Microbiological and Sensory Quality Changes in Unwrapped and Wrapped Sliced Watermelon

Abstract

Experiments were done to determine the major genera and groups of microflora which grow on unwrapped and wrapped slices of watermelon stored at 5 and 25°C for up to 8 d. Changes in sensory qualities of stored watermelon were also monitored. Pseudomonas, Escherichia coli, Enterobacter and micrococci comprised the predominant microflora, regardless of storage temperature. Growth was slower on wrapped watermelon than on unwrapped watermelon. Subjective ratings for color, aroma, appearance, flavor and texture of unwrapped watermelon stored at 5°C decreased more rapidly than ratings for wrapped slices. Results from objective measurements of color suggested that dulling and darkening was most rapid on the surface of unwrapped watermelon, and this was attributed to more rapid oxidation of pigments when exposed to air. Objective measurement of firmness showed that wrapped watermelon retained structural integrity for a longer time than unwrapped watermelon; however, subjective ratings for texture were not correlated with these values, indicating that texture is less critical than color and flavor when overall judgments are made on sensory quality of stored watermelon.