Extraction And Separation,Characterization Of Protein In Camellia Aleifera Seed Cake And Antioxidant Activity Of Its Digestion Products In Vitro

China is a large country in the field of Camellia oleifera Abel production. The oil seed cake is a byproduct of oil refinery of C. oleifera Abel.C. oleifera Abel is usually used to extract oil but the utilization rate of the tea seed cake is low. It not only results in waste of resources, but also puts pressure on the environment to some degree. Oil tea cake contains a large number of biological active ingredients that have physiologi-cal functions. Therefore, if we studied and utilized these active ingredients, it would have importantly practical significance to improve the comprehensive utilization rate for the oil tea cake. This paper had a systematic and comprehensive study on the pro-tein belonging to the oil tea seed cake. Step-by-step extraction method was used to extract protein, and albumin was extracted, purified and separated. Furthermore, the function and physical and chemical properties of tea seed cake protein isolates (TPI) were studied. In addition, the test model of digestion process of TPI in simulated gastric fluid (SGF) and intestinal fluid (SIF) was established, and antioxidant activi-ties of digestion products were also studied. It indicated that TPI can protect the stomach and intestine. The details and results were as follows:1. Albumin, globulin, alcohol-soluble protein and gluten were extracted success-sively, and their abilities to remove hydroxyl free radicals(OH) were also tested. The results showed that Albumin and gluten were the main components of the tea seed cake protein, accounting for45.86%and40.33%of the total protein respectively, while globulin and alcohol-soluble protein were less, accounting for5.62%and4.25%of the total protein respectively. Globulin almost did not have ability of removing hydroxyl free radical (OH), and at the same concentration, albumin had a significant ability to remove hydroxyl free radical. The removing rate was38.56%at the concentration of2mg/mL, while the rate was92.13%at the concentration of8mg/mL,showing a concentration dependence relation.2. The effect of NaCl solution (0.15mol/L), phosphate buffer solution (20mM, pH7.4) and Tris-HCl (20mM, pH7.4) on the extraction rate was compared, and the response surface methodology (RSM) was used to optimize albumin extraction process. The results showed that the Tris-HCl solution had the highest extraction rate The optimum extraction parametes of albumin were obtained as follows:temperature47℃, the ratio of material to liquid1:16, time50min.3. SDS-PAGE gel electrophoresis was used to determine the molecular weight of albumin, and albumin was separated by DEAE-Sephadex A-25anion exchange and Sephadex G-50gel chromatography. The results showed that the molecular weight of albumin ranges from10to40KDa. The B, a functional component, was obtained after albumin was separated by DEAE-Sephadex A-25anion exchange chromatography, and the removing rate of-OH was59.2%.Finally, the hydroxyl free radicals (. OH) removing rate of B-2reached70.82%after B was separated by Sephadex G-50gel chromatography. The molecular weight of B-2was about14000Daby SDS-PAGE.4. The function and the physical and chemical properties of TPI were studied. The results showed that TPI had better water solubility compared with SPI with its protein solubility reaching72.57%. Emulsifying activity and emulsion stability of TPI were better than those of SPI, but the foam ability and foam stability were lower compared with SPI. The oil-absorbing capacity of TPI was3.12g/g at30℃, higher than that of SPI (2.51g/g). Water-absorbing capacity of TPI was2.93g/g at pH7.0, being lower than that of SPI (3.67g/g).The denaturation temperature was88.33after differential scanning calorimetric (DSC) measurement.5. The protection of stomach and intestine by TPI was researched and the func-tional fraction was isolated. The digestion rate of TPI was reached80.01%, after it was digested by SGF and SIF. When the peptides adsorbed on macroporous resin DA201-C were eluted by75%ethanol, the ash content was significantly decreased and the protein content increased to92.79%, compared to86.65%before eluted. Accordingly, the removing rate of Hydroxyl free radical increased from61.75%to72.78%and that of superoxide anion (-O2) increased from44.78%to55.43%. When the eluted fraction was isolated by Sephadex G-25gel chromatography. four peaks were obtained. However, peak3had obvious radical scavenging activities, with the removing rate of-OH and-02were86.36%and60.23%respectively.