Model of inactivation kinetics of pressure resistant strains in low acid food by ultra-high pressure processing

The ultra-high pressure inactivation models of pressure resistant strains in low acid food were studied in order to describe and predict the inactive effects. Four kinds of spores from spoilage strains (Bacillus subtilis, Bacillus licheniformis, Bacillus stearothermophilus and Desulfotomaculum nigrificans) were inactivated under 300-500 MPa, and their survival curves were determined at selected time intervals. Weibull and traditional linear models were used to describe the ultra-high pressure inactivation model. Three criteria, accuracy factor (Af), mean square error (MSE) and regression coefficients (R2) were used to compare the linear and Weibull models. The results suggested that Weibull model fitted well at 300–500 MPa (R2>0.9), while the linear model could be applied only at 300 MPa (R2<0.83). The equation of Weibull would be beneficial to the food industry in selecting optimum combinations of pressure and time to obtain the desired target levels of bacterial inactivation.