Effect of temperature on inactivation kinetics of three strains of Penicillium paneum and P. roqueforti during bread baking

In this study, the inactivation kinetics of strains of Penicillium paneum and P. roqueforti were determined during bread baking. Three strains of P. paneum (PR03, PR04, and PR05) and P. roqueforti (PR06, PR11, and PR67) were used. Baking conditions were based on those used in baking industries (160 °C, 190 °C and 220 °C). The inactivation curves did not follow first-order kinetic, and as the primary model, the Weibull model was used with the fixed p-value. The t4D value was also determined, and the secondary model was built using the log δ as a function of the baking temperature. Lower values of δ and t4D were obtained at 220 °C, and the values of this parameter were different (p < 0.05) among the three P. paneum strains at 160 °C and 220 °C. Two strains of P. roqueforti (PR06 and PR11) showed the highest values of t4D at 190 °C and 220 °C (10.2 and 8.18 min. respectively). The results of this study demonstrate that the different baking temperatures of the bread making process may result in the survival of fungi in the product, which may be vital in limiting the shelf life of these products. The quantification of fungal inactivation during bread baking is critical for the design of thermal process aiming to balance quality and microbiological stability of industrialized loaves of bread.