Extraction Of Tea Seeds Protein And Antioxidant Activity Of Its Hydrolysates

Tea seed is Tea tree (Camellia sinensis O Ktze) seed, rich in15%to20%of the protein. Currently, processing applications for tea seed mainly is confined to the Tea seed oil and tea saponin production, while ignoring the development of protein. Tea seed protein ratio is efficient, as had a high nutritional value and can be developed resistance. Taking tea seed as experimental object, determine protein content by using Kjeldahl determination and learned that it is13.48%.Through the ultrasound-assisted extraction and enzymatic method extraction were used. Collection protein purity of high and hydrolyzes the protein, then gets the suitable protease for tea seed, and research tea seed protein hydrolysates antioxidant capacity, the gel filtration be used on separating protein hydrolysates and measuring molecular mass range. The main results are as follows:In order to improve the efficiency of tea seeds protein extraction, the ultrasound-assisted extractions were used. On the basis of single factor test, the optimization of maximum efficiency of protein extraction was investigated using orthogonal test with four variables including the ratio of solid to liquid, pH, extraction temperature and extraction time. The results showed that the optimized parameters of the almond dregs protein extraction process were as follows:the ratio of solid to liquid1:25, pH9.5, extracting temperature40℃， and extracting time40min. Under this condition, tea seed protein extraction efficiency can reach to79.54%, protein purity was74.76%.In this study, extraction protein from the tea seed by enzymatic method. By neutral protease was screened out, the results showed that the best effects of factors on extraction were alkali protease. In order to optimization the alkali protease extraction of tea seed protein by the quadratic regression rotational composite design. Based on the single factor, alkali protease concentration, pH, enzymatic extraction time and temperature were selected as the test factors. The regression mathematics model was established with extraction efficiency of tea protein. Optimization extraction conditions were achieved through variance analysis and mathematical model optimization. The results showed that the best condition for the alkali protease extraction of the tea seed protein:solid-liquid ratio of1:25, alkali protease concentration200U/g, pH10.5, enzymatic extraction time55min and temperature45℃.Under this condition, tea seed protein extraction efficiency can reach to75.83%, protein purity was79.86%.The degree of hydrolysis and DPPH free radicals scavenging activity of tea seed protein adopt alkaline protease, papain and neutral protease were role.The results show that alkaline protease hydrolysates have stronger scavenging activity and hydrolysates against DPPH free radicals have hign efficiency. On the basis of single factor test, optimum of enzymatic hytrolysis conditions by response surface methodology: concentration of substrate was3.4%, enzyme concentration was5800U/g, pH8.7, the temperature of hydrolyzing was57℃and the time of hydrolyzing was4h. Under these conditions, hydrolysates against DPPH free radicals reached85.68%, degree of hydrolysis is14.0%.The test determined the antioxidant activity of polypeptide tea seed sprouts. Reducing power and free radical scavenging ability of polypeptide tea seed sprouts are increased with the polypeptide concentration increased, in a certain range of dose relationship. When the peptide concentration was10mg/mL, the reducing power little higher then BHA (0.2mg/mL), its rate of superoxide anion radicals、hydroxyl radicals and DPPH free radicals reached66.54%、73.02%and86.34%, the IC50of superoxide anion radicals、hydroxyl radicals and DPPH free radicals were4.83mg/mL,3.28mg/mL and3.17mg/mL.The capability of scavenging sodium nitrite and disconnecting nitrosamine synthesis with tea seeds oxidative peptides were determined by spectrophotometer under simulated human gastric juice, and was compared with vitamin C. The results demonstrated that the sodium nitrite scavenging rate and the nitrosamine synthesis disconnecting rate both showed the positive correlation with the concentration of tea seed oxidative peptides. The capability of scavenging sodium nitrite was79.89%, the capability of disconnecting nitrosamine synthesis was70.97%.Compared with vitamin C, tea seed oxidative peptides has strong capability of scavenging sodium nitrite and disconnecting nitrosamine synthesis.Tea seeds protein hydrolysates were separated by gel chromatogrphy Sephadex G-25column. Obtain three fractions (Fra.I, Fra.II and Fra.Ⅲ) and superoxide/hydroxyl/DPPH radical scavenging capacity. The results show that Fra.II has stronger scavenging ability on free radicals, obtained in700nm in absorbance is0.195were measured using reducing power, superoxide radical was22.24%, hydroxyl radical was18.89%, and DPPH radical was21.66%.