An assessment of the microbiological quality and safety of raw drinking milk on retail sale in England

J Appl Microbiol. 2018 Feb;124(2):535-546. doi: 10.1111/jam.13660.

Abstract

Aims: This study aimed to review the microbiological results for raw drinking milk (RDM) samples submitted to Public Health England laboratories between 2014 and 2016 in order to produce up-to-date data on the microbiological safety of RDM and inform future risk assessments on its sale.

Methods and results: A total of 902 samples of RDM were collected from retail sale in England for microbiological examination. Overall, 454 of 770 samples (59·0%) taken for routine monitoring were of a satisfactory quality, whilst eight (1·0%) were 'unsatisfactory and potentially injurious to health' due to the presence of Shiga toxin-producing Escherichia coli, Campylobacter or elevated levels of Listeria monocytogenes or coagulase-positive staphylococci. In contrast, 16 of 114 (14·0%) of samples taken in follow-up to a previous unsatisfactory result and 5 of 18 (27·8%) of samples related to illness were potentially injurious. A total of 229 of 902 samples (25·4%) gave unsatisfactory results due to elevated aerobic colony counts and/or coliforms, whilst 139 of 902 samples (15·4%) were of borderline quality due to coagulase-positive staphylococci. Listeria monocytogenes was detected at levels of <100 CFU per ml in 66 of 902 samples (7·3%) and other Listeria species in 44 of 902 samples (4·9%).

Conclusions: Pathogens and/or indicators of poor hygiene were present in almost half of samples examined. Cows' milk samples gave a significantly greater proportion of unsatisfactory results compared to milk from other species (i.e. goat, sheep, buffalo, camel).

Significance and impact of the study: These results demonstrate the importance of maintaining strict controls on the production and sale of this product.

Keywords: Escherichia coli; Listeria; Salmonella; dairy; food safety; raw milk.

MeSH terms

  • Animals
  • Campylobacter / genetics
  • Campylobacter / isolation & purification
  • Cattle
  • Consumer Product Safety
  • England
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification
  • Food Contamination / analysis*
  • Food Microbiology
  • Listeria / genetics
  • Listeria / isolation & purification
  • Listeria monocytogenes / genetics
  • Listeria monocytogenes / isolation & purification
  • Milk / chemistry
  • Milk / economics
  • Milk / microbiology*
  • Sheep
  • Staphylococcus / genetics
  • Staphylococcus / isolation & purification