Microwave-assisted Extraction Of Water Enzymatic Hydrolysis Of Tea Seed Oil And Protein

In this paper, the extraction of puer tea seed oil by microwave-assisted aqueous enzymatic method, and the extraction technology, demulsification process and the antioxidant activity of protein hydrolysis were studied. The optimum conditions of the extraction of puer tea seed oil, the optimum demulsification conditions of puer tea seed emulsion, the scavenging rate of free radical of puer tea seed protein hydrolysis, and the relative molecular weight of puer tea seed protein hydrolysis were determined. The main findings are as follows:1The optimal conditions of microwave-assisted aqueous-enzyme extraction of puer tea seed oilThrough single factor and the orthogonal experiment to investigate the effect of the enzyme amount, enzymatic hydrolysis parameters and microwave parameters of the puer tea seed oil extraction rate. The optimal conditions for puer tea seed oil extraction were:The complex enzyme amout were α-amylase0.5%+neutral proteinasel.5%+papain1.5%+bromelain1.0%; the enzymatic hydrolysis parameters were the hydrolysis pH7.0, the ratio of solid of liquid1:6, the hydrolysis temperature60℃, the hydrolysis time6h; and the microwave parameters were microwave power600W, microwave temperature50℃, microwave time6min. In this optimal condition, the puer tea seed oil extraction rate was92.58%.2The optimal demulsification conditions of puer tea seed emulsionOptimization of demulsification of puer tea seed emulsion with freeze-microwave thaw by response surface methodology (RSM), the model was set up as follow: Y＝38.0663+4.9908X1+0.02068X2+1.3621X3+0.6785X4+3.2125×10-3X1X2+0.04163X1X3+0.03250X1X4-2.5000×10-4X2X3+1.4250×10-4X2X4-1.8750×10-3X3X4-1.2271X12-2.6100×10-5X22-0.01339X32-0.01251X42The model was a significant regression (P<0.0001), and the correlation coefficient was R2=0.9814and RAdj2=0.9629, it showed that there was a good correlation between the variable and dependent variables. The optimal demulsification conditions were as follows:freezing at-20℃for4h, microwave power500W, microwave thaw temperature50℃, microwave thaw time30min. Under these conditions, the demulsification rate was97.53%.3The fatty acid composition and quality analysis of puer tea seed oilThe content of unsaturated fatty acid of puer tea seed oil by microwave-assisted aqueous-enzymatic methods was80.57%, the content of oleic acid and linoleic acid were63.39%and16.76%respectively, the results showed the puer tea seed oil has high nutritional value. Compared with pressing, the content of unsaturated fatty acid of puer tea seed oil by microwave-assisted aqueous-enzymatic method was higher than, and it didn’t contain the erucic acid, the results showed that microwave-assisted aqueous-enzymatic method can better maintain the nutritional value. The peroxide value (mmol/Kg) was2.29, and the acid value (KOH, mg/g) was3.03, these results were conformed to the national standards of camellia oleifera seed oil.4Study on the antioxidant activity of puer tea seed protein hydrolysisFirst, used Vc as the positive reference, the total antioxidant activity of puer tea seed protein hydrolysis was studied. The result showed, the puer tea seed protein hydrolysis had antioxidant ability, and with the increase of protein concentration the antioxidant ability was stronger. Then, the scavenging rate of OH, DPPH-and O2-free radical were studied respectively. The result showed, the puer tea seed protein hydrolysis had scavenging effect on OH、DPPH· and O2-free radical, and with the increase of protein concentration the scavenging effect was stronger.5The relative molecular weight distribution of puer tea seed protein hydrolysisThe average length of puer tea seed protein hydrolysis was4.01, the Mw of those components was459.01Da. The relative molecular weight of puer tea seed protein hydrolysis were determined and analyzed by HPGPC. The content of oligopeptides of relative molecular weight below1000was increased from90.92%to95.75%, after ultrafiltration with membrane of weight cut off5000Da.