Phenolic Content, Antioxidant Capacity, and Browning Impact of Apple Slices during Microwave Drying: A Chemometric Approach

Apples represent a category of products frequently consumed by people, owing both to their beneficial effects on human health and to their antioxidant effects. Microwave (MW) treatment is a simple and fast method that can be used successfully in the food industry to obtain dry apple slices, rich in bioactive compounds and with a pleasant aspect. This study presents the effect of applying microwave treating to apple slices from two cultivars (Golden Delicious and Idared), for three, four, and five minutes, respectively, at a power of 450 W, in order to reduce the browning effect. For this purpose, the browning index (BI), chromatic parameters (CIE L*a*b*), total phenolic content (Folin-Cioc&acirc:lteu method), and antioxidant capacity (by Ferric Reducing Antioxidant Power (FRAP assay) were evaluated in the case of apple slices before and after MW treatment. Based on the results obtained, it can be argued that the microwave treatment results in a significant increase in the total phenolic content and enhances antioxidant capacity in the case of both apple cultivars. Apples from the Idared cultivar have a higher total phenolic content than apples from the Golden cultivar, and this concentration increased by 56.14% and 48.9%, respectively, after MW treatment. In terms of antioxidant capacity, Idared apples also recorded a higher value compared to Golden cultivars. According to the results of the multivariate analysis, there are variations between the two apple categories with regard to the phenolic content and the browning process: browning was inhibited at the five-minute exposure to microwaves. The apple processing domain may use our findings in order to produce high-quality finished products, with a pleasant aspect, which retain the bioactive compounds of the fruit.