Studies On Delaying Ripening And Senescence Of Harvested Pear(Pyrus Pyrifolia Nakai Cv.Huanghua) Fruits By 1-MCP Treatment And Its Action Mechanism

Huanghua pear(Pyrus pyrifolia Nakai,cv.Huanghua)is the one of the southern fruits for summer season.Pear has yellowish-brown epidermis,thin peels,large conical pulp,delicate white flesh,crisp texture to be juicy and delicious.Huanghua pear has a variety of nutrient,containing fructose,glucose,iron,phosphorus,vitamin C,carotene and so on.It is welcomed by consumers with a high nutritional value.Huanghua pear is liable to be bruised,soft and rotten after harvest,which affects seriously the edible quality,goods value and has difficulty in storage and transportation.In this study,taking the pear fruit varieties cultivated in Fujian as test material,new ethylene suppression products AnsiP-STM was used as a preservative,after treatment at temperature(25±1)? for 12 h,at temperature(25±1)?,85?90%relative humidity for storage.The main conclusions are as follows:(1)Compared with the control fruits,the treatments with 1-MCP at 0.045 ?L·L-1,0.45?L·L-1,0.9 ?L·L-1 and 1.8 ?L·L-1 lowered respiration rate and respiratory peak of Huanghua pear fruit,delayed the increase of cell membrane relative leakage rate of fruit,inhibited the decrease of hue angle(h°)value of fruit surface,kept higher fruit firmness,and kept higher contents of titratable acid in fruit,soluble sugar,reducing sugar and chlorophyll in pericarp,retarded the change of apparent color of fruit,and decreased fruit weight loss and fruit decay.Among the above 1-MCP treated fruits,the fruits pre-treated with 0.9 ?L·L-1-MCP for 12 hours could keep best fruit quality.From the results,it could be concluded that pre-treatment with 0.9 ?L·L-1 1-MCP for 12 hours could be used as the optimum conditions for maintaining fruit quality and prolonging storage life of Huanghua pear fruits during storage at(25±1)?.(2)Huanghua pear fruit respiration rate and breathing peak can be effectively reduced by the treatment of 0.9 ?L·L-1 1-MCP at(25±1)? storage,delaying the increase of fruit membrane permeability.The decrease of the hue angle h° value in fruit surface was inhibited to maintain a high fruit firmness,titratable acidity,ascorbic acid content,soluble sugar,reducing sugar and fruit chlorophyll content.The appearance change on fruit color was delayed and the fruit weight loss and decay were reduced to improve the effect of fruit storage and freshness-keeping.(3)The hardness of Huanghua pear fruit was maintained by the treatment of 0.9?L·L-1 1-MCP to reduce amylase,PME,PG,cellulase,beta-Gal,and other cell wall degrading enzyme activity.The decrease of starch content,cell wall material content,covalently bound pectin,cellulose,hemicellulose content and the increase of water-soluble pectin content were delayed,which retarded fruit softening effectively.(4)0.9 ?L· L-1 1-MCP treatment kept higher activities of active oxygen scavenging enzymes of Huanghua pear fruits such as superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)and ascorbate peroxidase(APX),and lipoxygenase(LOX),contents of endogenous antioxidant substances such as ascorbic acid(AsA)and glutathione(GSH),obviously decreased O2-.production rate and malondialdehyde(MDA)content.1-MCP treatment increased active-oxygen-scavenging capacity and delayed membrane lipid peroxidation of Huanghua pear fruits,which retarded their ripening and senescence.