Lipolysis Post Mortem in North Atlantic Krill

A~tract--1. Three common species of North Atlantic krill, Meganyctiphanes norvegica (M. Sars), Thysanoessa inermis (Kroyer) and T. raschii (M. Sars), have been stored at 0°C post mortem, and the lipolytic activity followed by measuring changes in the lipid composition during storage. 2. Both phosphoglycerides and triacylglycerols were subjected to extensive hydrolysis with the formation of free fatty acids in all krill species examined, whereas wax esters, constituting a considerable proportion of the lipids in the Thysanoessa species, were not hydrolysed at all. 3. In M. norvegica the triacylglycerols and phosphoglycerides were hydrolysed at similar rates, whereas in T. inermis and T. raschii the phosphoglycerides were hydrolysed most rapidly. 4. For all krill species examined, the rate of production of free fatty acids was nearly constant during the initial phase of storage, and subsequently declined on prolonged storage. 5. At the end of the storage period of 16-24 days, the free fatty acids constituted about 35% of the total lipid in M. norvegica, and about 50% in the Thysanoessa species. 6. The rate of production of free fatty acids was about the same in all the three species of krill and seemed to be independent of the total lipid content.