| Strawberries are rich in nutrients and have great benefits for human health, but they are very easy damaged during their selling and store up period, affect their quality and shelf life. In this paper the strawberry variety of "Fengxiang" was selected as experimental material, the activities of amylase, cellulase, polygalacturonase, polyphenol oxidase and peroxidase during strawberry senescence were studied and the microbic colonies characterization on strawberry surface was also analysed by physiological identifcation. The results were as follows:During the senescence process, the enzymatic activities in strawberry had different changes. Cellulase was gradually increasing with the senescence time and the activity of cellulose could reach 600U/g fresh weight; the enzyme activity of polygalacturonase fluctuated between 100~200U/g fresh weight. The amylase activity changed a little in early senescenc stage and presenting in a fluctuation later; in the later of senescence stage its activity was much higher than that before, the maximum could reach at 79.5U/g fresh weight. The data in polyphenol oxidase and peroxidase activity showed that they were first maintained an upward trend and were higher in the later senescence stage. The activity of polyphenol oxidase was the least in all the enzymatic activities and changed in a certain small range at the late stage of senescence.23 strains of microorganisms were isolated from strawberry surface. Among them 5 strains were belong to bacteria, 11 strains for actinomycetes, 4 strains for yeast and 3 strains were fungi.The major microorganisms responsible for strawberry corruption were bacteria, Rhodotorula, Dekkera,Hansenula anomala(Hans.)Sydow and pathogenic fungi(Aspergillus, Botrytis cinerea, Penicillium). So the control of some enzymatic activity and reduced microbial contamination in strawberry postharvest storage period would be very important to extend the shelf life of strawberry. |
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