Small-angle scattering for structure: unravelling casein micelle structure in milk and dairy products

by Prof. Thom Huppertz (Wageningen University; Friesland Campina)

Monday 8 Jan 2024, 14:30 → 15:30 Europe/Berlin

PH HS 3 (Physics Department)

In milk, unique association colloids called casein micelles are found. These particles, with a radius of ~100 nm, are highly hydrated (~75% water), with the dry matter containing ~95% protein and 5% salts, often referred to as micellar calcium phosphate. Industrially, coagulation of these casein micelles is of critical importance, as it is the basis of the manufacture of cheese and yoghurt, but also occurs in the stomach and therewith modulates the coagulation process. Given the importance of casein micelles in milk and dairy products, understanding their structure has been of key importance. While microscopic and light scattering methods provide insights into the size and shape of the particles and (bio)chemical techniques can be applied to determine composition, they do no provide insights into distribution of matter. For this purpose, SANS and SAXS have been employed, which have allowed the identification of calcium phosphate nanoclusters (radius ~2.5 nm), as well as protein-rich and water-rich domains. Elucidation of casein micelle structure using these techniques allows tailoring of micelle properties with applications in e.g., cheese, yoghurt or infant formula. Furthermore, they can be applied to understand casein micelle synthesis process in vitro, but also the influence of calcium sequestering salts in processed cheese products.