> If you can buy the product with the added sesame you could also buy the product without the added sesame, could't you?
No. That does not follow.
Before, with "may contain sesame" the product might or might not contain enough sesame to trigger your reaction as it was completely uncontrolled. Sure, 99 times out of 100 it was fine but when somebody ran sesame burger buns on the third shift it would make you barf for 48 hours. You simply cannot eat that product on the off chance that it might be bad even though 99% of the time it is fine.
After, you know there is exactly X amount of sesame and never more than that. You can test the product once and it either affects you or it doesn't. At that point if it doesn't affect you, you can buy the product and be confident that it won't change.
Manufacturing 101: Anything that isn't measured isn't controlled.
They will be measuring the sesame that they are adding as an ingredient. That's on top of whatever unmeasured amount of sesame was already present due to contamination.
The manufacturer will dial the measured sesame so that it will be large enough that "cross contamination" will be a rounding error.
It's fairly easy to get something below a reasonable threshold--run a batch or two without the contaminant and throw them out. After that, the background levels will be below the added ingredient measurement.
> The manufacturer will dial the measured sesame so that it will be large enough that "cross contamination" will be a rounding error.
Sure, the "completely uncontrolled" amount present before - in the "may contain sesame" situation where it was not added as an ingredient - was a rounding error. That's why if you can buy the product now you also could do it before.
In the case where someone ran the sesame buns on third shift it very much wasn't a rounding error afterward.
It's not just "adding sesame". It's also going to be things like "specifying the amount of time to run disposable product on the line to get below specified threshold".
It's about consistency. Maintaining documentable 0.001% contamination is much, much harder than maintaining 0.1% contamination.
There is no winning this battle via penalties. If you don't want sesame contamination, you have to make the economics worthwhile. Or simply ban sesame, but you're going to get major pushback on that.
> In the case where someone ran the sesame buns on third shift it very much wasn't a rounding error afterward.
If it is a rounding error compared to the level that you find acceptable now it was a rounding error compared to the level that you find acceptable now.
If 1% plus epsilon is acceptable and you can buy it now, 0% plus epsilon was surely acceptable and you could buy it before.
No. That does not follow.
Before, with "may contain sesame" the product might or might not contain enough sesame to trigger your reaction as it was completely uncontrolled. Sure, 99 times out of 100 it was fine but when somebody ran sesame burger buns on the third shift it would make you barf for 48 hours. You simply cannot eat that product on the off chance that it might be bad even though 99% of the time it is fine.
After, you know there is exactly X amount of sesame and never more than that. You can test the product once and it either affects you or it doesn't. At that point if it doesn't affect you, you can buy the product and be confident that it won't change.
Manufacturing 101: Anything that isn't measured isn't controlled.