76C-25 |
MAP storage of iceberg lettuce heads with pre-harvest application of various growth hormones |
R. M. BASEL, Lebensmittel Consulting, 10760 W. Co. Rd. 18, Fostoria, OH 44830, K. Racicot, Food Directorate, US Army Natick RD&E, Kansas Street, Natick, MA 01760, A. G. Senecal, Food Directorate, US Army Natick RD & E Center, SANTC-WRD, Kansas Street, Natick, MA 01760, and G. Staby, Perishables Research Organization, P.O. Box 1552, Healdsburg, CA 95448. Modified Atmosphere Packaging (MAP) can extend shelf life of lettuce. Growth hormone application has been suggested as a method to reduce pinking and decay defects. Better methods for shelf-life extension support military needs and provide the commercial sector with a higher quality product. The objective of this study was to determine the effect of MAP and hormones for extending the storage quality of iceberg lettuce. Growth hormones studied were Giberellin A 4,7 (GA), Benzyladenine (BA), Indole-3-Acetic Acid (IAA), and 1-Methyl cyclopropene (MCP). Iceberg lettuce (Silverado) were sprayed with water (Control), GA (20 ppm), BA (10 ppm), IAA (20 ppm), or MCP (0.5g/l) and harvested 24 hr. later, pre-cooled to 35° F and stored at 40° F. The product was evaluated for texture, L*a*b* color, subjective cut-core color, leaf color, decay, and edibility. Ethanol, chlorophyll, glucose, Refractive Index (Brix), Total Phenols, Polyphenol oxidase, and lipase were also measured. GA and BA hormone applications doubled the shelf of lettuce from 1 to 2 months compared to the MAP control. This is about 4 times longer than commercially produced lettuce. MCP and IAA also extended the shelf life over that of the MAP control but were less effective than GA or BA. GA was the most effective in maintaining leaf color. BA and GA also improved the cut surface color on the butt end. In addition, the hormone treatments had an effect on the respiration rate of the lettuce over time. MAP packaging coupled with growth hormone treatment can dramatically extend postharvest quality of iceberg lettuce by improving color retention, decreasing pinking, and lowering decay. Such practice can increase the shelf life of iceberg lettuce currently from 1-2 weeks to about 2 months.
Session 76C, Fruit & Vegetable Product: Fresh Fruits and Vegetables
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