Michigan By The Bottle Podcast Interview with Petraea Plus (Ep#79): Barrels ‘n’ Corks
What’s the difference between French and American oak? Why does a winemaker choose one or the other? What are “oak barrel alternatives”? Where does cork come from? Are the cork forests going extinct? What’s up with screw caps?
I had the opportunity to sit down with longtime friends, Michigan wine advocates, and fellow Michigan Wine Collaborative members, Cortney and Shannon Casey of MichiganByTheBottle.com and Michigan By The Bottle Tasting Rooms (Shelby Township, Royal Oak & Auburn Hills), to geek out about these and other fun questions. Give it a listen and follow along via our photo gallery below!
Petraea Plus is featured in the first 34 minutes, but keep listening because there are a lot of interesting tidbits about what’s happening in Michigan wines, some articles in national publications giving Michigan wines recognition, new Michigan wineries and cideries to visit, upcoming Hour Detroit articles on cold-hardy grape Marquette and port-style wines, January MBTB bus trip to Chateau Aeronautique’s new location, etc.
French oak barrels are made from Quercus petraea and Quercus robur, part of the sessile oak family. Originally used for building ships, the trees are tall and grow very few branches, making the trunks ideal for wine barrels.
The logs are huge and must be split by hand to retain the water-tightness that makes oak such an appealing material for holding wine and spirits. Because of this, fewer barrels can be made per French oak log vs. American oak logs (which can be sawn, automating the process and lowering costs).
A hand-split log is cut into rough staves for shaping into finished barrel staves. Before each stave goes to the cooperage for barrel-building, it is inspected for worm holes, knots, and other undesirable flaws, which are sorted out.
Finished barrel staves are arranged into a “rose” shape by hand by artisans (called “coopers”) at Tonnellerie Cadus in Burgundy, France.
The “roses” are toasted in order to bend the staves into a finished barrel shape, which also produces chemical reactions resulting in flavors and aromas (like spice, vanilla, caramel) that can complement wines during aging. The barrels are toasted for longer or shorter periods and using different methods to coax those flavors and aromas out of the wood.
The barrel heads are inserted and assembly hoops are replaced with finishing hoops…
…and then the barrels are sanded into the beautiful finished barrels you see in your favorite wineries.
Natural cork wine stoppers are produced from the bark of the cork oak tree, Quercus suber, that grows around the Mediterranean Sea in Portugal, Spain, Italy and northern Africa.
Cork bark is harvested by hand using traditional axes. Only after a tree is about 40 years old and on its 3rd harvest is the bark dense enough to be used as wine stoppers.
The cork bark is seasoned out in the elements ideally for about 9 months.
After seasoning, the cork bark is boiled to remove impurities and flatten it for punching into wine stoppers.
Cork bark being punched by hand to make wine stoppers. Note the chain mail gloves to protect fingers!
Machine-punched cork bark. The resulting “skeletons” are ground up, blended with adhesive, and extruded or molded into “technical corks,” which are usually less expensive than whole punched corks. Most sparkling wine corks are technical corks–take a look next time you pop some bubbly!
