柚木石油醚抽提物成分及其对心边材颜色的影响

为探究国产柚木抽提物对心材和边材颜色差异的影响,采用3种沸程的石油醚溶液分别对国产柚木的心材与边材进行抽提处理,利用气相色谱-质谱法分析抽提液的成分和含量,并以差异较大的抽提物溶液处理柚木边材,通过色度学参数表征柚木边材的变色情况,从而验证影响柚木心材和边材颜色的主要抽提物成分。结果表明:在3种沸程的石油醚抽提液中,柚木心材抽提物在成分种类数量和含量上均显著高于边材;不同沸程的石油醚对柚木心、边材中抽提物成分有一定的影响,其中30~60℃(低沸程)和60~90℃(中沸程)石油醚抽提物成分和含量的差异较小,而90~120℃(高沸程)石油醚抽提物的含量较高,约为中、低沸程抽提物含量的2倍;柚木心材抽提液中酚类、醌类、烯烃类物质的含量较多,但这些物质在边材中含量极低;4-叔丁基-2-苯基苯酚、2-甲基蒽醌(柚木醌)、全反式三十碳六烯(角鲨烯)是柚木心、边材抽提物含量差异最明显的物质。经角鲨烯溶液处理后的柚木边材表面颜色变黄,更接近心材颜色,因此,角鲨烯是导致柚木心边材颜色差异的重要抽提物成分。

Petroleum ether extractive components of Chinese teak and the effect on the color difference between heartwood and sapwood

In order to clarify the chemical color change of teak(Tectona grandis)from Yunnan,China,powder samples with a particle size of 0.250 mm to 0.425 mm were obtained by smashing the heartwood and sapwood of teak,and extracted by three kinds of petroleum ether with different boiling ranges,respectively.The extracted liquids were analyzed by the chromatography-mass spectrometry(GC-MS).Besides,the extractives with highly different contents of heartwood and sapwood were dissolved in acetone or N,N-dimethylformamide,which were used to treat the sapwood.The colorimetric parameters of the treated sapwood were measured for the verification of the key extractive compounds that affected the color.The results showed that the three kinds of petroleum ether extractives in heartwood were higher than those in sapwood both for the composition and the contents.The components of extractives in heartwood and sapwood of teak were certainly influenced by the petroleum ethers with different boiling stages.Nuance in composition and content was found in the petroleum ethers with 30-60℃(low)and 60-90℃(middle)boiling stages.The petroleum ethers with 90-120℃(high)boiling stages extracted the highest content,which were about twice of that extracted by the medium and low boiling ranges.The content of phenols,quinones and olefins in heartwood was extremely high,while it was exceptionally low in sapwood.In contents,4-tert-butyl-2-phenyl-phenol,2-methyl-anthraquinone and all-trans-squalene were the most distinct substances in petroleum ether extractives between heartwood and sapwood.The surface color of sapwood treated by all-trans-squalene turned yellow and became closer to the heartwood,which should be the important extractives that caused the discoloration to sapwood and heartwood of teak.