These experiments were carried out in order to note the comparative speeds of digestion of the usual modifications of milk used in the feeding of infants at varying ph concentrations and also to note the effect of adding rennin1 to the various foods. Emphasis has been placed on the relation of the ph of the gastric contents to digestion. This disadvantage of feeding cow's milk to babies has been in part ascribed to its high buffer effect in neutralizing gastric juice, and, conversely, the greater digestibility of human milk has been laid to the fact that it does not neutralize gastric juice to such an extent. The preparations of acid milk used in the feeding of infants lower the ph of the gastric contents and so are said to favor digestion, stimulate gastric motility and increase the antiseptic properties of the gastric juice.
FETTER D, SCHLUTZ FW. DIGESTION OF MILK AND OF MODIFIED MILK IN VITRO. Am J Dis Child. 1935;50(5):1101-1106. doi:10.1001/archpedi.1935.01970110009002