Dear Alan,
I think you mean the contaminant physical size is big ? You may well be correct but the validation of such logic will surely be problematic, both conceptually and practically ?.
IMO the basic, current, (auditor / processor) problem is that relevant data / accessible references which demonstrate detection limits for a variety of real food matrices are either unpublished or unreferenced. ? More likely the latter I suspect.
Rgds / Charles
Hi Charles, I mean that the signal that the test samples give off with respect to the threshold is BIG so in essence the marginality between 304 and 316 in most practical instances isn't that relevant. The issue (para 2 above) is that there is a lack of understanding of what is achievable/practical/reasonable with the physics of metal detection and the food industry/audit regimes rely on information from the manufacturers to arrive at something that minimises risk but is workable, in terms of the technology delivering 'metal free' food I think we arrived at this point a while back. However, metal still reached the consumer, so it's either below the specification of the equipment or above, the latter indicates a system (line control) failure.
Regards
Alan