Bulk Aging

Until recently, I have not bulk-aged my wines prior to bottling. Rather, I simply followed wine kit  instructions that tell you to wait for secondary fermentation to more-or-less come to an end, add finings, rack, and bottle. The whole process from opening the kit to bottling takes only a few weeks. There is no bulk aging.

After going through the "wine kit" process (without bulk aging) several times, I observe two main problems with wines made this way:

1.  Carbonation

Fermentation produces a lot of CO₂. Where does it go? CO₂ is dissolved in the wine until it reaches saturation. After that, CO₂ bubbles out of the wine into the air. When fermentation ends, there is still a lot of dissolved CO₂ in the wine, and it takes time to move into the gas phase. One way to release CO₂ is to agitate the wine (e.g. by stirring). Another way to get rid of it is to just give it time to gradually escape through the airlock.

If you don't give it time to escape before bottling, some of the CO₂ stays dissolved in the wine. All of my non-bulk-aged wines have a level of residual carbonation that detracts from the enjoyment. It's not much, but the carbonation is noticeable on the tongue. Who wants a tiny bit of fizz in their red wine?

Over the Christmas holidays, we opened up a bottle of a raspberry wine from a local winery. To our surprise, this wine contained more CO₂ than any of my homemade wines. The wine  released bubbles right there in the wine glass, just like sparkling wine. (And, no, it wasn't meant to be a sparkling wine!) The winery had probably bottled the wine before the CO₂ could escape. Fizzy fruit wine!

2.  Sedimentation

Finings do not remove 100% of the particulates from wine. Every time I used finings without bulk aging before bottling, a small amount of sediment has always appeared in the bottle. It usually takes a few months, but it's there and it spoils the appearance.

Sediment in rhubarb wine

An obvious way to prevent this from happening is to just let the wine age in a carboy (with an airlock) for a few months. By then, virtually 100% of the sediment should have crashed out in the carboy. By the time you bottle the wine, it should not be throwing any more sediment.

I have bulk-aged my most recent wines (two versions of Dragon Blood) and will write a separate post on them. Early observations are that the bulk aging solved the carbonation problem. I'm hopeful that there won't be any sedimentation in the bottles.

Wine Kit: Johannisberg Riesling

The last few months have been awfully busy at work and at home, and I have not had the time or energy for my fermentation hobby.  For almost 3 months, a CellarCraft Sterling Johannisberg Riesling kit has been sitting in my basement, waiting for me to open it.  Today, I started it.

First things first, being the kind of person I am, I was puzzled by the spelling of "Johannisberg" because I am more familiar with spelling of the city of Johannesberg, RSA.  It turns out that Johannisberg refers to the Schloss Johannisberg in the Rheingau region of Germany.  This is where the "late harvest" wines were, apparently, discovered.

Schloss Johannisberg

The wine kit itself is pretty standard.  It included two packets of bentonite clay, which is a fining agent.  As per the instructions, I mixed up the clay with hot water in the primary fermenter and then added the grape juice to it.  This is only the second time I have added a fining agent before the fermentation.  Why is this done?  Because the bentonite clay particles, which are negatively charged, react with positively charged particles in the wine, and these settle out.  This seems like a great way to remove macromolecules like proteins, which are a source of haziness in wines.

The following is a nice general review of fining agents and how they work:
A Clearer Understanding of Fining Agents



Image of Schloss Johannisberg:  http://commons.wikimedia.org/wiki/File:Johannisberg_Rheingau.jpg