Features of the fatty acid profile of down and guard fibers of felted wool of the Ukrainian Carpathian Mountain sheep breed

One of the characteristic problems of wool in the Ukrainian Carpathian Mountain sheep breed is its felting directly on the animal’s body, which may be accompanied by changes in the structural organization and lipid composition of wool fibers. In view of this, the aim of the study was to examine the characteristics of the fatty acid profile of free and bound internal lipids of down and guard fibers of normal and felted wool of this sheep breed. Wool samples were collected from mature ewes kept under pasture conditions. Free internal lipids were isolated by extraction with a chloroform and methanol mixture, and bound internal lipids were obtained after alkaline hydrolysis. Fatty acid composition was determined by gas-liquid chromatography after converting fatty acids to methyl esters. It was established that the wool felting process is accompanied by significant changes in the fatty acid composition of both free and bound internal lipids of wool fibers. The most pronounced changes concerned 18-methyleicosanoic acid (18-MEA). In the bound internal lipid fraction, the content of 18-MEA in felted wool significantly decreased in both down fibers ( P < 0.001) and guard fibers ( P < 0.001), whereas in the free internal lipid fraction its concentration increased ( P < 0.05). The felting process was also accompanied by changes in the content of individual long-chain saturated acids and a trend toward decreasing the proportion of unsaturated fatty acids. The results indicate that wool felting is accompanied by degradation and redistribution of lipid components in the cuticle layer of wool fibers, including partial destruction of covalently bound lipid complexes. The differences revealed between down and guard fibers reflect the important role of wool’s morphological heterogeneity in the development of structural and biochemical changes during felting. The study results confirm the important role of 18-MEA in maintaining the structural integrity and hydrophobic properties of wool fibers and suggest it can be considered a promising biochemical marker of lipid layer damage in the cuticle during wool felting.