Effect of chitosan-Aloe vera coating on postharvest quality of blueberry (Vaccinium corymbosum) fruit

The present study was carried out to evaluate the effect of chitosan-based edible coatings with Aloe vera extract on the postharvest blueberry fruit quality during storage at 5 degrees C. Firstly, A. vera fractions (pulp and liquid) were extracted from leaves and evaluated in terms of antifungal and antioxidant capacities. The choice of the most adequate chitosan and A. vera fraction concentrations to be incorporated in coating formulation was made based on the wettability of the corresponding coating solutions. Coatings with 0.5% (w/v) chitosan + 0.5% (w/v) glycerol + 0.1% (w/v) Tween 80 + 0.5% (v/v) A. vera liquid fraction presented the best characteristics to uniformly coat blueberry surface. Physico-chemical (i.e., titratable acidity, pH, weight loss) and microbiological analyses of coated blueberries (non-inoculated or artificially inoculated with Botrytis cinerea) were performed during 25 d. Microbiological growth and water loss levels were approximately reduced by 50% and 42%, respectively, in coated blueberries after 25 d compared to uncoated blueberries. After 15 d, weight loss values were 6.2% and 3.7% for uncoated and chitosan-A. vera coated blueberries, respectively. Uncoated fruits presented mold contamination after 2 d of storage (2.0 +/- 0.32 log CFU g(-1)), whilst fruits with chitosan-based coatings with A. vera presented mold contamination only after 9 d of storage (1.3 +/- 0.35 log CFU g(-1)). Overall, coatings developed in this study extend blueberries' shelf-life for about 5 d, demonstrating for the first time that the combination of chitosan and A. vera liquid fraction as edible coating materials has great potential in expanding the shelf life of fruits. (C) 2016 Elsevier B.V. All rights reserved.