Cholesterol and fatty acids oxidation in meat from three muscles of Massese suckling lambs slaughtered at different weights

Eighteen Massese male lambs fed mainly with maternal milk were slaughtered at 11, 14 and 17 kg. Samples of Longissimus dorsi (LD), Triceps brachii (TB) and Semimembranosus (Sm) muscles were collected. Total intramuscular lipids were extracted by means of a mixture of chloroform methanol 2/1. Cholesterol content and its oxidation product (COP) were determined by a gas chromatography apparatus equipped with an apolar 30 m column. Fatty acid oxidation was evaluated by means of thiobarbituric acid reactive substances (TBARS) extracting the sample with aqueous acidic solution. The effect of slaughter weight on oxidation of intramuscular lipids was found only in TB muscles. In this muscle the cholesterol content showed a decreasing trend, while the content of COPs significantly increased with the age of animals. Among the COPs, the 7-ketocholesterol and 7β-hydroxycholesterol were the most abundant, followed by α- and β- epoxy-cholesterol and cholestan-triol. The content of TBARS did not vary owing to a similar fatty acid composition of intramuscular fat across weight of slaughter. In any case, the values of TBARS did not reach the threshold of the detection of off-flavour in meat.