Abstract:The effect of pulse mode high-pressure on E.coli in fresh carrot juice was studied. Destruction kinetics of E.coli was investigated after pulse mode high-pressure treatment (300~600MPa, 1~4pulses). Enumeration was carried out in brain-heart infusion agar and violet-red bile agar to differentiate between surviving cells with and without injury. Results showed that with an increase in either pressure or pulse, both injured and killed cells increase significantly. At more than 400MPa, the increase of pulse, rather than pressure,makes the sterilization effect better. Two pressure pulses at 500MPa or a pressure pulse at 600MPa destroys the entire population (107.8cfu/mL) of E.coli in carrot juice. And on both BHIA and VRBA, pulse mode high-pressure destruction of E.coli in carrot juice follows first-order kinetics under experimental conditions. Modeling analysis showed that, for lethal effect, every 3.95, 1.76 and 0.83 pulses result in a decimal change of E.coli for 300, 350 and 400MPa, respectively; for injured effect, every 1.68, 1.26 and 0.48 pulses result in a decimal change of E.coli for 300, 350 and 400MPa, respectively. To achieve a same sterilization effect, when the pressure pulse decreases an order of magnitude the pressure has to increase by 229MPa and 206MPa, for BHIA and VRBA, respectively.