Model calculations of casein micelle size distributions

A previously proposed model for the formation and structure of casein micelles from subunits of variable composition is used to calculate theoretical micelle size distributions. Using the fractional content of κ-casein as the only variable but with a value near that observed in a sample of milk serum, the model successfully reproduces experimentally determined distributions. Predicted size distributions are quite sensitive to the value of the variable and shift toward smaller average size as the assumed fractional content of κ-casein gets larger. Also, there is a discontinuity in the distributions which predicts that there will be essentially no micelles with radii smaller than 25-30 nm. These predictions are all in accord with experimental observations. The good agreement between theory and experiment supports the micelle structure suggested by the model.