Effect of Coatings and Prolonged Storage Conditions on Fresh Orange Flavor Volatiles, Degrees Brix, and Ascorbic Acid Levels

Valencia oranges were treated with a commercial polysaccharide-based coating or a commercial shellac-based water wax or were left uncoated. The fruit were then stored at 16 or 21 degrees C with 95% relative humidity for up to 56 days. Samples were periodically analyzed for internal gases, flavor volatiles, water loss, degrees Brix, and ascorbic acid. Coated fruit had lower internal O2 and higher CO2 and ethylene concentrations than uncoated. Shellac-coated fruit had the lowest and highest amounts of O2 and CO2, respectively, at 21 degrees C. Generally, coated fruit showed higher concentrations of many volatile compounds as time in storage increased, most notably ethanol, ethyl butanoate, ethyl acetate' and alpha-pinene. This was especially true for shellac-coated fruit, for coated fruit at the higher storage temperature, and after the second month of storage. In contrast, levels of valencene, alpha-terpineol, and hexanol were generally lower in shellac-coated fruit and all coated fruit at the higher storage temperature. Several hydrocarbon and minor alcohol volatiles increased then decreased during the storage period. Some exceptions were alpha-pinene, sabinene, and isobutanol which generally increased in coated fruit by the end of the storage period. Shellac-coated fruit had significantly less weight loss than fruit subjected to all other treatments, whereas polysaccharide-treated fruit did not retard water loss compared to uncoated fruit. No significant differences were found for degrees Brix or ascorbic acid concentrations