The practice of adding sodium citrate to milk used as infant food has been common for many years. It has found application especially in the treatment of certain types of "feeding-cases" in which untreated milk, after entering the stomach, forms abnormally large chunks of tough curd, shown by Talbot1 to consist of casein. These lumps of curd may pass practically unchanged through the entire intestinal canal, causing mechanical irritation, which often results in serious interference with the process of normal digestion. Empirical practice has shown that this abnormal curdling of milk may, to some extent, be modified or controlled by the addition of sodium citrate at the rate of 1 or 2 grains per ounce of milk. While various suggestions have been offered to explain the results observed, these have been based so little on demonstrated chemical facts as to partake largely of the nature of guesswork.
BOSWORTH AW, VAN SLYKE LL. WHY SODIUM CITRATE PREVENTS CURDLING OF MILK BY RENNIN. Am J Dis Child. 1914;VII(4):298-304. doi:10.1001/archpedi.1914.04100400047003