关键词： 龙眼； 筛选； 保鲜效果； 应用
Abstract
The Longan fruit as experimental materials In this study, The paper studied that the inhibition function of microorganisms for longan in the period of postharvest, and the relationship between rotting of the Longan fruit and the activity of enzyme and the function of microorganisms, and the fresh mechanism.of microorganisms for longan fruit. The results were as follows.
Pathogens were isolated and identified postharvest of longan fruit with coated with the dilution plate method and by Microbial Identification System (MIS). The results showed that: fifty-four bacteria and 10 strains of pathogenic fungi were isolated,They were Staphyloccus simucans、 Micrococcus lutens-GC、Brevibacillus choshinensis、Clavibacter micrhiganenisis among the bacteria, and the content of bacteria in peel more than that in the pulp . We screened one antagonistic bacterium strains with the inhibitory effects on the longan fruit to keep fresh using the method of serial dilution, we named it for JK-2 . JK-2 strain was Breivbacillus brevwas.
The browning and rotting of longan pericarp had close relationship with the activity of POD and PPO. In a natural state, along with the decay of longan, the activity of POD, PPO increasing gradually,but Superoxide Dismutase (SOD) activity was contrary. JK-2 was made into the fermentation broth, which at the concentrations of 3×106 CFU/ml . Fermented JK-2 to get fermentation broth of 3×106 CFU/ml. Determined the activity of POD 、PPO、SOD and the MDA content of longan fruit after treated with the different concentrations of fermented of JK-2 under indoor temperature condition, The results showed that: JK-2×10 was able to inhibit POD、PPO activity and the MDA content, while promoting SOD activity.
The effects of the preservation were different by different storage methods,The results showed that: the effects of longgan fruit enclosing with paper were better than that using leaves to cover over it ,So we can store longgan fruit using the paper parcel, which keeping the longan fruit fairly quality ,and the length for preservation had prolonged on longan fruit; The different using way of JK-2 on the Preservation of longan were also different, The results showed that: the good fruit rate was higher than the control, using JK-2 treatment after five days of storage in room temperature of 29-30 degree and relative wetness of 60-70%. And the effects of the retaining freshness for longan fruit using JK-2 preharvest treatment was better than that using JK-2 postharvest handling.

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