Use of β-cyclodextrin and activated carbon for quantification of Salmonella enterica ser. Enteritidis from ground beef by conventional PCR without enrichment

Abstract

The high level of PCR inhibitors present in ground beef is a major factor that affects molecular based techniques, such as the polymerase chain reaction (PCR), for the detection of Salmonella enterica. In this study, the use of β-cyclodextrin and milk protein coated activated carbon (MP-CAC) allowed the PCR to detect low numbers of Salmonella seeded into ground beef without enrichment of samples. invA was used as target gene in the conventional PCR protocol. With 25 g samples of ground beef containing 7.0, 15, and 27% fat, treatment of stomached samples with 5.0, 10, and 15% β-cyclodextrin respectively followed by treatment with MP-CAC, resulted in the detection of 3 CFU/g (equivalent to 75 CFU in a 25 g sample). The total assay time was 4.5 h. The methodology described in this study for the detection of S. enterica in ground beef without enrichment is rapid, sensitive, and has the potential to be applied to a number of complex food matrices to detect low numbers of food-borne bacterial pathogens.

Keywords: Activated carbon; Ground beef; PCR; Salmonella; β-Cyclodextrin.