Significance of Enterobacteriaceae as index organisms for hygiene on fresh untreated poultry, poultry treated with lactic acid and poultry stored in a modified atmosphere

Abstract The significance of colony counts of Enterobacteriaceae on poultry, made at 37°C and at 42°C, and of Escherichia coli, as indicators of hygiene following storage at 6°C was investigated. Untreated chicken legs, legs decontaminated with 10% (w/v) lactic acid buffer, legs packaged in modified atmosphere (MA) and decontaminated (lactic acid buffer) legs packed in MA, were used as model systems. The enumeration of Enterobacteriaceae from plates incubated at either 37°C or at 42°C, indicated the hygienic condition of freshly processed items but not of those that have been stored at 6°C. Enumeration of Escherichia coli constitutes the most realistic means of defining the hygienic condition of poultry after storage of the product at 6°C. Moreover, it was found to be a good indicator of temperature abuse during storage. Decontamination with lactic acid in a buffered solution of 10% (w/v) at pH = 3·0 produced a c. 1 log 10 cycle immediate reduction in Enterobacteriaceae colony counts followed by a bacteriostatic effect on the psychrotrophic members of this group amounting to up to 3 log 10 during storage at 6°C.