| 1-Methylcyclopropene (MCP), an ethylene antagonist, can be used to extend the storage life and shelf life of horticultural crops. The cultural use of MCP on fruits and vegetables is a single application after harvest. This dissertation relates to two aspects of MCP: first, the potential of MCP-treated apples as a raw material for fresh-cut apples and, second, development of a controlled release device to enable continuous in-package application of MCP.; Fresh-cut apples are increasingly more popular and have the potential to increase the revenue stream of the apple industry. One of the objectives of this study is to evaluate how postharvest treatments such as MCP and controlled atmosphere (CA) storage, individually and in combination, affect the subsequent quality of fresh-cut apples over 9 month storage period. The combination of MCP treatment and CA storage resulted in slices with superior firmness but were highly susceptible to enzymatic browning. The combination treatment resulted in apple slices having a different volatile profile from apples receiving either of the individual treatments. MCP + CA storage apples are suitable as a raw material for fresh-cut apples only when the enzymatic browning can be minimized. When this is not the case, MCP treated apples and CA storage apples are the better choice to use. At 3 and 9 months storage of intact apples, MCP-treated apples were better than CA-storage apples. At 3 months, MCP treated apples had greater firmness and less susceptibility to enzymatic browning. At 9 months, the firmness of MCP treated apples was greater than the minimum threshold level and the slices were less sensitive to enzymatic browning than CA storage apples. At 5 and 7 month storage, CA storage apples and MCP treated apples resulted in slices with a similar quality.; The other objective of this study was to develop controlled release devices to enable a continuous in-package MCP treatment. Then, the release characteristics of several developed devices were evaluated as a function of temperature and relative humidity. In this study, four controlled release devices, monolithic (LDPE and EVA matrices) and reservoir (LDPE and EVA membrane) were developed. None of the devices released 100% of the available MCP. Among them, the LDPE monolithic device had the most desirable characteristics. The release characteristics of the device depended greatly on temperature and relative humidity. The total amount of MCP released and the release rate increased with increasing temperature. The effect of relative humidity at 22 and 5°C were different. The amount of MCP released and the release rate increased with an increasing RH at 22°C but RH had little effect at 5°C. It is anticipated that the device will to be used as a supplement to the single application after harvest for produce such as tomatoes, apples, and avocados that benefit from repeated or continuous treatment MCP treatment. |
