Color and chemical characterization of partially black-streaked heart-wood in teak (Tectona grandis)

Abstract

The heartwood of teak in certain areas of Java Island displays irregular black streaks along the annual rings. We investigated the color and chemical characteristics in a radial direction of partially black-streaked heartwood samples. Color properties (pH value, inorganic element, extractive content and extractive characterization) were measured in the color co-ordinates CIELAB system. The resultsshow that the black streak part was 12-15 brightness (L*) value units less than the normal heartwood. Furthermore, the black streak part had more red (a*) but less yellow (b*), hue (h) and chroma (C*) than the normal wood. The pH value, ash content and calcium contents of the black streak part were slightly higher than those obtained for the normal wood. The content of the low-polar extractive (n-hexane and ethyl acetate) of the black streak part was considerably higher than that for the normal wood. The blackening process was speculated to be a kind of defense mechanism indicated by remarkable amount of bioactive compound called tectoquinone.

Relationship Between Wood Color Parameters Measured by the CIELab System and Extractive and Phenol Content in Acacia mangium and Vochysia guatemalensis from Fast-Growth Plantations

“…Tropical species contain a large variety of extractives [ 16 ] and may affect wood color differently. For example, bioactive components called tectoquinones produce black streaks along the annual rings in Tectona grandis [ 20 ]. Thus, the color difference between sapwood and heartwood is probably the result of non-phenolic extractives in V. guatemalensis wood that were not considered in this study.…”

“…Therefore color measurements on wood powder were a good indicator to phenolics and extractives content and may be useful in breeding for higher phenolic content and we can increase decay resistance of wood. But despite these claims, the relationship between wood color parameters measured and extractive content in tropical species has been limited to a few species, among these Tectona grandis [ 20 ].…”

Electron Microscopy Observation of Biomineralization within Wood Tissues of Kurogaki

“…The mineral content of the sap is the highest during fall, and the crystals prove to be calcite of calcium carbonate and calcium oxalate existing within living cells of bacteria. This can be the reason why the crystals grow in a ring-like pattern in the late wet wood formed during the year [7][8][9]. Strontium carbonate is more insoluble than calcium carbonate and precipitates under appropriate conditions.…”

The accumulation pattern of ferruginol in the heartwood-forming Cryptomeria japonica xylem as determined by time-of-flight secondary ion mass spectrometry and quantity analysis

“…The formation of heartwood is important not only for a tree's durability but also for its mechanical strength when using wood materials (reviewed by Bamber and Fukazawa, 1985;Hillis, 1987;Taylor et al, 2002;Kampe and Magel, 2013). Various physiological changes occur during heartwood formation where xylem changes from sapwood to heartwood, including water distribution (Nakada et al, 1999a, b;Nakada, 2006;Merela et al, 2006;Kuroda et al, 2006Kuroda et al, , 2009, parenchyma cell death (Nobuchi and Harada, 1983;Spicer and Holbrook, 2007;Nakaba et al, 2008Nakaba et al, , 2012, cell wall structure (Matsumura et al, 1995;Sano and Nakada, 1998), chemical composition (Yoshida et al, 2004(Yoshida et al, , 2006Bito et al, 2011) and colour (Gierlinger et al, 2004;Lukmandaru et al, 2009;Lukmandaru 2011;Moya et al, 2012). Although these features of heartwood have been widely studied, the mechanism of inducing heartwood formation remains unclear (Kuroda et al, 2009;Nakada and Fukatsu, 2012;Kampe and Magel, 2013).…”