Optimization Of Freeze Dried Grape Seed Powder Processing And Its Oxidation Resistance Analysis

Grapes, the fruit of world's highest economic value, the planting area and yield of our country both ranks the forefront of the world. Grapes not only be with rich nutrient in pulp, but also contain a lot of nutrient substance and function components in seed and skin. Grape seed accounted for about 4% of the fresh fruit weight, and it is a by-product of winemaking and grape juice production, with strong function, rich source.In this study, did a series of tests with grape seed, then get the best technology of freeze-dried grape seed powder processing and analyze the resistance to oxidation of the final product. The main research results of this experiment are as follows:1. Combined with the grape planting area, yield and seed yield, procyanidins content, this study chooses cabernet sauvignon for test. Compared the effect of reducing bacteria and procyanidins content among steam sterilization, sterilization, salt water washing and sterile water washing, sterile water is the best aseptic method. For taking seed from fresh fruit directly and fruit juice production waste residue, this study add operations of pectinase processing, and select the best pectinase processing conditions through orthogonal test, the results show that the optimal parameters for pectinase processing is:concentration 0.4%, time 25 min, temperature 60 ?.Grape seed after pectinase processing, are cleaner, and its sugar content reduced by 65.97%, dry seed procyanidins content increased by 0.07%.2. By single factor tests and response surface method, the study obtains the best vacuum freeze drying parameters:material thickness 18.00 mm, edition set temperature 35 ?, vacuum degree 40Pa. Then doing experiment on this condition, to map Grape seeds drying curve and the diagram of drying time and moisture content.3. Functionality of the freeze-dried grape seed powder and dried grape seed powder is compared, through the determination of drying time, total phenol content, procyanidins content and antioxidant activity.Test result is:the total phenol content, procyanidins content and antioxidant activity of freeze-dried grape seed powder were higher than that of dried one by more than 0.46%, respectively is:the total phenol 101.96 mg/g, procyanidins 79.23mg/g, DPPH free radical clearance rate 83.5%, clearance rate of superoxide anion 72.50% and hydroxyl free radical clearance rate 80.46%, iron ion reducing power 0.902 (FeSO4 equivalent tendency mmol/L). Comparing the freeze-dried grape seed powder and commercially available one by in vitro digestion experiment, the results showed that the procyanidins content and antioxidant capacity of freeze-dried grape seed powder both are higher than the commercially available one's by more than91.20%,32.85%,22.90%,29.09%,95.45% respectively.4.By liquid mass spectrometry analysis, three kinds of procyanidins monomer, two kinds of dimer and three kinds of trimer can be detected.5.The grape seed powder should be chosen vacuum and opaque packaging, stored under low temperature, and suitable for application in the vinegar.