It seems that every year scientists find surprising new forms of food product contamination, new organisms or chemical contaminants. Food safety testing is the most effective way to identify contaminants.

Surprises often come in the most unusual forms, in the US and Canada, for example the source of an outbreak of Listeria monocytogenes in November and December of 2014 was found to be pre-packed caramel apples.1 There are no reports of any illness from noncaramel apples or caramel candy and there is still no conclusion as to how the caramel apples became contaminated. Nevertheless, in January 2015, apples from the supplier were recalled because of Listeria monocytogenes contamination. This was a surprise, as investigators were looking at the current list of usually suspect items such as raw produce like leafy greens and cantaloupe, meat, dairy and other proteins, as being the source of the outbreak.

The industry and the public have faced a few surprises, for example, in the 1980s and 1990s there was the unexpected discovery of E. coli O157:H7 in ground beef and apple juice, as well as the identification of Listeria Monocytogenes in ice cream. BSE in cattle was another issue which has now spanned decades. In the 2000s, the surprises were melamine and derivatives in place of food proteins, and E. coli O157:H7 in leafy greens. In recent years, we have had E. coli O104 in sprouts and other shiga-toxin producing strains of E. coli in ground beef and other raw products. Listeria monocytogenes in Cantaloupe was an unusual event too, as the regulatory personnel and industry mainly look for Salmonella in this product. Other surprising events were Avian flu, lead in candy made with pepper ingredients, acrylamide on fried and baked products, and salmonella in peanut butter made by large and reputable corporations.

These outbreaks, whether caused by micro-organisms, chemicals or food fraud, and the resulting recalls were considered unusual at that time, but the industry has learnt of additional substances, organisms or products that must be reviewed. Unfortunately, a percentage of the industry and the public have not understood is that there are really no 100% safe food products. Post process contamination is always a risk, even at home. It is just a matter of reducing the risks to an acceptable level.

Reducing Risks

Throughout human experience, the population has processed foods to reduce risk, a practice that still applies. Global food sourcing and consumer demand for more minimally processed products increases the levels of risk. While we know that minimally processed animal proteins have high risk, the European Food Safety Authority (EFSA) Panel on Biological Hazards2 have provided their opinion on the health risks that may contaminate food of nonanimal origin, especially bulb and stem vegetables. Their view is that pathogens such as Salmonella, Yersina, Shigella and Norovirus are “likely to survive on the surfaces of these vegetables for days to several weeks at both ambient and refrigerated temperatures”.3

Using this product category as an example, systems controls such as Good Agricultural Practices (GAP), Good Hygiene Practices (GHP) and Good Manufacturing Practices (GMP) should be the primary methods of control. To reduce the risk of Salmonella and Yersina, we need to prevent direct contact between food contact surfaces and food handlers and animal and human faeces, as well as preventing indirect contact between them and contaminated manure, soil or water. This requires some degree of testing of the manure, soil, water and food contact surfaces. If bulb and stem vegetables are to be used as ingredients, some testing is required of them and/or the finished product in order to mitigate the risks.

Sometimes, the most effective way to reduce risk is to test for the contaminants. Moulds produce
mycotoxins, and the simplest method of determining if a raw material is acceptable and in compliance with the regulations, is to obtain a statistically correct number of samples, and test them for the likely mycotoxins. Process controls may help prevent the growth of the mycotoxins but will not remove them, so testing is the solution to assuring compliance.

In certain instances only, testing the raw material of finished goods will determine if the product is what it is supposed to be, or whether it is contaminated with some chemical. Food fraud concerning honey with added sweeteners and olive oil not labelled as claimed, or not totally olive oil, can normally only be resolved through specific tests or groups of tests. It is not possible to supervise a supplier’s production facility 24/7, or assure that raw materials are not diverted en route. Although chemical contamination such as pesticides and veterinary drugs should be controlled by process controls, finished product testing is still required to verify compliance to regulations.

With each new pathogen, chemical contaminant or food fraud scandal, the industry learns how to control the risk. While validation of process controls is still an essential part of a food safety operation, testing is also essential to reduce the risk. It is essential to verify compliance of food safety processes, especially when there is no processing point to eliminate the microorganism or chemical contaminant along the food supply chain, just additional points of possible contamination. Food testing in the form of water, environmental, raw material, in process and finished product testing must be done in order to assure that the product being produced is compliant with regulations or standards, and is safe for consumption.

While we don’t yet know how the caramel apples became contaminated with the Listeria Monocytogenes, we now know that if this product and its ingredients, as well as the processing facility, were tested for the pathogen, a recurrence could possibly be prevented. This at least would be a positive step forward until another crisis or process failure occurs.

For more information, please visit SGS Food Safety website or contact:

Jim Cook
Food Scientific and Regulatory Affairs Manager
SGS North America, Inc.
t: +1 973 461 1493
SGS Agriculture & Food


1 CDC - Multistate Outbreak of Listeriosis Linked to Commercially Produced, Prepackaged Caramel Apples
2 Food Quality - EFSA Evaluates Risk From Pathogens of non-animal origin
3 EFSA - Scientific Opinion on the risk posed by pathogens in food of non-animal origin.