Originally Posted by
JDNSW
While not condoning its use to 'freshen' meat, it should be pointed out that sulphur dioxide is no more an ingredient of battery acid than air is - both are used in the process of making sulphuric acid. Battery acid is dilute sulphuric acid, which is made by catalytic conversion of sulphur dioxide to sulphur trioxide by adding oxygen. The acid is then made by dissolving this in water and diluting to the required strength.
Sulphur dioxide is legitimately used as a preservative in the dried fruit industry and in wine making. It is considered safe for human consumption in the quantities usually employed (although it may cause allergic symptoms for a few susceptible individuals, including myself!).
The problem with the use of it in fresh meat is not that the sulphur dioxide is harmful, but that the meat is supposed to be fresh, not processed, and it was almost certainly used to disguise the fact that the meat was obviously unfit for consumption.