Changes in the Physicochemical and Antioxidant Properties of Granny Smith Apples Depending on Drying Conditions

Abstract

In this study, the effects of air fryer and hot air drying methods applied at different temperatures (50, 60, and 70°C) on the physicochemical and bioactive properties of Granny Smith apple slices were comparatively investigated. The results showed that the air fryer method provided more effective drying performance compared to hot air drying due to its lower water activity (0.186–0.189) and moisture content (5.72–8.01%). In contrast, samples dried in an hot air drying exhibited higher moisture content (8.40–9.49%). Color parameters were only slightly affected by drying conditions, with increased pigment degradation observed at higher temperatures. The highest total phenolic content was determined in the sample dried at 60°C in the air fryer, and it was observed that moderate temperatures are more suitable for the preservation of phenolic compounds. The fact that antioxidant activity did not show a direct correlation with total phenolic content indicates that thermal treatments affect the structure of antioxidant compounds. Principal component analysis results showed that the samples differed significantly depending on the drying method. Overall, drying at 60°C using an air fryer was determined to be the most suitable condition for both effective drying and the preservation of bioactive compounds.