Separation and characterization of lipophilic extracts from barley straw

Barley straw was extracted with toluene-ethanol (2:1, vol/vol), chloroform, methyl tert-butyl ether (MTBE), hexane-acetone (2: 1, vol/vol), and dichlo romethane for 12 hours in a Soxhlet. The 51 individual compounds in 5 lipop hilic extracts were separated by gas chromatography. Free fatty acids (15.1 8-38.20%), sterols (1.41-10.42%), waxes (3.45-11.87%), steryl esters (5.04- 24.70%), and triglycerides (1.16-10.03%) were identified as the major 5 cla sses of lipids in the barley straw extracts. Minor components such as digly cerides (0.07-0.89%) and resin acids (0.12-0.57%) were also verified from t he straw lipophilic extracts. Nonlipids detected from the barley straw extr acts were composed of minor amounts of phenolic compounds (0.17-2.05%), not iceable amounts of azelaic and maleic acids (0.48-15.06%), and some quantit ies of co-extracted polysaccharides, ash, or salts. Of the individual compo unds in each group, 16 free fatty acids, 5 steryl esters, 3 sterols, 3 trig lycerides, and 2 waxes were quantitatively determined. Extraction with MTBE gave the lowest yield of total extracts (1.19%) but contained the highest amounts of lipophilic extracts (81.04%), which were enriched with steryl es ters (24.70%), free fatty acids (23.60%), waxes (11.22%), sterols (10.42%), and triglycerides (10.03%). In contrast, extraction with 2:1 toluene-ethan ol produced the highest quantities of total extracts (3.92%) but of the low est purity of the lipid substances (49.69%) and were comprised mainly of fr ee fatty acids (38.20%) and nonlipid substances such as maleic and azelaic acids ( 15.06%), phenolic compounds (1.89%), and noticeable amounts of rele ased polysaccharides, ash, or salts.