Effect Of Chitosan On Sprouting And Quality Of Postharvest Potatoes

Effect of different concentration chitosan on sprouting and quality of postharvest Favorita potatoes at 22±4℃, RH55%-80% and 4±1℃, RH70% storage was investigated. Furthermore, the content of solanine in different part of chitosan-treated potato during storage was determined by High Performance Liquid Chromatograph(HPLC). Also, effect of chitosan on Polyphenol oxidase(PPO) which was extracted from potato was assayed. Experimental results were as follows:(1) Through experiments with effects of different concentrations of chitosan treatment on potato tubers when stored at ambient temperature or 4℃, found that: ① chitosan treatment on potato has a certain extent inhibition on tuber sprouting, when the chitosan concentration was 20mg/kg, inhibition effect was the best; then the sprouting rate decreased as concentration increased; ② chitosan has a certain role for the inhibition solanine content increases in potatoes, while 20mg/kg chlorpropham was the best, followed by 20mg/kg chitosan, others was not obvious; otherswise 1000mg/kg chitosan has an opposite function, the result can also described that solanine in potato content and germination is proportional relationship.(2) Chitosan-treated potato tuber exhibited better potato quality based on the data of the content of starch, reducing sugar, and weight lose than that of the control at 22±4℃(RH55%-80%) and 4±1℃(RH70%) storage. When store at room temperature, chitosan showed a more significant effect than chlorpropham under the same concentration (20mg/kg) treatment, just the opposite as store at low temperatures.(3) Research on the effects of different concentrations of chitosan treatment on potatoes PPO activity in tubers, shows that chitosan can suppress PPO activity during potato at 22±4℃(RH55%-80%) and 4±1℃(RH70%) storage, and the lower the concentration of chitosan, the inhibiting effect is more obvious,20mg/kg chitosan is the best.(4) Further we extracted PPO enzyme from fresh potato tubers, explored the inhibition of water-soluble chitosan, polymer chitosan, chlorpropham and a-methyl naphthylacetate on potato PPO enzyme, shows the following conclusions: Water-soluble chitosan and a-methyl naphthylacetate has no inhibition on potato PPO, polymer chitosan and chlorpropham has; polymer chitosan showed noncompetitive performance types of inhibition mechanism on PPO, inhibition constants of free enzyme Kis is 18.18mg/kg, chlorpropham showed mixed effect on potato PPO inhibitory mechanism, inhibition constants of free enzyme Ki was 4.03mg/kg, the inhibition constant of complex of enzyme and substrate Kis was 30.66mg/kg.