Combined effect of nisin and high hydrostatic pressure on destruction of Listeria innocua and Escherichia coli in liquid whole egg

High hydrostatic pressure inactivation of Escherichia coli and Listeria innocua inoculated in liquid whole egg was improved significantly (P<0.05) with nisin addition at concentrations of 1.25 and 5 mg/l. A reduction of almost 5 log10 units in E. coli counts and more than 6 log10 units for L. innocua was obtained at 450 MPa and 5 mg/l of nisin. For this treatment, the two microorganisms were not detectable after 1 month of storage at 4°C. The amount of nisin added did not affect E. coli inactivation at 300 MPa. For L. innocua, 5 mg/l of nisin was more effective than 1.25 mg/l. Nisin showed no effect when samples were stored at 20°C after pressurization, except for samples with L. innocua containing 5 mg/l of nisin and treated with 450 MPa.