Abstract: The particle distribution of casein and the structure of casein micelle from milk, buffalo milk and goat milk were studied by nanoparticle size analyzer and scanning electron microscopy, respectively. The results suggested that the size distribution of casein and the structure of casein micelle from milk, buffalo milk and goat milk were significantly different. The average casein particle diameter from buffalo milk was 182.3 nm. The connected casein particles formed slender micelles, and the micelles cross-linked into a network structure. The average casein particle diameter from milk was 207.4 nm, and the connected casein particles formed thick micelles. The average casein particle diameter from goat milk was 173.8 nm, and the connected casein particles formed short casein micelles but the micelles can not be cross-linked into a network structure.

Key words: nanoparticle size analyzer, scanning electron microscopy, casein, size, micelle structure