MICROBIAL-GROWTH ESTIMATION IN LIQUID-MEDIA EXPOSED TO TEMPERATURE-FLUCTUATIONS

Comparisons of linear, square root and Arrhenius specific growth rate-temperature models showed no clear overall preference. At low a(w) and refrigeration temperature, the linear model was satisfactory for Brochothrix thermosphacta and Pseudomonas fluorescens. A linear relationship between (specific growth rate)-1 and lag phase was observed for these two psychrotrophs. The R2 for B. thermosphacta in 3% (a(w) = 0.968), 6% (a(w) = 0.950), and 9% NaCl (a(w) = 0.943) media was 0.865, 0.946 and 0.994, respectively. In 8% (a(w) = 0.973) and 20% (a(w) = 0.948) glycerol media, the R2 was 0.998 and 0.999, respectively. R2 for P. fluorescens growth in NaCl (3 or 4%) or glycerol (10 or 20%) media was >0.99. A cumulative growth adaptation function successfully estimated microbial growth at fluctuating temperatures.