The impact of Thymus vulgaris extractives on cedar wood surface energy: Theoretical and experimental of Penicillium spores adhesion

In this work, the effect of three Thymus vulgaris extract fractions on physicochemical properties of cedar wood was examined. Indeed, hydrophobicity, surface tension components Delta Giwi, electron donor (gamma(-)) and electron acceptor (gamma(+)) parameters of untreated and treated wood were assessed using contact angle measurement. The samples treated with ethyl acetate, methanolic and hexane-ethyl-acetate fractions have indicated the hydrophilic character qualitatively and quantitatively with values of (theta(w) =17.1 +/- 0.08 degrees, Delta Giwi = 46.51 mj/m(2), theta(w) = 10.7 +/- 0.40 degrees, Delta Giwi =35.36 mJ/m(2) and theta(w) =31.1 +/- 0.74 degrees, Delta Giwi = 24.64 mJ/m(2)) respectively, and more electron donor than untreated one. Moreover, the experimental and the theoretical prediction of Penicillium spores adhesion on untreated and treated substrates were also investigated. According to the values of the total free energy (Delta G(Tot)), the adhesion of Penicillium commune and Penicillium commun on untreated wood was found favorable. In contrast, all treatments of wood surface were made the adhesion conditions unfavorable. The environmental scanning electronic microscopy (ESEM) has shown also that the adhesion of both Penicillium spores studied on the treated wood was too low. Thereby, a good correlation between the theoretical prediction and the adhesion experiments has been found. Based on these results, the natural products tested could be considered as an alternative source of bioactive molecules for limited and inhibited the adhesion of fungal spores on wood and hence, for its preservation. (C) 2015 Elsevier B.V. All rights reserved.