The combined effects of pH, NaCl and temperature on growth of cheese ripening cultures of Debaryomyces hansenii and coryneform bacteria

Growth of five strains each of Debaryomyces hansenii, Brevibacterium linens and Corynerbacterium spp. in a laboratory substrate was investigated at combinations of pH, NaCl concentration and temperature similar to those in surface ripening of cheeses. For D. hansenii the effect of pH on growth was found to be insignificant, but a combination of NaCl and temperature had a significant effect. For strains of B. linens and the Corynebacterium spp., the combined effects of pH, NaCl and temperature were found to be significant. All strains of B. linens, C. ammoniagenes and C. flavescens were stimulated by 4.0% (w/v) NaCl. Quadratic polynomial models were developed that described the growth of D. hansenii as a function of NaCl and temperature and growth of B. linens and Corynebacterium spp. as a function of pH, NaCl and temperature. Model validation in the laboratory substrate showed a good agreement between predicted and observed values.