Many of such nutrients are available in the must and skins in the grapes them selves but in some cases are supplemented by winemakers with additions including diammonium phosphate (DAP), freeze-dried micro-nutrients (including Go-Ferm and Ferm-K) as well as the remnant of useless or extracted yeast cells this sort http://jaspersngat.collectblogs.com/18693166/a-simple-key-for-wine-equipment-unveiled