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Edible alginate-based coating as carrier of antimicrobials to improve shelf-life and safety of fresh-cut melon

Raybaudi-Massilia, Rosa M., Mosqueda-Melgar, Jonathan, Martín-Belloso, Olga
International journal of food microbiology 2008 v.121 no.3 pp. 313-327
food spoilage, shelf life, essential oils, plant extracts, food packaging, malic acid, bacterial contamination, sensory evaluation, Salmonella Enteritidis, food storage, fresh-cut foods, edible films, cinnamon, coatings, Cucumis melo, Cymbopogon citratus, food preservation, alginate gels, melons, physicochemical properties, food pathogens, polypropylenes
The effect of malic acid and essential oils (EOs) of cinnamon, palmarosa and lemongrass and their main active compounds as natural antimicrobial substances incorporated into an alginate-based edible coating on the shelf-life and safety of fresh-cut “Piel de Sapo” melon (Cucumis melo L.) was investigated. Melon pieces (50 g) were coated with alginate-based edible coating containing malic acid (EC) and EOs or their active compounds before to be packed in air filled polypropylene trays and stored at 5 °C for shelf-life and sensory studies. On the other hand, melon pieces were inoculated with a Salmonella Enteritidis (10⁸ CFU/ml) culture before applying the coatings containing malic acid and EOs or their active compounds to safety study. Controls of fresh-cut melon non-coated or coated with EC without EOs were also prepared. EC was effective to improve shelf-life of fresh-cut melon from microbiological (up to 9.6 days) and physicochemical (>14 days) points of view in comparison with non-coated fresh-cut melon, where microbiological and physicochemical shelf-life was up to 3.6 days and lower than 14 days, respectively. In addition, the incorporation of EOs or their active compounds into the edible coating prolonged the microbiological shelf-life by more than 21 days in some cases due probably to an enhanced antimicrobial effect of malic acid+EOs; however, some fresh-cut melon characteristics were affected such as firmness and color causing a reduction of physicochemical shelf-life. Significant reductions (p <0.05) of S. Enteritidis population in inoculated coated fresh-cut melon were achieved, varying the effectiveness of the coatings depending on the EOs or the active compound and their concentrations. According to the results, palmarosa oil incorporated at 0.3% into the coating appear to be a promising preservation alternative for fresh-cut melon, since it had a good acceptation by panellists, maintained the fruit quality parameters, inhibited the native flora growth and reduced S. Enteritidis population.