Interactions of phenolic compounds with milk proteins

This study showed that phenolic compounds mainly interacted with casein rather than whey protein. To prove this, the molecular interactions between phenolic compounds and milk proteins, such as casein and whey proteins, were investigated by measuring changes in their aggregate sizes of molecules. Size-exclusion chromatography was performed to determine the aggregate sizes of milk proteins. Results showed that when casein was mixed with an extract of green tea, grape, or cranberry, the aggregate size of casein increased as a result of chemical interactions between casein and the phenolic compounds. Meanwhile, only a negligible change in the aggregate size was observed when whey protein was mixed with phenolic compounds, implying little interaction. The higher affinity of these polyphenolic compounds with casein proteins was correlated with the high recovery potential of polyphenolic compounds in the cheese-making process as caseins are the main proteins in cheese curd. These results could help to design manufacturing processes of functional dairy products that improve yield and quality attributes.