FOOD & DRINK TECHNOLOGY 91
Even more recently we have seen the rise in importance of the pathogenic Escherichia coli. It was in the 1990s that
E.coli O157 was identified as a potent pathogen usually associated with minced beef. We now understand that the O157 strain is one of many hundreds of pathogenic
E.coli known as Shiga Toxin producing
E.coli (STEC) that can cause severe illness. Tey have been found in meats, raw dairy products and even fresh produce.
In 2011 in Germany one strain,
E.coli O104 caused around 4000 cases of illness and 50 deaths. Te strain had not previously been recognised as a problematic pathogen; the issue was traced back to sprouted fenugreek seeds used raw in salads. Since then in the UK, STEC outbreaks have also been linked to handling potatoes and eating watercress.
So what of the future? So far consideration has been given only to bacterial pathogens but we are now able to more fully understand the role of viruses in foodborne illness. It has recently been estimated that Norovirus causes around 200,000 cases of illness in England and Wales every year. Some will be due to person-to-person spread but perhaps something over 20,000 cases will be foodborne. Tis virus has been associated with raw shellfish in the past, but its link to eating fresh produce is now being considered.
Te virus is highly infective and the consumption of just 10 virus particles can cause illness, the major symptom of is vomiting which can spread the virus still further and infect more people. Hepatitis A and E can also be foodborne. Hep A is associated with similar foods to Norovirus, but Hep E has recently been linked with pork products and has been reported to have a degree of heat resistance.
What can we conclude from this? Firstly that we need to be constantly aware of the importance of microorganisms in our foods. New research and the development of new testing methods expand our knowledge of what causes issues, and what could become a problem in the future. None of the organisms in this article are difficult to control and eliminate from foods, the design of recipes and processes that keep foods safe can be straightforward.
However, lack of knowledge of such organisms and their controls leaves the potential for food safety failures to occur. Additionally, we live in a time when the pressure to modify
products is great, this can be problematic for product stability. If we change anything about our food, eg the type of cooking used, levels of preservative, salt, sugar, the type of package, or even the way we consume it, then this may alter the delicate balance between microbiological stability and safety, and instability resulting in the survival and growth of organisms causing spoilage and potentially illness.
Understand what keeps a food microbiologically safe and stable, maintain safety controls, and never make changes unless they have been fully microbiologically validated, this should result in control over pathogens and safe food products.
Dr Roy Betts is Head of Microbiology, CampdenBRI, Chipping Campden, Gloucestershire, UK.
www.campdenbri.co.uk
www.scientistlive.com
Fig. 2. The importance of microorganisms in our foods must not be underestimated and new testing methods are expanding our understanding of potential problems.
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