Mould fungi can grow on virtually any substrate and are particularly common on cellulosic materials such as wood. Fungicides can limit the risk of mould attack, but increasing concerns about pesticide use have encouraged a search for more natural protection methods. Cinnamaldehyde is a promising antifungal candidate, but has not been fully effective. In this study, chitosan and cinnamaldehyde were used to prepare an emulsion to reduce the volatility of cinnamaldehyde, and the antimould performance of the emulsion-treated wood was evaluated. The ability of cinnamaldehyde chitosan emulsion was assessed for inhibiting mould growth as well as its effect on membrane function and hyphal morphology of Aspergillus niger. Cinnamaldehyde chitosan emulsion can reduce the amount of free cinnamaldehyde, thereby increasing the retention rate of cinnamaldehyde. The control ability of wood treated with 3.0:1.0 molar ratio of aldehyde to amino group in cinnamaldehyde chitosan emulsion against A. niger was 95.8%. Mould growth was limited in the presence of the emulsion. The treatment appeared to disrupt cell membrane function as evidenced by increased levels of extracellular proteins and nucleic acids. The results suggest that the cinnamaldehyde chitosan emulsion improved the stability of cinnamaldehyde in aqueous solution as well as effectively protected wood from mould.
The improvement of wood decay resistance is more inclined to eco-friendly methods such as the application of natural products, but the low durability of some natural products as wood preservatives limits their applications. In this study, vanillin catalyzed by laccase was grafted into poplar wood to increase wood decay resistance and can remain in wood for longer period. The reaction system of vanillin, ABTS, laccase and phosphate buffer solution was impregnated into poplar wood using vacuum-pressure method, and reacted at 40 °C for 6 h. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) were used to confirm the grafting reaction actually occurring during the process. The decay resistance, leaching resistance and mechanical strength of grafted wood were evaluated. Energy-dispersive X-ray (EDX) mapping was used to characterize the vanillin distribution. The results indicated that vanillin grafted poplar wood had good decay resistance, leaching resistance and higher strength. The mass loss of grafted poplar wood exposed to white-rot fungi [Trametes versicolor (L. ex Fr.) Quél.] and brown-rot fungi [Gloeophyllum trabeum (Pers.: Fr.) Murr.] decreased from original 46 and 13% to 9 and 4%, respectively, even after leaching. The modulus of rupture (MOR) and modulus of elasticity (MOE) of the grafted poplar were 11 and 26% stronger than original poplar wood. Vanillin was found in wood cell wall. It was actually esterified onto wood catalyzed by the laccase.
The cinnamaldehyde, salicylic acid, stearolic acid and citric acid were plant-derived organic compounds that can be activated to fungi, that could degrade the wood in long term. The compounds with concentrations of 3%, 5% and 7% assisted by different dispersants were impregnated into poplar (Populus nigra L.) specimens by the vacuum-pressure method. After that, weight percentage gain (WPG), decay resistance against white-rot fungi (Trametes versicolor) and brown-rot fungi (Gloeophyllum trabeum), color change, dimensional stability and mechanical properties including modulus of elasticity (MOE) and modulus of rupture (MOR) were measured. The results indicated that cinnamaldehyde impregnated poplar showed antifungi activity against both G. trabeumand T. versicolor, and citric acid impregnated poplar showed antifungi activity against G. trabeum. The color of poplar specimens before and after impregnated cinnamaldehyde and citric acid had a little change, dimensional stability had been improved and mechanical properties especially for MOR increased significantly.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.