| Rapeseed is increasingly becoming a major crop in China. Meal proteins have a well-balanced composition in regard to FAO requirements. But there are little reports on esculent function and bioactivity of rapeseed protein and peptide.Defatted and dehulled meal of double-zero rapeseed variety (HuaZa-3) was used as material in this study. A research on preparing rapeseed protein fractionation and part of their functional properties were performed. Based on this, rapeseed albumin was sequentially hydrolyzed with alcalase and flavourzyme and was separated into three purified three grades-RSP-1, RSP-2 and RSP-3.The bioactivities of crude rapeseed peptide(RSP-R) and its purified grades were investigated, including the antioxidant activities, inhibition effect of tumor growth and influence on immune ability , induce the apoptosis of Hela cells, inhibiting effect on angiotension I-converting enzyme(ACE) activity of SHR. (in Vitro).This dissertation researched RSP systematically from preparation to bioactivities. The main results are shown as follows:1 Classification of rapeseed protein isolateAlbumins and globulins were found to be the predominant proteins in Hua-Za 3 meal, comprising 36.8% and 31.6% of total proteins. While glutelins and prolamins were 29.1% and 2.5%,respectively. The molecular weight of fractionation was shown by SDS-PAGE and the structure of albumins is simple. Amino acid profile of the isolates indicated that the essential amino acid of each protein fraction nearly reach to 50%. Albumins have better function, including water absorption, oil absorption, emulsifying activity and emulsion stability. In addition, the albumin maintains their native capability because of low-temperature pressing, So albumin can be widely applied in the food and beverage industry.2 Preparation of rapeseed peptidesDouble-enzyme can not only increase the DH ,but remove the bitter of RSP.In our experiment,Rapeseed Albumin was hydrolyzed with sequentially alcalase and flavourzyme. Degree (DH) were used as response values in analysis of response surface regression (RSREG), considering the mouth-sense , the optimum conditions of alcalaseenzymatic hydrolysis have been determined by mono-factor analysis and response surface methodology as follows, pH :8.0, hydrolyzing temperature: 50.1C,enzyme concentration: 0.38AU per gram of substrate, concentration of substrate:4.87%. Flavourzyme is used by step for 2h after reacted lh with alcalase, the degree of hydrolysis of rapeseed albumin can go up to 28%.Hydrolysates were clarified by filtration to remove insoluble substrate fragments, and the filtrate was lyophilized and freeze-dried for further use. The hydrolysates(RSP-R) was graded by Sephadex G-25 column with distilled water as eluant .fractions were pooled into three major groups(RSP-l , RSP-2 and RSP-3).Protein content in RSP-l,RSP-2 and RSP-3 were 71.76%, 79.23% and 86.14%;crude polysaccharides were 22.64%, 13.88% and 5.18%. Molecular weight of each grade were bigger than 5000,1052 and 563 Dal. Contents of amino acids determined by HPLC in three grades differed from each other.3 Antioxidant activities of rapeseed peptidesAfter injecting 50,100 mg/kg-d 15d for 15 d, MDA levels in serum in the RSP group were obviously lower than that of the control (P < 0. 05) ;So RSP could improve the antioxidant capacity in vivo. The results in vitro showed that RSP had higher reductive activity and can scavenge hydroxyl radicals.RSP had powerful inhibiting activity on active oxygen within certain concentration. As for malondialdehyde(MDA) formation and H2O2-induced of mice liver ,RSP-R and RSP-1 had better inhibiting effects than RSP-2 and RSP-3 .exhibiting dosage-depended . but little inhibiting effect on MDA induced by Fe2+. There were not much influence of RSP on hemolysis of mice red blood cell. In a word, antioxidant activities of RSP-R and RSP-1 were better than others.4.RSP can inhibit the growth of S180 tumor,the mechanism may have something to do with its antioxidant activities and increasing organizeimmune capa...
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