Sensitivity of Listeria innocua to high hydrostatic pressure at low temperature in Ringer's solution and milk

The research was performed to investigate the effect of high hydrostatic pressure low temperature (HHPLT) on Listeria innocua in Ringer's solution (RS) and raw milk (RM). The physicochemical properties of RM were studied at 300 MPa and 10 degrees C. Compared with the control, protein and lipase activities were reduced at HHPLT in RM. The L -values (luminance) of LHPLT applied RM were significantly (P < 0.05) decreased for colour Pressure application at 300 MPa for 90 min totally inactivated L. innocua at -20 degrees C in both RS and RM. L. innocua showed resistance to low pressure (200 MPa) in RM. Overall, increasing the pressure with applications at -20 and -30 degrees C resulted in a higher (P < 0.05) inactivation of L. innocua than at 10 and 20 degrees C. HHPLT applications to frozen RM resulted in the retention of textural characteristics.