LAUSR

Abstract The objective of this study was to estimate the growth rate, lag time and the times for the appearance of visible mycelium ( t v ) of six fungal species ( Paecilomyces variotii , Penicillium paneum , Penicillium polonicum , Penicillium spinulosum , Penicillium citrinum and Aspergillus sydowii ). The growth parameters were determined at 20 °C, 25 °C and 30 °C and in two culture media (18% Dichloran Glycerol Agar - DG-18 and Dichloran Rose Bengal Chloramphenicol Agar – DRBC) aiming the selection of most appropriate strains for use in challenge tests and for the development of predictive models. Seventy-two growth curves were obtained after measuring the diameter of the colonies for 14 days at 20 °C, 25 °C and 30 °C. Values of growth rate between 1.4 and 11.1 (day −1 ) were obtained in this study. Faster growth rates (> 7 day −1 ) were observed for Pa. variotii (LMQA-001) and P. paneum (LMQA-002) at 25 °C. The lag times varied between 0.7 and 4.2 days, with 50% of the values being as short as 0.7−1.4 day. The variability between the species was analyzed and coefficients of variation (CV) of 44.2% and 41% for the growth rate were observed at 30 °C. At 20 °C and 25 °C, CV varied from 28.3% to 32.9%, respectively. Given these results, Pa. variotii and P. paneum could be considered for further use in microbiological challenge tests aiming to assess the robustness of bakery products formulations.