We discovered this product in Australia on our last visit. You use it to remove sulfites from wine.
Sulfites are a natural result of the winemaking process, and are one of the by-products you get when yeast turns sugar into alcohol. Sometimes they are added to stop the fermentation process, but this is being done decreasingly often. I'm not sure how adding a man made bleach to a natural product is supposed to make it healthier.
There was no blog post yesterday - we were busy on Friday and just didn't get around to it, sorry.