Lipase: A Review

Abstract

These pages were written with the hope that they might prove useful to those who know little about lipase, and to those who know nmch. The references cited may not be the first paper on a given topic nor the last. The first publica- tion may be indecisive, incomplete. The last may be less informative than an earlier publication. Some may feel that too much has been omitted; an equal number may feel that too much has been included. So be it. If these pages help some to understand what is already known; if they point the way for further research; if they stinmlate some to start new investigations, then the time spent in writing this has been well spent. At one time, some chemists doubted that normal milk contained lipase. It is now accepted that the great majority of cows secrete milk containing" fat- splitting enzynles but, in most cases, these enzymes are inactive. Under certain conditions they may become active and cause serious loss. In view of this fact, it is more important to know the activity of lipase in raw milk than to know the quantity; and handlers of milk must pay particular attention to those factors which increase or reduce the activity of the enzyme. 2 Several times in the history of the dairy industry, new methods of handling or processing milk have activated the lipase system and produced rancid flavors. ttomogenization is the best known example of this. Raw nfilk becomes rancid so quickly after homogenization that the sale of homogenized milk would be impossible if lipase could not be inactivated by simple means. As a second example of changes in practice which led to trouble with lipase, we may cite the change in temperature of separation which occurred in the mar- ket cream industry some years ago. At one time, milk was warmed to a fairly