Estudo preditivo da viabilidade e da ação antagonista de Lactobacillus acidophilus LAFTI L10 em iogurte integral de leite de cabra

Abstract

The incorporation of probiotics in fermented milk, in addition to the consumer health benefits, can contribute to the inhibition of pathogenic cultures present in food. This research aimed to make a predictive study of the probative behavior of Lactobacillus acidophilus LAFTI L10, during the fermentation and storage stages of goat yogurt, and the mathematical methods on the prediction of antagonistic action of this type of Pseudomonas aeruginosa (CCCD-P004), Staphylococcus aureus (CCCD-S009), Salmonella typhimurium (CCCD-S004) and Escherichia coli (CCCD-E009), inoculated in goat yogurt. For the study of probiotic viability, the selective counting of L. acidophilus in the MRS medium was added to the antibiotic clindamycin, and the data were adjusted for the Banaryi and Roberts model, with the aid of the DMFit 3.5 software. A model displayed with good fit to the observed data, with regression coefficient> 0.97 and mean square error (RMSE) close to zero. As yogurt samples and without probiotics, they were contaminated with suspension pathogens with a concentration equivalent to a scale of 1.0 in McFarland, allowed and stored at 4 ± 1 °C for 42 days. A count of the different bacteria was performed every 24 hours and the data were adjusted to the models of Baraniy and Roberts, Weibull and Bifhasic, using the software DMfit 3.5 and GInaFit 1.7. The statistical evaluation was performed using the statistical parameters R2, RMSE, polarization factor and precision of analysis and variance (ANOVA), using Statistic for Windows 7.0. Observe a greater reduction of pathogens in the quantities with the addition of probiotic, attesting to its antimicrobial property. The Barany and Roberts model was the most adequate to describe the inhibition of the P. aeroginosa, S. typhimurium and E. coli strains, with RMSE of 0.16, 0.14 and 0.19, respectively. The biphasic model better explained the behavior of the type S. aureus, with RMSE of 0.18 and R2 equal to 0.98. The addition of L. acidophilus has proven to be an effective alternative for making goat's milk yogurt more safely and modeling can be an ally of the dairy industry in terms of process optimization and risk management.