Bioactive compounds, antioxidant activity, and sensory qualities of red-fleshed apples dried by different methods

Abstract

The aim of this work was to study the effect of three drying methods, namely convective drying (CD), vacuum-microwave pretreatment with convective drying (CMWV), and freeze-drying (FD), on the bioactive compounds, antioxidant activity, color, and sensory attributes of red-fleshed apple cubes. Different drying methods considerably affected the quality factors of the product. The highest concentration of remaining phenolics was observed in the FD apples. Chlorogenic acid constituted the main phenolic compound, representing 60% of all phenolics in fresh and dried red-fleshed apples; cyanidin-3-galactoside was the major anthocyanin. The amounts of anthocyanins were considerably reduced using all three procedures for drying. However, the CD apple cubes exhibited the highest antioxidant activity while the CMWV samples had the lowest. Substantial differences in color were observed. The FD apple cubes had about 20% higher values for L*(lightness) and a* (red parameter), and they had better sensory attributes of color and odor than the other dried samples.