Application Of Oscillatory And Pulsed UHP For B.Subtilis Spores Germination And Inactivation In Milk

To develop a method of germinating and sterilizing B.Subtilis spores with minimal heating was studied by the combined effect of oscillatory and pulsed UHP, pressurization times, and operations cycles. The condition above room temperature was benefit to UHP sterilization. At 40℃,seven pressurization cycles with the first pressure at 200MPa for 5min,followed by an ambient pressure pause for 1min, then another 700MPa pressurization for 5min, decreased the spores count from 107 to 102-103cells/ml. Temperature was found to have a significant effect on the germination of B.Subtilis Spores during treatment. CoMPared 40℃ with 4℃, the percentage of B.Subtilis Spores germination showed 80.11% and 55.42% respectively. Germination was markedly increased to 94.74% when B.Subtilis Spores were treated with 200MPa, 40 ℃ for l0min. And B.Subtilis spores inactivation was greatly promoted by increase of the pressure. Under 700MPa at 40 ℃ for 10min, the survivor level was the worst (0.004%). During oscillatory and pulsed pressurization period, along with the temperature, oscillation cycle is a very critical factor in achieving sterility. However, vessel pressurization time has a little effect on B.Subtilis Spores.