When stock goes off-condition

Supplement stock ages on your shelf as well as the customer's, and most of the ways it degrades cannot be seen.

Four ways it stops being salable

It caked. Moisture got in. Visible, and the most likely to come back to you.

It went rancid. The fat oxidized, faster in whey and other animal proteins than in plant-based. Detectable by smell.

It lost potency. The actives declined. Not detectable by any means available without an assay.

It passed its date. Which may or may not correspond to any of the above.

Only two are visible

That asymmetry is the problem. A tub that looks and smells fine can be substantially under its label claim, and you would have no way of knowing without testing it.

Which is why a declared shelf life has to come from stability evidence rather than convention, and why old stock is a testing question rather than a judgment call.

What you cannot do with it

You cannot re-blend it back to potency, you cannot dry out a caked tub, and you cannot repackage it into a fresh-looking container and call the problem solved.

And you should not discount it. A supplement sold cheap because it is near or past date is a product whose quantitative claim may no longer be true, sold to the customer least able to evaluate it.

Preventing the write-off

Batch to sell-through rather than to the testing economics, which push the other way. Store your own stock sealed, cool and dry, to the same standard you print on the label. Rotate oldest first with dates on the outer.

And keep reserve samples so that a question about an older batch can be answered by testing rather than by guessing, which is also what the rule expects.

References