Effects of high-pressure homogenization and ultrasonic treatment on the structure and characteristics of casein

To provide a basis for the reasonable choice of new non-thermal processing techniques in milk processing, especially high-pressure homogenization and ultrasound. In this paper, we investigated the structural changes of the casein that was treated independently by the above two technologies, using multiple spectroscopic techniques. Furthermore, the casein's functional characteristics were detected such as solubility, foaming, emulsifying, finally comparing the discrepancies in protein allergenicity. Research consequences are as follow: the secondary and tertiary structure of high-pressure homogenized casein changed; more hydrophilic amino acid residues were exposed, the surface hydrophobicity became worse, while the solubility remarkably ameliorated. In contrast, the content of anti-parallel structure of ultrasonic casein grew, the stability was relatively improved; more non-polar groups and hydrophobic side chains appeared leading to hydrophobic interaction reinforced. No matter what kind of processing methods, it can improve foaming and emulsifying properties to a certain degree. It is worth mentioning that the allergenicity of casein was crippled.