Background: Rabbiteye blueberries are an excellent source of nutrients and phytochemicals. They are often dried, which can degrade health-promoting compounds. Means of shortening exposure to high-temperature drying air are desirable. Five cultivars of rabbiteye blueberries ('Premier', 'Tifblue', 'Brightwell', 'Alapaha', and 'Powderblue') were dried in a jet-tube fluidized bed air dryer with varying pretreatments including mechanical abrasion and osmotic dehydration.
Results: Drying time ranged from 66 to 95 min at 107 °C, achieving a final water activity of 0.347-0.605. Prior osmotic dehydration significantly reduced the drying time. Vacuum osmotic dehydration for 70 min achieved similar moisture contents to soaking blueberries for 24 h. Jet-tube dried blueberries exhibited greater color saturation than commercially available blueberries. While drying reduced the total monomeric anthocyanin (TMA) content, this occurred to a lesser extent than by other processing methods. The total phenolics content (TPC) and antioxidant capacity (H-ORACFL values) increased after drying. 'Premier' was the most preferred vacuum-infused dried blueberry, with a water activity (aw) of 0.53 and 157 g H2O kg(-1). 'Tifblue' was most preferred amongst the overnight-infused and also unsweetened dried blueberries.
Conclusion: Jet-tube drying can substantially reduce drying times while yielding blueberries with good color, sensory properties, TMA, TPC, and H-ORACFL values. Furthermore, some cultivars produce better-quality dried blueberries than others.
© 2012 Society of Chemical Industry.