90 FOOD & DRINK TECHNOLOGY
Food microbiology: we ignore it at our peril
We need to be constantly aware of the importance of microorganisms in our foods, says Dr Roy Betts.
Selon le Dr. Roy Betts, nous devrions constamment être conscients de l’importance des microorganismes dans l’alimentation.
Wir müssen uns über die Bedeutung der Mikroorganismen in unseren Lebensmitteln stets bewusst sein, so Dr. Roy Betts.
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Fig. 1. There is a fine balance between microbiological stability and safety of food products. Inability results in the growth of organisms that can cause spoilage and illness.
Recent data from 2009 suggests around 25% of the UK population suffers from food poisoning every year, and that this figure was 43% higher than it was in the early 1990s, although improved diagnosis and reporting may have some impact on this figure.
t is tempting to believe that we are now aware of all of the microbiological problems
that we face in our foods and are well prepared to understand and tackle them. Public health statistics tell us otherwise, and give us a warning that we ignore food microbiology at our peril.
Te organism causing the biggest issue is Campylobacter; although this organism was first observed in the late 19th Century, it was not recognised as a major food pathogen until the 1970s. It is now acknowledged as the biggest cause of outbreaks of food poisoning in the UK. Its source is predominantly poultry
and recent figures suggest that 59% of UK retail poultry is contaminated. However it is not hard to kill the organism, proper cooking will do it easily. In recent years the issue of undercooking and a keenness to serve items such as chicken pate in an undercooked format has exacerbated the issue.
Salmonella has long been recognised as a cause of food poisoning and in the 1990s its presence on poultry and eggs was a major issue. However, interventions in poultry breeding and vaccinations of poultry flocks against Salmonella have substantially reduced the issue in these foods. It is, however, continuing to cause problems in other foods, particularly those that have a low moisture content, such as dried spices, nuts, seeds etc. In such conditions Salmonella will not grow, but it survives and is still able to infect consumers, contaminate other foods and it has become clear that Salmonella, like many other organisms, becomes much more resistant to heating when it is in low moisture conditions, so ‘normal’ cooking temperature of, for example 70 to 80°C, will not affect it.
But what of other ‘newer’ organisms. Listeria monocytogenes was not considered a food related problem until the 1980s. Te unique nature of this organism is its ability to grow at temperatures as low as 0°C, potentially causing issues in even well refrigerated foods. While not causing great numbers of illnesses, perhaps only 250 per year in the UK, approximately 25% of people will die from the infection, so it is an organism to take very seriously.
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