EDIBLE COATINGS ON FRESH SQUASH SLICES: EFFECT OF FILM DRYING TEMPERATURE ON THE NUTRITIONAL AND MICROBIOLOGICAL QUALITY

Abstract

The exposure of foods to the temperature and humidity needed to dry the coatings can have deleterious effects on their quality. A critical analysis of the film drying conditions on quality indexes for butternut squash slices is presented. During the coatings drying, the samples lost significant amounts of weight and ascorbic acid. Only during the drying of the chitosan coating for 100 min at 20C and for 30 min at 50C that the ascorbic acid contents were not significantly reduced. The application of casein and carboxy methyl cellulose coatings did not cause significant reductions in the counts of mesophilic aerobic microorganisms (5.75–6.00 Log CFU/g). Chitosan coated samples presented significant log reductions showing the higher reductions the samples dried for 30 min at 50C (5.02 Log CFU/g). For the preservation of the nutritional and microbiological quality indexes of squash slices, the best coating conditions would be chitosan dried for 30 min at 50C. PRACTICAL APPLICATIONS The continuous consumer interest in high quality and food safety, combined with environmental concern, has induced the development and study of new edible coatings that avoid the use of synthetic materials. The edible coatings, formed from Generally Recognized as Safe materials, have the potential to reduce weight loss, respiration rate and improve food appearance and integrity. It is one of the most effective methods to maintain food quality. Antimicrobial films and coatings have innovated the concept of active packaging and have been developed to reduce, inhibit or delay the growth of microorganisms on the surface of food in contact with the packaged products. In addition, the edible coatings allow the incorporation of food additives with antimicrobial effects that might help reduce microbial spoilage during postharvest.