Study On Making Preservative Of Snap Beans By Using Chitosan

This study dealed with making preservative of snap beans that were distinguishing vegetable in Hei Longjiang province by using edible chitosan and other material. (l)By taking crab shell as raw material, a treatment by use of acid and alkali was carried out to extract chitin. Afterwards, conducting a de-acetyl treatment prepared chitosan; (2)By separating and appraising pathogen during the storage period of snap beans, five types of presertives were used for inhibiting the propagation of the pathogen and compared their inhibition zones and inhibitory content to determine their antimicrobial effect; (3)By determining sense index, moisture and nutrition composition of snap beans, the quality changing pattern of snap beans was discussed. The Lg9(34)orthogonal test design was adopted to determine the optimum level of the chitosan preservative. The results showed that: (l)When chitin was mixed with 55% NaOH solution in proportion of 1:10(W/V, g/mL) and the reaction took place at temperature of 105癈 for 6 hours, chitosan having a de-acetyl percentage of 94% and viscosity of >200cps could be available; (2)The pathogens were Xanthomonas campestris and Botrytis cinerea. Sodium dehydroacetate is most effective antimicrobial agent; (3)During the storage, the quality changing regularity of snap beans was: the content of water, victamin C and reducing sugar decreased constantly, the content of chlorophyll decreased at first, then increased slowly until a cumulative peak appeared, and decreased finally. After snap beans with a chitosan-based coating were kept in storage at 12癈, 80-85% RH for four weeks, sense index and internal quality of these coatings such as the content of water,victamin C, chlorophyll and reducing sugar were higher thanthese of control group. And sense index of test groups stored at room temperature 30℃, 50~60%RH for 10 days were higher than these of control group. The results of Lg9(34) orthogonal experiment showed that the optimum proportion of the preservative was respectively as follow: Chitosan quantity 2.0%, Sodium dehydroaceate 0.2g/kg, 6-BA...