Identification of physical contaminants in food
By Kathryn Hope 1 October 2015
Foreign bodies form the biggest single cause of consumer complaints received by many food and drink manufacturers, retailers and enforcement authorities. The accidental inclusion of unwanted items may sometimes occur in even the best managed processes. Rapid and accurate identification of foreign body material found in food is essential for determining the source of contamination and implementing measures to handle the incident and prevent occurrences.
When examining a foreign body the analyst will consider the following questions:
- What is the foreign body? Often the complainant will have made up their own mind what the foreign body is, for example they may believe they have found a fragment of glass, when further investigation may result in the identification of the foreign body as salt, sugar, plastic, or a mineral, all of which can look very similar to the naked eye.
- Where has it come from? For example if it is glass, is the source more likely to be a lightbulb, window glass, a casserole dish or drinking glass?
- Has the foreign body been in contact with the product from which the complainant has reported it? Examining surface deposits adhering to a complaint sample may provide information on the environment in which the foreign body was situated prior to discovery.
- Are there any signs the foreign body has been through a process? Cut marks, heat damage and overall condition are taken into account when looking to answer this question.
Many types of foreign bodies are found in food and drink and investigated in the microscopy section including insects, metal, minerals, fibres and hair, fingernails, droppings, bone, ceramic, tablets and capsules, paint and anything in between! A common foreign body we are asked to investigate is glass. A fragment of glass from the bottom corner of a jar is a case in point. These are often produced when someone is trying to scrape the last contents of a jar of for example jam or peanut butter using a spoon or knife, when a little excess pressure causes a small hole to be punched in the bottom corner of the jar.
Another example of a recurring foreign body is a fragment of dental amalgam. These tend to be dark in colour and so are easily spotted. Curiously, white dental fillings are very rarely reported as foreign bodies - probably because they're much less easily seen! Dental fillings and tooth fragments are often associated with hard foods such as crusty bread or biscuits, or sticky foods such as toffee.
We use a whole range of analytical techniques to identify foreign bodies including, light microscopy, compound microscopy, x-ray microanalysis and FTIR spectroscopy. The skill is to use the right technique for the detective work that the circumstances demand.
For more information regarding your physical contaminant identification issues please contact