The Role of Processing Conditions on the Color and Antioxidant Retention of Jet Tube Fluidized Bed-Dried Blueberries

Jet tube fluidized bed drying was investigated as a means of rapidly generating shelf-stable and high-quality sweetened and non-sweetened blueberries. Sugar-infused and noninfused scarified Rabbiteye blueberries (Vaccinium ashei 'Brightwell') were dried at 99, 107, and 116 degrees C. Prior scarification of the blueberry surface aided in decreasing the drying time. Increased lightness (L*) values were most notable at higher drying temperatures for sugar-infused blueberries, suggesting loss of pigments. Total monomeric anthocyanins level, initially 7.65 mg cyanidin-3-O-glucoside equivalents (C3G eq)/g extract, decreased as drying temperature increased and ranged between 4.07 down to 1.51 mg C3G eq/g extract for dried blueberries. The total phenolics content increased with drying for noninfused blueberries, with highest levels of 31.6 mg gallic acid equivalents (GAE)/g extract for samples dried at 107 degrees C. With the exception of sugar-infused berries dried at 107 and 116 degrees C, the dried blueberries maintained or demonstrated slightly increased hydrophilic oxygen radical absorbance capacity (H-ORACFL) values, indicating that their antioxidant capacity was retained upon drying. Blueberries dried at 107 degrees C possessed the greatest preference scores and best retention of blueberry flavor and required a relatively short drying time.