Understanding variation in casein micelle structure using re-assembled casein micelles

Cow’s milk proteins play an essential nutritional role in the diet and an important technical role in making various dairy products. Roughly 80% of these milk proteins are caseins. Caseins are mainly present in casein micelles which are colloidal particles that contain casein molecules, minerals, and water. The size and structure of casein micelles have important influences on making traditional dairy products, and can be used for developing novel foods, such as animal-free dairy products. Although there is consensus on general aspects of casein micelle structure, the effect of natural variation in composition and post-translational modifications on structure are largely unknown. A possible way to study casein micelles’ structure is to use casein micelles that are assembled in vitro. Such casein micelles are called re-assembled casein micelles (RCM) or artificial casein micelles (Schmidt et al., 1977). In this project, RCM will be used as a tool to study the size, structure, and properties of casein micelles. Using purified caseins, different methods will be applied to make RCM. Different methods of making RCM will be compared and evaluated. Using this technology, the effect of casein molecules with different amino acid sequences, reflecting genetic variation, and post-translational modification on casein micelle size and structure will be studied. Different combinations of αs1-, αs2-, β-, and κ-caseins will be used to assemble RCM. The obtained knowledge can be used as important guidance to make an animal-free product, for instance by assembling yeast-based casein into casein micelles.

Aim
This project aims to understand how variations in casein affect the size and structure of casein micelles.

Approach
RCM will be assembled under different conditions to understand how processing factors affect the size and structure of RCM. Then the RCM will be used as a tool to study how variations in casein affect casein micelles’ size and structure.

References
_{Schmidt, D. G., & Koops, J. (1977). Properties of artificical casein micelles. 2. Stability towards ethanol, dialysis, pressure and heat in relation to casein composition. Neth Milk Dairy J.}