Resumen

VALBUENA, Emiro et al. Growth prediction of lactococcus lactis subsp. Lactis in sterile skimed milk as a function of temperature. Rev. Cient. (Maracaibo) [online]. 2008, vol.18, n.6, pp.745-758. ISSN 0798-2259.

Several mathematic models have been developed to predict the behavior of bacteria populations in growing phase and controlled conditions at the laboratory. Many of these models have been validated under food production, transportation and storage conditions. The objective of this study was to adapt a mathematical model using equations obtained as a result of the analysis with secondary models of regression coefficients from the Gompertz equation, to predict population of Lactococcus lactis subsp. lactis in the growing phase in reconstituted and sterilized powder milk, controlling temperature in a range of 9 to 39°C. Prediction was done by the analysis of “A” and “B” coefficients, using the square root model, obtaining R² values = 0.819 and 0.991, respectively. Furthermore, a hyperbolic model was used for modeling “D” (R²= 0.812) and “M” (R²= 0.995) coefficients. Finally, a reparametrized expression of the original Gompertz model was obtained replacing each regression coefficient by the described equation, in relation to the different studied temperatures. Thus, this model was used to directly predict the population of microorganism under study at any temperature in the studied range. Small differences were obtained between both, the experimental and the adjusted populations, according to the application of the developed model. A well balanced distribution of the residual values was observed. The use of this type of models is recommended to describe growth of combined microorganism populations in products such as commercial pasteurized milk.

Palabras clave : Lactococcus lactis; Gompertz model; predictive microbiology; bacterial growth.