Bacteria holds key to dairy hygiene analysis

Related tags Milk

A study into microorganisms in raw milk has found that bacteria can
be useful as routine indicators of on-farm hygiene practices.

The findings could have a significant impact on milk production practices. Freshmilk is nearly sterile, and contaminating microorganisms present in fresh milk are introduced from the cow's udder and teats, the milking equipment or the storage tank.

Throughout the world, total viable counts (TVCs) are used by the dairy industry as an indicator of raw milk quality. TVCs were introduced by the UK Milk Marketing Boards during the mid-1980s and their acceptance was consolidated in EU dairy hygiene directive 92/46/EEC.

A source of variation however comes from the microbiological methods used by testing laboratories.

Research group RSSL​ points out that the agar pour plate method for measuring TVC has now been superseded by Bacto-Scan methods which use automated flow cytometry and epifluorescence staining. Although BactoScans produce very rapid TVC results, they suffer from the same problems as the pour plates, in that when results are compared with those arising from government dairy hygiene inspector audits, there seems to be no correlation between total bacterial counts in milk and farm hygiene audit scores.

In the present study, bacterial indicators were measured in terms of TVCs, E. coli, coliforms, Bacillus spp., Bifidobacteria spp., and Pseudomonas spp. Farms were visited and audited using custom-developed audit forms.

ADAS Consulting and Direct Laboratories carried out the survey at 24 UK farms during 2003 and 2004. The findings have recently been published in the Journal of Food Protection.

The study comes as the rise in global food production, processing, distribution and preparation has led to growing pressure on the food chain to minimise outbreaks of food borne diseases.

In industrialised countries, the percentage of people suffering from foodborne diseases each year has been reported to be up to 30 per cent.

And in the US, for example, around 76 million cases of foodborne diseases, resulting in 325,000 hospitalisations and 5,000 deaths, are estimated to occur each year.

Sixty-one deaths and 73,000 illnesses - such as bloody diarrhoea and hemorrhagic colitis - are blamed on eating foods contaminated with E. coli each year, according to the US Centers for Disease Control and Prevention.

Related topics Markets Regulation & Safety

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