| Sesame is one of the most important oil seed crops, it is mainly used for oil. Sesame oil processing by-product of sesame dregs is abundant in protein, but sesame dregs are mainly used for fertilizer or animal feed, this causes lower protein utilization and a great waste of protein resources; Protein from human intaking, after a variety of enzymes in the digestive tract degradation, while the body absorbs protein mainly in the form of peptides( two peptides, three peptides), but not in the form of free amino acids, therefore, the sesame dregs are used as raw material to prepare high quality protein and develop additional value higher protein peptide product, have broad application prospect and important practical significance.Defatted sesame dregs powder was made by wet sesame dregs as raw material, after drying,degreasing, grinding and series of pretreatments. This paper on the basic of sesame dregs component, sesame protein extraction, protein peptide preparation were studied, based on further study of the functional properties of protein peptide. The main conclusions were listed as following:(1) Two kinds of sesame dregs and defatted sesame dregs were rich in nutrients,especially in protein and carbohydrates. Sesame dregs contained high fat(11.29%) and protein(37.63%), while the protein content of defatted sesame dregs was higher than 42%, fat had been reduced to 4%, the content of other nutrients than the relative increase of sesame dregs.(2) Defatted sesame dregs were used as raw material to extract sesame protein by alkaline extraction followed by acid precipitation. The effects of amount of alkali addition,temperature, time, liquid-solid ratio and extraction times on the extraction rate of protein were investigated through single factor experiments and response surface methodology. The results showed that the best extraction conditions were as follows: amount of alkali addition18%,temperature 74.6°C, time 291 min, liquid-solid ratio25:1 and 1 extraction times. Under these conditions, the extraction rate of protein was 75.59%.The protein content in the sample was68.95% after the protein extracting solution was deposited on p H4.0. The highest content of17 amino acids was measured by high performance liquid chromatography, which was glutamate(21.74%), followed by aspartate and leucine, and the lowest was dicysteine(0.39%).(3) Four proteases of Alcalase, Papain, Neutrase and Protamex, were selected to preparesesame protein peptide, based on the degree of hydrolysis and reduction capacity of enzymatic hydrolysis product. The results showed that Alcalase was suitable enzyme.Through the single factor experiment and orthogonal experiment design, the optimum condition of enzymatic hydrolysis was as follows: temperature 50°C, p H 10.0, time 5h,amount of enzyme 4000 u.g-1, concentration of the substrate 3%. Under these conditions, the degree of hydrolysis was 20.35%.(4) Four components could be got when the sesame protein enzymatic hydrolysate was preliminary purified by sephadex-G25 gel chromatographic column.The molecular weight distributions were 17692-5732 Da ? 5732Da-3319 Da ? 3319Da-1705 Da ? <1705Da. The determination of the in vitro antioxidant capacity, protein enzymatic hydrolysate and four components had antioxidant activity, both with superoxide anion free radical, hydroxyl radical and DPPH free radical scavenging ability, with the increase of the concentration, the clearance rate was increased,which less than the 5732 Da of the three components was the main active ingredient, but the molecular weight and the relationship between the oxidation resistance remained to be further purification and research on protein peptide. |
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