M. Steiner wrote:

I have a feeling that some small manufacturers just play around with
ingredients sometimes and don't bother to change the label, to reflect
the change in ingredients.  And how do you prove it?

Dear Monica,

You must be very passionate, approaching fanaticism to prove it.
Recently I spent $1250 to test some lab samples for diet soda.  My
daughter chose to do an aspartame study for a school project, measuring
breakdown rates of diet soda in the fridge.  She discovered a secret:
aspartame broke down into formaldehyde and DKP (diketopiperazine), a
neurotoxin.  The lab testing is very expensive.

Robert "NOTMILKMAN" Cohen
http://www.notmilk.com