Colour changes in beech wood modified with essential oils due to fungal and ageing-fungal attacks with coniophora puteana

Fungal attacks on beech wood (Fagus sylvatica L.) samples (25 × 25 × 3) mm were performed using the brown-rot fungus Coniophora puteana over a period of8 weeks, without or with their previous accelerated ageing in a Xenotest and a drying oven. Due to the fungal and ageing-fungal attacks, respectively, the top surfaces of the reference beech samples obtained a darker yellow-red shade according to the CIE-L*a*b* colour system. Similar changes in the colour coordinates L*, a*, and b* were found for the beech wood modified with the essential oils which were less fungicidal efficient – lavender, sage, tea-tree, and the oil-mixture. On the other hand, the colour changes in the beech wood modified with those essential oils which had a better fungicidal efficiency – birch, clove, oregano, sweet flag, savory, and thyme – were less significant, confirmed by Duncan’s test. Linear correlations with greater or lesser significance were established between the changes in the colour parameters (ΔL*; Δa*; Δb*; ΔE*) and the corresponding mass losses (Δm)of attacked beech wood, the best for positive Δb* which identified its yellowing.