Effect of enzymatic dephosphorylation on in vitro digestion of purified bovine caseins

This study investigated the impact of dephosphorylation on the in vitro digestibility of bovine α s -caseins (α s1 +α s2 ) and β-caseins. Three phosphorylation states were generated using bovine alkaline phosphatase: fully phosphorylated (native), partially dephosphorylated (α s1 : 65%, α s2 : 35%, β: 60%), and fully dephosphorylated (α s1 : 0%, α s2 : 25%, β: 0%). Digestibility was assessed using the INFOGEST 2.0 protocol, which employed the O-phthaldialdehyde assay to measure the degree of hydrolysis (DH) and LC-ESI/MS Single Q to track the breakdown of intact caseins. Results showed that dephosphorylation of α s -casein and β-caseins increased DH during both gastric and intestinal phases. For α s -caseins, DH development differed significantly among all phosphorylation states, which were found in both gastric and intestinal phases. At the same time, no significant differences were observed between partially and fully dephosphorylated β-caseins. These findings indicate that dephosphorylation increases the digestibility of caseins and is more pronounced in the digestibility of α s -casein compared to β-casein.