Modelling the effect of temperature, pH, water activity, and organic acids on the germination time of Penicillium camemberti and Penicillium roqueforti conidia

In this study, the influence of environmental factors on the germination time of Penicillium camemberti and Penicillium roqueforti conidia was evaluated. To do so, the effects of i/temperature, pH, water activity, and ii/organic acids were determined using models based on i/cardinal values, and ii/minimum inhibitory concentration (MIC) respectively. Cardinal values for germination of conidia were not observed to be species dependent. Minimum temperatures were estimated to be below the freezing point, with an optimum of 26.9 °C, and a maximum of 33.5 °C. For both species, minimal and optimal aw values were found to be 0.83 and 0.99, respectively, while for pH these values corresponded to 2.9, and 5.6. MIC values could not be determined for lactic acid because conidia of both species germinated in up to 1 M concentrations, the highest concentration tested. At pH 5.6, P. camemberti (MIC = 0.197 M) was more sensitive to propionic acid than P. roqueforti (MIC = 0.796 M).