Oak & Oxygen
Wine develops differently in an oak barrel versus a glass container. Oak barrels are porous and release a small amount of oxygen to the wine. The gradual release of oxygen, known as micro-oxygenation, takes the edge off of grape tannins, giving the wine a softening effect. Oak barrels also have their own tannins that further protect the wine from oxidation and reduction. Additionally, many winemakers favor oak for the phenols that impart flavors, such as vanilla, cocoa, and spice, to the wine. Glass carboys offer none of these benefits.
|Wine in barrel and carboys|
After our crushed grapes and juice (known as must) had completed the alcoholic or primary fermentation, it became wine. The wine was pressed and then transferred into glass carboys for malolactic or secondary fermentation. During this process, the tart malic acid found in grapes was converted to softer-tasting lactic acid with the help of lactic acid bacteria.
In the early stage of malolactic fermentation, the wine was moved from one container to another at certain intervals to get rid of sediments. The process is known as racking. The discarded sediments, known as the lees, are primarily made up of dead yeasts and grape debris.
About three weeks into malolactic fermentation and during the third rack, we moved a third of our wine into the new barrel for the first time. The remaining two-third returned to glass carboys. We monitored the wines monthly; topping up, testing, and tasting. The wines remained in their respective receptacles for another two months before they all completed malolactic fermentation. We were pleased that all the wines did well even as different taste profiles gradually developed.
|Racking wine from carboys into the barrel|
The fun part of the experiment is the sample tasting! We tasted both oaked and unoaked samples over time. We took notes and observed the evolution of the wine, our ability constantly tested with a bit of voluntary intoxication.
After over five months of tasting during the round robin, the taste profiles of the different samples confirmed our theory:
- The sample with little to no oak was bright with high acidity. The tannins remained coarse, and the wine ranged between low to medium-bodied.
- The sample with at least two months of oak contact had more concentrated cherry, vanilla, cocoa flavors with medium acidity. The tannins were distinctly smooth and velvety, and the body was medium to full.
|Tasting wine samples|