Inactivation of microorganisms in orange juice by high-pressure homogenization combined with its inherent heating effect

Abstract

The combined effects of high-pressure homogenization (HPH) and inherent increase in temperature on the survival of Lactobacillus plantarum and Listeria innocua were studied in orange juice. L. innocua was found to be very sensitive to HPH processing, and combination of 110 MPa and 20 °C (48 °C outlet temperature) or 150 MPa and 20 °C (57 °C outlet temperature) for 2 s was sufficient to achieve a reduction higher than 5 log cycles from the initial bacterial count. L. plantarum appeared to be more HPH resistant, and no effects on the microbial counts were found up to 80 MPa. Inactivation higher than 5 log cycles of L. plantarum was achieved after HPH treatment at 150 MPa and 19 °C (56 °C outlet temperature) for 20 s or 21 °C (57.5 °C outlet temperature) for 10 s. Inactivation kinetics of L. plantarum were fitted to a log-linear-tail equation, biphasic and Weibull models. Kinetic parameters increased with outlet temperature indicating an increase in the inactivation rate. The survivors’ curve showed two subpopulations with different resistance to HPH treatment. Weibull model was found to be the best candidate to characterize the microbial behavior after HPH processing being the error in the prediction below 4%. This study shows a novel approach for pasteurization of fruit juices by using the combined effect of pressure and inherent increase in temperature caused by HPH processing.