I was talking with someone who works at Kedem grape juice. He told me that although they put Potassium Metabisulfite in their grape juice by the time the manufacturing process is done and you actually open your grape juice there are only 2-3 parts per million of "free SO2." That number seems incredibly low to me. Is it possible that he's correct or is he for sure wrong?
(Note it does say "contains sulfites" which is only necessary if there's at least 10 ppm, but it could be that they calculate this at an earlier stage or that they calculate total SO2, not free SO2.)