Spatial distribution of αs1-caseins and β-caseins in milk gels acidified with glucono-δ-lactone

Acid-induced destabilization of casein micelles leads to coagulation of milk which plays an important role in the formation of yogurt. The resulting protein network is formed by aggregation and reconfiguration of casein micelles, including the release of a portion of caseins from these micelles. It is so far unknown how individual αs1-and β-caseins are organized within this complex network, and how their distribution depends on yogurt composition and processing. Here, we imaged the spatial distribution of caseins using stimulated emission depletion (STED) microscopy and single-molecule localization microscopy (SMLM). We used fluorescently tagged antibodies against αs1-and β-caseins to localize them inside glucono-δ-lactone (GDL)-acidified milk gels. We conducted quantitative skeleton analysis of STED images and showed that αs1-and β-caseins contribute with different levels of connectivity to the acid induced milk network. [Display omitted] •Super-resolved microscopy imaging of αs1-caseins and β-caseins in glucono-δ-lactone (GDL) acidified milk gels.•Quantitative study of the connectivity of αs1-casein and β-casein microstructures in GDL-acidified milk protein networks.•αs1-caseins accumulate in loosely connected domains, while -casein microstructure is as connected as the entire network.