STR barrels
An STR barrel is a used wine barrel that has been shaved, toasted and re-charred on the inside, so it suits the maturing of spirits. The method was developed by the late Dr. Jim Swan. Santing Beer and Spirit Barrels supplies STR barrels in French and American oak, from 50 to 225 litres, in light, medium, medium+ and heavy toast.
How is an STR barrel made?
S - step 1
3-5 mm is scraped from the inside of the oak surface of the barrel to remove some red wine residue that might otherwise give undesirable tannic and sulfurous notes (and possibly a home for unknown bacteria), but not to the point of removing all the wood stirred by the wine that might give desirable fruity notes.
T - step 2
The barrels are then toasted to break down the hemicellulose and lignins in the wood structure into wood sugars and other desirable flavor compounds that are soluble in alcohol.
R - step 3
Re-charring with an intense flame that caramelizes the wood sugars, causing the spirit to penetrate deeper into the staves, increasing the surface area of the inside of the barrel by creating shallow cracks, and acting as a built-in "carbon filtration system" that can clean up unwanted off-notes in just-distilled spirits.
See also the STR barrels.
