Evaluation of temperature effect on growth rate of Lactobacillus rhamnosus GG in milk using secondary models

The application of secondary temperature models on growth rates of Lactobacillus rhamnosus GG, the much studied probiotic bacterium, is investigated. Growth parameters resulting from a primary fitting were modelled against temperature using the following models: Hinshelwood model (H), Ratkowsky extended model (RTK2), Zwietering model (ZWT), and cardinal temperature model with inflection (CTMI). As experienced by other authors, the RTK2, ZWT, and CTMI models provided the best statistical indices related to fitting the experimental data. Moreover, with the biological background, the following cardinal temperatures of L. rhamnosus GG resulted from the study by the model application: t _min = 2.7°C, t _opt = 44.4°C, t _max = 52.0°C. The growth rate of the strain under study at optimal temperature was 0.88 log₁₀(CFU mL^?1 h^?1).