Impact of high intensity pulsed electric field on antioxidant properties and quality parameters of a fruit juice-soymilk beverage in chilled storage

The effects of high-intensity pulsed electric fields (HIPEF) treatment (35 kV/cm, 4 is bipolar pulses at 200 Hz for 800 or 1400 mu s) on the microbial stability, quality parameters and antioxidant properties of a fruit juice-soymilk (FJ-SM) beverage along the storage time at 4 degrees C were compared to those obtained by thermal pasteurization (90 degrees C, 60 s). HIPEF processing for 800 mu s ensured the microbial stability of the beverage during 31 days; however, longer microbial shelf-life (56 days) was achieved by increasing the treatment time to 1400 mu s or by applying a thermal treatment. Peroxidase and lipoxygenase of HIPEF treated beverages were inactivated by 17.5-29% and 34-39%, respectively; whereas thermal treatment achieved 100% and 51%. During the storage, vitamin C content and antioxidant capacity depleted with time, and they were higher in FJ-SM beverages processed by HIPEF than in those thermally treated. Instead, total phenolic content of beverages did not present significant changes over the time, and it was higher in the 1400 mu s-HIPEF treated beverages. In general, color, soluble solids, pH, and acidity values were not significantly affected by the processing treatments. Beverage viscosity increased over time, regardless of the treatment applied. Hence, application of HIPEF may be a good alternative treatment to thermal processing in order to ensure microbiological stability, high nutritional values and fresh-like characteristics of FJ-SM beverages. (C) 2010 Elsevier Ltd. All rights reserved.