Authors : S. Basak , H.S. Ramaswamy and J.P. Smith
Abstract: Effect of high pressure (HP) treatment, ranging from 5-60 min at 50-400 MPa, on the destruction of microorganisms in fruits and vegetables was evaluated. The pressure destruction of microorganisms was dependent on the magnitude of pressure, pressurization time, type of microbial population and commodity. The studies showed that the initial population of naturally occurring microorganisms for all fruits decreased by 2 log cycles at a pressure of 200 MPa, while a similar treatment was slightly less effective for vegetables (resulting in about one log-reduction). After HP treatment at 400 MPa, there were no microbial survivors in vegetables suggesting that there were possibly no spores present. Death rate curves were analyzed by the biphasic pressure destruction behavior established previously for enzyme inactivation. The reduction in microbial population due to pressure alone (without a hold time) was designated as the pressure pulse kill (PPK). The PPK values were dependent on the commodity and increased with pressure. Pressure destruction of microorganisms followed a first order reaction (R2<0.90) during the pressure-hold time. Pressure sensitivity of kinetic parameters D and k were well described by pressure z-value (PDT approach) and activation volume ( V ) (Arrhenius approach). The PPK factor should supplement these models when used for describing pressure destruction kinetics.
S. Basak , H.S. Ramaswamy and J.P. Smith , 2003. High Pressure Destruction Kinetics of Microorganisms in Selected Fruits and Vegetables. Journal of Food Technology, 1: 142-149.