Rock phosphate, food grade?
I'm probably going to add a little food grade gypsum, as a mineral yeast food, to a bread formula I'm thinking about making. I'm thinking also of phosphorous in the sense that yeasts like that as well.
"Yeast requires water, carbon sources such as starch and simple carbohydrates, nitrogen preferably as ammonium as it cannot assimilate nitrate, sulfur, phosphorus (often as inorganic phosphate), and minute quantities of vitamins and elemental mineral ions including B, Ca, Co, Cu, Fe, K, Mo, Mn, Mg, Ni, and Zn.
Oh wow, that's a long list of required minerals! Ideally, I'd want food-grade rock phosphate, rather than some of the fancier chemicals, but searching didn't result in any quick results, nothing that is specifically labeled as food grade. Powdered rock phosphate is widely available for agricultural use.
This says rock phosphate is used for livestock feed. Evidently there is a food grade available, or at least one that is considered safe for animals to consume. Perhaps it is not labeled as "food grade"?
I just thought I'd ask to see if anyone knew anything about food-grade rock phosphate.