To me this suggests a very simple solution. Legislate that each ingredient parcel must come with an audit trail. Assign to each parcel a reference number - a UUID or hash - that can be used to trace back its entire life and history. The solution seems so obvious that there are probably significant obstacles against doing so that I am not aware of. If such a system is implemented, then the next time a contamination breaks out, the source can be quickly identified and eliminated, then apologies can be made, and business can resume as normal.
>> The spread of norovirus in Simi Valley and Boston was caused by breaches of protocol, Ells says
Eliminating contamination entirely is a highly desirable goal, but outbreaks will likely continue occur regardless of anti-contamination measures. As a result, it makes sense to make it as easy as possible to shut down outbreaks before they become crises.