Detection of foreign bodies in food products

Foreign bodies have become the number one source of consumer complaints in the food industry.

The considerable efforts made since the 1980s to ensure the hygiene and quality of food products have borne fruit, with a marked reduction in health-related incidents and complaints attributable to microbiological or chemical contamination of products.

However, incidents attributable to the presence of foreign bodies, although also fewer in number than in the past, are attracting more attention. The food crises of recent years have heightened the demands of consumers and retailers alike. As a result, a consumer complaint about a foreign body can take on considerable importance when relayed to different levels (customer, media, justice).

The integrated fight against the presence of foreign bodies is part of the overall HACCP ("hazard analysis critical control point") approach adopted by agri-food businesses, including the identification of critical points, preventive monitoring measures and corrective actions, and the search for upstream and downstream partners:

• knowledge of foreign bodies potentially present from raw materials to finished products, identification of their nature, origin and frequency;

• selecting and implementing appropriate preventive measures ;

• choose, in addition, detection and sorting solutions that minimize the probability of finding a foreign body in the finished product;

• definition of traceability measures, alerts and product recalls ;

• preparing for a potential crisis so that we can manage it more effectively.

The key to this approach is prevention work, which above all calls for common sense, rigorous line practices, and training and empowerment of production and maintenance personnel.

Detection and sorting systems should only be used as a complement, as a last line of defence against an accidental occurrence upstream, or when a machine incident is always possible and requires continuous monitoring (glass container breakage on a filling line, for example).

Various techniques are available, as described in this article, to detect, spatially locate and sort for ejection any foreign bodies that may be present: capture of ferromagnetic particles with magnets, electromagnetic technologies (metal detectors), technologies using industrial imaging, either by means of cameras (optical sorting systems with various wavelengths – visible, ultraviolet, infrared, multispectral), or by means of "computer reconstructed" images from rapid scans of the product or special sensors...