Indigenous enzymes in milk: A synopsis of future research requirements

Milk contains a large number of indigenous enzymes, with differing functions, stability to processing, impact on dairy products, and significance for consumer safety (e.g., antimicrobial enzymes). Some enzymes are of interest for their beneficial activity (e.g., lactoperoxidase), some for use as indices of processing (e.g., alkaline phosphatase) and some for effects on the quality of dairy products (e.g., plasmin, lipoprotein lipase), which may be either positive or negative for different products. The study of enzymes in milk is a key specialisation within both the fields of biochemistry and dairy science, and remains an active research subject. Many questions remain to be answered about the nature and significance of milk enzymes, and progress is in some cases hampered by inconsistencies in assay methodologies being used; some of these issues are discussed in this article, the content of which was generated in part by discussions at the First IDF Symposium on Indigenous Enzymes in Milk, Cork, Ireland, 20–22 April 2005.