Characterizing Lactic Acid Bacteria and Thermotolerant Coliforms in Spoiled Dairy Products from Bosnia and Herzegovina

The rising foodborne disease outbreaks poses significant challenges to key objectives in food microbiology. This trend is primarily attributed to global population growth and intensified food production. A thorough microbiological assessment of end products is therefore crucial.

We evaluated the bacterial presence and abundance in various dairy products (sour cream, cottage cheese, buttercream, cream cheese, pasteurized milk, protein-rich milk, and yogurt) sourced from a local supermarket in Bosnia and Herzegovina. Two enumeration methods (pour plating and most probable number) were employed alongside morphological, biochemical, and molecular analyses (Gram staining, oxidase test, catalase test, indole test, lipolytic activity assay, and RT-qPCR). Our focus was on spoilage-causing lactic acid bacteria (LAB), hygiene indicator thermotolerant coliforms (TC), and the foodborne pathogen Salmonella spp. 

Six out of seven dairy products harbored high levels of LAB, suggesting potential spoilage, except for cottage cheese. Additionally, both TC and Escherichia coli exceeded acceptable microbial limits, particularly in pasteurized milk. Furthermore, initial tests detected presumptive Salmonella spp. in cream cheese, protein-rich milk, and yogurt.

These results highlight the need for stringent sanitary practices during dairy production to extend product shelf-life and prevent premature spoilage from unwanted bacterial presence. Moreover, eliminating pathogen contamination during manufacturing is crucial to mitigate serious food safety risks, including potential food poisoning.