Diacetyl tartaric acid is the modified organic acid that is combined with monoglyceride to create an acid-resistant emulsifier — the ester better known in the trade as DATEM. The chemistry joins diacetyl tartaric anhydride to mono- and diglycerides of edible fats, producing an emulsifier with an unusual talent: it stays functional in acidic doughs and batters where ordinary emulsifiers fail. Bakers use it to strengthen gluten networks, improve dough tolerance to mechanical stress, and increase loaf volume — it is one of the classic dough conditioners of industrial bread-making. It also stabilises emulsions in products like coffee whiteners and whipped toppings. As a food additive it is assessed and permitted within set limits, and it exemplifies the technical emulsifier class: molecules engineered for a specific hostile environment, in this case acidity.