Combined effects of osmo-and air-dehydration treatments on chemical, antioxidant and morphological characteristics of blueberries

Osmo-air dehydration treatments are widely applied to fruits in order to prolong shelf-life, reduce packaging and logistic costs, and to provide ingredients to be used in various food formulations. In this work, osmo-air dehydration was applied to blueberries (Vaccinium corymbosum); blanched blueberries were dipped in 60\ub0Bx sucrose and 48.6\ub0Bx fructose/glucose osmotic solutions (aw = 0.90) for 24 hours, and the osmotic exchanges were determined by mass balances (water loss, solid gain, sugar intake, changes in total phenolics and anthocyanins). Untreated and infused berries were subsequently air-dried at 70\ub0C to final moisture content of 10-14%, and drying kinetics as well as compositional and morphological changes of berries were followed in the course of drying. Data show that the osmotic treatment caused significant losses in the antioxidant components (total phenolics, total and individual anthocyanins) and in the antioxidant activity. Losses in the antioxidant components also occurred in the course of air-drying, with similar kinetics in untreated and infused blueberries. Glucose/fructose infusion gave better results in terms of morphological changes during the subsequent air-drying process, with lower shrinkage and wrinkling of the berries