Fermented rice horchata I have been making some horchata (using white rice, cinnamon and water). I left it for a day and when I returned, it looked slightly fermented (a stream of bubbles were coming out of it and it was frothy ever so slightly). I blended and sweetened it and it tasted delicious, with a slightly tangy taste.

My question is will it be safe to eat? I see no reason why it shouldn't be, after all it is no different to fermented ginger beer, but I would like to have some advice.
There is a pathogen, Bacillus cereus, which can grow on rice left out at room temperature and cause food born illness.

I was unable to find any references to proper fermentation of horchata which is normally not fermented as far as I can tell.

You may wish to be cautious in the future.