Studies On Effect Of Natamycin On Muscat Grape Postharvest Preservation

Natamycin is a natural and efficient biological preservative,which has better physical and chemical stability,security,non-toxic and the fungi and yeast can be effectively inhibited by it.In this paper,experiments were designed to examine the inhibition of natamycin on Botrytis cinerea. Meanwhile, muscat grapes were used as the test materials,which were treated with the different concentrations of natamycin before the harvest of grape, The inhibitive activity of natamycin on Botrytis cinerea was studied through through fliter method,growth rate method,hanging drop slide method and living damage inoculation method and the changes storage quality and physiology of grape fruit were studied through determination of appearance,quality and physiological indicators.The results of different natamycin solution systems A302showed that0.5g/L natamycin combined with0.1%of citric acid was the most significant.The results indicated that the inhibitive activity of natamycin combined with citric acid on postharvest Botrytis cinerea was higher significantly (p<0.05%) than the individual treatment,in which0.5-1g/L natamycin combined with0.1%of citric acid had the best effect. The inhibition rate of the mixture of0.1%of citric acid and0.5-1g/L natamycin on mycelial growth and conidial germination increased by69.93%and65.61%respectively,which was33.24%and54.40%higher than sum of inhibitory rate of each component respectively and median effect concentration(EC50) were0.435�'�0.491g/L on mycelial growth and conidial germination, and the disease spot area of grapes was reduced significantly.The normal temperature (25±0.5℃) storage experiment suggests that the good fruit rate was increased by15%, the Vc content and the TA content of grape fruit were increased by9.7%and12.2%respectively. Meanwhile,the fruit firmness was maintained by0.5g/L natamycin,the lower respiratory intensity was maintained by the same treatment,good flavor was kept and the quality of storage was improved.The cold storage (0±0.5℃) experiment suggests that the activities of POD and CAT were inhibited by temperature and natamycin.On the one hand,the POD and CAT activity level of stability can be controlled directly or indirectly by0.5g/L natamycin combined with0.1%of citric acid, the SOD activity was increased effectively,active oxygen was removed timely and effectively, membrane permeability was controlled effectively, the content of MDA was reduced and the aging process was slowed down; on the other hand, the Pro and total phenol activity level of stability can be controlled directly or indirectly by0.5g/L natamycin combined with0.1%of citric acid, the PAL、β-1,3-glucanase and endo-chitinase activity were increased effectively, fruit surface pathogen infection was inhibited,the PPO activity was reduced and the resistance of disease was improved.As the biopreservative of grape,the postharvest decay of grape fruit which was led by the pathogenic fungi was inhibited effectively by natamycin.Effect of0.5g/L natamycin was the most significant.