Effect of probiotic bacteria Lactobacillus casei and Lactobacillus acidophilus on the survival of Staphylococcus aureus and Escherichia coli in lactic cheese and its qualitative characteristics

Some probiotic microorganisms can prevent the growth of pathogenic microorganisms in addition to improve the intestinal microbial balance. In this study, the qualitative characteristics and viability of two foodborne pathogens (Staphylococcus aureus and Escherichia coli) lactic cheese were investigated. For this purpose, in the first stage, four types of lactic cheese (60 samples) were produced as probiotics (containing Lactobacillus casei and Lactobacillus acidophilus) and non-probiotic with 3 and 4.5% fat milk in three replicates, and the quality parameters were evaluated at days 0, 14, 28, 42 and 56. Then, 12 types of lactic cheeses [(probiotic/non-probiotic) fat percentage (3 and 4.5%) and pathogenic microorganisms (absence, presence of Staphylococcus aureus or Escherichia coli)] (180 samples) were prepared and the viability of pathogenic microorganisms in the presence of probiotic was evaluated on days 0, 7, 14, 28 and 35. The addition of probiotics to lactic cheese significantly reduced fatty acid oxidation and increased acidity and volatile nitrogen compounds (P < 0.05). The addition of probiotics to high-fat cheeses increased non-protein nitrogen compounds but decreased in low-fat cheeses. The addition of probiotic to lactic cheese significantly reduced the growth of S. aureus and E. coli (P < 0.05). Increasing fat percent did not show a significant effect on bacterial growth inhibition by probiotics (P < 0.05). Due to the effects of adding probiotics on decreasing the pathogenic bacterial growth and not significantly altering the sensory properties of lactic cheese, it is recommended to use these probiotics in the production of low-fat lactic cheese.