Barrel Aging and Barrel Selection

As members of the Silverado Trail Wineries Association, we participate in the Silver Pass weekend twice a year. Participating wineries will offer special tastings, library releases, barrel sampling, food and more. The pre sale price of $30 for a full day of visiting these wineries is a helluva deal, AND Proceeds go to the Child Development Centers of the Napa County School District.

Earlier this month we participated in the Silver Pass weekend and offered our world class wines for tasting and our world famous Paella A La Jason Donoho (John’s son-in-law). Okay, “world famous” may be a bit of a stretch, but its dang good stuff.

Jason & his 4 ft diameter Paella Pan

During the event, we get lots of questions about how & why we do certain things – Some are basic, some are not. One question asked was: Why do you use French Oak barrels? I thought this basic question would be good to include in our blog and that it would be best answered by our winemaker, Anna Monticelli. Seemed simple enough. I thought she could answer that in a short paragraph, two at the most. Boy, was I wrong! I was impressed when I read her response and only noted one misspelling to correct. But then it turned out that “adsorption” really is a word. Lastly, her formatting was impeccable, but my skills at transferring the document were not.

Barrel Aging and Barrel Selection by Anna Monticelli
1. Great red wines are traditionally aged in oak barrels.
2. There are many benefits of barrel aging including clarification.
a. Wine settles and naturally clarifies itself better and faster when aged in a barrel, rather than a vat or tank, because of the smaller volume.
b. Oak has a natural adsorption phenomena that aids in the wine’s clarification.
c. Barrels are more sensitive to temperature than vats or tanks, so there is usually more tartrate precipitation during the winter.
3. There is more softening of the wine tannins and aroma development during barrel aging. Oak is porous and therefore wine is subject to micro-oxygenation whereas tanks are large airtight vessels that are theoretically inert. This controlled oxidation modifies the phenolic composition of the wine. The oak increases binding of the tannin and anthocyanin molecules, in turn stabilizing the color and softening the tannins. The amount of micro-oxygenation depends on the origin of the barrels, regularity in topping and the type and position of the bung. One study suggests that 16% of oxygen passes through the wood, 63% through gaps in the staves and 21% through the bunghole.
4. Wine aged in oak barrels extracts aromatic compounds that increase a wine’s complexity. A winemaker must match the appropriate amount of oak to the wine. If there is too much oak influence, a wine will be overpowered by the oak flavors and the fruit and varietal characters will be masked. You can’t make a wine great just by aging it in oak. The wine must have a certain aromatic finesse and sufficiently complex structure to benefit from oak aging.
5. Geographical origin and oak species have a huge influence on the effect on the wine.
a. French oak primarily comes from 4 main regions (Limousin, Centre, Bourgogne and Vosges). There are 2 species of oak trees that grow in these areas:
i. Quercus robur or Quercus pedunculata – High extractable polyphenol content and low odiforous compounds. These species produce coarser grained wood.
ii. Quercus petraea or Quercus sessilis – high aromatic potential and low levels of extractable ellagitannin. These species produce wood with finer grained wood.
b. Central European oak is primarily of the species Quercus farnetto. They have some similarities to French oak.
c. American oak is predominantly the Quercus alba white oak species. This type of oak has a lower phenolic content and higher aromatic compounds than other species, especially methyl-octalactone (sweet, coconut, vanillan, maple aromas).
6. Oak must be “seasoned” before it is coopered.
a. Natural seasoning generally takes 2-3 years. The oak is cut into staves and stacked outside where it weathers and seasons in the open air. The wood naturally matures and the physical, aromatic and organoleptic properties of the oak improve. Enzymatic reations also influence the flavor profile.
b. Artificial seasoning is when the staves are dried in an oven for approximately a month. Artificially seasoned wood has more astringent tannin and bitterness. It also has less vanillin and aromatic components.
7. After the oak staves are seasoned, they must be toasted and coopered. The oak can be toasted by traditional fire methods or convection oven. There are light, medium and heavy toasts. Toasting is used to eliminate the “green wood” flavors. The length and temperature of toasting changes the amount and types of volatile compounds. Generally, heavier toasting produces more toasty and vanillin flavors as well as complex flavors.
8. I use approximately 55-75% new French oak on the Piña wines depending on the vineyard. I prefer using French oak on our Cabernets because it is more subtle, complex and refined. I think it complements our Cabernet grapes better than American or central European oak because it enhances the fruit characters without overpowering the wine.