Predictive Modeling of the Growth of Lactobacillus Viridescens under Non-isothermal Conditions

Food spoilage by microorganisms is a major problem that can generate large economic losses to industries, making critical the application of technologies for predicting shelf life, aiming to obtain products with higher quality. The Lactic Acid Bacteria (LAB), including Lactobacillus viridescens, are among the main groups of microorganisms responsible for spoilage of refrigerated meat products, vacuum packed and under modified atmosphere. The growth of the LAB can be predicted by mathematical models, which describe the influence of various environmental factors (such as non-isothermal conditions) on microbial growth. The objective of this study was to obtain a mathematical model able to predict the growth of L. viridescens in non-isothermal conditions in culture medium (MRS broth). Six isothermal growth curves (at 4, 8, 12, 16, 20 and 30̊C) were described by Baranyi and Roberts model and the dependence of maximum specific growth rate (μmax) parameter on the temperature was described by square root secondary model. The model was validated using L. viridescens experimental data in the temperature ranging from 6 to 10°C and 5 to 11°C, changing every 12 and 24h, respectively. The results showed that it was possible to predict safely (bias factor greater than 1) the growth of L. viridescens in MRS broth under non-isothermal conditions. The observed prediction deviations may have been caused by abrupt temperature changes, generating intermediate adaptation phases.