Racking in Moonlight, Acetobacter, Fermenting “dry,” and White Winemaking

Q. When is the best time to rack my wine in preparation to bottle? I was told by an old friend of the family to never bottle on a rainy or cloudy day and to always bottle when the moon is full. Is there any truth to this?
Annie Grey
Cincinnati, Ohio

A. While there is so much hooey out there about “don’t rack during a new moon” or “only bottle during a full moon,” the winemaking dictum you mention is based, at least loosely, on fact. It’s not so much about the full moon (though that makes for better marketing stories, perhaps), it’s about the barometric pressure. Full moons are best seen on a clear night. Clear, cloudless nights often correspond to conditions of high or rising barometric pressure. High barometric pressure means that any dissolved gas that may be in your wine will want to stay more dissolved in solution. Fewer rising gas bubbles means that less sediment on the bottom of your wine containers will get kicked up. Less sediment means a clear wine and hence, a better, cleaner rack and, if you’re bottling at the same time, a clearer, more microbe-free wine in the bottle. The converse is also true — rainy days tend to mean low pressure, more tendency for gas to come out of solution, kicking up lees and making your wine more cloudy. 

How cloudy is cloudy? And can you only rack or bottle when the weather is nice? Like so much in wine, it’s all relative. Sharing some details from the annals of my own years making, racking, and bottling wines, let me put a practical spin on it: If wineries really saw enough quality improvements by only racking or bottling once a month, or when the weather was clear, the world’s wine industry would be a heck of a lot smaller than it is. I’ve only ever worked for one winery where the practice of racking on high barometric pressure days was ever employed and then it was a recommendation only and not to get in the way of barrel maintenance, bottling schedules, or the important flow of wine through the facility. The best time to bottle is different for different kinds of wines — reds typically need more time bulk aging (in barrel, carboy, or tank) than whites and may be bottled at 18 months of age, whereas fresh, young whites can be ready in less than 6 months after fermentation. 

Being that you’re a home winemaker with a much smaller number of vessels than the average commercial winery, you probably can afford to wait for a high barometric pressure day (check your local weather news for norms in your area) to rack or bottle, if it makes you feel like you’ll make a better wine. If you want to get really accurate, I suggest investing in a barometer instead of squinting up at the sky.

At the end of the (dark and stormy?) day, I’m not sure if weather or moon phases have much to do with when one should perform certain winemaking tasks. Getting the timing right (asking yourself if the wine has had enough days and weeks to settle properly, for instance) should be your guiding principle. 

Q. I just made my first batch of wine with the help of a friend who has been making wine for several years. We used frozen raspberries and sanitized everything. later, When I bottled I got a hint of vinegar and was hoping the sample taste was in my head and not for real. Tonight, on opening our first bottle, my husband said, “I taste vinegar!” That then confirmed my awful thoughts. Is there anything that I can do to salvage my first attempt at winemaking or should I just pour it all out? 
Lori Washington
Wilmington, Delaware

A. The quick and dirty answer to your question, and quite possibly not the one you want to hear, is that you’re best off dumping your vinegar bottles of wine down the drain. Once your wine has been infected with vinegar-causing bacteria, Acetobacter, there is nothing you can feasibly do to remove or reduce the vinegar content in your wine. 

Big commercial wineries can take advantage of reverse osmosis technology and remove their acetic acid, still a relatively expensive and rare “salvage” maneuver. Unfortunately, home winemakers don’t have the volume (or the thousands of dollars) to justify such treatments, nor is there the equipment small enough to run home winemaker-sized batches. At the end of the day, home winemakers are better off concentrating on preventing, rather than curing, high acetic acid (the main ingredient in vinegar) levels. 

Acetobacter are ubiquitous in our general environment — in fact, you’re probably breathing some in right now. Since they’re so ever-present, we will never be able to completely exclude them from the winemaking environment. All we can do is try to restrict their access to the things they need to thrive and multiply: Oxygen, a happy environment, and a food source. To try to reduce the chances that Acetobacter will infect future batches, keep the following in mind:

Keep pH as low as possible and acid as high as possible, within intelligent style limits. Bacteria are repressed by higher acidity and thrive in high-pH environments. I like red wines to finish MLF (malolactic fermentation) at a pH no higher than 3.75. 

If there is headspace in your bulk storage containers (barrels, carboys, kegs, etc.), blanket the surface with carbon dioxide or argon. These gases are heavier than air and can help exclude oxygen from the surface of the wine. Keeping containers topped and completely full is one of the most important things you can do. 

Clean and sanitize all winemaking equipment before it touches your wine.

Be especially vigilant with finished wines. These wines don’t have the natural protection that carbon dioxide gas provides to fermenting wines and so are especially vulnerable to the effects of poor sanitation, oxygen ingress, and exposure to environmental microbes. 

Use adequate sulfur dioxide during all stages of a wine’s life. This is one of the biggest blunders I see new winemakers make. Finished wines need to be stored at 20–35 mg/L free SO₂ (low-pH wines closer to 20, higher-pH wines closer to 35) and bottled with about the same amount. 

If you don’t want to dump this batch out, you could always try to turn it into a delicious homemade vinegar (raspberry vinegar is amazing!). Check out this article on making wine vinegar we ran in a past issue at: www.winemakermag.com/article/make-vinegar

Remember that an ounce of prevention is worth a pound of cure — and maybe you can salvage some good homemade gifts of raspberry vinegar out of your first attempt at wine.

Q. I have an Elderberry wine that does not want to stop fermenting even though it has reached a specific gravity of 0.998 (-0.5 °Brix). Did I put too much nitrogen or nutrients into the wine and that is what is feeding the yeast? I added DAP (di-ammonium phosphate) 24 hours after inoculating the must with RC-212 yeast. When the hydrometer read 1.040 (10 °Brix) I added in Fermaid-K. I racked everything at 1.015 (3.8 °Brix). Do I just let the fermentation continue or do I rack and add sorbate? 
Lenny Martin
Enfield, Connecticut

A. I definitely think you should wait for the fermentation to complete and then rack and add sulfur dioxide. I doubt you’ll have to add any sorbate to protect against a re-start fermentation because I believe your wine is almost dry! Every wine is unique and as such hitting the “perfect” dry number is almost never possible. I’ve known dry wines to be completely done at 1.000 specific gravity (SG) (0 °Brix). There’s no magic in absolutely needing a wine to cross a 0.996 or even 0.995 (-1 or -1.3 °Brix) line. Some wines may have a certain degree of unfermentable sugars in them, believe it or not. I don’t have any specific (no pun intended) experience with elderberry wine but it’s possible you’ve got a must with an unusually high amount of pentoses (five-carbon sugars), which yeast can’t ferment. I’ve seen plenty of commercial wines in my career be “done” fermenting, taste dry and have 3 g/L “residual sugar,” and my usual “OK, it’s dry” target is 2 g/L. In fact, I don’t think I’ve ever seen a 0.00 g/L residual sugar wine in my entire life. 

I would check, however, that your SG hydrometer readings are accurate. Hydrometers are an instrument for reading density of liquids and are usually calibrated against water at 60 or 68 °F (15.5 or 20 °C). The first thing you can do is check the calibration and ensure it is properly calibrated. If it is off in water at the recommended temperature, be sure to incorporate how far off it is into any future measurements. If your wine sample is warm, your hydrometer will sink, giving an artificially “dry” reading. Conversely, if your wine sample is cold, the hydrometer will float too high, giving you an abnormally “sweet” reading. Sometimes tiny bubbles from a fermentation can stick to the glass or plastic sheathing of the hydrometer and act like mini life preservers, causing the hydrometer to float artificially high. In your case, with what seems like an active, bubbly fermentation, I’d be willing to bet that some clingy little bubbles are adding slightly to the “float” you might be experiencing. Also be sure you’re reading your hydrometer lines at eye level. 

One of the big tells when a fermentation is complete is when it stops bubbling. Is the hydrometer reading still actively going down or is it stopping/settling at 0.998 (-0.5 °Brix)? If it’s still moving slightly every day or so don’t worry about it, you’ve still got an active fermentation. Does it still taste sweet? If so, and if your SG readings are moving and you’ve got plenty of bubbles like you report, you likely still have an active fermentation that just needs to finish and take its sweet (ha, I did it again!) time. Have you checked it with a Clinitest tablet to see if that registers any residual sugar? If a Clinitest assay registers dry, your hydrometer has stopped going down and you’re still having lots of bubbles, then it’s likely you’ve got a secondary fermentation happening, which could signal a spoilage organism. If you think it’s dry, rack and sulfur it. 

Q. I like to bring fresh white juice into the winery rather than starting from grapes. I have more experience with red wines from grapes but my addition ratios/timings do not seem to work well if applied to the white juice. For reds, my additions begin with amount by weight per number of lugs at 36 pounds (16 kg) per lug. For example, 1⁄4 tsp. potassium metabisulfite for every two lugs of grapes. I shift my addition rates to estimated finished volume of wine based on an estimate of 5 gallons (19 L) of finished wine for every two lugs of grapes. When using fresh juice for white and rosé wines, how should adjustments be made and addition rates be calculated as compared to red grape processing? Also, does the juice require any enzymes since it is juice and not fruit? For reds, I wait until the cap falls before pressing. For whites and rosés, should racking timing be determined by specific gravity/Brix since there is no cap to monitor?
Hal Bell
Bacchus Winery
Fredericksburg, Virginia

A. It seems like you’ve found something that works for your red grape winemaking — making additions based on your 36-lb. (16-kg) lugs of grapes. Your estimated yield for grapes fermented on the skins turning into wine seems about right. Most small-scale winemakers, often using hand-cranked equipment, can get about 155 gallons per ton (2,000 lbs.) or 590 L/910 kg of grapes, so your guesstimate of 5 gallons per 72 lbs. (19 L/33 kg) works out to be in that neighborhood. Don’t forget to adjust, of course, for any water you add. 

I’m not surprised that you don’t get the best results doing the same types and rates of additions for whites. Though it might feel like you’re a little lost when trying to translate your red protocols to making white wine, the good news is that most winemakers find it’s much easier to calculate white juice/wine additions because you already know the amount of liquid you’re dealing with and dosing into.

Whites and reds are different animals. Whites ferment cooler and generally more slowly, which preserves the delicate aromas. Whites typically don’t need pectic enzymes unless your pressed juice had a high degree of solids when it was shipped to you. In my experience, they don’t need as many nutrients as a red fermentation because the grapes tend to be picked earlier so retain their nitrogen and amino acids better. 

If you’re able to get Brix, titratable acidity (TA), pH, ammonia, and amino acids measured by a wine lab, those will be your best guides for where your white wines need to go and what kinds of additions you need to make. 

For sulfur dioxide in white juice, I’m typically adding about 40 ppm (mg/L) at pressing. Be sure to check with your juice supplier on this; there may already be SO₂ in the juice and you may not need to add any more. 

With manufacturer-specific things like enzymes, nutrients, or even yeast, I definitely recommend reading the company’s literature and add conservatively in their recommended range. Most manufacturers have great websites with guides and their recommendations will most often be in easy-to-calculate measurements like g/L, mg/L, or mL/hL. If you need help doing any of those conversions, search the internet with conversion phrases like “L to gallons.” I often use the handy winemaking conversion and addition calculator at: www.winebusiness.com/calculator

To answer your last question: Yes, I would wait for a dry/not dropping specific gravity/Brix measurement as your signal to add the sulfites post-primary fermentation. Visual cap drop can be a sign for red ferments, but you’re correct, you won’t see something comparable on a white fermentation where the juice level in your tank or carboy will remain about the same.