The Effect of Various Fruit Juices Preservation Methods on Their Antioxidant Properties

Fruit juices constitute a valuable source of vitamins and bioactive compounds exhibiting strong antioxidant properties. The aim of the study was to evaluate the effect of different preservation methods on the antioxidant properties. The materials were: chokeberry (Aronia melanocarpa), blueberry (Vaccinium corymbosum), passion fruit (Passiflora edulis) and mango (Mangifera indica). Obtained juices were subjected to six preservation methods: three types of pasteurization (HTST, MTST, MTLT), two types of microwaving (30 and 15-s) and sonication. One part of each juice was a control sample, not subjected to preservation. The antioxidant capacity (DPPH, ABTS), total polyphenol content (TP, FBBB), total flavonoids (TF), and total anthocyanins (TA) were determined. A. melanocarpa juice exhibited the highest polyphenol content and the greatest antioxidant capacity, reaching of ca. 665 and 1020 mg TE/100 mL (DPPH and ABTS, respectively). Juices from V. corymbosum, M. indica, and P. edulis demonstrated lower antioxidant capacity resulting from significantly lower polyphenol content, including flavonoids and anthocyanins. Processing of fruit juices has an impact on the content of their bioactive compounds. Conventional preservation methods based on heating treatment may lead to losses of antioxidant properties, while microwaving and sonication did not reduce them and, in some cases, even enhanced them. In blueberry juice, most of treatments increased antioxidant capacity. In passion fruit juice, the highest activity was observed after HTST and sonication, whereas microwaving and MTLT significantly reduced antioxidant capacity. Overall, all analyzed juices represent valuable sources of bioactive compounds whose properties may be of importance from both nutritional and technological perspectives. Especially A. melanocarpa deserves to be regarded as superfruit.