Investigation on Shelf Life of Carrot Juice Processed by Pulse Electric Field

Effects of PEF processing (25 kV/cm for 200 mus at 1 Hz) on enzymes and quality-related parameters of carrot juice were investigated during 28 days storage at 4degC and compared with effects of traditional heat pasteurization at 95degC for 15 sec in this paper. PEF treatment inactivated 37.35% and 52.14% of the activity of PME and PPO in carrot juice respectively, and the Activity of enzymes remained significantly constant during 28 days storage at 4degC (p > 0.05). PEF-treated carrot juice retained better turbidity than thermal-pasteurized juice, accompanying with insignificant changes in color indices (L, a, b, DeltaE and browning index) throughout storage. PEF treatment decreased the non-enzymatic browning reaction, and kept browning index almost stable throughout storage. The pH value of juice had no significant change after PEF treatment, and remained almost constant during storage time. PEF treatment caused an 8% decrease of the carotene content, and another 6.2% reduction of carotene content was observed after stored at 4degC for 28 days.