Sunday, May 17, 2009

Wine Flavors Introduced by Oak Aging



I am thinking about whether to treat my 2008 Merlot with oak chips, and I was interested to see this article on what chemicals are found in oak chips. To my surprise most of them have some sort of desirable flavor, with the notable exception of the trichloroanisole. I am surprised that there are trichloro compounds in wood at all. This one does not seem to have severe safety issues, but I understand it has the Champagne producers concerned about adulteration via wine corks.

Fernández de Simón and others have published the work of GC/MS work on several species of wood that are commonly used to store food and impart flavor to them. They made a lengthy list in J Agric. Food Chem 57:8 (2009). I have extracted out the most important components from American Oak that has been "toasted." There are several other wood species in the work. 

People should not be surprised to learn that wine scholars have been researching these extractives for years, and there is a lot published on them. 

The graph at right shows the relative proportions of the top ten extractives. There are many more. 

2,4,6-trichloroanisole (100 ppm)- This is the compound responsible for cork taint, and it ruins the flavor of wine even at nanogram/L levels. Smells like moldy newspaper

syringaldehyde(226 ppm), coniferaldehyde (96 ppm), sinapaldehyde (239 ppm) - vanilla related aldehydes

butyrovanillione (113 ppm) = zingerone = vanillyl acetone - also found in ginger; medicinal uses

Whiskey lactone (beta-methyl-gamma-octalactone) (32 ppm)- One of the main components of aroma in whiskey

Furfural (395 ppm) - almond-like, sometime describes as burnt; increases with the "toasting" of the oak wood

5-methyl furfural (34 ppm)- spicy, carmel-like, sweet
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