96-10 |
The effect of tomato variety and MCP on postharvest life. |
R. M. BASEL, K. Racicot, A. Senecal, and G. L. Staby. Lebensmittel Consulting, 10760 Co.Rd.18, Fosteria, OH 44830 Many fresh market tomatoes have a limited shelf life. Increasing tomato shelf life would have both military and civilian benefits. The objective of this study was to evaluate the shelf life of 12 tomato varieties treated with 1-methylcyclopropene (MCP). MCP is a gas that can inhibit the negative effects of ethylene by blocking the attachment of this hormone to receptor sites in cells. Tomatoes were stored in modified atmosphere packaging (MAP) at 20 C. MCP was added biweekly at 0 and 200 ppb. Tomatoes were evaluated for color, defects, firmness, edibility index and total plate counts. Package oxygen, carbon dioxide and ethylene levels were also monitored. The results show that tomato variety had the greatest effect. Commonly used fresh market varieties showed limited shelf life while many processing varieties exhibited longer shelf life, some as long as three months. These longer storing varieties are firmer when ripe and are more resistance to cracking and other defects. Since these types are often picked ripe commercially, there is generally good flavor development initially and after storage. The major problem encountered was that spoilage of one tomato in a package was likely to cause invasive spoilage of neighboring tomatoes. Adding a desiccant was shown to be helpful but did not totally control this problem. These longer storing varieties do not seem to be very sensitive to ethylene as indicated by the small benefits of MCP treatments. However, it is possible that enough MCP was lost through the MAP films resulting in inadequate treatment and benefit and/or multiple MCP treatments are needed to block newly formed receptor sites. These results suggest that the most important parameter to prolonging tomato shelf life is the variety. A barrier to limit moisture loss such as those established using MAP is also essential. The major issue in commercialization of such varieties for long-term storage is control of neighbor-promoted spoilage and discovery of bruised or initially defective tomatoes before storage.
Session 96, Fruit & Vegetable Products
|