1-Methylcyclopropene (1-MCP) has been found to inhibit ethylene action and thus it can delay the fruit ripening process. The effects of 1-MCP (90 ppb for 12 h) on softening related changes were determined through physiological changes, fruit firmness and activities of the cell wall degrading enzymes including α-galactosidase, β-galactosidase, pectin methylesterase (PME) and xylanase during ripening in papaya (Carica papaya L. cv Sekaki). In this study, fruits were treated with 90 ppb concentration of 1-MCP gaseous vapors for 12 h in airtight container maintained at 28oC. After the treatment fruits were placed at ambient temperature (28oC). Papaya treated with 1-MCP experienced a significant delayed in skin color development, weight loss and reduced firmness loss compared with the fruit without 1-MCP treatment. As softening progressed, activity of the cell wall degrading enzymes in fruit without 1-MCP treatment increased significantly coincident with a rapid decline in fruit firmness. With 1-MCP application, fruit experienced a delay in activity of cell wall degrading enzymes but continued to increase until later stage of ripening. Thus it may be suggested that 1-MCP treatment may aid in delaying softening-related process and thereby extended the postharvest life and maintained the quality of the ‘Sekaki’ papaya fruit.
Japanese cucumber (Cucumis sativus L.) could easily develop chilling injury when held at 7°C or below, thus limiting
its storability and reduces consumer preference. Chitosan coating is known to be one of the methods used for preserving
perishable fresh produce. This work was extended out to look into the efficacy of low molecular weight (LMW) chitosan
coatings on chilling injury (CI), antioxidant levels and shelf life quality of Japanese cucumber. Fruit were coated with
0.5, 1.0 and 1.5% chitosan prior to cold storage at 7°C and 90-95% relative humidity (RH) for 12 days. The result
showed that fruit coated with lowest concentration of chitosan (0.5%) was the most effective in alleviating chilling injury
symptoms and reduced the increase of lipid peroxidation (MDA content) compared to higher concentrations (1.0 and
1.5%). Furthermore, when Japanese cucumbers were coated with 0.5% chitosan, it was able to maintain the postharvest
quality and storability with higher firmness and delayed increase of weight loss. On the other hand, cucumber coated
with 1.5% chitosan demonstrated high level of ascorbate peroxidase (APX) and catalase (CAT) activities than in 0.5 and
1.0% chitosan. This finding suggests a role for chitosan coating in alleviating oxidative stress that would lead to CI
problems during cold storage.