Cinética do crescimento in vitro de bactérias em meio de cultivo contendo extrato de cascas e sementes de tamarindo

Abstract

Predictive microbiology has been applied, through mathematical models, in order to predict the behavior of microorganisms when exposed to varied growth conditions. This science has gained prominence since it allows to predict growth rates and lag phase duration of contaminating pathogenic microorganisms in food. In this context, this work aimed to evaluate the effect of temperature (10 to 45 ° C), pH (5.0 to 9.0), sodium chloride concentration (0 to 8.5%) and concentration of bark extract and of tamarind seed in 80% ethanol (0 to 10%) in the in vitro growth of Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella Enteritidis and Enterococcus faecalis. The parameters were evaluated according to fractional factorial design 24-1 plus 3 central points. The bacteria were incubated under the proposed conditions and the primary model of Baranyi and Roberts was adjusted to the experimental data (correlation coefficients between 0.72 and 1) to obtain the growth rates and the lag phase time. In general, there was growth inhibition for all bacteria, with rates ranging from -0.03 to -6.04 Log UFC / mL h. Through the analysis of the Pareto graph it was found that pH was the parameter that had the most significant effect. However, the extracts of bark and tamarind seed also showed significance in the inhibitions. In this study, the in vitro growth of pathogenic bacteria was predicted in a culture medium containing extract of tamarind residue, which showed a weak potential to be used as a natural antimicrobial.