Kinetic changes of antioxidant parameters, ascorbic acid loss, and hydroxymethyl furfural formation during apple chips production

In this study, the kinetic change of the antioxidant properties were determined during apple chips production using three different cultivars. Using a rotary forced-air dryer, apple slices were dried at three different temperatures (65, 70, and 75 degrees C). The ascorbic acid content, total phenolic content (TPC), total flavonoid content (TFC), Oxygen Radical Absorbance Capacity (ORAC) and Trolox Equivalent Antioxidant Capacity (TEAC), and hydroxymethylfurfural content were analyzed. Phenolic compounds of apple chips were also identified by chromatographic separation. Thermal degradation of ascorbic acid was fitted to first-order reaction kinetics. TPC, TFC, ORAC, and TEAC values, and hydroxymethylfurfural content increased with drying time and temperature where the data were fitted to first-order and zero-order reaction kinetics. Reaction rate constants were influenced by temperature, based on the Arrhenius model. The primary phenolic compounds of apple chips were gallic acid, chlorogenic acid, catechin, caffeic acid, epicatechin, and rutin.