effect of mixed edible coatings containing gum tragacanth and aloe vera on postharvest quality of strawberries during storage

The effects of mixed coating based on aloe vera (ag) and gum tragacanth (gt) on the microbial, physicochemical and sensorial properties of fresh strawberries were evaluated during 20 days of storage (1 oc, 95 % rh) compared to uncoated fruits. the coating solutions were prepared by mixing solution of ag diluted 1:3 with distilled water and gt solution (0.6 % w/v in distilled water) at different concentrations (25 % ag +75 % gt, 50 % ag +50 % gt and 75 % ag +25 % gt). microbial stability (fungi (yeasts and molds) and total aerobic bacteria), physiochemical characteristics (ascorbic acid (aa), weight loss, firmness, titratable acidity, soluble solid content (ssc), anthocyanin content, total phenolic and antioxidant activity) and sensory attributes (color, taste, odor and overall) of the samples were evaluated after 0, 4, 8, 12, 16 and 20 days of storage compared to uncoated fruits. comparing with untreated fruits, 50 % ag +50 % gt treatment significantly (p <0.05) decreased the microbial growth, weight loss and aa degradation and maintained firmness, anthocyanin and phenol contents and antioxidant activity. a greater visual acceptance was observed in fruits treated with 50 % ag + 50 % gt. the combination of ag/gt solution as a proper coating formulation in addition to have high antimicrobial activity; have great potential to extend shelf life of fresh strawberries.