Fermentation Troubleshooting with Wine Kits

The failure rate of wine made from kits is very low. Looking back at my database for the last 14 years and eliminating the weirder stuff (you simply would not believe how many pets find their way into fermenting vessels) it turns out that if you follow the instructions closely and have generally sound sanitation and storage practices, along with a healthy dose of patience and the good sense to take and record specific gravity and temperature readings, chances are you’ll make good wine 99.9% of the time.

However, there is that teeny percentage when the kit goes sideways, and something a little stronger than patience is required. That’s when it’s time for take-no-prisoners troubleshooting. To help out with charting your problems, this topic will be divided into three sections over three issues. This section is on fermentation problems — slow, fast or unfinished fermenting activity. The second will be visual problems (color and clarity issues), and the last will be odor/flavor problems (aroma, bouquet and stinkiness).

Before we shoot your troubles, carefully re-read your kit instructions. Wine kits sometimes have instructions and procedures that contradict what are accepted techniques for fresh grape/fresh juice winemaking. There are a lot of reasons for these non-intuitive procedures, but they all boil down to the same thing: That’s the way that the kit ferments, clears and stabilizes best, as proven by numerous lab trials. Departing from the steps in the instructions is the second most common route to failure that we see in the quality control department. (The first? Temperature.)

Second, not only do techniques for grapes not apply to kits, but also instructions are not transferable between one brand/type of kit and another. It would be nice if every manufacturer had identical instructions, but they’re all just trying to ensure that their particular kits are successful the greatest number of times for the largest number of users.

Finally, the instructions for your kits will probably change at least once every couple of years. This schedule is based on how many sets are ordered at once, because manufacturers don’t want to hold lots of printed instructions in inventory. The technical folks save up all of their notes on procedural changes and improvements based on consumer feedback and lab trials, and the copy editing folk hack away at the endless task of making them more readable. It’s a necessary part of the process, but it means that there’s a good chance that the last instructions you read a decade ago are woefully out of date, and following them may prevent you from making the best wine you can.

Required equipment

A lot of troubleshooting requires measuring temperatures and taking specific gravity readings. You’ll need a good floating thermometer, a test jar and a hydrometer, along with a dedicated notebook to record your observations and scratch out a little math: The best way to improve your winemaking is to keep good and careful records.

Wine won’t begin fermenting: Temperature

When yeast is pitched according to kit instructions, you usually see foaming or bubbling within 48 hours. If nothing seems to be happening, the first step is to take a fresh specific gravity reading and compare it to the one you took and recorded when you made the kit up. If it shows a drop from the original, even though you don’t see any foam or activity, you’re experiencing “secret fermentation.” For several complex reasons, sometimes yeast like to hide their light under a bushel, quietly getting to work without too much foaming or fizzing. In this case the immediate solution is to relax and let the wine ferment on its own.

If the gravity has not dropped, double-check that you have actually added the yeast. If you find your package of yeast sitting inside the box, or think you may have discarded it, add yeast immediately. If you can’t find the package that came with the kit, make sure you add an identical strain to the one recommended: It’s the only way to be sure that your kit turns out the way it was intended. Check your gravity for the next three days to make sure fermentation is proceeding.

If the temperature of the must is below the manufacturer’s recommendation (typically 72-75 °F/22-24 °C) you will have to warm the must up by wrapping it with a heating belt or by other means of direct heat. Don’t set it on a heating pad or blanket: This concentrates the heat and can cause electrical damage, or even a fire. Most of the time the yeast recovers from being too cold and begins fermenting on its own within 24 hours, but if not, double-check the temperature of the must and pitch another package of yeast.

This is the most common error in kit wines, and the easiest to avoid. Make sure to use warm water to make up the kit, not cold water straight from the tap. Many municipal groundwater sources run below 55 °F (13 °C) year-round, making it too cold to use in a kit that’s been sitting at room temperature.

If you know you added yeast, and it still isn’t fermenting, again: Check the temperature of the must. If it’s much above 90 °F (32 °C), you may have added too much hot water to the must, and the yeast could be dead. Cool the must by freezing a couple of bottles of water, sanitizing the outside and dropping them into the fermenter. Alternately, you can drape a wet towel around the fermenter and direct the breeze from a fan at it (this technique is great during heat waves as well). When the temperature is below the recommended maximum in your instructions, go ahead and pitch a fresh package of yeast.

There is a definite window of opportunity for correcting the must temperature or adding a missed package of yeast: If you catch a non-fermenting kit within four days, you can probably get it going without repercussions. Keep in mind, however, that unprotected grape juice is an excellent growth medium for all kinds of bacteria: If the must smells sour, or looks moldy you are probably out of luck. In any case, monitor your fermentation for signs of contamination during the rest of the process.

Wine won’t begin fermenting: Additives

If you’ve added the yeast, the temperature is okay, and it’s still not fermenting within 24–48 hours, have a careful look for the additive packages that came with the kit. If you have accidentally added the stabilizers to the kit, you may have a terminal problem on your hands.

If it’s just the sulfite packet that was added, sometimes a very strong yeast starter culture can overcome moderate levels of free sulfur dioxide. Start a package of yeast in a quart (one liter) of commercial apple juice warmed to 75 °F (24 °F), along with a teaspoon of yeast nutrient. Shake the bejabbers out of the juice and nutrient mixture before adding the package of yeast, as a little dissolved oxygen will help the yeast get started. After 24 hours, or the onset of very vigorous activity, pitch the entire quart into your must. Don’t worry about changing the flavor: It won’t be significant, and a small flavor change is less important than getting your must started ASAP.
Another couple of good restarting techniques: Take a wine that is ready to be racked from the primary fermenter to the carboy and harvest the yeast sediment remaining after the wine has been racked. The best way to do this is to leave the yeast sediment in the primary fermenter and pour the non-fermenting must on top of it. Finish up with a good stir, to get all of the yeast cells into suspension. This will be a rich source of very active yeast, and should restart just about any fermentation.

If you’ve added the sorbate package included in the kit, discard the wine. Sorbate prevents yeast breeding, and virtually all efforts at starting fermentation in the presence of sorbate end in failure.
If you’ve avoided all the above conditions, and your wine still won’t ferment, your yeast may have been inactive: A fresh package should get things on the road. Again, make sure it’s the same variety and type of yeast included in the kit.

One thing that may seem like a good idea, but actually doesn’t work with wine kits, is adding extra yeast nutrient. Wine kit manufacturers all add very nearly the maximum amount of yeast nutrient a kit can handle. It’s not going to be a low-nutrient situation that hampers your fermentation, and extra nutrient not used by the yeast will stay behind in the wine and leave an unpleasant flavor.
Fermentations fast and slow

If your wine ferments to dryness (as measured by your hydrometer reading) in less than half the time required in the instructions, your temperatures may be too high. Try the wet towel trick described earlier to cool it down. The trouble with hot fermentation is that yeast tends to generate its own heat after a certain point, and you could have a heat-related yeast die-off and a stuck fermentation later.

If your wine ferments to dryness in less time than specified in the kit instructions, wait the minimum amount of days indicated in the instructions before racking to the secondary fermenter. This will ensure that an appropriate amount of sediment is left behind in the primary, and could prevent problems with fining and clearing later.

Once in a while we see a kit that has been racked to the primary too soon that has a large amount of oak chips still in suspension. These can collect in the airlock and block it, causing pressure to build up until suddenly it’s Krakatoa Cabernet on the ceiling.

If you do find your wine shooting out of the airlock, you’ve racked it into the carboy too soon. Rack it back into the primary and wait for it to hit the correct gravity. Don’t be fooled if it calms down immediately after racking. All that has happened is the CO2 has been knocked out of solution by the agitation of racking (it is pretty agitating to have to do an extra racking) and the wine will soon be foaming vigorously again.

If your fermentation is proceeding too slowly, try warming your must up to the recommended temperature, and practice patience. Don’t rack the wine on day 7 if the specific gravity is higher than recommended in the instructions. Wait for the appropriate gravity reading.

One thing we frequently see hampering fermentation schedules is repeatedly fluctuating temperature. Most of us never think about it, but when we leave for the day we turn the furnace off, dropping ambient temperature in our fermentation area, and when we come home, we warm our house up. This drives yeast crazy, and it can often cause it to go dormant while it waits for more favorable conditions. You may need to isolate your fermenter in an area with a more steady temperature.

When fermentation won’t quit

Sometimes a carboy will continue to bubble long after it should have stopped. First things first: Check your specific gravity. If it’s high, give the wine a vigorous stir, make sure the temperature is at the high end of the specified range and wait.

If it’s in the right gravity range, you may be experiencing one of two phenomena. First, the wine may actually be finished fermenting, but due to changes in temperature or barometric pressure it is out-gassing carbon dioxide at a rate that looks like active fermentation. This could be exacerbated if your wine fermented quite slowly (as in a cool fermentation) and is saturated with CO2. The other possibility is that an organism that can continue to access nutrients long after the cultured yeast has finished is fermenting the wine. This could be random bacteria from the environment (most commonly lactic acid bacteria) or a mutant or indigenous yeast. In this case, when the wine has hit its target gravity, and the requisite number of days has passed, it is imperative that you proceed with the stabilizing and clearing procedures in the instructions. By stabilizing in a timely fashion (at the correct specific gravity) you’ll prevent organisms from doing any significant damage to the kit.