Effect Of Volatile Metabolites Of Hanseniaspora Uvarum On Storability Of Postharvest Strawberry

Using antagonistic yeasts to control postharvest diseases of fruits and vegetables had become a research hotspot in recent years.Antagonistic yeasts were safety,environmental protection,and had good inhibition to fruit and vegetable plant disease.Yet the study of antibacterial mechanism and volatile metabolites of antagonistic yeasts was very little.This thesis taken "Hong yan" strawberry as the research material,Hanseniaspora uvarunm as the experimental strains,studied from three aspects,the inhibition of volatile gas on strawberry grey mould,the effect of volatile gas on strawberry storage performance,and volatile gas composition analysis.The specific research results were as follows:1.Strawberry fruits treated with Botrynis cinerea were sealed in the dryer which contained several culture mediums with yeasts in the bottom.The results showed that volatile gas of yeasts reduced the incidence of grey mould.In active carbon added test,the effect of volatile gas on grey mould was disappear which indicated that the volatile gas of antagonistic yeasts was the dominating factor for decreasing the incidence of grey mould rather than low oxygen and high carbon dioxide gas caused by yeasts or strawberry fruit respiration.2.Strawberry fruits with Botrytis cinerea were sealed in the dryer and fumigated in 0 days,1 day,2 days,3 days respectively,infection situation were finally observed.The result showed that strawberry fruit fumigated in three days had the lowest incidence rates of grey mould,and the incidence of strawberry fruit gradually decreased with longer duration of fumigation.Thus,in 1～3 days of yeast growth cycle,the longer time was fumigated,the bacteriostatic effect was better.3.Strawberry fruits fumigated under normal temperature and low temperature for three days,were stored under the conditions of air temperature at(2 ±1)℃ and relative humidity at 95%.The effects of volatile gas on strawberry storability were studied.The result showed that volatile gas could significantly reduce the rot of strawberry fruit,keep strawberry appearance better,slow down the change of weightness,hardness,color,soluble solids,pH.This volatile gas could also enhance the enzyme activities of peroxidase(POD),superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX),polyphenoloxidase(PPO),phenylalanine ammonia(PAL),the super oxygen anion generation and reduce the accumulation of malondialdehyde(MDA)content.For the effect on strawberry refrigerated quality,low temperature fumigation treatment was better than the normal temperature fumigation treatment,while no siginificant difference was between them.This speculated that volatile gas can improve the storage performance of postharvest strawberry.4.The volatile gas of H.uvarum combined with or without B.cinerea,which inculated in strawberry fruit were determinate by GC-MS.The results showed the dominant gas compositiones of yeast were alcohols,acids,esters and aldehydes.When cultured together with B.cinerea,the antimicrobial constituents in the volatile gas increased.The composition such as 1,3,5,7-cyclooctatetraene,propanoic acid,ethyl ester,1-butanol,3-methyl-,acetate,nonanone and 3-methyl-,1-butanol,ethanol had been confirmed as antibacterial.The experiment confirmed volatile gas of H.uvarum had inhibitory effect on grey mould.Due to the complexity of volatile gas composition,various sort,the main antibacterial ingredients and antibacterial mechanism should be further studied.