Atomic force microscopy to assess the mechanical properties of individual casein micelles

Casein micelles (CMs) are ∼100 nm natural colloids found in milk resulting from the complex and unresolved association of casein monomers, phosphorus, calcium; latter being either directly bound to phosphoserine residues caseins or present as nanoclusters insoluble micellar calcium phosphate (MCP). Dairy products such cheese yogurt colloidal gels formed by CMs destabilization, for which texture ability be processed essentially determined rheological properties. Those properties depend on physico-chemical conditions used during gel formation (e.g., pH, temperature, ionic content). However, questions remain about origin this dependence at microscopic scale. In particular, we still do not have a clear picture specific contributions rigidity elementary bricks comparison with inter-particles interactions their spatial distribution. work, Atomic Force Microscopy (AFM) is evaluate changes nanomechanical single following modifications that known affect MCP content rheology enzymatic (i.e. decrease pH CaCl2 addition). AFM direct indenter assesses CMs’ elastic deformation gives an estimate Young modulus. We show ±18–24% w/w depletion enrichment content, modulus significantly decreases increases, respectively. This correlation suggests variations individual could explain macroscopic upon conditions.