Well prompted, Genie - I remember after reading your note that when I used to make beer I could use potassium metabisulfite quite happily but sodium metabisulfite made me cough like hell! My friend reckoned there was no difference but my chest didn't believe him! Funny you mention fruit juices as well. Even before the ashtma lemon barley water brought on coughing attacks like nothing else.

Cheers

DtG