Impacts of hot air and vacuum drying on the quality attributes of kiwifruit slices

Abstract Hot air and vacuum drying were performed to investigate changes in the moisture content, hardness, l -ascorbic acid content, antioxidant activity, and surface color of kiwifruit samples over the course of the drying process at temperatures of 50, 60, and 70 °C and a vacuum drying pressure of 3.00 kPa. The residual ratio of AsA and the antioxidant activity in the dried kiwifruit samples was 0.75–0.99 and 4.3–5.5, respectively. The l -ascorbic acid changes in the kiwifruit samples during the hot air drying process followed first order reaction kinetics. Changes in the sample hardness and antioxidant activity were represented by zero-order reaction kinetics. The sample surface color changes after drying were also measured, and the total color change (Δ E ) of the samples at all temperatures and for each drying process was greater than 12. The sample color changes (Δ a * ) after vacuum drying at each temperature level were significantly ( P