Alginate-Based Edible Coating to Enhance Quality and Shelf-Life of Fresh-Cut Watermelon (Citrullus Lanatus)
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Fresh-cut watermelon is appreciated for its taste, flavor, and juiciness. However, there are challenges in maintaining the freshness since fresh-cut processing of fruits promotes faster deterioration. Our objective was to determine the effectiveness of multilayered antimicrobial edible coating on the shelf-life of fresh-cut watermelon while keeping its original attributes for longer, without affecting its sensory properties. A set of solutions containing sodium alginate (0.5, 1, 2% w/w), beta-cyclodextrin, trans-cinnamaldehyde (antimicrobial agent), pectin, and calcium lactate were used as coating systems for fresh-cut watermelon cylinders. The samples were coated by the layer-by-layer dipping technique and stored at 4 degrees C for 15 days. Results were analyzed individually for each quality attribute evaluated, and the best concentration among the solutions to improve each attribute was found. Watermelon quality was measured in terms of texture, color, juice leakage (weight loss), oBrix, and pH. Microbiological analysis consisted of total coliforms, yeasts and molds, aerobics, and psychrotrophs. A consumer test was carried out (~ 40 panelists) to support the objective quality data. Panelists scored the samples using a 9-point hedonic scale. Uncoated samples served as controls. Quality tests were conducted at days 1, 3, 7, 12, and 15 of storage. Sensory tests showed high acceptance (P < 0.05) of the coated samples when compared to the controls. Quality attributes, particularly texture (firmness) and juice leakage (weight loss) were enhanced (P < 0.05) by the coating. Microbiological analysis demonstrated that alginate-based edible coating has a huge effect against microbial growth. 1% sodium alginate coating provided better preservation in terms of quality parameters, microbiological growth, and sensory acceptance. These results indicate that different ratios between solutions present a significant variation for each quality attribute measured in this study; and the thickness of the coating as well as the amount of antimicrobial are critical for shelf-life extension of fresh-cut watermelon. Hence, application of an alginate based multilayered edible coating has tremendous potential to enhance microbial quality and extend the shelf-life of fresh-cut watermelon.