Today’s heightened occurrence of food allergies and intolerances is difficult to ignore. Approximately 15 million people in the United States are suffering from at least one allergy or intolerance; changing lifestyles, increased protection from germs, plus certain ‘healthy’ or ‘exotic’ eating trends could all be contributing to this rise.

Eight major food allergens — milk, egg, peanut, tree nuts, wheat, soy, fish and crustacean shellfish — are responsible for most of the serious food allergy reactions in North America. Allergy to sesame is an emerging concern.

Additionally, milk proteins and lactose are among the most common food allergens.

New research presented at the American College of Allergy, Asthma and Immunology’s (ACAAI) Annual Scientific Meeting suggests that over 2% of all U.S. children under the age of five have a milk allergy, and 53% of food-allergic infants under 12 months have a cow’s milk allergy .

For dairy processing facilities, having a robust cross-contamination and cross-contact strategy is necessary. The response by equipment manufacturers is to offer smarter, more flexible ways for dairy processors to adapt their cleaning procedures and minimize hygiene challenges.


Is your factory machinery sanitary?

Larger dairy manufacturers will, where possible, segregate production areas handling known allergens such as nuts. For smaller manufacturers, this option might not be available. In this case, the emphasis must fall on hygiene and good process practices.

In fact, where allergens may be present and there is a risk of contamination being passed from batch to batch, cleaning must go well beyond normal hygienic requirements. Even where heat processing is involved, allergens can still survive high temperatures.

While not an exhaustive checklist, the following areas of advice provide a good starting point when it comes to the overlap between allergen control and metal detection:


  1. Equipment cleaning protocols: These should be formalized and included in staff training. Every cleaning procedure needs to be verified and documented. As part of a validation process, regular tests, including swabs of critical control points, should be scheduled to ensure these areas are allergen-free.
  2. In-process metal detection: Priorities and hazard analysis will be different for every plant, yet many manufacturers will want to screen different ingredient streams, liquid and solid, for contaminants rather than relying on end-of-line conveyor-based metal detection for packaged product. Where ingredients have been assessed as higher risk, it makes sense to screen them at an upstream point in the process. The costs associated with rejecting contaminated finished product would far exceed the cost of rejecting the contaminant upstream in a small amount of raw materials.
  3. Powders and liquids: Product residues potentially including allergens, can be especially troublesome in gravity metal detection systems for powders and particulates. This might apply to dairy that uses different types of dried or frozen ingredients for flavoring, thickening or fortification. Likewise, liquids, semi-liquids and slurries in pipeline systems can pose problems of their own. For example, adding dairy proteins may not be a problem when drinks are milk-based, but the same filling line that handles waters and other soft drinks fortified with protein sources such as whey may also run dairy-free products. Hygiene procedures must be thorough in both settings.
  4. Overall system design: Efficient product changeovers are critical to productivity. For factory managers facing regular changeovers, it is essential for processing, filling and packing lines to be designed to facilitate both quick and thorough cleaning.
  5. Metal detection system design: When specifying in-process metal detection, contact surfaces on conveyor, pipeline and gravity systems should be as smooth and crevice-free as possible. This is partly to ensure that no traces of product, allergens or bacteria are left, but also to reduce the risk of cleaning agents that may not be completely rinsed off.
  6. High-pressure cleaning: The construction of the metal detector should be sufficiently robust to withstand this high-pressure cleaning. It is important to identify equipment with an ingress protection (IP) rating appropriate to the washdown regime being applied. For high-pressure cleaning, IP69K should be the minimum IP rating.
  7. Reject mechanism: Special attention should be paid to the reject device. Ideally, this will be easily detachable and re-attachable to allow thorough cleaning.
  8. Other sources of risk: There are many possible sources of cross-contamination in a dairy processing facility. Critical cases where operators are at a potentially high risk of spreading allergens — for example, moving ingredients around the floor in unsealed containers, running allergenic products at the start of the shift rather than the end, and not changing or cleaning protective equipment — need to be addressed and the message driven home

Purchasing the best metal detection equipment for the job may constitute only one portion of a much bigger picture for a complex dairy business with multiple product lines. Yet it provides evidence that your company is taking the threat of contamination from allergens and pathogens seriously and will make a real and valuable contribution to reducing those risks.