Seaming: tools and monitoring for microbiological risk control

The crimping of metal cans is a mechanical operation designed to assemble the lid, known as the base, onto the body of a can. The purpose of the seam is to close the container after filling, and thus seal the can against subsequent recontamination, particularly microbiological recontamination.

Good hygiene and HACCP guidelines for the canning industry consider crimping to be an essential element in guaranteeing the safety of the finished product. The staff in charge of this operation (setting up crimping machines and monitoring crimping quality) must have the necessary skills for the job.

Microbiological instability in canned foodstuffs in metal cans, whose origin is not due to a heat treatment defect, is generally due to a leak in the seam, even if in-process controls have proved to be compliant.

After a review of the operations involved in forming a seam on a metal can, this article presents the tools and means for controlling the quality of the seam, as well as the methodology for carrying out this control.

However, the correlation between tightness and dimensional measurements remains complex to establish, as it depends on many variable factors. Cans with dimensional faults (values below recommendations) may be leaktight during leak testing; conversely, cans with dimensional measurements close to recommendations may, in some cases, be non-leaktight during bubble testing (vacuum testing).

A glossary of key terms is provided at the end of the article.