Postharvest Changes in Antioxidant Capacity, Enzymatic Activity, and Microbial Profile of Strawberry Fruits Treated with Enzymatic and Divalent Ions

Strawberry fruits are highly perishable and cannot be stored for more than 1-2 days at ambient condition. Therefore, it was thought desirable to enhance the shelf-life of harvested strawberry using pectin methyl esterase and divalent ions. The freshly harvested fruits of strawberry were treated with different concentrations of pectin methyl esterase (50-300 units) and divalent calcium ions (calcium chloride) for 5-30 min using response surface methodology-Box-Behnken design. The treated and untreated (control) fruits were packed in plastic punnets and stored at two different temperature conditions, viz., 7 A degrees C with 80 % relative humidity (RH) and 25 A degrees C with 60 % RH, for evaluating the shelf-life. Appropriate physico-chemical and microbiological parameters were determined at alternate days during their storage. Overall firmness and color values (L, a, b) decreased, while physiological weight loss (percent) increased during their storage. No food-borne pathogens, viz., Salmonella, Staphylococcus, and coliforms, were observed during storage. Total antioxidant capacity and ferric reducing antioxidant power decreased, while lipoxygenase and polyphenol oxidase activities increased during storage at 7 and 25 A degrees C. The shelf-life of treated strawberry was found to be 10 days at 7 A degrees C as against 6 days for control fruits under similar conditions. The treated strawberry had shelf-life of 2 days compared to 1 day for control maintained at 25 A degrees C.