Chemical composition of lipophilic extractives released during the hot water treatment of wheat straw

Treatment of wheat straw with hot water at 80–95 °C for 0.5 h at pH 6.0–8.0 released 41.0–53.0% of the original lipophilic extractives. The chemical compositions of six lipophilic extractives were determined by GC on a medium-length high-temperature capillary column without derivatization, thus giving a method for direct determination of individual components of free fatty and resin acids, sterols, waxes, sterol esters, and triglycerides. The extracts contained 68.7–75.8% lipophilic substances, comprising mainly free fatty acids (25.8–48.4%), waxes (9.4–27.0%), sterols (4.1–8.0%), triglycerides (3.3–11.0%), and sterol esters (2.6–5.1%). Minor amounts of diglycerides (0.3–0.5%), resin acid (0.5–3.1%), and phenolic compounds (0.9–3.6%) were also quantitatively determined in the extractives.