Comparative Study Of Methyl-Tert-Butyl Ether Extractives From RYE And Rice Straw
Keywords:Rye straw, rice straw, methyl tert-butyl ether, lipophilic extractives, phenolics
AbstractThe chemical composition of lipophilic extractives from rye and rice straws has been comparatively examined. Free fatty acids (19.04-22.95%), sterols (12.54-14.60%), waxes (9.53-27.14%), steryl esters (16.02-18.19%), and triglycerides (5.72-11.38%) were identified as the five major classes of lipids in the two straw extractives. Minor components of diglycerides (0.23-0.42%) and resin acids (0.05-0.12%) were also verified from the two straw lipophilic extracts. Of the individual compounds in each group, fifteen free fatty acids, four sterols, three waxes, five steryl esters, and three triglycerides were quantitatively determined. The most abundant saturated free fatty acids were palmitic acid (C16:0, 3.96-4.24%) and tetradecanoic acid (C14:0, 2.95-3.62%), whereas linoleic (C18:2) and/or oleic (C18: 1) acids (1.87-2.09%) were the most dominant unsaturated free fatty acids. β-Sitosterol was identified as a predominant component, accounting for 83.89% of the total sterols in rye straw extract and 94.45% in rice straw extractives. Palmitic acid palmityl ester was verified as a dominant component in a group of waxes, accounting for approximately 70% of the waxes analyzed in the two extracts. The steryl esters analyzed were composed mainly of steryl laurate (0.29-0.95%), steryl myristate (3.20-3.56%), steryl palmitate (1.86-2.28%), steryl margarate (2.20-2.93%), and steryl oleate (2.13%). Of the triglycerides verified, glyceryl tripalmitate (0.23-1.64%), 1,2-dipalmitoyl-3-oleoylrac-glycerol (1.06-2.08%), and triolein (cis-9) (0.77-1.61%) were identified in this group.
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