Light-induced Color Variations of Japanese Cedar (Cryptomeria japonica) Heartwood Extracted with Various Solvents

柳杉(Cryptomeria japonica D. Don)心材具有紅色或黃紅色紋理，但曝露在使用環境中，材色容易產生變色。因此，本研究除分別探討柳杉紅色及黃色心材木粉經四種溶劑萃取後的含量和顏色變化外；亦探討四種溶劑萃取過的柳杉心材木粉經光線照射後的顏色變化。試驗結果發現，高極性溶劑（甲醇或乙酸乙酯）所萃取出來的抽出物含量比低極性溶劑（氯仿或正己烷）所萃取出來的抽出物含量高；且高極性溶劑較容易將柳杉心材中的顏色物質萃取出來，而由紅色心材萃取所得之顏色物質含量較黃色心材為多。比較四種溶劑萃取後柳杉心材木粉受光影響的顏色變化，發現正己烷和氯仿二種溶劑所萃取後的柳杉心材木粉較易產生明顯的變色，且顏色均會趨向於較高彩度的紅色軸色相。以上結果顯示，柳杉心材中易受光線影響而產生變色的成分存在於甲醇及乙酸乙酯抽出物中。

關鍵字

柳杉；心材；抽出成分；變色

並列摘要

The heartwood color of Japanese cedar (Cryptomeria japonica D. Don) is red or yellowish red. Unfortunately, the pleasant appearance of Japanese cedar wood is susceptible to discoloration after exposure to the elements. Therefore, the objectives of this study were to investigate the extractive contents of reddish and yellowish Japanese cedar heartwoods using 4 solvents and to compare color variations of extracted wood meals after exposure to plant lamps. Results demonstrated that the contents of Japanese cedar heartwood extractives obtained by extraction with highly polar solvents (methanol and ethyl acetate) were higher than those extracted with low-polar solvents (chloroform and n-hexane). In addition, the color constituents of Japanese cedar heartwood were readily extracted by the highly polar solvents, and more were obtained from the reddish than from the yellowish heartwood. Comparisons of color variations of the 4 extracted meals after exposure to plant lamps revealed that discoloration of specimens extracted with either n-hexane or chloroform was quite significant; their chromaticities increased and became redder. These results revealed that the methanol- and ethyl acetate-soluble extracts of Japanese cedar heartwood are more susceptible to discoloration by light.

並列關鍵字

Cryptomeria japonica ； heartwood ； extractives ； discoloration

國際替代計量

Light-induced Color Variations of Japanese Cedar (Cryptomeria japonica) Heartwood Extracted with Various Solvents

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