EFFECT OF DEXTRAN COATING ON STRAWBERRY QUALITY DURING REFRIGERATED STORAGE

Abstract

The use of edible films and coatings made of natural materials such as polysaccharides provides a sustainable technological alternative to traditional plastic food packaging materials as one of the contemporary methods for preserving food items and guaranteeing their quality and freshness throughout their shelf lives. This is especially important for fresh fruits as highly perishable. The aim of the present study was to investigate the effect of dextran-based coating on strawberry (Fragaria × ananassa) quality attributes during refrigerated storage. Dextran was synthesized using dextransucrase from Leuconostoc mesenteroides T3. Coating solution was made by dissolving 12g of dextran in 300 mL distilled water. Glycerol (25% w/w) and Tween 80 (5% w/w) were added as plasticizer and surfactant, respectively. Strawberries were coated by dipping in coating solution or water (control) and after drying were placed in plastic trays and stored at 8 °C. The influence of coating on strawberry quality was assessed through measuring the percentage of weight loss (WL), total soluble solids (TSS) and titratable acidity (TA) of the coated fruits and compared with the control uncoated samples. The percentage of WL increased during storage in both coated and uncoated strawberries and although it was less for the uncoated strawberries, the difference was not significant. The TSS content was lower in dextran-coated fruit during the entire storage period. Since TSS is an indicator of the ripeness of the fruit it could be concluded that dextran coating slows down the ripening, thus increasing the shelf life. Unexpectedly, coated strawberries exhibited lower TA values. However, the relative changes were significantly smaller among the coated samples group, implying that the coating slows down the respiration process in which the acids are consumed. Overall, the results of this work show that the dextran coating has the potential to preserve quality of strawberries during cold storage.