Heat resistance and inactivation of meat spoilage lactic acid bacteria.

Abstract

Heat resistance and inactivation of processed meat spoilage lactic acid bacteria was investigated in vitro and by in-package pasteurization of South African vacuum-packaged vienna sausages. In vitro heat resistance of four lactic acid bacteria strains was low, since reductions of at least one log cycle in bacterial numbers occurred upon heating at 57, 60 and 63°C in quarter-strength Ringers solution for one minute. In vitro heat resistance data were used to calculate three in-package pasteurization treatments of increasing severity for vacuum-packaged vienna sausages. Depending on treatment, pasteurization in a water cooker at 67°C increased microbiological shelf life of sausages 10, 14 and 17 times that of control samples, during storage at 8'C. Although in-package pasteurization successfully decreased growth of spoilage lactic acid bacteria and increased product shelf life fit did not entirely prevent spoilage by pediococci. Since pasteurization also promoted growth of potentially pathogenic Bacillus and Clostridium, safety of pasteurized vacuum-packaged vienna sausages was compromised.