Effects of chitosan edible film coatings on the physicochemical and microbiological qualities of sweet cherry (Prunus avium L.)

In this study, the effects of chitosan edible film coatings on the physicochemical and microbiological qualities of sweet cherry (Prunus avium L.) were investigated. Sweet cherries were coated with 1% chitosan [two of which were produced from shrimp waste originating from the Marmara Sea in Turkey (Chitosan-1, Chitosan-2) and the other two of which were commercially produced (Commercial-1 and Commercial-2)] and stored at 4 degrees C for 25 days or 20 degrees C for 15 days. Various physicochemical (weight loss, pH, titratable acidity, total soluble solids, water activity, respiration rate, total carbohydrate content) and microbiological (total mesophilic aerobic bacteria, total psychrophilic aerobic bacteria, total coliform bacteria, yeasts and molds) qualities were measured. After storage, the least weight loss was found to be 8.85% in Chitosan-2 coated sweet cherries at 20 degrees C and 16.18% in the control group stored at 4 degrees C. The lowest titratable acidity value was observed in the control group (0.657%) at 4 degrees C and in the Chitosan-2 coated sweet cherries (0.600%) at 20 degrees C. The water activity value was determined at 0.969-0.974 for all sample groups and storage conditions at the end . of each period. The total count of mesophilic aerobic bacteria in the sweet cherry coated with CH-1 and CH-2 was found to be below the detectable amount (< 2 IogCFU/g) while that for the control group was 2.74 log CFU/g at 4 degrees C. Coating sweet cherries with CH-1 and CH-2 inhibited yeast and mold growth at 4 degrees C for 25 days while the highest yeast and mold count was determined as 4.75 log CFU/g in C-2 coated sweet cherries at the end of storage. It has been determined that each tested chitosan coatings have different effects on various quality characteristics at distinct storage temperatures. When microbiological analyses are taken into consideration, it can be concluded that chitosan, especially those produced from shrimp wastes, have high antimicrobial effects and can be used effectively in increasing the shelf life of sweet cherries.