A MODEL FOR THE COMBINED EFFECTS OF TEMPERATURE AND SALT CONCENTRATION ON GROWTH-RATE OF FOOD SPOILAGE MOLDS

We modeled mold growth on a solid culture medium at various temperatur es and NaCl concentrations by using five common food spoilage molds (P enicillium roqueforti, Trichoderma harzianum, Paecilomyces variotii, A spergillus niger, and Emericella nidulans). For the description of the growth rate (expressed as the increase in colony diameter per unit of time) as a function of temperature and NaCl concentration, a six-para meter model has been developed, The model combines either the Rosso-ty pe or the Ratkowsky-type temperature dependence with the NaCl concentr ation dependence derived from the relationship between the growth rate and root(1 - water activity), as proposed by Gibson and coworkers (A. M, Gibson, J, Baranyi, J, I, Pitt, M. J, Eyles, and T, A. Roberts, In t, J, Food Microbiol, 23:419-431, 1994), The model will be of use to f ood microbiologists whose aim is to predict the likelihood of fungal s poilage.