Study On The Extraction Of Naural Fresh-keeping Agents For Fruits And Effection On Fruit Keep-freshing

Lilac flower and Rheum officinale are traditional natural plant in China,have an extensive activities in the aspects of antimicrobial activity and antibacterial materials in food and so on. Pathogens were separated from affected parts of two kinds of postharvest fruits (Red Globe Variety and mandarin orange of Three Gorges). After purificated,the pathogens were transferred back to fruits in order to measure the pathogenicity . The selected main pathogenic bacterium of Red Globe Variety and mandarin orange of Three Gorges as the purpose bacterium , extraction process of antimicrobial constituents from Lilac flower and Rheum officinale were studied, then compounded them were to arrived at the better proportion of the combination solution. Used combination solution on fruit ("winter-jujube"and"mandarin orange of Three Gorges") fresh keeping. This research would provides a necessity to guide on developingand using Chinese herbal medium extracts on antisepticise and fresh-keeping.No. 2 strain pathogenic bacteria was identified as Deuteromycotina,Hyphomycetes,Moniliales,Moniliaceae,Cephalothecium and it caused black spot disease of Red Globe Variety. The main screening pathogenic bacterium of"mandarin orange of Three Gorges and winter-jujube"were: Alternariaalternata, Monilinia fructicola and Penicillium expansum.Optimization of their ultrasonic wave extraction conditions were studied by the single factor and orthogonal tests. The optimum concentration of ethanol solution as extracting solvent, the ratio of solid to liquid, distill time and distill temperature were as followed,Lilac flower: 75%, 1:15, 45 min, 40℃; Rheum officinale: 80%,25 min,1:45,90℃。Combination solution were generated by the above Lilac flower and Rheum officinale extractions. Inhibitory effects of extrations and combination solution were made by means of MIC. The tests showed that, combination solutionⅡwas the best combination solution, which has the strongest inhibitory effect on any pathogenic bacteriums in the study, its colony diameter was 2.088cm .The results of storage on winter-jujube and mandarin orange with Chinese herbal combination solution that: the storage at (16±1)℃and -2~-3℃, the Chinese herbal combination kept winter-jujube's firmness index. Meantime, the treatment effectively prevented decrease of Vc content and increasing of reducing sugar content.The tested winter-jujubes mandar in treated with Chinese herbal combination has the best fresh-keeping quality with good fruit rate 94.45% during storage of 15 days at room temperature, 10.4% higher than that of control; during storage of 100 days at low temperature the good fruite rate 94.18%, 8.95% higher than that of control. Chinese herbal combination solution treatment effectively protected the cell membrane system, reduced the accumulation of MDA, and also maintained the POD activety in a high level and weakened the membrane lipid peroxidation, as a result it gave winter-jujube better protection and slowed down its progress of senescence.The test of bacteriostasis and storage showed that: combination solutionⅡhas a certain bacteriostsis effect on fruit storage and fresh keeping, it can be used on fruit fresh keeping as crude preservative.