Physical contaminants

foreign bodies

There is little more off-putting to customers than when they find what they consider to be a 'foreign body' in their food. Most consumer complaints to manufacturers and retailers derive from this. Sometimes the object is a perfectly natural component of the food - but in all cases it is important to find out what it is and how and when it got there. Campden BRI offers a fast, accurate service for the identification of adventitious and deliberate contaminants, helping to pinpoint its source and advising on preventative solutions.

Glass fragments

Light microscope examination for features such as size, colour, curvature, surface scratches and deposits is followed by X-ray microanalysis in the scanning electron microscope. This quick non-destructive test gives a spectrum of the elements found in a sample, and results are compared with data from a large reference collection of known glass samples to make an identification.

Metal, stone and plastics

These, and other non-biological materials, are subjected to a similar examination process to that used for glass samples. X-ray microanalysis can distinguish between different metals, including the different types of stainless steel. With plastics, other techniques such as Fourier Transform Infrared (FT-IR) spectroscopy can be used to "fingerprint" the material. This technique is also invaluable for many pharmaceutical tablets and capsules.

Insects

In most cases these can be identified by examination using a light microscope. In a few cases, results may need to be confirmed by more detailed examination of certain features in the scanning electron microscope.

Extraneous vegetable matter

This is often identified by light microscopy to demonstrate its cellular structure, using various histochemical stains to identify the chemical nature of the material. Similar approaches can be used to identify other similar samples such as rodent droppings.

Hair and fibres

These are usually identified using light microscopy and compared with a reference collection of known samples. Polarised light microscopy can be a valuable aid with many artificial fibres. In the case of asbestos fibres, X-ray microanalysis is used to confirm an identification by determining the chemical composition of the mineral.

Has it been heat processed?

Heat processing of many once-living samples such as insects destroys enzyme activity in the sample, and hence tests for enzyme activity can be used to determine if the sample has been heat-treated in many cases. In other cases, such as glass or metal, the condition of surface deposits such as starch can give indications as to the history of the sample.

Species?

In addition to the above techniques DNA-based analysis can be used to identify several species.

Other foreign bodies

The above is only a selection of the foreign bodies which are most frequently identified. We have a wealth of experience of dealing with a wide range of unusual objects over many years.

We also run a foreign body proficiency identification scheme (FOBS) for other laboratories to check their competence.

Contact us

If you would like further information about our physical contaminants services please email us at information@campdenbri.co.uk or call our switchboard on +44(0)1386 842000 and they will be happy to direct your call to the relevant person.