Résumé :
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The heat resistance (55-65 °C) of Clostridium perfringens vegetative cells in ground beef and turkey that included 0, 0.15 or 0.3% (w/w) sodium pyrophosphate (SPP) was assessed in bags heated using a water bath. The surviving cell population was assayed on tryptose-sulfite-cycloserine agar. The decimal reduction (D)-values in beef that included no SPP were 21.6, 10.2, 5.3, and 1.6 min at 55 57.5, 60, 62.5 °C, respectively; the values in turkey ranged from 17.5 min at 55 °C to 1.3 min at 62.5 °C. Addition of 0.15% SPP resulted in concomitant decrease in heat resistance as evidenced by reduced bacterial D-values. The D-values in beef that included 0.15% SPP were 17.9, 9.4, 3.5, and 1.2 min at 55, 57.5, 60, and 62.5 °C, respectively; the values in turkey ranged from 16.2 min at 55 °C to 1.1 min at 62.5 °C. The heat resistance was further decreased when the SPP level in beef and turkey was increased to 0 3%. Heating such products to an internal temperature of 65 °C for 1 min killed >8 log(10) cfu g(-1). The z-values in beef and turkey for all treatments were similar, ranging from 6.22 to 6.77 °C. Thermal death time values from this study should assist institutional food service settings in the design of thermal processes that ensure safety against C. Perfringens in cooked beef and turkey.
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