Pasteurization of fresh orange juice using low-energy pulsed electrical field

Using the hurdle approach, temperature, acidity, and number of pulses were varied to maximize microbial inactivation in orange juice. The effect of PEF combined with the addition of nisin, lysozyme, or a combination of both to orange juice was also investigated. Optimal conditions consisting of 20 pulses of an electric field of 80 kV/cm, at pH 3.5, and a temperature of 44degreesC with 100 U nisin/ml resulted in over a 6-log cycle reduction in the microbial population. The process was most influenced by a change in temperature (p < 0.0001). Following treatment, there was a 97.5% retention of vitamin C, along with a 92.7% reduction in pectinmethylesterase activity. The microbial shelf-life of the orange juice was also improved and determined to be at least 28 d when stored at 4degreesC without aseptic packaging. Gas chromatography revealed no significant differences in aroma compounds before and after pulsing.