Assessment of the relationships between extractive content, mould growth, and drying methods of Scots pine wood using multivariate data analysis

Wooden construction material is a sustainable contribution to carbon sequestration and long-term storage. Despite its strength, sustainability and versatility, the vulnerability to biodeterioration is an issue. Therefore, this study aimed to identify the differences in mould growth features and surface extractive composition of the Scots pine (Pinus sylvestris L.) sapwood sideboards between air- and kiln-drying methods using multivariate data analysis. Air and kiln-dried sideboards were used to extract different low molecular compounds from the surface layer, assess the moisture content, and conduct a mould test. Principal component analysis revealed the grouping of the drying types. This was confirmed by partial least-squares discriminant analysis, which allowed the sideboard characteristics of the two wood drying types to be described. An outlier was detected among the air-dried observations. The collected data show more intensive mould growth on kiln-dried Scots pine sideboards than on air-dried ones. Higher amounts of total lipophilic compounds, phenols and inorganic components were found on the kiln-dried sideboard surface. Also, surface extractives from kiln-dried sideboards contained higher amount of almost all analysed fatty and resin acids, except for the oleic acid, which was more prevalent on the air-dried sideboard surface. Low-molecular-weight sugars, namely glucose, saccharose and fructose, were present in significant amounts on the surface of the kiln-dried sideboards. This has presumably contributed to the rapid spread of mould. In general, multivariate modelling allowed to establish that the method of wood drying significantly influenced the redistribution of extractive components on the surface and the subsequent mould growth.