Effect of blanching time, slice thickness and drying temperature on antioxidant activity and curcumin content of turmeric rhizome (var. Salem)

Freshly harvested turmeric rhizomes of Salem variety were procured from a farmer’s field. Turmeric rhizomes were cleaned, peeled, and sliced to 2, 3, 4, 5, and 6 mm thickness. Sliced turmeric rhizomes were blanched at 100 °C for 15, 30, 45 and 60 min in autoclave. These blanched turmeric rhizomes sliced were further dried in a tray dryer at 30, 40, 50, 60 and 70 °C temperature. Effect of slicing, blanching and drying temperature on antioxidant activity and curcumin content were evaluated. Response surface methodology was used for analysis. The linear terms of blanching time, slice thickness and drying temperature were affected significantly for antioxidant activity and curcumin except drying temperature was not significant for curcumin content. Interactions effect of all three variables were non-significant for antioxidant activity and curcumin. Quadratic effect of blanching time was negatively observed significant for antioxidant activity, whereas quadratic effect of all the three variables was negatively significant for curcumin content of the dried turmeric rhizomes.