Thermal resistance of Salmonella enterica serotypes, Listeria monocytogenes, and Staphylococcus aureus in high solids liquid egg mixes

Abstract

Decimal reduction times (D-values) were determined for Salmonella enterica serotypes, Listeria monocytogenes, and Staphylococcus aureus in two high solids egg mixes designated A and B (water activity [aw] = 0.76 and 0.82; solids = 53.12 and 52.63%; pH = 5.09 and 5.29; viscosity = 183 and 119 centipoise/s, respectively) using a low-volume (0.06 ml) sealed glass capillary tube procedure. For Salmonella, D-values ranged from 0.035 (70°C) to 0.193 min (64°C) in product A and from 0.048 to 0.193 min in product B. For Listeria, D-values ranged from 0.133 (70°C) to 0.440 min (64°C) in product A and from 0.074 to 0.364 min in product B. For Staphylococcus, D-values ranged from 0.332 (70°C) to 1.304 min (64°C) in product A and from 0.428 to 1.768 min in product B. For Listeria, the D-values of all heating temperatures were significantly higher (P < 0.01) in product A than in product B. The similar trend was also observed for Salmonella and Staphylococcus but only at 66°C for Salmonella and 64°C for Staphylococcus. Greater temperature dependence was observed for Salmonella inactivation in the low aw and low pH product (A), while the product (B) with the higher aw and pH had greater temperature dependence for Listeria. Compared across both egg mixes and all heating temperatures, the Staphylococcus strains were from 6.2 to 11.7 times more heat resistant than S. enterica serotypes and from 2.2 to 7.5 times more heat resistant than L. monocytogenes. Copyright ©, International Association for Food Protection.