Microbiological Quality of Raw Ground Chicken Processed at High Isostatic Pressure

Freshly ground raw chicken that had average aerobic and anaerobic bacterial populations of about 10⁶ colony-forming units (CFU)/g was packaged and sealed in polyfilm pouches. Pouches were shipped on ice for high-pressure processing at ambient temperatures. Temperatures during the l0-min high-pressure treatment never exceeded 28°C. Samples were immediately cooled to <4°C and returned to the originating laboratory where counts of aerobic and anaerobic bacteria were made during storage at 4°C. Samples were considered spoiled at the time counts by either of the two bacterial enumeration methods reached 10⁷ CFU/g, based on the upper limit of the 95% confidence interval of the three trials. Applications of 408 MPa, 616 MPa and 888 MPa to the samples resulted in estimated microbial spoilage times of 27 days, 70 days, and >98 days, respectively. The type of bacteria that survived best in the pressure-treated samples were the facultatively anaerobic psychrotrophic bacteria, Carnobacterium divergens and Serratia liquefaciens .