Properties of Included Phloem in Teakwood (original) (raw)
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Journal of Forestry Research, 2009
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 results show 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. Keywords: Tectona grandis; black streak; extractives; inorganic materials
The Characterization of Black-streaked Heartwood in Teak: Inter-tree Variation
Wood Research Journal, 2014
The objective of this study was to investigate the variation in the color and chemical characteristics of black-streaked heartwood of teak and explore the relationship of these chemical properties with the degree of blackening. The samples used were outer heartwood parts from 11 trees with black streaks both thin and thick and 7 trees with normal heartwoods for comparison. The colorimetric analysis in CIEL*a*b* system was used to determine the brightness values (L*) of blackstreaked heartwood of teak ranging from 40~49 and a thick portion produced appreciably higher average values of extractive contents including n-hexane, ethyl acetate, and total extractive content as well as tectoquinone contents and pH values but lower squalene content compared to those in normal wood. The degree of blackening in the black-streaked heartwood was highly correlated to its extractive contents, especially the ethyl acetate soluble extractive content (r = −0.94) while moderate correlations were measured between the brightness index and tectoquinone content (negative) and squalene (positive). Moreover, no significant difference was found in the ash and individual inorganic elements contents between the group. The increase in pH values was observed to have corresponded with a decrease in brightness (r =-0.75). Therefore, the blackening was assumed to be due to the polymerization of quinones in weakly acidic conditions.
Discolored Components from the Black-streaked Heartwood Extracts of Teak
Wood Research Journal, 2021
With regard to black-streaked discoloration of teak wood, the ethyl acetate extract from successive extraction was examined. By column chromatography, tectol and and two unknown compounds i.e. C-1 (molecular weight of 240) and C-2 (molecular weight of 210) were isolated. Discoloration tests, i.e. air oxidation, acidic (acetic acid), and alkaline (potassiun hydrogen carbonate) treatments were conducted to the isolated and other standard quinoine compounds (tectoquinone, lapachol, 2-tert-buthyl-anthraqunone, 2-hydroxy-methyl-anthraqunone). The results showed that tectol changes its color by the considerable decreasing in brightness whereas C-1 showed huge decrease in yellowness by air oxydation. Tectol did not change its color in pH value of 2.9 to 8.3 but C-1, C-2, and lapachol did change. Tectoquinone was hardly change color under alkaline or acidic treatment. The difference in quinone coloration might be due the structural features of a hydroxyl group and a double bond conjugated.
Colour Properties and Extractive Content in Young Teak Woods
Proceeding of the 9th International Symposium of Indonesian Wood Research Society, 2019
Wood color is one of important quality parameters for many end-products and is associated with wood extractives. In this study, the colour of teak wood from young trees was investigated in relation to extractive content. The samples were 8 trees of Mega teak (superior teak wood, 5 years) planted in Gunungkidul (Jogjakarta) and 3 trees of Seruyan teak (conventional plantation, 7 years) from Sei Seruyan (Centrak Borneo). The results demonstrated that difference site significantly affected the colour properties in the CIE L*a*b* space (L* lightness, a* red/green axis,b* yellow/blue axis), particularly in the sapwood. Further, the heartwood of Seruyan teak exhibited a significantly yellower (high b* values) than Mega teak. By successive extraction (petroleum ether, dichloromethane, acetone/water, ethanol/water and hot-water), different extractive composition between the sites was found. Seruyan wood had higher proportion in acetone/water solubles than Mega wood in both sapwood and heartwood. The difference in color between sapwood and heartwood was mainly the result of a lower concentration of extractives in sapwood with exception for ethanol/water extractive content. In the sapwood, the highest correlation was observed between hot-water extractive content and parameter L* or b*. The a* and b*-coordinate turned out to be negatively strongly correlated with hot-water extractive content in the heartwood region. The result suggests that the phenolics measurement from successive fractionation should be conducted for better prediction in wood colour.
Gas Chromatography in Plant Science, Wine Technology, Toxicology and Some Specific Applications, 2012
This is the first report on the chemotaxonomical study of teak heartwood. The tree samples were collected from three regions, Purwakarta, Gunungkidul, and Randublatung, for a total of 87 individuals. Based on the principal component analysis, three types (T,I and L) can be obtained from the relative content of isodeoxylapachol and tectoquinone. TypeT, TypeI and TypeL refers the heartwood with high tectoquinone (over 16 %); high isodeoxylapachol (over 6 %); and low tectoquinone - isodeoxylapachol relative contents, consecutively. Based on geographical distribution, it is found that TypeI is the major type in Gunungkidul while TypeL is the most abundant in Randublatung.