Abstract
Coliforms have a high incidence as causative agents of foodborne illnesses. This study aimed to assess the bactericidal activity of Lactobacillus acidophilus at varying concentrations against total coliforms in fresh cheeses made from raw milk, employing imaging techniques and microorganism counts. Six milk samples were collected from the Model and Central markets in Barranca, Peru. Triplicate total coliform counts were conducted for each sample, and the most contaminated one was selected for further analysis. This sample underwent three treatments with different concentrations of Lactobacillus acidophilus (5, 6, and 7 log CFU 10 ml-1) to produce fresh cheeses. Subsequently, triplicate total coliform counts were performed for each treatment. An image analysis of the cheese structure was conducted to quantify the cavities and their areas caused by coliform bacteria. Furthermore, a control cheese was prepared for subsequent comparison to determine the final reduction in population. The control cheese displayed a total coliform count of 6.9 ± 0.02 log CFU g-1, 214 ± 12.03 cavities, and 0.4 ± 0.2 mm2. Post-application of Lactobacillus acidophilus resulted in a maximum reduction of 3.79 ± 0.09 log CFU g-1, yielding 44 ± 6.88 cavities with 0.1 ± 0.04 mm2 compared to the control sample. Treatment with a concentration of 7 log CFU 10 ml-1 of Lactobacillus acidophilus exhibited the most significant bactericidal effect on the total microbial population of coliforms present in fresh cheeses made from raw milk obtained from the Model and Central markets in the city of Barranca.
