2.3 | Analysis of the fatty acid composition
FA composition of freeze-dried LD muscle samples was quantified using Agilent 6890 gas chromatography mass spectrometry (GC/MS) (Agilent Technologies Inc., Wilmington, DE). The FAs were methylated with acetyl chloride/methanol (1:10, v/v), and hendecanoic acid methyl ester (C11:0) was used as an internal standard (1mg ml-1). The DB-23 column (60 m × 0.25 mm, film thickness 0.25 μm) temperature was held at 130°C for 1 min and then was increased to 260°C at a rate of 4°C min-1. Subsequently, the injector and detector (FID) temperatures were set at 270°C, and the helium flow ratio was 2 ml min-1. An automatic split injector was used with a ratio 30:1. By comparing the retention times of the individual FA peaks with the known standards (37 component FAME mixture), the fatty acids could be identified.