Isovaleroyl triglycerides from the blubber and melon oils of the beluga whale ( Delphinapterus leucas )

The fatty acid compositions of the blubber and melon oils from the beluga whale ( Delphinapterus leucas ) have been determined by gas liquid chromatography (GLC). The melon oil contains a high level (60.1 mole %) of isovaleric acid, substantial amounts of long chain branched acids (16.9%), and very little polyunsaturated material (0.5%). The blubber oil contains less isovaleric (13.2%), fewer long chain branched acids (2.7%), and appreciable amounts (10.9%) of the polyunsaturated acids typical of marine oils. The blubber and melon oils were also examined for lipid class composition by thin layer chromatography on silicic acid, direct GLC of the hydrogenated oil, and gel permeation chromatography. Both oils are composed almost entirely of triglycerides, which can be separated chromatographically into molecules containing 0, 1 and 2 isovaleric acid moieties. No triisovalerin could be detected. The blubber oil contains 68.9 mole % normal triacyl‐, 24.2% diacyl‐monoisovaleroyl‐, and 7.0% monoacyl‐diisovaleroyl‐triglycerides (acyl=long chain acid). Monoacyl‐diisovalerin constitutes 86.7 mole % of the melon oil. This unusual compound may play a role in the echolocation system of the beluga whale.