Study On The Activity Analysis And Application Of Extracts In Vegetable And Fruit Preservation From Oxalis

The genus Oxalis which is blindly important Chinese herbal medicine belongs to the family Oxalidaceae in botany classification. Currently, a few studies show that the extractions of Oxalis have relatively high antimicrobial and antioxidant activity. In future, Oxalis will become a kind of promising natural fresh-keeping agents. In this paper, Oxalis was extracted successively by systematic solvent method to investigate its biological activity and was used for fresh-keeping as vegetable and fruit antistaling agents.1.Activity Analysis:The whole plant of Oxalis was collected and soaked with a certain amount of 95% ethanol, the active substances were extracted from yellow and red flower Oxalis successively extracted using chloroform,ethyl acetate and n-butanol.The four different polar solvent(chloroform,ethyl acetate,n-butanol,aqueous) extracts were evaporated under reduced pressure to obtain four kinds of crude extractum respectively which were studied on the antibacterial, antitumor in vitro and antioxidant experiments.The scavenging capacity on DDPH radical,hydroxyl radical and superoxide anion free radical were tested in the antioxidant experiments, though comparison and analysis, chloroform and ethyl acetate extracts of yellow and red flower Oxalis have relatively high antioxidant activity. In the antibacterial experiments antibacterial activity on Staphylococcus aureus, Escherichia coli, Albicans Saccharomyces and Pseudomonas aeruginosa of the four fractions from yellow and red flower Oxalis were studied by minimal inhibitory concentration method(MIC), the results indicated the extracts have inhibitory activity to Escherichia coli and Albicans Saccharomyces.2.The Preparation of Oxalis fresh-keeping Coating and Preliminary Screening:The aqueous extract of Oxalis was obtained by microwave assisted hot water method, then added different ratios starch-acroleic acid copolymer aquogel, mixed evenly, leaded to the preparation of different groups Oxalis fresh-keeping coating. The coating was used to treat the tested fruits and the weight loss and disease rate of treated fruits during storage were periodically measured in order to its fresh-keeping effect, the results showed that copolymer aquogel with a 4:1 ratio of starch-acroleic acid and the 1g/m L of aqueous extract of Oxalis evenly mixed which were the best proportion to obtain the Oxalis fresh-keeping coating.3.Application of Vegetable and Fruit preservation with extract of Oxalis :Taking daughter orange, cherry,cherry tomato, orange as materials, the effect of Oxalis fresh-keeping agents of presvative on nutritional indicators and antioxidant system were studied. The results indicated that, compared to control, all Oxalis fresh-keeping agents treatment could significantly reduce weight loss and disease rate, maintain the content of total acid, soluble solidand total sugar, protect VC, enhance the CAT, SOD activity and decrease the POD activity. Meanwhile it could slow obviously retain the consumption of nutrient content, and prolong the shelf-life.