Effect of 1-methylcyclopropene on ripening of postharvest persimmon (Diospyros kaki L.) fruit

Postharvest persimmon fruit (Diospyros kaki L. cv. Qiandaowuhe) was stored at 20 degrees C after being exposed to 3 mu l l(-1) l-methylcyclopropene (l-MCP) for 6h or not (control). Several parameters (firmness, respiration and ethylene production, pectic substances and cell wall hydrolysis enzymes activities) were examined to determine the efficacy of l-MCP treatment in delaying persimmon fruit ripening. Results showed that 'Qiandaowuhe' persimmon fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak CO2 production and ethylene production was observed on the fourth day. Fruit softening was accompanied by a progressive increase in water-soluble pectic substances (WSP) and a progressive decrease in chelator-soluble pectic substances (CSP) and alkali-soluble pectic substances (ASP). The activities of pectinmethylesterase (PME) and polygalacturonase (PG) started increasing sharply and reached a maximal value on days 4 and 6, respectively, and then decreased slowly. l-MCP treatment delayed the onset of climacteric ethylene production and respiration in persimmon fruit, and also significantly retarded the activities of PME and PG during ripening at 20 degrees C. Consistent with the activity trends of cell wall hydrolysis enzymes, l-MCP treatment also delayed the depolymerization of CSP and ASP and reduced the increase of WSP compared with the control fruit. Thus, application of l-MCP can greatly extend the postharvest life of 'Qiandaowuhe' persimmon fruit. (c) 2005 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.