Study Of Preservative And Fresh-Keeping Effects Of Tea Extracts On Postharvest Peaches

The pathogens infection and oxidative aging for metabolism are the main reasons of fruit decay. In order to inhibit postharvest peach from pathogens infection and oxidative aging, the effect of tea extracts on post-harvest peach preservation and its mechanism were investigated. The main results are as follows:1、Certain concentration of tea polyphenols (TP) could apparently restrain peaches from browning and dehydrating, delay the loss of soluble solids contents (SSC), significantly postpone fruit softening and the loss of vitamin C (Vc), reduce the production of malondialdehyde (MDA) and regulate the activity of polyphenol oxidase (PPO). Thus, TP treatment could delay aging and decay of postharvest peach.2、The inhibition effects of tea extracts A and B on Monilinia fructicola and Rhizopus stolonifer were studied by plate growth rate method in vitro. The results showed that the minimal inhibitory concentrations (MIC) of tea extract A on the above two fungi were respectively 20.0 g/L、60.0 g/L, and the median effective concentrations (EC50) were 10.4 g/L、7.8 g/L. The MIC of tea extract B on above two fungi were respectively 40.0g/L、40.0 g/L, and the EC50 were 7.4 g/L、1.5 g/L. The mixture of tea extract A and B had only an additive action through co-toxicity coefficient method. Their mixture with a ratio of 3.5:4.9 of A:B could significantly induce the morphological changes of M.fructicola and R. stolonifer. The study stated that tea extracts A and B had significant inhibition against the two fungi and the antifungus mechanism may be that they could affect pathogenic fungus growth.3、The antifungus experiment in vivo showed that tea extracts mixture could delay M. fructicola infection into peaches and reduce peach sickness rate. They also could postpone the appearance of R. stolonifer. The results also showed that the mixture could enhance the activities of phenylalanine ammonia-lyase (PAL) and polyphenoloxidase (PPO) and enhanced the disease resistance of peach fruits. The results suggested that tea extracts mixture could inhibit the infection of pathogenic fungi into peaches and its antifungus mechanism might be relative to that they cound induce the enhancement of defense enzymes.4、The preservative and fresh-keeping experiment on peaches showed that tea extracts mixture could reduce the loss of SSC, Titrable acid (TA) and Vc, delay the second respiratory peak, decrease the respiratory intensity, reduce membrane permeability and MDA content and enhance the activity of PPO and PAL. The results showed that tea extracts mixture displayed good preservation effect on peach through keeping cell membrane intact, regulating related defense enzymes activities and delaying aging.