| In this paper, The'Yali'pears were treated with 1-MCP, nitric oxide, SNP solution and modified atmosphere (MA) packaging. The effects of these treatments on fruit quality, core browning, metabolisms of cell phenolic substance and active oxygen were investigated. The results were as follows:1-MCP treatment delayed respiration rate and ethylene production of'Yali'pears at all three concentration levels of 0.25,0.5 and 1.0μl/L tested, with 1.0μl/L level was the most effective, when stored at cold temperature. The treatment was capable of maintaining high fruit firmness, inhibiting the increase of soluble solids content (SSC), delaying the decreases of pulp titratable acidity (TA) and vitamin C (Vc). Fruit core browning was also largely reduced with 1-MCP treatment. Therefore, 1.0μl/L 1-MCP treatment was recommended before'Yali'pear storage.When stored at room temperature, 1-MCP treatment not only reduced respiration rate and ethylene production, but also delayed the peak time of respiration and ethylene.1-MCP treatment also resulted in higher firmness, lower SSC, reduced phenolic content and PPO activity, postponed the decrease of the contents of antioxidant substance(AsA and GSH)contents and SOD activity. Treatment with 1-MCP reduced the accumulation of O2- and H2O2, inhibited the accumulation of MDA and core browning. The results showed that 1-MCP could inhibit core browning through regulating the metabolisms of phenolic and active oxygen.'Yali'pears were fumigated with10, 20, 30μl/L nitric oxide (NO) and then stored at cold temperature. The treatment of fumigation with NO reduced the peak value of ethylene production rate, maintained higher firmness and the effect of treatment with 20μl/L NO was best. The NO treatment reduced soluble sugar and soluble solids content, maintained higher starch and NO content of pulp, and retarded the degradation of covalent soluble pectin and accumulation of ionic soluble pectin and water soluble pectin. Moreover, NO fumigation decreased the activities of polygalacturonase (PG),β- galactosidase (β-Gal) and delayed the peak of PG activity of fruits. The treatment with NO reduced the phenolic content and PPO activity of core, and retarded H2O2 accumulation, reduced the core browning. Therefore, it indicated that NO fumigation could delay the softening and ripening process, reduce the core browning, and thus maintain better qualities of'Yali'pears.Using sodium nitroprusside (SNP) as a nitric oxide (NO) donor, the effects of different concentrations of SNP on fruit qualities and phenolic metabolism of'Yali'pears were investigated. The results showed that 0.1 mmol/L SNP obviously inhibited respiration rate, ethylene production, and the increase of SSC, maintained higher fruit firmness, SNP treatment also reduced phenolic content and PPO activity, increased NO content, inhibited the decrease of AsA and GSH, and reduced the core browning. The effects of 0.05 and 0.2 mmol/L SNP were not obvious.In this paper, effects of packaging with micro-perforated polyethylene film and normal PE film package of 30μm thickness on fruit quality were tested on'Yali'pears. For the control fruits were not packed. The results showed that concentration of CO2 grow much more slowly in micro-perforated PE film than that in normal PE film during storage. Packages with micro-perforated film could much more effectively inhibit the increase of SSC and decrease of AsA and GSH, reduce core browning, retard accumulation of H2O2. Compared with control, Fruits packaged with normal PE film browned much more seriously, and the quality of pears declined much fast. The fruit of firmness was between the control and treatment groups. It may suggest that micro-perforated PE film bags may be much more suitable for'Yali'pears packing than the present, much more prevalent, normal PE film during'Yali'pear storage. |
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