Color Precursors in Douglas-Fir

The need for knowledge of the minor components of wood associated with color and color formation is growing because of the development of high yield pulping processes and the increasing competition in lumber markets based on appearance. This paper outlines the isolation and attempted purification of one of these color precursors, a polymeric leucoanthocyan idin from Douglas-fir. Although obtained in low yields of 0.02 to 0.05 percent of the moisture-free wood, the isolated leucoanthocyanidin material showed high color-producing ability equivalent to 26 percent of that obtainable from pure monomeric leucocyanidin with propanol-hydrochloric acid. Chemical and spectral properties of the isolated material were similar to a synthetic polymeric leucocyanidin prepared by polymerizing monomeric leucocyanidin in the presence of acid ion exchange resin. A new detecting reagent for leucoanthocyan idins consisting of a mixture of methanol, glycerol, and hydrochloric acid, which permits subsequent spraying with other detecting reagents is described.

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