Contents: Surveillance of foodborne disease | Phasing out ethylene oxide | Campylobacter in cattle and sheep | Campylobacter (and others) in the kitchen | The Food Safety ToolKit™
Phasing out ethylene oxide
Following a meeting of the Australia and New Zealand Food Regulation Ministerial Council in August, it was announced that the phasing out of ethylene oxide for the treatment of herbs and spices in Australia is now complete. The announcement followed assurances from the Australian Food and Grocery Council (AFGC) that their members, representing 99 per cent of trade by volume in these items, no longer use the process.
The Ministerial Council thanked the AFGC for its contribution to this result and noted that various mechanisms have been used to ensure that small producers and importers of herbs and spices are aware of their obligation with regard to ethylene oxide.
The original timetable for the end to the use of ethylene oxide as a sterilant for herbs and spices (by official removal of the temporary maximum residue limit of 20 mg/kg) was 1 October, 2003.
The phasing out of ethylene oxide because of its potential carcinogenic properties was accompanied by an approval by the former Australia New Zealand Food Safety Council for the use of irradiation up to a maximum dose of 30 kGy for the decontamination of herbs and spices. This was the first such approval for irradiation of foods in Australia (Food Safety & Hygiene, September 2001).
It is therefore of interest to note that the major importers of herbs and spices have relied on 'steam sterilisation, batch selection and good manufacturing practice' to achieve the desired microbiological quality of these products. While irradiation as approved in the Food Standards Code has been proved to be effective in eliminating pathogens from herbs and spices (World Health Organization, 1988), producers, importers and users have preferred to seek other ways of reducing the microbial load of these products. This load can be substantial (International Commission on Microbiological Specifications for Foods, 1998) although in recent years herbs and spices have rarely been involved in foodborne illness outbreaks. A significant proportion of herbs and spices would have been treated with ethylene oxide during that time.
The food industry has long been aware of the risks associated with unprocessed herbs and spices and various strategies are now being used to reduce their microbial load in a manner which will avoid the irradiation controversy. These include (British Food Journal 104 2002 724):
cfu = colony forming unit
Heat treatment
Whole or ground herbs and spices can be pasteurised by flash processing with steam. The process has to be carefully regulated to achieve maximum kill and minimise loss of volatile flavour and colour. Reductions in load of greater than 90 per cent have been reported but the process does not achieve total elimination - nor of course did ethylene oxide. However as some spices, e.g. pepper, are not uncommonly carrying an initial load of around 106 cfu/g, a 90 per cent reduction would mean a residual population of 105 cfu/g and a 99 per cent reduction would leave 104 cfu/g. Fortunately a small proportion only of the initial load is likely to be made up of potential pathogens.
Improved agricultural practices
Major spice traders are now working more closely with producers to obtain 'cleaner' raw material for processing. This will assist in lowering microbial numbers but cannot eliminate risks as the product is still largely processed (dried) in the open air. There is also little that can be done to improve the hygiene of agricultural practice for those herbs which are harvested from the wild. Another concern is that in some countries, e.g. India, trading groups assemble lots from small-scale market gardeners.
Product selection
Assessment of numerous batches of herbs and spices and selection of the microbiologically cleanest to be directed to the most sensitive food products can be effective. However, considerable time must be devoted to this exercise for it to be meaningful - contamination of a batch is unlikely to be evenly distributed - and in poor cropping years, there may not be suitable quantities available.
When herbs and spices are directed to food product categories which receive a pathogen reduction step, e.g. thermal processing or cooking, the hazard posed by small numbers of pathogens carried into the product by the ingredients is not great. Some products, however, which receive no terminal process, e.g. flavoured dairy-based dips, must receive added herbs and spices of high microbiological quality if the risk of foodborne illness is to be minimised.
Usually the pathogens commonly associated with some herbs and spices, e.g. Salmonella spp., have to grow to large numbers in the food product as consumed to pose a hazard. However, this is not always the case particularly if the food is consumed by sensitive consumers. Readers may recall from the September 1996 issue of this bulletin, the incident in Germany in 1993 when paprika-powdered potato crisps caused an outbreak of salmonellosis which affected around 1,000 people. Most cases were young children and investigation revealed that contaminated paprika gave rise to levels of no more than 0.04-0.45 organisms per gram in the snacks as eaten.
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