Developing a time and effort-effective, highly sensitive TaqMan probe-based real-time polymerase chain reaction protocol for the detection of Salmonella in milk, yoghurt, and cheese

Abstract

A time- and effort-effective, highly sensitive method combining brief pre-enrichment for only 4 h in a non-selective broth and TaqMan probe-based real-time PCR was developed for the detection of different concentrations of a cocktail of 8 Salmonella Typhimurium strains in milk and dairy products. As few as 1 cfu 25 mL−1 of Salmonella in milk was detectable, and sensitivity was not influenced by the presence of contaminating microflora or using milk containing different combinations of fat and solids-not-fat. The method could be also successfully used for detecting Salmonella during the preparation and cold storage of yoghurt and soft cheese. It was able to detect injured cells in cheese prepared from 10% and 12% salted milk after 3 months of cold storage. Given that the method generates quantitative data related to the numbers of the pathogen in these products, it is recommended for use in microbial risk assessments, and hazard analysis critical control point (HACCP) plans.