Phytochemical and physical properties of blueberries, tart cherries, strawberries, and cranberries as affected by different drying methods

Abstract

The effects of hot-air drying (AD), freeze drying (FD) and Refractance Window drying (RWD) on the retention of anthocyanins, phenolics, flavonoids, vitamin C and B, and antioxidant capacity (ORAC) in blueberries, tart cherries, strawberries, and cranberries, as well as organic acids and proanthocyanins in cranberries and chlorogenic acid and catchins in blueberries were evaluated. Changes in color, glass transition, specific heat, and surface morphology of the dried fruits were also evaluated. The quality retention in the dried fruits was found to be product and drying method specific. The FD products exhibited a better retention of vitamin C, ORAC, anthocyanins, and phenolics than the AD and RWD fruits. The RWD produced samples with a less effective ORAC, anthocyanins, and phenolics retention, but a higher total vitamin B retention compared to the FD products. The AD-dried fruits displayed significantly lesser quality retention in most of the quality indexes measured in the study.

Keywords: Anthocyanins; Blueberry; Cherry; Cranberry; Freeze drying; Refractance Window drying; Strawberry; Vitamin C.