for the preparation of walnut peptides.
The preparation of bioactive peptides by fermentation method refers to a method of preparing bioactive peptides by hydrolyzing proteins with enzymes produced by microorganisms. At present, fermentation method is mainly divided into liquid fermentation and solid fermentation. Liquid fermentation has been favored for a long time because of uniform fermentation and easy control of fermentation conditions (temperature, pH, sterile conditions); compared with liquid fermentation, solid state fermentation has the characteristics of high yield, low energy consumption, wide source and relatively simple operation. In solid state fermentation, microorganisms are in the wild and have the unique advantage of producing enzymes and other metabolites that cannot be produced in liquid state fermentation, so it is gradually gaining attention. In actual production, fermentation preparation is usually used in combination with enzymatic digestion to prepare bioactive peptides, which not only can reduce the production cost of active peptides, but also can play the role of detoxification and de-bittering of raw materials in the production. Fermentation preparation of bioactive peptides can effectively promote the efficient utilization of protein resources and the safe production of bioactive peptides. In recent years, many scholars have carried out process research on fermentation preparation of walnut peptides. The best process conditions were 84 h fermentation time, 8 g/100 mL substrate mass concentration, 8.0 starting pH, 11% inoculum and 33 ℃ fermentation temperature. Under these conditions, the mass concentration of walnut peptides was able to reach 2.58 mg/mL and the hydrolysis degree reached 37.5%, while Bacillus subtilis was found to be significantly more effective than Aspergillus niger and Bacillus subtilis in fermentation, and was a potential superior bacterium for the preparation of walnut peptides by liquid fermentation. Liu Xiao et al. prepared walnut peptides by treating walnut meal with Aspergillus niger and Bacillus subtilis in solid-state fermentation, and the results showed that there were differences in the optimal process parameters and yields between Aspergillus niger and Bacillus subtilis, and the yields of walnut peptides prepared by fermentation of the two bacteria were 158.61 mg/g and 243.97 mg/g, respectively. The differences in molecular mass distribution, peptide and amino acid contents of walnut peptides prepared by the two bacteria were compared It was determined that Bacillus subtilis was more suitable for solid state fermentation of walnut meal to prepare high quality walnut peptides. Although liquid fermentation is a more mature technology than solid fermentation, solid fermentation has the advantages of better fermentation process, more friendly to the environment and more cost effective, and may have better application prospects in the preparation of walnut peptides.
Walnuts are a dual-use resource, and studies have shown that walnut peptides have various biological activities such as antioxidant, cardiovascular protection and anti-cancer. In recent years, walnut meal has become more and more popular as a potential plant protein source, and many researchers have carried out studies on the preparation of walnut peptides based on walnut or walnut meal protein, and screened a series of active peptides and investigated their functional mechanisms.
Oxidative stress is an important cause of human aging and other aspects of disease, so the screening, preparation and application of antioxidants are receiving more and more attention. There is a wide range of antioxidants, which are used as antioxidants in food processing, but also play a functional role in health food, cosmetics and drug development. Since some of the chemically synthesized antioxidants have certain toxic side effects, natural antioxidants have attracted much attention from researchers by virtue of their safety. Antioxidant peptide is a kind of bioactive peptide with antioxidant activity, which can effectively eliminate ABTS cation radicals, hydroxyl radicals and DPPH radicals generated by oxidative stress, as well as peroxides and reactive oxygen species in the human body, so as to achieve the purpose of cell protection. Studies have shown that the antioxidant activity of peptides is closely related to the type, composition, molecular quality and structure of amino acids. Sulfur-containing amino acids (methionine, cysteine) have a greater influence on the antioxidant capacity of peptides, and peptides of basic amino acids (histidine, lysine and arginine) can inhibit the oxidation of unsaturated fatty acids triggered by free radicals. Walnut peptides with molecular mass less than 800 Da have more hydrophobic amino acids (Trp, Val, Phe, Leu, Ile, Ala, Met) and better antioxidant efficacy; moreover, peptides with higher content of glutamic acid, aspartic acid, leucine and phenylalanine have stronger antioxidant potential. At this stage, more researchers have extracted peptides with high antioxidant activity from walnut protein hydrolysate, and explored and discussed the antioxidant effects of walnut peptides and their molecular mechanisms, so as to explore their functional and economic values.Chen Huiping et al. isolated and purified walnut protein meal hydrolysate by UPLC-ESI-MS/MS technique, and identified 77 peptides, which were similar to The peptide WSREEQEREE and peptide ADIYTEEAGR were isolated and identified as having the strongest antioxidant capacity compared to reduced glutathione and ceruloplasmin, which had strong hydroxyl radical scavenging ability and ORAC and protective effect on H2O2-damaged PC12 cells. Gao Yawen et al. studied WEKPPVSH, the hydrolysis product of walnut protein, and found that the target peptide could inhibit the ROS level and the changes of superoxide dismutase (SOD) and catalase (CAT) activity in lipopolysaccharide-injured cells by measuring the intracellular ROS level before and after the effect of the target peptide. It was found that the target peptides could exert antioxidant effects by inhibiting ROS generation and increasing CAT and SOD activity in lipopolysaccharide-damaged cells.
The cardioprotective activity of food-derived peptides is mainly reflected in the anti-hypertensive activity. ACE inhibitory peptide can inhibit ACE activity, promote vasodilation, reduce blood volume and lower blood pressure, and play an important physiological role in anti-hypertension. The mechanism of action of ACE inhibitory peptide extracted from walnut is shown in Figure 3. Currently, some patients taking synthetic ACE-inhibiting drugs develop side effects such as dry cough, taste disturbance, and rash. Food-derived ACE inhibitory peptide has high biological activity, low toxicity and easy metabolism in human body, and walnut protein ACE inhibitory peptide is a potential target for the development of food-derived ACE inhibitory peptide.
Memory loss is mainly caused by β -amyloid peptide (A β) accumulation, dysfunction of the cholinergic system, high glutamate content, mitochondrial dysfunction, oxidative stress and inflammatory response. Studies have shown that both low molecular mass peptides and hydrophobic peptides of memory improving peptides exhibit better neuroprotective activity. Walnut peptides have good memory improving activity. Wang Shuguang et al. investigated the neuroprotective effects of walnut hydrolysis products on scopolamine-induced cognitive and memory impaired mice, and the results showed that the hydrolysis products of walnut protein significantly improved the behavior of cognitive and memory impaired mice and normalized the level of cholinergic system disorder and oxidative stress in the brain of mice, and then the hydrolysis products were identified and found that Peptide FY and SGFDAE had the strongest protective activity. The higher content of arginine, aspartic acid and glutamic acid in walnuts (with a dose-effect relationship, with high doses showing inhibitory effects) enhanced the memory improving effects of walnut peptides. In addition, strong antioxidant peptides in walnuts also have positive effects on memory improvement. Zou Juan et al. found that walnut peptides protect against Aβ25-35-induced memory impairment in mice by counteracting oxidative stress and reducing inflammatory response, and walnut-derived peptide PW5 also improved cognitive impairment in APP/PS1 transgenic mice. Walnut peptides have certain neuroprotective functions, and in the future, in-depth research can be conducted for neurodegenerative diseases such as Alzheimer's disease and memory improvement, in order to develop memory improving walnut peptide products with high efficiency and low or no side effects.
Li Qingyong et al found that walnut peptides have a positive role in uric acid metabolism, and peptide WPPKN (640.8 Da) and peptide ADIYTE (710.7 Da), isolated and purified from walnut protein hydrolysis products, were able to reduce serum uric acid and have potential as functional food components for the treatment of gout and hyperuricemia, and experimental results showed that tryptophan-containing walnut The experimental results showed that the tryptophan-containing active peptide of walnut could effectively inhibit xanthine oxidase, and the tryptophan content was linearly correlated with the inhibitory activity of the active peptide of walnut. In lipid metabolism, it has been shown that walnut peptides can reduce the increase in hepatic and epididymal fat mass (induced by high-fat diet), and reduce serum total cholesterol, triglycerides, LDL cholesterol, and hepatic cholesterol and triglycerides, reduce hepatic steatosis, and reduce body mass and improve the damage caused by disorders of lipid metabolism and hepatic fat accumulation. Li Li et al. found that walnut peptides have certain hypoglycemic effect through brewer's yeast model and type 2 diabetes animal model, and the hypoglycemic effect of walnut peptides is better than that of walnut protein. In bone metabolism, Dai Jiahe et al. found that the chelate of walnut peptide and calcium could promote calcium absorption and transport by regulating the TRPV6 signaling pathway, and the application of walnut peptide and calcium chelate could effectively improve bone density, and promote bone formation. The chelation of walnut peptides with calcium can effectively improve bone density and promote bone formation, thus achieving better prevention of calcium deficiency and maintaining the balance of bone metabolism.
The preparation of walnut functional peptides based on walnut meal has attracted much attention from researchers and governments all over the world, and the research on the preparation method, separation and purification, identification and efficacy of walnut peptides has been rapidly developed, and many walnut peptides have been developed, and the functional health mechanism of walnut peptides (antioxidant, cardiovascular protection, memory improvement, etc.) has been gradually clarified. Some walnut peptides have been used in the development of health food and industrialized production. However, the research of walnut peptides is still in the development stage, and there are still many research works to be carried out. The preparation of walnut peptides and the process of separation and purification affect the performance and efficacy of its final processed products, and the research in the preparation process and other aspects need to be more refined, which can provide the basic guarantee for the accurate production of high quality walnut peptide products. There are more studies on the activity of walnut peptides, but only a few walnut peptides have more in-depth biological activity research, which is far from industrial application. Walnut peptide bioactivity research is mainly reflected in its extraction and preparation process, peptide amino acid composition and sequence, relative molecular mass, bioactive mechanism of action, etc. The more mature biological activity research on antioxidant, cardiovascular protection, memory improvement, etc. is only at the level of animal experiments, and clinical experiments need to be strengthened in the later stage to clarify the metabolism and action of walnut peptides in human body. In the development of walnut peptide health food, special dietary food and special medical food, excessive attention is paid to its functional role and potential health and medical value, and there is a certain disconnection with the actual product development, and there is a lack of research on the efficient extraction and preparation, quantitative acquisition, activity modification, targeted absorption and metabolism, bioavailability of walnut active protein peptide, etc., while the operability and cost of processing are neglected to the product development and As a result, most of the products are still in the research stage or experimental stage and cannot be industrialized. With the rapid development of modern food technology, the research on the functional nutrition and industrialization of walnut peptides will continue to deepen, and the development and application of walnut peptide products will certainly promote the development of comprehensive utilization technology of walnut industry and realize the high value utilization of walnut.