IMPACT OF DRYING PROCESSES ON BIOACTIVE PHENOLICS, VITAMIN C AND ANTIOXIDANT CAPACITY OF RED-FLESHED APPLE SLICES

The impact of drying (air-, oven- and vacuum-drying) on bioactive polyphenolics, vitamin C and antioxidant capacity of slices of "Redfield" apple, a red-fleshed apple cultivar, was investigated. The drying process significantly impacted the concentration of specific phenolic compounds and vitamin C concentration in dried slices. The loss of epicatechin, cyanidin-3-O-galactoside, phloridzin and quercetin glycosides occurred during oven-drying. The concentration of all the phenolic compounds in vacuum-dried apple slices at 20C for 24 h was comparable to that of fresh apple slices. Antioxidant capacity measured by oxygen radical absorption capacity was significantly reduced by the oven-drying as compared to other drying methods. PRACTICAL APPLICATIONS These results suggested that vacuum-drying offers a great potential for preserving bioactive compounds during dehydration process for obtaining nonfried apple chips. Red-fleshed apples have potential for use in value-added snack product manufacturing because of the presence of anthocyanins in the flesh. However, nonuniform color distribution in red-fleshed apples is an issue for quality measurement.