Indigenous enzymes in milk: Overview and historical aspects—Part 1

The indigenous enzymes in milk have been the subject of research since 1881 when the first report on an indigenous enzyme (lactoperoxidase (LPO)) appeared. These enzymes originate from an animal's blood plasma, leucocytes (somatic cells) and the apical membrane or cytoplasm of the secretory cells. By the early 20th century, seven indigenous enzymes had been identified in milk: LPO, catalase, xanthine oxidase, proteinase, lipase, salolase (arylesterase) and amylase. These were probably the most widely recognised enzymes at that time and, in addition, some of them were relatively easily assayed or were technologically important. The progress of research on these enzymes to the present date will be reviewed in this article.