I posted this elsewhere too but just by way of a heads up:
I recently bought some "food grade" hydrochloric acid from 'solvent-shop' on ebay, intending it for water-treatment. When it arrived there was nothing at all on the container that indicated it was food grade so I asked them about this; apparently they consider it suitable for use around food (like cleaning food-making machinery) but tell me it is 'not' suitable for ingestion.
In fact they seemed unaware there even are any grades of hydrochloric acid that could be used in food itself. So my understanding of 'food grade' hydrochloric and theirs is clearly not the same, and it seems unlikely that this product complies with E507 or any other food-additive level of specification. How bad it actually is if ingested I've no idea, but thought it worth a mention. Mine looks set for patio-cleaning duties.