The Content of Phenolic Acid and Aldehyde Flavor Components of White Oak As Affected by Site and Species

Samples of two white oak species, Quercus alba (L.) and Quercus robur (L.) were collected at two separate sites in Michigan9s lower peninsula. Mean maximum and minimum temperatures were warmer and mean monthly precipitation during the growing season was lower at Site 2. HPLC was used to identify and quantify phenolic acids and aldehydes in ethanolic extracts of chipped heartwood. Q. alba had significantly higher quantities of vanillin when compared to Q. robur, and Q. robur had higher amounts of gallic, protocatechuic, caffeic, and sinapic acids and higher total phenolics. Site was not as important as the species but did have an influence. Wood from Site 2 had higher total phenols, including sinapic and ferulic acids. There was also a significant site vs. species interaction for syringic, p-coumaric, and sinapic acids. Principal component analysis (PCA) successfully separated species along PCs 1 and 2.