Combinatory Effect of Thermal Treatment and Blending on the Quality of Pomegranate Juices

In the food industry, browning and colour alteration are usually the main problems to solve in red juices. In an attempt to ease complications due to pomegranate juice processing, the combination of thermal treatment, storage at selected temperature and blending of juices was assessed as a novel and combined solution. A pure monovarietal juice, a combination of two widely distinct varietal juices (75 % Mollar de Elche + 25 % Wonderful) and a blend of pomegranate juice plus lemon (75 % + 25 %, respectively) were compared after pasteurization at two different heat treatments (high temperature-short time (HTST) and low temperature-long time (LTLT)). The effect of processing on the bioactive composition and colour parameters was monitored during juice shelf-life at two storage conditions (room and refrigeration temperatures). The reaction kinetics of main phytochemicals and a factorial analysis were also performed in order to achieve comprehensive data on the evolution of juice quality during storage. Results displayed how blending can protect the desirable properties of pomegranate juices better than pure monovarietal juices. Likewise, a high specificity between thermal treatment and kind of juice was found for each considered parameter. HTST exhibited a higher protective role than LTLT for blends of varietal pomegranate juices, whilst LTLT seemed to protect mixtures with lemon much better than HTST. Moreover, the concomitant degradation of anthocyanins and vitamin C and their role in colour variations were exposed. Overall, the array of outcomes might provide a satisfactory solution of colour alteration in pomegranate juices as well as red fruits in general.