Quite a few of those nutrients can be found in the ought to and skins in the grapes themselves but sometimes are supplemented by winemakers with additions such as diammonium phosphate (DAP), freeze-dried micro-nutrients (for instance Go-Ferm and Ferm-K) and perhaps the remnant of useless or extracted yeast cells http://finnltagn.blogzag.com/15628791/a-secret-weapon-for-wine-making