| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1996: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
Japanese ceder (Cryptomeria japonica D.Don) comonly called sugi, grow well almost all over Japan. Its timber has been extensively used in the construction of Japanese houses and utilized widely for various purpose in wood industries of Japan. But one of the most important problems is discoloration of sugi wood. Normal Sugi heartwood color is beautiful like salmonpink, but abnormal color due to darkness and blackness is not desirable by the people. It is commonly said that the phenolic compounds (norlignans) of sugi are closely related to the coloration. The relationship between the blacking phenomenon of sugi heartwood and norlignans was investigated, and the results were as follows :
1.Cause.
(1) In the black heartwood, norlignans were decreased. (2) Especially hydroxy-sugiresinol and seuirin-C were decreased to a very high level. (3) The moisture content, and pH value of the black heartwood were greater, than those of normal heartwood. (4) Larger concentration of the HCO_3-anion and the K^+ cation in the black heartwood might indicate greater content of potassium hydrogencarbonate. (5) Sequirin-C changed to dark purple by the alkaline treatment.
It can be concluded from the above results that the black coloration of sugi heartwood might be due to changes of the sequirin-C in a weak alkaline condition with potassium hydrogencarbonate.
2.Prevention.
(1) Methanol extracts of the black part contained considerable amounts of norlignans, by both treatments of the acid-methanol (0.1% AcOH in methanol) and reductive methanol (0.1% ascorbic acid in methanol). (2) Especially, the norlignan contents in the treatment of reductive methanol from the black heartwood was almost the same as that of the normal heartwood. (3) sequirin-C was increased to a very high level by the reductive treatment.
It can be concluded from the above results that the black coloration of sugi heartwood might be prevented by the acid and reductive treatment.
The above-mentioned contents are research results.
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