Increase in the content of low-molecular carbohydrates at lumber surfaces during drying and correlations with nitrogen content, yellowing and mould growth

Abstract

In this study a quantitative analysis of the low molecular carbohydrates (predominantly sucrose, fructose and glucose) in a series of lumber samples of Pinus sylvestris and Picea abies taken at various distances from the surface has been made. The increase of nitrogenous compounds towards the surface had been shown in a previous study. Several of the lumber samples showed a marked sugar accumulation at the surface, which correlated quite well with a corresponding nitrogen accumulation. In one case, the total amount of the three sugars was as high as 4.9% of the dry matter content in the 0-1 mm layer. It was of special interest to note that samples with high nitrogen and sugar contents also had a yellow surface colour, which probably formed during the drying process by the well-known Maillard reaction -a complex of reactions occurring when sugars and amino adds, peptides and proteins are heat-treated together.Growth of the mould fungus Penicilliurn brevicornpactum was well correlated with the content of nitrogen and low molecular carbohydrates in adjacent samples. The initial colonization was somewhat delayed in material from the outermost sapwood zone despite high nutrient contents indicating effects of antifungal compounds from the bark or toxic Maillard reaction products effective against germination. Growth of Aspergillus versicolor was likewise most elaborate on samples with the highest nitrogen and soluble carbohydrate content but the results also indicate a sensitivity to antifungal compounds present.

Changes in chemistry, color, dimensional stability and fungal resistance of Pinus radiata D. Don wood with oil heat-treatment

“…The heat-degraded compounds with low molecular weights tend to migrate towards the surfaces along with extractives (Theander et al 1993;Sundqvist and Morén 2002). The oil viscosity increment confirms indirectly the removal of materials from wood (Mabery 1923;Powers 1950).…”

Effect of oil impregnation on water repellency, dimensional stability and mold susceptibility of thermally modified European aspen and downy birch wood

“…However, only limited attempts have been made to test the durability of TM wood against mold [15,16]. Several factors are involved in the onset of mold in different wood products, such as the moisture content of the wood, the relative humidity (RH), favorable ambient temperatures and climate stability [17,18]. Wood cells contain compounds such as sugar, starch and nitrogenous compounds that further influence the severity/intensity of mold growth [17,19].…”

“…Several factors are involved in the onset of mold in different wood products, such as the moisture content of the wood, the relative humidity (RH), favorable ambient temperatures and climate stability [17,18]. Wood cells contain compounds such as sugar, starch and nitrogenous compounds that further influence the severity/intensity of mold growth [17,19]. As wood products are prone to developing mold depending on the ambient environmental conditions, durability tests are important to ensure the aesthetics of the wood products, the reduction of health hazards and the service life of wood.…”

Modificação da cor original da madeira de Eucalyptus grandis através de tratamentos termorretificadores

“…A alteração da cor da madeira após a termorretificação pode ser explicada pela combinação de vários fatores, sendo eles: (a) a dissolvição, oxidação e decomposição dos extrativos e outros componentes químicos; (b) a formação de produtos oxidativos, tais como quinonas e produtos da degradação das hemiceluloses e lignina, os quais migram às superfícies da madeira; (c) a remoção ou migração dos extrativos e compostos nutritivos tais como açúcares de baixo peso molecular e aminoácidos em direção às superfícies da madeira; e (c) o aumento relativo no teor de lignina após o tratamento, em decorrência, principalmente da degradação das hemiceluloses (AKYILDIZ et al, 2009;BEKHTA;NIEMZ, 2003;ESTEVES et al, 2008;KAMKE, 2006;SUNDQVIST;MORÉN, 2002;THEANDER et al, 1993;TJEERDSMA et al, 1998;VARGA;VAN DER ZEE, 2008). Segundo Varga e Van der Zee (2008), as madeiras com grandes quantidades de extrativos solúveis em água apresentam alterações mais intensas de cor após o tratamento.…”