The Maillard reaction for wood modification: The influence of reagent concentrations, reaction temperature and soaking time on the leachability and cell wall penetration of reagents

Finding efficient ways to decrease wood decay caused by fungi and increasing its dimensional stability is an important issue in timber construction and other applications. A possible way to avoid wood decay by fungi and increase its dimensional stability, is by reducing the water content of wood. Water is a primary condition for fungal growth and induces shrinking or swelling in wood. By bulking the wood cell walls with chemical reagents, the space where water normally occurs gets occupied. For effective protection using impregnation modification, it is a requirement that the bulking agent is located mainly in the cell wall of the wood and is non-leachable in service. To create a commercially-viable process, the modification requires a water-based delivery system, the use of low-toxicity impregnation agents, thermal-curing and no concerns regarding toxicity at end of life of the modified wood product. In previous work it was found that the use of the Maillard reaction appeared to be a promising way of bulking the cell wall (i.e., when reacting lysine, glucose, and citric acid), but with varying success and a high degree of leaching. To reduce leaching and increase of wood bulking, reaction conditions like soaking time, reagent concentrations and reaction temperature were investigated in this work to determine their effect on wood treated with lysine, glucose and citric acid. In general, it was observed that lower soaking times, higher reaction temperatures, and higher reagent concentrations were favourable for the Maillard reaction to proceed.