Composition of cholesterol and its precursors in ovine milk

Abstract

Identification and concentration of cholesterol and its precursors were investigated in ovine milk. In order to ensure a wide variety of milk composition, 45 samples were taken during the year from the bulk milk of five herds (ranging from 130 to 2500 adult ewes) corresponding to five breeds and located in different places in Spain. Gas chromatography/mass spectrometry analysis allowed the identification of small quantities of squalene, lathosterol, desmosterol, dihydrolanosterol and lanosterol. Neither campesterol nor -sitosterol could be detected in the studied samples. The mean values (mg·100 g -1 fat) were: cholesterol 288.44 42.22; squalene 1.80 0.99; lathosterol 1.81 0.82; desmosterol 0.41 0.30; dihydrolanosterol 4.15 2.40 and lanosterol 6.86 1.88. With the statistical model used, the cholesterol concentration in milk fat was shown to be influenced by an interaction between the factors time of year of sampling and breed, but the variations observed do not show a clear trend. Cholesterol / minor sterols / ewe milk / fat / gas-chromatography / mass-spectrometry