I was proud to see my letter was selected for publishing in your great column (October–November 2011). Unfortunately the question was misunderstood. I didn’t intend to suggest stopping “paying back the angel’s share.” In fact, continual topping off has become one of the primary tenets of my wine religion! Instead, I wanted to discuss the possibility that adding back whole wine to the barrel while evaporation took away only water (and alcohol?) wouldn’t result in a concentration of all the other constituents and therefore the flavor, and therefore be something to encourage. Wine in, water out, more wine in, more water out?
Thanks for clarifying your question a little bit. I am glad to hear you regularly top off your barrels, it’s a practice all of us need to do. Alcohol and water definitely do evaporate out of barrels (along with small amounts of other volatile aroma constituents of wine) and the resulting headspace does need to get refilled as this occurs. I find that topping monthly, usually replacing between 1⁄4 to 1 gallon every time, is enough to keep my wine sound. The given amount of wine you lose in the “angel’s share” as you refer to it above will change depending on the humidity and temperature of where you store the barrels, as well as the age and stage of your wine. I always lose more volume when my wine is very young and going through ML as it’s so gassy. The CO2 blows off and you lose volume as the wine settles down. And I lose less when the wine is sulfured and simply aging, anywhere after about four months of age. Don’t forget that you also lose volume due to lees loss every time you rack off of lees of course, too.
I have to admit, I’ve never seen an industry or academic study that looked at the concentration of non-evaporating (i.e. color, tannin etc.) compounds in wine over time due to water and alcohol loss being replaced by wine. If you look at it from a physics and chemistry point of view, it would seem that some kind of concentration could be happening.
However, as the non-evaporating flavor and texture compounds in wine form less than 1% of the total wine volume (around 0.01–0.5%, most of the volume of water and ethanol) I would imagine that any possible effect would be so slight that the human palate would not detect it. And if we can’t tell the difference, then why do more topping than you normally would?
Remember, every time you open your barrel, you introduce air and potentially some undesirable spoilage organisms. I’m happy only opening up my barrels once a month to top them up. Though you could presumably speed up evaporative loss by warming up your cellar or decreasing the humidity, I’m not sure I would do that either. Warm temperatures, over time, can encourage spoilage yeast and bacteria to grow while dry air will wreak havoc on any barrels that you might have empty and could even dry the outside of full barrels unevenly, possibly leading to barrel integrity problems later on. I’m not sure that any incremental benefit in wine color and flavor concentration you might get (emphasis on might get) would justify tweaking with the rate that wine evaporates from your barrels and has to be replaced by . . . more wine!
For the first time in many years of winemaking, I noticed a white and green powdery mold on the wooden basket of my wine press and inside of my wooden fermenting barrel. These items were stored out in a shed and, I think due to rain and humidity this summer, both were infected to the point where they couldn’t be used this year. I have scrubbed the basket of the press with a stiff brush soaked in a meta solution and so far no mold has returned, but someone told me that the mold spores can get way down into the wood. Is the basket no longer any good? Is the cast iron base of the press useable if I clean it with a meta solution? And what about the barrel?
I certainly wouldn’t throw the baby out with the bathwater or the crush equipment out with the sanitizing solution in this case. A little accumulated mold on a wooden basket press or fermentation barrel doesn’t faze this Wine Wizard. It shouldn’t phase you, either, because it sounds like you are taking all the appropriate steps to clean (scrubbing to remove the surface film and mold) and then sanitize (do a deeper dig with a potassium metabisulfite solution) your equipment.
Absolutely, mold spores can get into wood and are sometimes never totally removed. However, you have to look at how you use your equipment. Though I can’t make any guarantees against some heretofore unidentified voracious wine-ruining super-bug, I would wager that the short time the wine is in contact with your wooden basket press while pressing is not long enough to cause major contamination. The wine will be “living” in your fermentation vessel a little bit longer, of course, but during its time there presumably you have inoculated the must with a strong, reliable yeast strain (like I always suggest to my readers). During an active yeast fermentation, those organisms will dominate the environment (that is the idea for a dry, complete fermentation) and will usually out-compete the potential bad guys that might be lurking in your wood.
The cast iron parts should be no problem. If you’re worried, try cleaning using a caustic cleanser on the basket followed by a sulfite or citric acid soak.
Now if you had a storage barrel that was super-covered in rabid-looking fuzzy mold? That might make me pause a little bit. Finished wine doesn’t have the rampant microbial population of a young, strong fermentation and so is a little bit more fragile and needs our help defending itself. It also will be hanging out in that barrel for a long time (presumably about 12 months?) so its house needs to be clean to start with or all sorts of unwanted microbial houseguests could take root. Little bits of mold that easily come off, don’t come back and don’t cause any kind of lingering aromas don’t make me too worried to use a barrel again. But major mold infections in barrels that cause sour smells, volatile acidity or ethyl acetate aromas during empty storage, especially if the smell comes back after a good cleaning, should probably be turned into planters. I feel you’re 100% OK to use your basket press, but leave it to your judgment about how bad the mold in the wooden fermenter looked as to whether you want to use it again.