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.

Master of Science / Food Science Institute / Fadi M. Aramouni / Fresh cut fruits are products with minimal processing, modified by cutting, washing, packaging and refrigeration. The objective of this review is to present an overview of the available technologies for processing fresh cut fruits and technologies that could have some potential to be used in the future due to the increased consumption of fresh cut fruits. Fresh cut products are ready to eat, have high moisture content, have lack of lethal step to eliminate microbial pathogens and have the potential for temperature abuse; all these factors make quality and safety a priority. Fresh cut products sales have increased as a consequence of increased consumption of fruits and consumer attitudes toward convenience. Fresh cut fruit differ from fresh fruits in that the tissue and cell integrity have may been disrupted resulting in consequences such as changes in ethylene production, respiration, membrane degradation, metabolite accumulation, water loss and microba spoilage. However, the response to cutting depends on other variables such as cultivars, maturity and raw material quality, shape of cut, sharpness of blade, temperature and atmospheric composition. Consequently, there are enzymatic changes that impact the shelf life and quality of these products. In addition to quality and safety the nutritional value is an important factor too because consumers demand products as close to fresh as possible. The evaluation of the nutrient losses and how to reduce them through different treatments such as the introduction of vitamins and minerals in coating treatments or other treatment has become a priority too. There is a real need to find alternatives for preservation of fresh-cut fruit in order to minimize the changes that occur in the fruit tissues as a consequence of wounding. Alternatives, combined or modified methods have been proposed such as the use of alternative antibrowning, ethylene scrubbing, heat treatments, alternative antimicrobials, alternative packaging films, vacuum impregnation, osmotic dehydration, high hydrostatic pressure, use of edible coatings, radiation, bio preservation and other technologies.