Improving Nutritional Value of Dried Blueberries (Vaccinium corymbosum L.) Combining Microwave-Vacuum, Hot-Air Drying and Freeze Drying Technologies

Blueberries (Vaccinium corymbosum L.) were dried combining microwave-vacuum, hot-air drying and freeze drying technologies to retain their nutritional value. Polyphenol retention, total polyphenols, anthocyanins, and antioxidant activity were evaluated in dried blueberries. Glycoside compounds for ellagic acid, quercetin, and kaempferol exhibited a higher retention than phloridzin, and R- and S-naringin in dried blueberries following dehydration. Freeze and HA-MIVAC dried blueberries had a higher retention of total polyphenols and anthocyanins. Freeze dried blueberries had higher antioxidant activity, followed by the combination of HA-MIVAC, MIVAC and HA drying methods. FD, HA-MIVAC and MIVAC treated blueberries had a higher retention of individual polyphenols than HA treated blueberries, indicating that the nutritional properties of berries may be retained to a greater extent when these processes are employed.