Effects of spray drying on antioxidant capacity and anthocyanidin content of blueberry and grape by-products

The degradation of nutraceutical components caused by spray drying of cull blueberry extract and grape pomace extract was investigated. Samples collected before and after spray drying were tested for antioxidant capacity using Oxygen Radical Absorbance Capacity (ORACFL) and Total Phenolics; and for individual anthocyanidins. In Study 1, the maximum ratio of fruit solids to maltodextrin was determined to be 30:70 using a pilot-scale spray dryer. Maltodextrin was also found to have a protective effect on the nutraceutical components during spray drying. There was significantly higher retention of nutraceutical components with increased levels of maltodextrin. In Studies 2 and 3, the air inlet temperature of the spray dryer was kept constant for all runs at 150°C, with varying outlet temperatures of (a) 80 and (b) 90°C. The degradation of nutraceutical components was not significantly different at the two selected outlet temperatures. ORACFL reduction for blueberry and grape samples after spray drying was 66.3--69.6% and 5.9--14.7%, respectively. After spray drying, total phenolics reduction for blueberry and grape samples was 8.2--17.5% and 8.3--19.2%, respectively. Individual anthocyanidin reduction for blueberry and grape samples was 50--70% and 30--60%, respectively. The experimental spray dried powders compared favorably to commercial blueberry powders.