39F-7

R. D. HAGENMAIER, Citrus and Subtropical Products Laboratory, USDA/ARS, 600 Ave. S, NW, Winter Haven, FL 33881 and P. Shaw.

Tangerines and related specialty citrus fruit tend to develop off-flavor when coated with resin-based, high-gloss citrus coatings. Our objective was to determine what type of coatings are best suited for such fruit. Fallglo, Robinson, Sunburst, Dancy and Murcott tangerines, Nova and Orlando tangelos and Temple oranges were treated with experimental and commercial fruit coatings, stored for seven days and evaluated for changes in sensory flavor, flavor volatiles and internal gases. Flavor degradation after 21°C storage was greatest for fruit harvested late in its season and treated with resin-based coatings that had lower oxygen permeance than wax-based coatings. Flavor degradation was minimal when internal carbon dioxide <14%, internal oxygen >1%, and ethanol content of juice < 1500 ppm after seven days at 21°C. Changes in concentrations of ethyl acetate, ethyl butyrate, isopentanol, isobutanol and 2-methyl-3-buten-2-ol correlated highly with changes in ethanol content, although relative rates of change were quite dependent on the citrus variety. The optimum coatings for best appearance and flavor of citrus specialty fruit depends on harvest date, with high-gloss, low-permeance, resin-based coatings useful early in the season, and lower-gloss, high-permeance, wax-based coatings later in the season.