Determination of bioaccessibility of phenolic compounds in fresh and dehydrated blueberries (Vaccinium corymbosum L.).

Blueberries (Vaccinium corymbosum L.) contain compounds with antioxidant properties that are beneficial to health. The effects of fruit preservation (freeze-drying, osmotic dehydration, and convection drying) on antioxidant capacity (DPPH and ORAC), total polyphenols and total anthocyanins were studied. Convection drying best preserved the total polyphenol contents and antioxidant capacity. While, freeze-drying and convection drying showed no significant differences in total anthocyanins. To determine the effects of the preservation techniques on the phenolic compounds/antioxidant capacity, their bioaccessibility was determined by a static model of in vitro gastrointestinal digestion. The results of the intestinal stage (ileum) showed that convection drying improved the preservation of antioxidant properties (DPPH), reaching values of 91.6% bioaccessibility (29.1 mmol Trolox equivalents (TE)/g DW) and 48.7% (9.4 mmol TE/g DW) for the freeze-dried berries. Meanwhile, osmotically dehydrated berries exhibited the lowest percentage of bioaccessibility of the antioxidant compounds at 27.6% (4.0 mmol TE/g DW). It was concluded that total polyphenols, total anthocyanins and antioxidant capacity are better preserved by convection drying, followed by freeze-drying and osmotic dehydration.