The greater inhibition observed in the control ham that was heat treated and cooled (from 54.4 to 7.2 C) after 3 h of storage (holding) suggests that factors other than sodium nitrite and sodium erythorbate may contribute to C.perfringensspore germination and outgrowth in meat. Residual oxygen in the meat samples even after vacuum packaging was evaluated as the responsible factor for the differences observed. Anaerobic packaging of meat samples containing NaNO2 at 0 and 100 ppm, with or without sodium erythorbate resulted in C. perfringenspopulations of 5.91, 3.78 and 3.63 log CFU/g, respectively in ham cooled within 15 h subsequent to 3 h of refrigerated storage (Fig. 5). For the same formulations prepared aerobically, final C. perfringens populations of 2.43, 2.66 and 2.19 log CFU/g were observed subsequent to cooling from 54.4 to 7.2 C when the prepared product was held for 3 h under refrigeration.
Cooling of ham (from 54.4 C to 7.2 C within 15 h) immediately after preparation (within 3 h) showed lower (p 0.05)
C. perfringens spore germination and outgrowth compared to the product that was stored under refrigeration for 24 h under vacuum (Fig. 5). Preparing the ham under anaerobic conditions enhanced (p0.05) C. perfringensspore germination and outgrowth during subsequent abusive cooling, and the C. perfringenspopulations were similar (p>0.05) to ham that was vacuum packaged and stored for 24 h under refrigeration. Incorporation of sodium nitrite (100 ppm) alone or in combination with sodium erythorbate (557 ppm) into the meat formulation minimized the effect of the refrigerated storage (under vacuum) and the anaerobic meat preparation (oxygen depletion) on enhancing C. perfringens spore germination and outgrowth.