Effects of high intensity pulsed electric field processing conditions on vitamin C and antioxidant capacity of orange juice and gazpacho, a cold vegetable soup

Orange juice and gazpacho, a cold vegetable soup, were submitted to high intensity pulsed electric field (HIPEF). The effects of electric field strenght, treatment time, pulse frequency, width and polarity, as process parameters, on vitamine C retention and antioxidant capacity of both products were evaluated and compared to those in a heat pasteurization. Vitamin C was determined by HPLC and antioxidant capacity through the inhibition of the DPPH° (1,1-diphenyl-2-picrylhydrazyl) radical. Orange juice and gazpacho retained a 87.5-98.2% and 84.3-97.1% of vitamin C, respectively, after HIPEF treatments. Pulses applied in bipolar mode, as well as lower electric field strength, treatment time, pulse frequency and width, led to higher levels of vitamin C retention (p<0.05). HIPEF-treated orange juice and gazpacho always showed a vitamin C retention higher than that of the heat-pasteurized products. There were no differences (p<0.05) in antioxidant capacity between HIPEF-treated and untreated products, whereas heat-treated foods showed lower values of antioxidant capacity.