Study On Sesame Protein Peptide Preparation And Activity

Sesame has attracted much attention to the food and human health,as it is rich in protein,oil and other nutrients.Traditional processing mainly uses its oil components.Nowadays,plant-based protein is widely favored,related research on its protein has grown up to be a hot topic.In this paper,sesame protein peptides were prepared with a low-temperature meal prepared from Zhongzhi No.34 sesame seed for related research.The two types of sesame meal obtained in this study by hydraulic cold pressing and subcritical extraction methods are cold pressed sesame meal(CPSM)and subcritical sesame meal(SSM).Crude protein content of CPSM and SSM samples were 28.80 ± 0.17%,37.22 ±0.21%,and the crude fat content was 22.19 ± 0.06%,6.12 ± 0.05%,respectively.Both of them are low-temperature meals,but the residual oil content of CPSM is higher,while SSM further enriched the protein content of the meal by removing the residual oil.A comparative study on the preparation of sesame protein peptides by Aspergillus oryzae fermentation and alkaline protease enzymatic hydrolysis.On the basis of successively exploring the three factors of fermentation solid medium water content,fermentation time,and the amount of Aspergillus oryzae spore powder,the optimal parameters for preparing sesame protein peptides by the Aspergillus oryzae fermentation method are: temperature 30℃,medium water content 40%,1 g/20 g of spore powder,and 72 h of fermentation time,the yields of SSM and CPSM peptides were 6.43 ± 0.06% and 5.92 ± 0.15%,respectively.Alkaline protease digestion conditions are: p H 10,substrate 2%,enzyme amount 10000U/gsubstrate,time 1 h,reaction temperature 50℃,the yields of SSM and CPSM peptides are8.53 ± 0.07%,6.41± 0.13%,respectively.For the same kind of sesame meal,there is a significant difference in the yield of sesame protein peptides prepared by Aspergillus oryzae fermentation and alkaline protease enzymatic hydrolysis(p<0.05).For the alkaline protease enzymatic hydrolysis method,there is a significant difference between the yield of SSM polypeptide and the yield of CPSM polypeptide(p<0.05);for the fermentation method of Aspergillus oryzae,the yield of SSM polypeptide is not significantly different from the yield of CPSM polypeptide.Considering related factors,this study used alkaline protease to hydrolyze SSM to prepare sesame protein peptides.The optimal process conditions for preparing sesame protein peptide by alkaline protease enzymatic hydrolysis of SSM were:SSM particle size 40 mesh,Substrate concentration 2%,p H 10.9,protease dosage 9700U/gsubstrate,temperature 51℃,reaction time 2 h,the yield of SSM polypeptide is 12.38 ±0.13%.Use ultrafiltration membranes of different molecular weights to intercept and separate SSM polypeptides to obtain different separation components SSMP-1(8-10 KDa),SSMP-2(5-8 KDa),SSMP-3(3-5 KDa),SSMP-4(1-3 KDa),SSMP-5(< 1 KDa).The Zeta potential and PDI of each component were measured,and it was found that SSMP-2 had the best dispersion in an aqueous solution,and SSMP had the worst dispersion.Compared with other components,SSMP-2 has the largest number of negative charges on its surface,and its Zeta potential is-20.00 ± 0.87 m V.Fluorescence emission spectrum analysis that the absorption wavelength of SSMP and every component are 350 nm,and the order of fluorescence intensity is SSMP-5(3371)> SSMP-4(1759)> SSMP-3(1280)> SSMP-2(1055)> SSMP-1(588.4)> SSMP(585.9).SEM analysis shows that SSMP presents a thick block and porous planar structure;SSMP-1 and SSMP-2 are relatively broken,presenting irregular flaky structures with tiny protrusions on the surface;SSMP-3,SSMP-4,and SSMP-5 The microstructure is also fragmented,and the surface is flat and smooth.The research on the anti-radical activity of SSM polypeptide and its components found that within the experimentally limited concentration range,it has a certain scavenging ability for DPPH,PTIO,and ·O2-free radicals,and has a certain dose-effect relationship.Sesame protein peptides with relatively small molecular weight components have the highest scavenging rate of free radicals.Using the obtained sesame protein peptides and the separated components,the three ions of Ca2+,Mg2+,and Zn2+ were chelated,and it was found that all of them have strong chelating ability,the chelating rate is above 50%.SSMP-2 has the highest chelation rate for Ca2+ and Mg2+,72.72 ± 0.17% and 71.15 ± 0.67%,respectively;SSMP-3 has the highest chelation rate for Zn2+,67.14 ± 0.24%.Fluorescence spectroscopy analysis found that after the chelating reaction with Ca2+ and Mg2+,the fluorescence intensity decreased and the maximum absorption peak was red-shifted;after chelating reaction with Zn2+,the red-shift effect occurred,but the fluorescence intensity tended to increase.Infrared spectroscopy analysis shows that sesame protein peptide and its components can chelate with Ca2+,Mg2+,and Zn2+,and the vibration absorption wavelengths of the three characteristic peaks of-NH2,COO-and C=O have a certain regular change,which characterizes sesame.Both amino and carboxyl groups in protein peptides participate in the chelation reaction of three mineral ions.SEM analysis shows that sesame protein peptide and Ca2+,Mg2+,and Zn2+ can form chelate with certain stability,and their microstructures are mostly encapsulated and adhere to each other to form a "bridging effect" and appear as aggregates;molecular weight When the smaller sesame protein peptide molecule forms a chelate,its original structure will change significantly.