Minerals and vitamins are added to the dough at the creaming stage, or the wet stage of dough-making step. Vitamins and minerals premixes are easier to mix at the liquid stage
Average losses of vitamins: A >30%, D >30%, E - 40%, B1 >40%, B2 >30%, Niacin >20%, B6 >30%, B12 >30%, Folic acid >40%, C >40%.
Average losses of minerals: 5%
Soft-dough type of biscuit will loose 50% more B1, and B2 than the hard-dough type.
Important amount of B1 is lost in the dough prior to baking, if the dough is kept a long time before being baked, up to 60% after few hours. B1 is sentitive to high pH.