Effects of enzymatic dephosphorylation on infant in vitro gastrointestinal digestibility of milk protein concentrate

• Dephosphorylation of milk protein concentrate was affected by phosphatase and pH.
• A series of milk protein concentrate with 0–69% dephosphorylation were obtained.
• β- and αs1-casein in modified milk protein concentrate showed multiply isoforms.
• Dephosphorylation improved gastric clotting property of milk protein concentrate.
• Dephosphorylation improved infant digestibility of milk protein concentrate.

This study investigated the effects of dephosphorylation extent on infant in vitro gastric clotting property and gastrointestinal digestibility of milk protein concentrate. Dephosphorylation was affected by phosphatase type and incubation pH. A series of milk protein concentrate with 0–69% dephosphorylation were obtained by incubation with calf intestinal alkaline phosphatase at pH 6.5 for 0–420 min. Both β- and αs1-caseins in the modified milk protein concentrate showed multiply dephosphorylated isoforms with different numbers of phosphate groups depending on the extent of dephosphorylation. With increased dephosphorylation of milk protein concentrate, the gastric clotting extent decreased and the gastrointestinal digestibility increased under infant in vitro conditions. These results suggested the potential of developing a dephosphorylated milk protein concentrate, with improved gastric clotting property and gastrointestinal digestibility, to simulate the multiply phosphorylated patterns of human casein and hence to further the humanization of infant formula on a molecular level.