Trilogy of Barrel aging
TALK 1: David Rosenthal, Chateau Ste. Michelle
Discussing barrel-making, oak growing regions and differences, differences in oak species
Sizes: 10-600L barrels… up to oak tanks, which are used for rieslings, as they do not much impart much oak flavor, but some mouthfeel.
Empty barrels are more vulnerable to contamination, ozone is best for cutting microbial growth. Sodium percarbonate, soda ash and citric acid are also used.
Wine tasting: 5 chardonnay samples, different producers and barrels.
1: Boutes, American Oak
2: Barrel Associates, American Oak, deep toast, (tastes like fireworks)
3: Boutes, French Oak, subtle and simple
4: Dargaud and Jaegle, French Oak
5: World Cooperage, French Oak (more fireworks)
He describes differences here, but I’m not super great at picking out barrel-based differences in wines.
TALK 2: Dr. James Osborne, Oregon State
Barrels are “good” for microbial growth due to rough surface, semi-porous so some access to oxygen, wood sugars can be used by some microorganisms (Brett).
Acetobacter: bad, almost always.
Lactobacillus: used to be used in ML fermentation (wine), now considered spoilage.
Pediococcus: can produce ropiness (extracellular polysaccharides) and lots of diacetyl.
Brettanomyces: “british brewing fungus”, a survivor, difficult to diagnose via microscopy, slow growing, poor competitor with Saccharomyces, don’t need oxygen but it can stimulate growth, can utilize many sugars even trehalose and ethanol, can penetrate up to 8mm into barrel staves.
Brett flavors: Lactones (b-damascenone), volatile phenols (4-et phenol, 4-et guaiacol), acids (acetic, isobutyric, isovaleric), alcohols, esters, lipid oxidation products.
Barrel maintenance: cannot fully eliminate all microbes, but topping off, use inert gasses, keep bung area clean, isolate infected barrels, santize thief, store empty barrels with compounds mentioned in TALK 1 (ozone is most popular).
TALK 3: Femke Sterckx, Wood Aging and Monophenols
25 different monophenols in wood-aged beer, many with vanilla or spicy characteristics. Precursors are lignin, hydroxycinnamic acids, some are bound in glycosides. Oak aging is often with oak chips. More wood chips are associated with higher monophenol content. Various compounds are more related with medium toasted barrels while others are more associated with heavy toasted barrels. Higher ethanol, higher lagering temperatures, and low pH helps with monophenol extraction.
Please excuse typos and shorthand. I tried, I really did. But the trip to Shangai Tunnel and elsewhere has left me sapped of the energy to proofread this material. Enjoy if you must.