Comparative evaluation of quality properties and volatile profiles of lemon peels subjected to different drying techniques

In this study, effects of different drying techniques (open-air drying [AD], hot air drying [HAD], microwave drying [MWD], and freeze-drying [FD]) on quality properties and volatile compound profiles in lemon peels were examined. For those purpose, water-holding capacity, water activity, bulk density, color, pH, titratable acidity, total phenolic content, antioxidant activity, ascorbic acid content, total carotenoid content, and volatile compounds of dried lemon peels were determined. Among the drying methods, the highest retention of phenolics, ascorbic acid, and carotenoids were provided by FD. A total of 56 volatile compounds were identified in dried lemon peel powders. MWD samples contained the largest number of volatiles, whereas HAD samples had the highest volatile content. Principal component analysis on volatiles indicated that there is a convenient relation between the AD, HAD, and FD samples.