Kits wines are designed so that the average person can produce a nice, drinkable wine. However, for the home winemaker interested in making the highest quality wine possible, there are several avenues to getting the best performance from your starting materials and making a truly great wine. As with any style of winemaking — whether from grapes, juices or kits — solid fundamentals are required. Beyond that, however, knowing some of the key winemaking aspects that are specific to kits will allow you to take your kit winemaking out of the box.
Make Your Kit Wine Shine
Each item in a kit has a specific purpose. Likewise, every step in the instruction sheet is there for a reason — and, the combination of ingredients (the contents of your wine kit) and procedures is tested many times. However, sometimes the point of a kit item or procedural step is that it is foolproof. For the advanced kit winemaker — who knows what he or she is doing and takes a more careful approach to winemaking — there are adjustments you can make that will lead to better wine. So get ready to take you kit wine making to the next level.
So you’ve got your kit wine home and are wondering if there are ways you can improve it. Some books advocate additions and manipulations, others propose different ways of processing. But wine kits respond best to good winemaking practices, rather than quick fixes or manipulations. By treating your wine kit as you would fresh grape must, you can use all of the techniques that professional winemakers use. Along with these good practices, there are a few pitfalls you will need to avoid. Here are a dozen tips to help you make great wine from a box.
1. Keep Good Records
Like any hobby you tackle, you’ll be able to replicate your successes and avoid your failures by keeping records of both. Get a notebook for winemaking (a plastic cover is a good idea!) and track the type of kit, the code number, the date it was made, specific gravity, temperature and any variations in your technique or measurements.
The code number is very important. Manufacturers put a production code on every kit, and while they may seem a meaningless jumble of numbers when you write it down, it’s the first thing your retailer will need to know if you have any problems with your kit. Most instruction sheets have spaces set aside to record this information, so you can simply hole-punch the instruction sheet and keep it in a binder.
A good follow-up is to write down your impressions of the wine as time passes. A few notes can help judge how the wine develops in your cellar, and will refresh your memory if you’re trying to decide whether to make this wine again.
2. Carpe DieM (Seize the Day)!
The instructions that come with kits are designed to produce good wine in four to six weeks. But with more time (and less effort) you can produce wine that’s not only good, but great. By relying on specific gravity readings to decide when to rack from the primary fermenter to a carboy — rather than simply following the recipe for a set period of days — you can make noticeable improvements in your wine. Of course, all the kit instructions ask you to do this anyway, but not many people follow through.
Instruction sets have a predetermined period for each phase of winemaking. The schedule usually goes something like 7–21–28 (7 days in the primary, 14 days in the secondary, add stabilizers and finings, and bottle 7 days later). A better sequence would go something like 5–20–50–90.
The 5-day primary fermentation period is arbitrary. Good winemaking techniques normally dictate transferring to the secondary once the danger of foaming through the airlock has subsided, so monitor the fermentation — the specific gravity should be less than 1.010 in most cases — and rack when the most vigorous bubbling is finished. As an alternative, if you have a 6.5-gallon (25-L) carboy, you may wish to conduct the primary fermentation there, under an airlock. Be wary, however, of oak powders or other additives that may foam up and clog the bung, possibly resulting in a messy spray. There are other alternatives, such as using two 5-gallon (19-L) carboys, but however you do it, be sure that the kit is rehydrated to the correct volume before pitching your yeast.
Fifteen days after racking to the secondary, test the gravity, rack, fine and stabilize, and then leave the wine 20 days to finish settling. Test the gravity, rack again and leave it an additional 50 days before bottling or bulk aging. (Bulk aging is holding the wine in the carboy for an extended period. This replicates bottle aging, with the benefit that it allows a long period for the wine to finish clearing on its own.)
Conscientious topping up and careful attention to sulfite levels will prevent oxidation in the carboy over this period. Once the 90 days has passed, you can go to a solid rubber or silicone bung, instead of a bung and airlock, to further reduce the chances of oxidation. Most white kit wines will be ready to bottle after 90 days, but the heavier reds will continue to improve for at least an additional 90 days.
There comes a point of diminishing returns, however, and a bottle is a perfectly good place to age wine, as well. If you’re stuck for fermenting and storage space, go ahead and bottle after the 90-day period, but remember to hold your wine for at least three months before sampling it. It will be worth the wait!
3. Whip it! Whip it good!
The one thing you don’t want to change in the instructions is the mixing and stirring of the kits. To make a properly balanced wine, you need to stir the full 6-gallon (23-L) volume vigorously, prior to pitching the yeast. This is crucial: The concentrates are so viscous that they don’t mix easily with the added water. Indeed, unless the must is well “whipped,” it will stratify, with the top layer being very dilute (below specific gravity 1.050) and the bottom layer extremely concentrated (sometimes above specific gravity 1.100). Not only would this throw off any attempt at a specific gravity reading, but the top stratum will ferment readily, until the yeast is exhausted, while the bottom layer will not ferment successfully at all. This will leave a weak-tasting wine, low in alcohol and high in residual sugar — not a desirable result.
4. Analyze for Quality
Taking accurate measurements will allow you to chart the progress of the fermentation, and to make reasoned additions of stabilizers and any other blending materials you would like. Also, whenever you do make an addition or adjustment to your kit, always follow the procedure of “test-add-test,” to confirm that your adjustment has had the desired effect. Like the tailors say, “Measure twice, cut once.” (For a more in-depth discussion of these, consult a good winemaking handbook, such as Daniel Pambianchi’s “Techniques in Home Winemaking” (Véhicule Press, 2008), which has a good chapter on making wine measurements at home.)
Examples of measurements that are useful include:
• Hydrometer readings for charting the progress of fermentation and calculating the alcohol content. Calibrate your hydrometer by putting it in distilled water at 60 °F (15 °C). It should read exactly 1.000. If it doesn’t, you need to get a new hydrometer or apply a correction to every reading. If your hydrometer reads 0.004 high at 60 °F (15 °C), for example, add 0.004 to every subsequent reading taken at 60 °F (15 °C).
To calculate potential alcohol, take the original gravity of the must, subtract the gravity of the finished wine, and multiply that number by 131. This will give you the percent alcohol by volume. For example, if you started out with a gravity reading of 1.088 and had a finishing gravity of 0.998, the difference between the two would be 0.090. Multiply that by 131 and you get 11.79 or roughly 12% alcohol by volume (ABV).
• Post-fermentation acid testing: Typically the acid in white wine kits is between 5.5 and 7 grams per liter, and between 5 and 6.5 for reds. You may wish to increase the acidity if you are sweetening the wine post-fermentation, or if you prefer a “snappier” flavor. An important note: Acid testing cannot be done in a wine kit before fermentation, as the acids are bound to the sugars in the must by the pasteurizing process, making the readings artificially low. If you are making an acid addition, one tablespoon (15 mL) of tartaric acid weighs approximately 4 grams when dry. For an accurate measurement, however, it’s much better to use a gram scale when making these additions.
• Measuring the level of sulfite in your wine: Kit additive packages generally contain 1.5 to 6 grams of sulfite, yielding somewhere between 15 and 60 PPM of free SO2 at bottling. Unless you have poor storage conditions, 60 PPM is on the high side, and even with good storage 15 PPM is on the low side. Rather than rely on the sulfite powder that comes with the kits, you can measure your sulfite levels and make accurate additions based on your results (for more information, see the sulfite calculator in the Resource Guide section of winemakermag.com). This is especially important if you are changing the kit timeline by adding extra rackings and increasing the aging time. Although pH testing can be done on wine kits after fermentation, it really isn’t necessary. All wine kits are adjusted below a pH of 3.5, and are strongly buffered against change. As with acid testing, pH tests on pre-fermentation kits will not be accurate.
5. Manipulating Specific Gravity for Fun and Profit
Many home wine kits start with a specific gravity of 1.080 or less. This leads to alcohol contents below 12 percent, and, generally speaking, soft wines that age easily and drink well while young. This isn’t a bad thing, given that many people make wine kits intending them for early consumption, but if you wish to cellar the wine, you can increase the starting specific gravity to produce a higher potential alcohol and a more balanced finished product. You will need to determine whether this is appropriate in all cases. A 15% alcohol by volume (ABV) Piesporter isn’t going to impress anyone, and will never be well-balanced, but a Zinfandel with a potential alcohol content of 11.8% ABV could benefit from a modest increase.
A pound of sugar made up to 1.0 gallon (3.8 L) with water will give a specific gravity of about 1.042. A pound of sugar dissolved into a 6-gallon batch (roughly 450 grams in 23 L) will increase specific gravity by 1.007. This yields a 1 percent increase in the alcohol percentage.
Two caveats to manipulating the specific gravity of your kit: First, don’t add more than two pounds of sugar in total, as this could lead to weakened fruit character and unbalanced, hot, alcoholic characters (sounds like the plot of a romance novel!). Of course, this depends on the style of kit: If a 10 percent Piesporter doesn’t suit you, you’re better off making a more alcoholic style, such as Chardonnay, as opposed to increasing the alcohol content. Of course, always test-add-test to make sure you’ve accomplished your goal.
There is another way to increase the starting gravity of the kit without adding sugar, by making the volume up to 5 gallons (19 L) instead of 6 gallons (23 L). This would seem to be even more attractive when you consider that almost everyone has 5-gallon (19-L) carboys, not 6-gallon (23-L), and beer brewers use 5 gallons (19 L) as their standard.
The problem with this sort of manipulation is that it makes rough, unbalanced wine, with plenty of power but no finesse or elegance. The finished wine takes a very long time to age to drinkability, and few people can manage more than a couple of glasses before the acidity and tannins catch up with them.
By deleting 20 percent of the volume of the kit, you increase the acidity, tannin and total solids by 20 percent. Yes, this makes a stronger wine, but think of making frozen concentrated orange juice: Does leaving out half the water make better orange juice, or just thicker, sweeter, stronger juice?
There are other considerations as well: The wine will take longer to ferment, and may not clear well. Some kits with high specific gravity (typically ones that emulate styles such as Amarone or “big” Chardonnay) already start with a specific gravity in excess of 1.100. Failing to dilute them correctly will give them a starting specific gravity so high that they will quit fermenting with several percent residual sugar, resulting in hot, sweet wine — not everyone’s cup of tea!
People who are attracted to this technique would be better served by using a higher-quality kit instead. The juice-concentrate six–week kits contain single-strength grape juice and very flavorful concentrates. Smaller kits (those that contain more concentrate and less fresh juice) make good wine, but tend to express less character. The big kits cost more money, but when you consider that you are getting nearly 25 percent more wine — by making the full 6 gallons (23 L) you get 29 or 30 bottles, compared to 24 or 25 bottles from 5 gallons (19 L), the difference, particularly the difference per bottle, is very low.
6. Choose Your Yeast and Select Your Temperature
In years past, high fermentation temperatures were recommended for wine kits, due to the nature of the yeast used. Given that viability rates were low in packaged yeast, higher temperatures assured full attenuation. Nowadays kits come with some variation of high-quality monocultural dried yeast, which will successfully ferment the product in a range of 60 to 80 °F (15 to 27 °C). By lowering the temperature of the must to around 60° F once fermentation has started, you can retain more of the fruity aromas of the kit and minimize ester production in the yeast, giving a cleaner wine, with more aroma from the fruit. Note that the lower temperature will result in longer fermentation times, so keep checking your hydrometer.
Further, the yeast in your kit was probably chosen primarily because of its fermentation characteristics (clean, rapid, thorough attenuation) rather than for its ability to express character or enhance bouquet. By choosing a style of yeast suited to the type of wine, you can enhance the flavor of the kit. Yeast manufacturers publish the characteristics of their strains (in particular, some of the new liquid cultures are very good) and WineMaker provides a comprehensive list of popular strains on the Web at www.winemakermag.com/guide/yeast.
7. Take Your TiMe
One aspect of wine kits that manufacturers bemoan is the notion that because they can be ready to bottle in four or six weeks, consumers assume they are ready to drink in that time. Nothing could be further from the truth. This merely describes the minimum processing time necessary to produce clear wine ready for bottling. Even the most basic four-week kit will improve immensely with three months of age, and a juice-concentrate kit could shock you with the huge improvements it will show over a few years.
8. GO LIGHT With Fining Agents
The fining agents used in kits are normally chosen for their ability to clear the wine completely within the span of seven to 14 days. This is an admirable goal most of the time, when the expectation is that the wine will be ready in four weeks, but this goal doesn’t allow for the longer fermentation and settling times that a dedicated winemaker can use. By extending the winemaking timeframe, the amount and types of finings can be substantially reduced.
A good philosophy behind fining use is that one should do the absolute minimum necessary to clear the wine. The kit may contain three ounces (80 grams) of bentonite, along with gelatin and silicon dioxide, but after a year of aging it may only need a half-ounce (15 grams) of bentonite and one-quarter of the amount of gelatin — or even just a single addition of Sparkolloid — to achieve brilliant clarity. Many times, after a year of aging, the kit will not require fining at all.
For white wines, however, even if they appear brilliant in the carboy, it’s best to do a protein check on them. Remove a single bottle and chill it near freezing. If it shows cloudiness or haze when chilled, it needs to be fined, either with bentonite or another protein-stripping fining agent. For a more thorough discussion of fining, see “The Fine Art of Fining” (Spring 2000).
Trials can be conducted on the wine to determine which fining agents will work best. There are as many fining options as there are wine-kit manufacturers, and each regards its fining process as the only one that works — however, experience should be your guide when adding finings. If you normally see good results with a small dose of gelatin, then you will probably continue to experience success with it in your kits.
9. Filtering things out
Should you filter your wine kit? Yes, if you want to. For the most part, however, kit wines clear to complete brilliance without filtration. To see if your kit is brilliantly clear, take a sample glass into a darkened room and shine a flashlight through it. Don’t look into the light; instead, look at the glass from the side to see if the beam is visible as it travels through the wine. It could look something like a sunbeam travelling through a dusty room. If you can see the beam, the material in suspension may drop out later in the bottle, or it may change the appearance or aroma of the wine over time. In that case, you should filter.
There’s a lot of talk about whether filtering strips flavor or character from wine. In reality, wine-kit manufacturers and filter companies do not sell filters to the home winemaking market that are fine enough to do any real stripping of wine. When a wine tastes different or flat after filtration, it’s due to “filter shock.” Some of the aromatic compounds in wine go into hiding after the jostling and shearing they are subjected to inside a filter pump. With a month or two of rest in the bottle, they come right back. For a detailed discussion of filtering, see “Choosing a Filtering System” at winemakermag.com.
10. Add Additives EARLY
Kits can come with a variety of additives. Pre-fermentation additives include oak (as powder, chips, cubes, chunks or strips), elderflowers and elderberries. Post-fermentation additives include “sweet reserves” and flavor boosters. By understanding the manufacturer’s intent behind these products, you can choose whether you want to include them in your kit.
• Oak derivatives have come a long way in the last ten years. They are made from top-quality European and American air-dried, toasted oak, as opposed to what some people suspect (sawdust and floor sweepings). By including them in the primary fermentation the wine changes the oak biochemically, transforming the more aggressive aromas and flavors, making them softer and integrating them into the wine, much in the same way that barrel fermentation does. It also increases the amount of polysaccharides (long-chain unfermentable sugars) that contribute to length on the palate and mouthfeel. You can add extra oak, leave it out or change the toast level. You may even choose to add the oak post-fermentation to achieve a more assertive character. Keep in mind that the manufacturer will have included what their trials show to be an appropriate amount of oak for the style. If you leave the oak out of your Australian Chardonnay, don’t be surprised if it seems excessively fruity, as the oak is there to balance ripe grape characters. Likewise, doubling the oak in your kit could result in a finished product that tastes like extract of plywood.
• Elderflowers are the flowering buds of the Sambucus niger plant, a bush found in Europe. They add a flowery aromatic quality that is desirable in some soft German-style whites. Whether you think this is a positive addition or not is up to you: It certainly enhances the bouquet of a Piesporter style wine.
• Elderberries are the dried fruit of the Sambucus niger. They take the place of red-grape skin contact, providing color, aromatics and tannin. While this does give the wine a darker color, it is slightly unnatural, and the flavors tend to be broad and plummy. Still, some people enjoy the character elderberries give to otherwise undistinguished wines.
11. Add ADDITIVES LATE
• Most kits contain potassium sorbate. Manufacturers use this preservative to guarantee the success of their kits in a variety of sanitary conditions. Sorbate prevents the growth of spoilage organisms, which could alter the flavor and aroma of the wine as time passes. As an advanced winemaker, your sanitation should be good enough to ensure that no spoilage organisms would invade your wine. So you have the option of leaving it out. Sorbate has a subtle, although definite, sweetish taste. By skipping the sorbate addition, you can improve the varietal character and finish.
Keep in mind, however, that if the wine kit contains a sweet reserve or a flavor booster (F-Pack), you will certainly need to add the recommended sorbate, lest you experience refermentation in the bottle. Also, if you’re not completely assured of your ability to exclude spoilage organisms, and to maintain a correct sulfite level, you should add the sorbate.
• “Sweet reserves” or wine conditioner is usually invert sugar and sorbate, and is designed to give a residual sweetness of between one and four percent. You can benefit from tasting the wine and making smaller trials with a portion of the sweet reserve before adding the entire amount.
If you wish to sweeten the wine before bottling, pay attention to the minimum and maximum amounts specified on your wine conditioner bottle. Because wine conditioner is a sugar solution, it contains sorbate to help prevent refermentation in the bottle. Adding the minimum recommended amount will ensure that the wine gets a sufficient level of sorbate to prevent any refermentation, while staying below the recommended maximum will prevent a sorbate flavor in the wine.
• Flavor boosters (F-packs) contain natural grape concentrate and essences to give a natural sweet flavor to the finished wine. This replicates the German tradition of Süssereserve, juice held back from the fermentation to sweeten the wine before bottling. For the most part, kits are formulated specifically to use these packs, and could taste unbalanced without them.
12. Extras, Extras!
• Tannin: One complaint previously leveled at many red wine kits has been that they lacked tannin, and thus were unbalanced and soft. With advances in raw materials processing, most of these concerns have been addressed. Indeed, adding extra tannin to the kit may have unintended side effects. Some red kits have a grapeskin extract added as a color enhancer. Tannins will bind to this additive, pulling it out of suspension, leaving the wine a light pink color. As this has a cascade effect, even more tannin will be pulled from the wine, leaving it very soft and flabby.
The best approach is to choose a six-week juice-concentrate wine kit, which will have more naturally occurring tannin in the first place.
• Concentrate: In the past, to achieve higher levels of apparent extract and flavor, people have topped up their kit with extra concentrate or reduced the volume of water added. Rather than manipulate a kit you find bland, it would be better to choose a higher-quality kit that provides a richly flavored final product without manipulation. You can’t make a silk purse out of a sow’s ear, so try starting with silk!
• Grape skins or grapes: Sometimes winemakers make “second run” wines, using either sugar-water or kits to make an additional batch of must with the skins pressed from a red grape fermentation. Looking at it another way, the addition of pressed red grape skins to a red wine kit will make a large impact on not only the tannin level of the finished wine, but also on the color and aroma. Five or ten pounds (2.3 to 4.5 kg) of grape skins can be fermented with your kit, and simply scooped out when it comes time to transfer to the secondary (you may wish to press the skins or squeeze them in a straining bag).
For whites, adding the skins from a white pressing or a few pounds of varietal grapes to a kit for a period of two to 24 hours can make a very aromatic white wine with little extra effort. Strain the skins after the soaking period and proceed as normal for the kit. I’ve tried this with Muscat grapes and a Gewürztraminer kit with excellent results. The drawback to this technique is that grape skins are only available in season. If you have room in your freezer, you could use them at your leisure (the skins will need to be frozen immediately after pressing; they spoil quickly).
• Malolactic fermentation: Do not add a malolactic bacteria to wine kits. Most juices are tartrate-stabilized prior to concentrating or blending (see “How Kits Are Made,” page 32), and thus contain a very high proportion of malic acid. Malolactic fermentation would convert this malic acid to lactic, leaving a kit with a pH above 3.8 and a flabby character. It would also be susceptible to bacterial infections.
Also, there are some situations in which a small amount of sorbate may be present in juices or concentrates. Malolactic fermentation in the presence of sorbate yields hexadienol, which produces the odor of rotting geraniums.
• Barrels: A complete discussion of the use of barrels in winemaking is beyond the scope of this article, but all of the positive qualities that an oak barrel can contribute to a grape wine apply to kits as well. A caveat is to monitor your barrels carefully. As discussed above, a barrel contaminated with malolactic bacteria could render your wine undrinkable. If you are going to put your wine into a barrel, remember to exclude the oak powder or chips that came with it, or you may wind up with “Chateau Plywood.”
Thinking outside the box
By applying good winemaking techniques — and avoiding steps that are more likely to negatively impact a wine — we can not only make decent wine from kits, we can make very good wine from kits. And as the technology for juice and concentrate processing advances, ever-better kits will be available. While home winemakers will always regard fresh grapes as the best source for fine wine, we have a viable alternative for making high-quality wine, quickly and conveniently.
How Wine Kits Are Made
Wine kits contain concentrate, juice and other staples like acid and sulfite. The process that brings these things together to make a kit is fascinating. First, manufacturers contract to purchase grapes from growers by specifying conditions at harvest (acid, pH, Brix and color) and organoleptic qualities (flavor and aroma). When the grapes are ripe, they are harvested and taken to a winery, where they are sulfited and crushed.
White grapes are pressed and the juice is pumped into a settling tank. Enzymes are added to break down pectins and gums, which would make clearing difficult after fermentation. Then bentonite is added to the juice and re-circulated. After several hours the circulation is shut off and the tank is crash-chilled below freezing. This helps precipitate grape solids and prevents spoilage. When the tank is settled and the juice almost clear, it is roughly filtered, the sulfite is adjusted, and it is either pumped into tanker trucks for shipment to the kit facility or into a vacuum concentrator.
Red grapes are crushed, sulfited and pumped through a chiller to a maceration tank, where special pectinoglycolytic enzymes are added. These break down the cellulose membrane of the grape skins, extracting color, aroma and flavor. The tank is chilled to near-freezing to prevent the must from fermenting. After two to three days, the red must is pumped off, pressed and settled. The pressed grape skins then undergo secondary processing to extract further skin components, which can then be added back to the juice.
Vacuum concentrators work like the reverse of a pressure cooker. By lowering the pressure inside the tank, water can be made to boil at less than 120 °F (49 °C). At temperatures this low, browning and caramelization are prevented and water comes off as vapor, leaving behind concentrated juice. Because some aromatic compounds can be carried away in this vapor, there is a fractional distillation apparatus on the concentrator to recover these essences, which are then returned to the concentrate after processing is finished.
The juices and concentrates are then shipped to the kit facility. They are pumped into nitrogen-purged tanks, tested for quality and stability, and held at very low temperatures. This both speeds up the formation of wine diamonds (crystals of potassium bitartrate from the tartaric acid naturally occurring in the wine) and preserves the liquids.
After the quality control checks are passed, the juices and concentrates are blended in giant tanks. When the formulation is approved, the must is pumped through the pasteurizer. The pasteurizer is a heat exchanger that rapidly heats and then cools the must, killing yeast and spoilage organisms, but not caramelizing the must. From there it goes into the bag filler, which purges the sterile bags with a double flush of nitrogen and then fills each bag.
The bags are then capped and loaded into the kit boxes, after which the additives are placed on top. The boxes are shrink-wrapped and packed on a skid for a quality-assurance microbiological hold. This hold can last from three days to a week, while the product is examined for bacterial or yeast activity. If it passes, it is shipped to the warehouse, and from there to dealers, and finally, into the hands of the customer.
What’s on the horizon
Wine-kit manufacturers are always striving to improve kit quality. There are two basic approaches. The first is to use higher quality grapes for the juices and concentrates. While this is easily done and yields good results, it has a self-limiting factor: cost. At a certain point, the higher cost of raw materials will drive the price of the kit to the point where the market will no longer bear it — after all, if a kit costs as much per bottle as Chateau Latour, wouldn’t it be easier just to buy the Latour? Still, better and better raw materials are making their way into the hands of home winemakers.
The second approach is to find new ways to process the raw materials, ways that preserve more of the character of the grapes. In the early days of kit manufacturing, typical concentrates were made in vastly different ways than they are now. Time has improved the technology to the point where concentrates and juices are no longer caramelized during concentration or pasteurization, and a better understanding of oxidative processes has given us juices which are fresh and maintain varietal character. There are many exciting new avenues of research and they include the following:
• Cone technology: A way of processing fresh juices that preserves all of the aromatics.
• Essence recovery: Special fractional distillation units recover all of the aromatic compounds normally lost to the air.
• High-solid concentrates: By including more fruit pulp, pips and inner stem material, more of the varietal quality of the grape can be expressed in the finished wine.
• Selective skin components: Derived from red grape skins, these specially prepared components not only increase any specific varietal character, they also provide stable sources of tannin for the wine.
Warming Up to Ferment – Maintaining Fermentation Temperatures
Temperature control for kit winemaking is important, but it’s one of those things that never gets the attention it deserves. The bottom line is that most people make their kit wines too cold — far too cold — which leads to a large number of immediate concerns and downstream processing problems for the kit.
So why do they do it? There’s lots of blame to go around: partly it’s a misunderstanding of how wine kits perform best, partly it’s marketing pieces that trumpet the benefits of “cold-fermented in stainless steel” and finally it’s because some people won’t read or obey instructions — hah, bet you wondered when I’d get around to blaming the customer!
While it’s true that some white wines benefit from cool fermentation, that’s a very small percentage of wines that are made. The idea behind keeping it cool is that the very most delicate and volatile aromas, which contribute that top 1% of the aromatic nose of a wine, can be blown off of a fermentation that is too warm. But this only applies to grapes that have been picked cold, transported cold, crushed cold and kept cold at every single step of the way. Let the temperature warm up for even a short time and those low-weight molecular compounds are simply gone.
Consider a wine kit for a moment. The fruit is picked cold, of course. Pressed cold, sure — nobody heats a press or puts it anywhere but in the shade. Also pumped, transported and blended cold, as this keeps down spoilage at every step of the way. But at some point, the juice is going to go through a pasteurizer and hit 160 °F (75 °C) before being cooled back down for packaging. You can see where this breaks down the whole cold-all-the-time ideal.
With that negation of the low-weight molecular compounds, not only are there no benefits to cool fermentation, there are a lot of potential problems. Kits that are too cold at yeast pitching time have a very slow onset of fermentation. This is because the dried yeast pitched into the must has to soak up some liquid and soften up before it can go to work. This allows the yeast’s integument (outer skin) freer passage of nutrients and sugar in, while waste products, like alcohol and carbon dioxide, out.
Think of the integument like a complex balloon of layered fatty-acid esters. It more-or-less resembles a bubble of grease with the living machinery of the cell inside. Soak your bacon platter in cold water and I don’t care how much dishwashing liquid you use, your dishes will still be coated in a solid greasy layer. But switch to warm water, and the grease will soften and slough off. Same deal with yeast cells. A warmer must equals a softer outer integument.
There are some folks who like to re-hydrate their yeast before use. Theoretically this has benefits — only, however, if you do it exactly according to the instructions, and use water at 100 °F (~40 °C). This really softens up the yeast. The drawback is that you have to acclimate the yeast to the must temperature. If you pitch 100 °F (~40 °C) yeast slurry into 65 °F (18 °C) must, the temperature sheer will kill most of the yeast immediately. And then the yeast metabolism will slow right down, due to the chilly conditions. Dry pitching is fast, safe and easy.
Getting a quick start and breeding as rapidly as possible has many benefits, not least of which is the greedy-jerk factor: by rapidly breeding, the yeast tie up all the nutrients and resources necessary to complete cell-wall synthesis and new cell production. This form of competitive exclusion ensures that other organisms, which could invade the wine and ruin it, are left without a food source. Warm, happy yeast are kind of like those really big guys ahead of you in the buffet line. You can pretty much kiss that plate of shrimp goodbye!
Another effect of increased speed of onset of fermentation is that the sooner the yeast start producing ethanol, the sooner the wine is protected by the sanitizing power of that alcohol, and a fast onset can ensure a thorough fermentation that doesn’t leave any sugars or nutrients for other wine-spoiling organisms.
Giving you gas
Low temperature fermentations run a risk of slowing or stopping altogether. Yeast is a living organism. When cold, it metabolizes much more slowly. Keep yeast too cool for too long and they can go dormant or even die, leaving a wine with residual sugar and a stuck fermentation.
Plus, colder fermentation temperatures contribute to the retention of carbon dioxide (CO2) gas in solution. As the yeast metabolize the sugar, they don’t just produce alcohol, they also make a lot of carbon dioxide. But they let it go in extremely small amounts at a time, and certainly not in a bubble big enough to see. In fact, that bubble in your airlock is the combined effort of tens of millions of yeast cells. It’s not until the wine is totally saturated with microscopic bubbles of CO2 that it begins to fizz out of solution.
And one quirk of CO2 saturation is that the colder a liquid solution is, the more gas it will hold. Think of two cans of soda, one buried in ice, the other in the back window of your car on a sunny day. Open both and the cold one barely hisses, but is powerfully fizzy when you take a slug. The hot soda foams madly when you open it, but it’s very nearly flat when you taste it.
This has a lot of downstream implications for clearing and flavor development. Gassy wines are difficult to clear, as the finings keep getting lofted back into suspension by CO2 bubbles. They are also often stinky because the CO2 also brings along fellow travellers, like a whiff of H2S (hydrogen sulphide, that rotten-egg smell). All fermentations produce a little H2S, but it’s normally blown off in the course of a warm, vigorous fermentation, and it easily gets trapped with the CO2. Pyew!
And it’s more difficult to stir a cold wine to degas as required by most kit instructions. You can stir a cold wine all day long and still harvest more gas bubbles, and you’ll still wind up with a little fizz when you go to bottle. Warm it up to an appropriate temperature and the living (and stirring and degassing) will be easy.
A number of astute readers — and by definition, if you’re reading this column you are very astute, probably good looking to boot — are going to ask, “If cold fermentations are so heinous, how do commercial wineries get away with it?” They get away with it because they’re making tens of thousands of gallons of wine at a time, and can wait until the wine finishes on its own time. And a lot of time is what it can take with some cold fermentations, taking months simply to finish before any additional processing (stabilizing and fining) can be attempted.
Also, as I mentioned earlier, there aren’t that many extremely cold fermentations. Many red wines are allowed to rise up to 90 °F (32 °C) in order to extract more color and tannin from the skins and warm fermentations are necessary to a variety of styles of both red and white wines.
Now that we’re agreed that warmer is better, the first step for making sure you’ve got the right temperature is to get a thermometer. Most winemaking equipment kits include a food-grade floating thermometer in the standard box. These work fine, but are a little bit pokey, and being made of glass they are fragile. There are a variety of instant-read thermometers available for kitchen use that can be adapted, as long as the probe portion of the thermometer reaches far enough into the must. I have to confess that a deeply held gadget lust guided my purchase of the ultimate winemaking thermometer: my digital infrared thermometer. It’s one of those gadgets so much better, so profoundly improved over regular technology that it changes everything. It reads almost instantly, is incredibly accurate, and lets you survey multiple carboys in seconds. You can tell right away if your must is warm enough for pitching, or if you need to work on temperature regulating your fermenting area.
The one I use is the Reed ST-882. I got it for less than a hundred bucks from a lab supply company and it’s good from -58 to 1000 °F (-50 to 538 °C). It’s so incredibly useful that I tote it around and find things to point it at in my spare time. Is that sugar syrup ready for peanut brittle? I can tell from the house next door! It even has an aiming laser that allows you to precisely focus on your intended target. You may not wish to shell out that kind of dough for a gadget, but whatever sort of thermometer you wind up with, the most important thing is that it gets used regularly.
Getting it right
What’s an appropriate temperature? The top of the range mentioned in your wine kit instruction set. Typically they list a range such as 65–75 °F (18–24 °C), so you want to shoot for 75 °F (24 °C) from pitching day to bottling day, to ensure you can get your kit finished in the correct time frame and properly clarified and degassed. The most crucial part of this will be the temperature of the must before you pitch the yeast. If it’s not warm enough, you’ll need to get it up to temperature before the rubber (yeast) hits the road (fermenter).
If you’ve already made the kit up and it’s too cold, the most important thing is to avoid adding the yeast until you get the temperature up to the right level. By far the quickest way to do this is to immerse the fermenter in a washtub or bathtub full of warm water, and monitor the temperature, stirring gently until it comes into range. It’s important not to leave the water running while you’re out of sight of the bucket: not only could it overflow, even worse the bucket could tip over in the rising water and you’ll have a Cabernet and soap scum blend!
If you can’t lift the primary fermenter into a tub you can put it in the warmest spot in the house and use a warming strategy: an electric blanket, a place by the fire or a small space heater gently directed at it. All of these things will work well, but have some risk: never, ever put the fermenter on top of an electrically heated pad or blanket. This can cause dangerous shorts, hot spots and even fires. Also, don’t leave it unattended by a fireplace or with a heater pointed at it — it could get too hot and the must could boil or the fermenter could even melt.
It helps to think of your wine as a helpless baby. You wouldn’t leave any living thing unattended wrapped in an electric blanket, so don’t do it to your poor yeast! Keep stirring to distribute the heat and keep checking the temperature on a regular schedule to make sure it doesn’t overheat. If your fermenter does overheat from inattention, then you have to make an effort to cool it.
If you’re making up your kit and want to make sure it’s warm enough, the simplest strategy is to get part of your water additions from the hot water tap in your sink. This assumes that you’re using your own tap water to make up kits, a practice I normally recommend (read more about water in WineMaker’s February-March, 2008 “Wine Kits” column). It takes a bit of fiddling, stirring and temperature monitoring, but it does ensure instant temperature gratification.
If you’re using bottled or spring water you can heat up a portion of it to make up the must. Don’t heat it up to boiling — too much chance of overheating or even potentially cooking a portion of the must when you add it. Instead, blend a gallon (3.8 L) of boiling water with a gallon (3.8 L) of cool water and slowly add it to the must, stirring and checking the temperature as you go. It sounds a bit tedious on paper, but it goes quickly and easily in your winemaking area.
What to do once you’re there
Maintaining the temperature of the fermentation is easier than you might think. Even in the small volumes of a 5-gallon (19-L) fermentation vessel, the metabolizing yeast create enough of their own heat to buffer against a slight chill. As long as the fermenter is in a reasonably warm place, within a couple of degrees of your target temperature, it should get along just fine.
What about a cool house? With increasing energy costs, very few people leave their homes at 70 °F (21 °C) during the day while they’re out — except perhaps those folks living in the scorching South who are cooling it to that level! But this article is about coming in from the cold, not retreating from the heat. If you do turn down the thermostat in the morning, you’ll need a strategy to keep your wine from icing over.
First, find the warmest room in your home. A handy tool for this is a min-max thermometer, commonly sold at gardening stores and home centers. As the name suggests, it records the highest and lowest temperature of the sampling period. Put it in the room, come back in 24 hours, check it and reset it and you have your answer. With my min-max I found out that my pantry, next door to the hot water heater, stays at 75 °F (24 °C) year-round, making it a perfect place to dry herbs or ferment wine. Who needs a pantry anyway?
If you’re lucky enough to have zone-control over your house heat you can forget the min-max testing, arbitrarily pick a space and adapt it. If not, then there are very small fan-driven ceramic heating units available for less than $40. The elements in them never get hot enough to start a fire; they’re thermostatically controlled and use minimal amounts of electricity. They can keep a small room comfortably warm for very little cost. Just make sure to monitor your fermentation regularly until you’re certain that the temperature is stable and the room is neither too hot nor too cold for your wine.
If it’s only a single carboy and you don’t want to heat the whole room, or if you don’t mind spending money on even more gadgets, then you may wish to invest in the available fermentation temperature control devices. The simplest and least expensive of these is the Brew Belt. Looking like a blue plastic men’s belt — ah, the sartorial splendor of the 1970’s never dies — it slides around the carboy and plugs into the wall socket, maintaining a steady 70–72 °F (21–22 °C). While the manufacturer does not recommend using it with glass carboys, it works fine with all sorts of plastic. I’ve got a half-dozen in my winemaking drawer and wouldn’t leave home without them.
A bit fancier (and useful for glass carboys) is the FermWrap Heater, which looks like a sheet of MACtac with a power cord. It is safe for use on glass carboys, but you’ll have to figure out how to judge the temperature you can maintain with it through trial and error — or not; there is an optional kit to go with it that includes a temperature probe and a digital controller that lets you dial in the desired temperature and then puts a computer in charge of maintaining it.
Now if only those FermWrap characters were working on my jet pack and my moon holiday! In the meantime, the most important thing is not to worry: a little thermometer work and a little warm water will take care of most of the temperature adjustments your wine will need.
There’s A Fungus Among Us -Yeast Selection
It’s an integral part of every fermentation, it can’t be seen with the naked eye. Without it, you’d be drinking sweet grape juice, and yet for the average winemaker, it’s more mysterious than any other aspect of their hobby. In fact, although it’s part of every drop of wine made, until the mid-1800’s nobody knew it existed! The mysterious ingredient: your yeast. This article will discuss the nitty and gritty of kit-yeastiness, based on a half-dozen questions that I am constantly asked.
•How do you choose the yeast in the kit?
•Can I swap the supplied yeast for a strain I like better?
•What about those liquid yeasts?
•Should I rehydrate like the yeast manufacturer wants, or just sprinkle like the kit manufacturer says?
•Can I lower the temperature to get better fruitiness from the kit yeast, or can I raise temperature as I’ve heard that helps red wine fermentations?
•Can I stop the yeast at the end of fermentation and get a sweeter wine, as some commercial wineries do?
1. How We Choose Yeast
Kit manufacturers use a whole slate of criteria when they choose the yeast for their wine kits. First, they (loosely) follow the yeast company’s recommendations. Second, they run many yeast trials on every kit they develop to ensure that the yeast strains can meet the following conditions during and after fermentation:
Quick fermentation — most kits are designed to be bottled between four and eight weeks after yeast pitching. If the yeast is poky, carboy turnover will be too slow.
Thorough fermentation — unfinished (sweet) table wines or wines that referment in the bottle are major concerns for beginning winemakers.
Flocculation — the ability of the yeast to settle out after fermentation.
Low foaming — too much foam can overwhelm primary fermenters, fouling fermentation locks and spilling wine.
Yeast health — the ability of the yeast strain to cope with pasteurized juice and concentrate.
The last one is crucial. All kit wines have to go through pasteurization — that is, they get heated to around 160 °F (71 ºC) for approximately one minute and then cooled very rapidly, before the heat can burn, brown or caramelize them. While careful HTST (high temperature, short time) treatment ensures minimal impact on flavor and aroma, some of the sugars bond to other compounds in the juice during pasteurization, making them much more difficult for the yeast to consume.
So, once the speed, thoroughness and ability to correctly ferment pasteurized juice are taken care of, manufacturers do a number of trials to choose which yeast is going to yield the best flavor and aroma characteristics for a kit. Over years of experience — including ongoing trials for new strains — the field of appropriate yeast for kit wines has been narrowed to only five or six dozen. While this number represents a lot of potential choices for the kit winemaker, it’s pretty small compared to the hundreds of different yeast strains that are available to folks who make their wine from grapes.
Once the obvious dogs are weeded out, the wines go to tasting panels, to determine which one best expresses the varietal character of the wine and the terroir of the grapes, both when the wine is very young (less than two months old) and as it ages longer.
2. Swapping Yeast
From the above, it’s obvious that kits don’t react in a straightforward fashion to normal grape winemaking manipulations. A yeast strain that might guarantee a wonderful expression of varietal character in a grape wine may not deliver in a kit. However, you can safely experiment with your kits if you wish: there’s no guarantee that you’ll dislike the results of a change in yeast, and in fact you may be pleased. How will it turn out? Neither I, nor any of the other manufacturers, will know unless we’ve run the particular fermentation trial ourselves. Which of course takes us back to square one: if we have run the trial, and you don’t see your favorite yeast in your kit box, then we’ve chosen a different one on purpose. However, that’s just our taste. I’ve said this before: The great thing about making wine is making exactly the wine you want.
But, if you’re just thinking of dipping your toe in the yeasty water, then you might consider running a trial yourself. You could split your kit into two 3.0-gallon (11-L) batches and ferment one with the original yeast, and the other with the alternate you’ve chosen. You’ll need some extra equipment and careful measuring to split the finings and stabilizers that came with the kit.
While this does entail the cost of another primary fermenter and a couple of 3-gallon (11-L) carboys, it has some advantages: If your experiment doesn’t yield optimum results, you can blend the two together and salvage a drinkable wine. If it fails completely, you’ve got half a batch to console yourself.
3. Liquid Yeast: Straining Yourself
Liquid wine yeast is becoming more and more popular. Originally, liquid yeast strains were championed by homebrewers of beer. They have an advantage over dried strains in that it’s possible to make quite pure cultures of liquid yeast (i.e. monocultures), where dried yeast will always have a certain (small) percentage of non strain-specific yeast in the mix.
While dried strains are not strictly speaking monocultures, they have a genetic advantage — the K-factor. It’s a bit complicated, but it boils down to this: Most wine yeast strains don’t like competing for their dinner (sugar). They have a number of survival strategies for edging out potential competitors, like speed of breeding, acid tolerance and alcohol tolerance, but K-factor is the coolest. It is their ability to secrete a tiny little protein that actually kills their competitors.
This puts an entirely new spin on the term “germ warfare.” While you innocently listen to the joyful bubbling of your airlock, your yeast is in the trenches, stalking the enemy, rubbing him out, and stealing his lunch. By the way, you can’t react to this protein — unless you happen to be a yeast cell reading this, you’re perfectly safe from any K-factor protein.
The liquid yeast manufacturers are graciously working with the kit companies at this time to see which kits respond to the liquid yeast best, but so far no kit manufacturer has released the results of any trial — it’s a bit early, but enthusiasts can rest assured, we’re looking into it very closely. In the meantime, if you want to conduct your own liquid yeast trials you can either split your batch as described earlier, or go whole hog, as suits you. Be sure to follow the specific yeast manufacturer’s instructions.
4. Rehydrating Yeast
If you look at the instructions in your wine kit, they will likely instruct you to sprinkle your packet of yeast directly on to the must. Yet, if you read the yeast package (and many winemaking textbooks), they recommend rehydrating the yeast. If the objective is to deliver the maximum number of yeast cells to the must, which technique is best?
It turns out that the answer is not as simple as choosing between one or the other. When performed correctly, rehydrating gives the highest live cell counts and the quickest, most thorough fermentation. The catch is that it has to be done precisely. The Lalvin yeast folks for instance, ask you to add the yeast to 10 times its weight in water at 104–109 ˚F (40–43 ˚C).
Breaking it down, first it’s important to use the correct amount of water at the correct temperature. Using juice from your must isn’t recommended, and who can tell how much 10 times 5 grams of water is? Anybody? (Okay, it’s 50 milliliters (mL), or about one-fifth of a cup.)
Second, the temperature range is inflexible. The outer integument of a yeast cell is made up of two layers of fatty acids. These layers soften best in warm water, much as greasy film will come off of dishes best in warm water as opposed to cold. Once it has softened up, it will allow the passage of nutrients and waste products in and out of the cell much more efficiently. If the water isn’t warm enough, the cell won’t soften. If the water is too warm—generally anywhere above 126 ˚F (52 ˚C) — the yeast cells will cook and die.
Third, you have to worry about temperature shear. Yeast is terrifically sensitive to environmental conditions. If it goes too quickly from a favorable temperature to a less favorable one, weakened cells may die and others may go dormant, in an attempt to ride out the temperature shift. This reduces the number of live, viable cells available to ferment the must, and gives spoilage organisms a chance to get a foothold, potentially ruining your wine. So if you are rehydrating your yeast, you’ll have to wait as the yeast cools to within two degrees of your must temperature before adding it: accuracy counts!
On the other hand, simply dumping the yeast onto the top of the must should result in lower cell counts. Empirical evidence shows this isn’t the case: the yeast seem to know what they’re doing. Generally, a five-gram packet of yeast will have less than a six-hour lag phase on an average wine kit. This is perfectly acceptable and isn’t long enough to allow spoilage organisms to get a foothold in your wine. Plus, it’s a heck of a lot simpler than going through the rehydrating process, fraught as it is with risks.
You can rehydrate your yeast if you absolutely want to, but be sure to do it accurately and precisely. The rest of us will tear open the package and dump it in — spending the extra time sampling our last batch!
5. Controlling Your Temperature
Temperature should be maintained at the prescribed 68–78 °F (18–24 °C) for the majority of kit wines, with the majority of yeast included. Because the fermentation schedule is so short (i.e., under two months) cooler temperatures will extend fermentation times and throw off fining and stabilizing schedules, increasing the difficulty of clearing and stabilizing the wine for bottling. The big problem isn’t usually waiting for the gravity to drop, as most yeast will continue to ferment at a moderate pace with lower temperatures and should add less than a week total to your fermentation. The problem usually lies with CO2 saturation.
Think of it this way: carbon dioxide gas, or CO2 is soluble in a liquid solution in inverse proportion to the temperature of that solution. Put another way, colder wine is fizzier wine. If you’ve kept your fermentation cool until the yeast is finished, you’ll have a wine saturated with CO2 gas. You’ll need to completely de-gas at fining and stabilizing, both to ensure that the wine clears effectively and to eliminate trapped fermentation odors before going to the bottle.
On the other hand raising the fermentation temperature causes simple fruity qualities to become suppressed while the more complex, “winey” characters are enhanced. I’d have to say that this is most likely not going to yield good results in kit wine. The kit has already been through a process of thermalization (being pasteurized) and many of the processes attempt to retain as much fruitiness and varietal character as possible.
6. Halt! Yeast Police!
Most kit wines intended to be finished as sweet wines are first fermented more or less completely dry and then sweetened post-fermentation.
Commercial wines on the other hand, sometimes have the fermentation halted before it is completed, allowing the remaining sugar in the must to provide the sweetness. Could this be something you can do at home with your kit wine?
In one sense, yes — this is something you can do with your kit. In another, altogether more accurate and correct sense, no — it’s an advanced winemaking technique that could quite literally blow up in your face.
In order to get yeast to quit fermenting you’ll most likely need to stun them with preservatives (sulfite), fine them out of suspension, sterile filter them out of solution and then use a growth suppressant (sorbate). It’s a lot simpler to wait for the fermentation to complete, and then to back-sweeten your kit.
Water In Wine Kits
Wine kits require the addition of some water, to reconstitute the kits to their full 6–gallon (23–L) size. Since the retail water industry has made a big deal about the quality of water in North America, many people assume they need some kind of specially treated water to add to their kits.
This chapter is going to go into a little bit of the chemistry of water. Very little: I’m not a trained chemist and the deeper complexities of the subject actually make me want to cry and hide my head. As a matter of record, I was miserably failing chemistry in school until I got Ted Harp for a teacher. While none of the simplified (and possibly errant) chemistry that follows is his fault, he was an inspiring teacher who convinced me stick to it and learn all about what made things fizz, corrode or go “boom” in a satisfying fashion — thanks Mr. H!
But I first have to say that I’m not a fan of processed or bottled water. I personally do not use any bottled water if I can avoid it. My reasons are several:
• I hate paying for something that’s readily available for free.
• Plastic water bottles are made from oil. These days, oil is a big deal.
• Bottles have to be transported from somewhere. More oil.
• Nobody can prove bottled water is better than decent municipal tap water.
In a blind tasting, Decanter magazine judged 24 different waters and the majority of tasters preferred tap water that had been fetched from a drinking fountain outside the testing room. The panel was made up of sommeliers and Masters of Wine, and was done blind. It’s pretty telling that local tap water placed third, while $100/liter H2O in a crystal-studded bottle placed nearly last.
My final reason for not liking bottled water has to do with style. Watching people lumber around everywhere with a bottle of water clutched to them, sipping water every few minutes in public, fussing over the right kind of water . . . what the heck happened to us as a society? When did we all simultaneously forget to get a drink before we left the house? I have a sneaking suspicion that water bottles are the new security blanket and that some people feel as long as they drink lots of water every day, at least they’re doing something to improve themselves. Mainly I think they just like to pee a lot.
But enough of my bottled-up cynicism: since kit wines are almost all intended to make 6 US gallons (23 L) and they start off at between two and 4.2 gallons (7.5 to 16 L) depending on the type of kit, they require the addition of two to four gallons (7.5 to 15 L) of water. Since the water was originally removed from the grape juice by some method of distillation (vacuum, spinning cone, reverse osmosis, etc.) it would follow logically that the only thing that should be added back would be a variant of distilled water — as pure as chemically possible. After all, no minerals or trace elements were removed, so water with minerals and such would alter the character of the wine.
This turns out to be one of those things that while technically true, it’s also completely unimportant. It turns out that unless your water tastes or smells absolutely horrible or is contaminated with bacteria or high mineral counts, it’s just fine to use in making up wine kits — really. Before we jump into the specifics of water for use in wine kits, let’s take a brief look at water in general.
Water is an abundant chemical — 71% of the Earth’s surface is water. The human body is composed of roughly 55% water for adult females and 60% water for adult males. Our blood is about 95% water. Most importantly, for our purposes, the percentage of water in most wines ranges from 85 to 91%, depending mostly on their alcoholic strength. Of course, most winemakers who make their wines from grapes do not add water to their wines. The water in their wines comes from the grapes they crushed. (Occasionally, water may be added to bring down the sugar content of high °Brix grapes.) But, for folks who make (non-grape) fruit wines and kit wines, water is a concern.
The chemical formula for water is H2O, meaning water is composed of two hydrogen atoms and one oxygen. If you could visualize a single molecule of water, you would see a relatively large central oxygen atom with two smaller hydrogen atoms attached as if the oxygen atom had sprouted ears. Because the “ears” are not on polar opposite sides of the oxygen, water caries a slight positive charge near the hydrogen atoms and a slight negative charge on the side away from them. It’s this polarity that makes wine such a great solvent. In fact, this polarity is the basis for almost all of the chemistry of living organisms. For a home winemaker, the polarity of water means that this molecule can dissolve most of the flavors, aromas, colors and tannins found in wine grapes. Water also provides an environment that yeast cells are happy in, as long as there are also some sugars and other nutrients available. So, water is abundant, has wonderful properties for sustaining life — both ours and that of yeast cells. But, what do you need to know about it when you make kit wine?
With that basic information stated, let’s address the most common concerns about the water used for making kit wines.
1. Chlorine added to disinfect municipal (city) water is a sterilant. It kills yeast and smells like a pool — icky.
Municipal water treatment is a fascinating topic. No other human endeavor has saved as many lives, or improved the quality of life for the whole planet as proper water treatment has done — something most of us take for granted. The United Nations even declared 2008 the International Year of Sanitation, focusing efforts on providing clean drinking water to those in need.
The process for treating tap water usually involves pumping it into storage tanks, screening out leaves and sticks, adjusting the pH (if it’s too acidic, it can leach metal from pipes) flocculation (actually a fining process, just like that which wine goes through), sedimentation (where the fined goo falls out of suspension), filtration and finally disinfection. All but the last step is pretty straightforward — they’re all processes to ensure that the water is clean and free of turbidity (suspended debris).
Disinfection is what throws people. It’s natural to assume that because you can smell chlorine or chloramines in your water supply (the additive is essentially the same thing as household bleach) that it’s going to affect the wine. What actually happens is this: all juices used in winemaking, be they kits or even fresh grapes, contain sulfite compounds. They’re present on all grapes. When added to a solution containing chloride ions (the form the chlorine takes in water) sulfites bind to the ions instantly, forming stable chloride salts such as potassium chloride (KCl) or sodium chloride (NaCl).
If the last chemical name sounds familiar, that’s because it’s common table salt. If you bind out 100% of the chlorine in municipal tap water with sulfite, you’ll wind up with about two grains of table salt per 6-gallon (23-L) carboy. That teensy amount won’t have much effect, especially when it’s mixed into a wine with a Brix of 25 and a whole lot of acid, sugars, and solid material. So, there are no worries from municipal water treatment.
2. The pH of water varies a lot, so it’s better to add distilled water (with a pH of 7.0) to make sure the pH of the kit isn’t thrown off.
pH is one of those concepts that can be summed up easily in a phrase — the measure of acidity/alkalinity in a liquid solution — but is more difficult to grasp in a concrete way. The number really represents the negative logarithm of the concentration of hydrogen ions (H+) in a liquid solution. In referring to the CRC Handbook of Chemistry and Physics, one can find many pages of explanation about things like activity coefficients of univalent electrolytes in solution, but readers will forgive me if I pretend such things don’t exist. The important bits to remember about pH and wine are:
pH is a numerical scale running from 1 to 14. Right in the middle, 7 is considered neutral, neither acidic nor alkaline: pure water at 77 °F (25 °C) is pH 7.0. Above 7 is alkaline; below 7 is acidic. Because wine contains a lot of acid, it generally has a low-ish pH, somewhere above 3 but below 4. A pH of 3.4 is a pretty sweet spot for most wines. At lower pH levels wine can be sharp-tasting, and at higher ones it oxidizes easily, is subject to more bacterial attacks and doesn’t age well.
In solutions containing other ions (like a kit wine), activity and concentration will not generally be the same. Activity is a measure of the effective concentration of hydrogen ions, rather than the actual concentration; it includes the fact that other ions surrounding hydrogen ions will shield them and affect their ability to participate in chemical reactions. These other ions change the effective amount of hydrogen ion concentration in any process that involves H+.
So it’s not just the amount of acid in the wine kit that affects the pH, it’s a bunch of other junk in solution as well. This is sometimes referred to as buffering. Kit wines tend to be very heavily buffered, partly because they contain very high levels of solid material (usually above 35% before dilution) and partly because the effects of concentration and pasteurization include some bonding of acids and sugars and some release of ions. It’s more frightening chemistry talk, I’m afraid, but trust me, wine kits are ferociously buffered.
And water isn’t. And that’s why the pH of tap water is pretty much inconsequential — there’s almost nothing there to release hydrogen ions. When chemists calculate the pH of a weakly acidic solution, they usually assume that the water does not provide any hydrogen ions. Add the wimpy tap water to highly acidic, heavily buffered kit wine and POWIE! The water will meekly do as it’s told, and get swamped in a tsunami of acids and dissolved solids from the kit.
Of course, this assumes that you have drinkable tap water. If your tap water is either corrosively acidic or comes out in chalky lumps, then sure, it will affect the pH. But then, that’s also not drinkable, now is it?
3. My water is stinky, dreadful tasting, brown and lumpy, has high mineral counts, crawls out of the tap and attacks the cat.
This statement only covers properly treated potable water. Some sources of groundwater have high levels of sulfur compounds, which make it stinky, like rotten eggs. Some surface water has tannins (from plant material, usually leaves in the fall) or other organic material (algae in spring) that can be detected. Sometimes high runoff levels or impacts on water mains will make water turbid (cloudy) with dirt and organic materials. In all of these cases you may want to treat the water through filtration before using it to make wine — if it’s objectionable out of the tap, it’s going to be objectionable in the finished wine. If it’s more convenient for you, you could use bottled water as well.
High mineral counts are also a flag for concern. If you’re on rocky soil and getting groundwater, then you may have high levels of carbonates, magnesium, sodium, sulfates and calcium. Your local government will have water analysis available to all ratepayers so you can have a look at it. A good rule of thumb is that if you see any mineral count over 50 ppm (sulfates can be a little bit higher without worry) you need to talk to your water company about it. If you’re on your own well, you need a laboratory assessment of the water, not only to check the mineral counts, but also to make sure it’s not contaminated with bacteria from ground run-off. Most folks on wells are doing this anyway — it makes good sense.
The one mineral that’s an evildoer of unending awfulness is iron. In any concentration over 10 ppm it will give a fermented product the flavor of rust or copper. Some folks claim it tastes like blood, but I stopped being a vampire after Tom Cruise made it uncool, so I’m not sure of that. If your local water has high iron levels, you definitely need to keep it out of your kit.
As a general rule of thumb, if your water is hard enough to break rocks and smells like it’s been drank once already (like in my ancestral stomping grounds of Southern Saskatchewan) and strangers won’t drink the stuff and complain your coffee tastes funny, that’s a great indication that you might want to choose bottled or filtered water.
There are any number of filter systems out there. Most rely on cartridges to trap or block particulate matter and carbon blocks to remove metals and halomethanes (more chemistry!) and such. They’re pretty efficient and shouldn’t be too expensive. Some more complicated filters include ion-exchange water softeners that remove high levels of minerals. Because all of these softeners use proprietary technology it’s difficult to make a blanket statement about their usefulness. Some of the older models stripped out certain mineral ions but left others in their place. Some newer ones clean up after themselves. If you’re using a water softener, talk to the people who sold it to you and explain that you want to use the water to make up wine. If they get confused with that, tell them it’s a bit like making bread, and you’re worried about how it will affect the flavor.
In the thirty years I’ve been making wine from kits, I’ve never used anything but the water that came from the tap, and never given it a second thought. But I’m lucky enough to live in a rainforest with abundant, perfect water. But if you’re reading this, you’re probably lucky too, with plentiful clean water at your disposal. If it’s good enough to drink, it’s good enough for winemaking. But if you’re unsure go ahead and use bottled or filtered water: it can’t hurt your finished wine and will give you good exercise lugging around water bottles — always good for building up a thirst!
Degassing Your Kit Wines
Your wine finally seems ready. Weeks of fermentation pass, followed by sessions of racking, stirring, testing, bottling and corking. Then comes months of aging . . . until you can barely stand it. But today is like Christmas morning — the day you get to taste your new batch. You pull the cork, but disconcertingly there is a small “pop.” And when you pour yourself the first glass, small bubbles collect around the edges of the crystal. The wine has a sharp taste and an odd flat aroma. You have to face up to certain facts — your wine has gas.
When I talk to home winemakers, either troubleshooting, at lectures or in seminars, the top three questions that consistently come up are always about clearing, stirring and de-gassing. It’s not surprising that the three come up so frequently; they’re all aspects of the same thing. The reason why they come up with kit makers is due to the difference between kit winemaking and commercial winemaking.
Most people assume the difference between kit winemaking and commercial winemaking is due to raw materials, but that isn’t so. Kit wines use the same grapes, juices and concentrates that many large wineries use in their commercial offerings. (Hey, I’d like to be able to claim the smarts for inventing the use of concentrates and juice for winemaking purposes, but like all my good ideas, it was stolen from someone else — in this case the commercial wine industry).
The actual difference between kit winemaking and other types lies in the production schedule. Kits are designed for ease-of-use and sure-fire results from the first time out. This means getting them fermented quickly and in the bottle before they can be spoiled by oxygen, which helps deny spoilage organisms the opportunity to breed and ruin the wine. Wine from kits goes from the box to the fermenter and finally to the bottle in a very short period of time, usually less than eight weeks. Very few commercial wines are bottled this quickly.
This foreshortened production schedule actually doesn’t harm the quality of the finished wine, since fermentation activity is almost always complete within 14 days in any wine (think of Beaujolais Nouveau). However, it does pose complications due to carbon dioxide (CO2) gas.
When any wine (or beer, or cider) is fermented, the yeast consume and metabolize sugars, converting them into alcohol, carbon dioxide gas and a bunch of lesser compounds (esters, ketones, aldehydes, all of which contribute to the flavor and aroma of the finished wine). Flavor is good and everyone likes alcohol, but the carbon dioxide isn’t intended to be a final participant in the wine — unless you’re making Champagne, in which case nothing in this article applies.
Carbon dioxide (CO2) dissolved in wine produces some odd effects. First, it produces carbonic acid when in liquid solution, giving it a sour and unpleasant flavor. Second, it changes the mouthfeel of the wine. If you’re not expecting the prickle of CO2, it can be surprising — imagine, for instance, if your chicken-noodle soup was fizzy: that would be pretty weird! Third, the gas itself seems to trap some of those fermentation aromas generated by the yeast, making the wine seem less fruity than it should be — and perhaps even a little stinky.
Sadly, I witnessed this first hand at an amateur winemaking competition in Colorado. As head judge, I had to taste the tough ones that needed a third judge as arbiter. Too many times I poured a great looking bottle of wine and checked: good color, sparkling clarity and a gorgeous hue. But when I first put my nose into the glass, I got nothing. The wines had slightly sharp character, but without fruit — no varietal identification or much else to go on. The wine had gas!
Then there’s the other issue with dissolved CO2 — clearing. If there’s dissolved carbon dioxide in the wine when you add your fining agents it will bubble and fizz, preventing the finings from doing their job as well as preventing the yeast from settling out, leaving your wine cloudy and undrinkable.
At commercial wineries the finished wine is aged in bulk or in barrels, usually for over a year, giving the CO2 plenty of time to come out of solution. In sealed barrels, the gas escapes even faster, as sealed oak barrels develop negative pressure, actually vacuuming the CO2 out of solution rapidly. Large wineries rarely have to worry about degassing issues.
The Solution? Stir . . .
So what’s a conscientious winemaker to do? That indeed, is a stirring question, ha-ha! Okay, setting aside my penchant for double-entendre, kit wines substitute vigorous stirring for long aging in order to affect degassing.
Kit wines generally contain the direction “stir vigorously” at the fining and stablizing process, somewhere around the three to four week mark. This is a bit ambiguous (usually due to limitations of space in the instructions) but it really means “stir until there is no more CO2 gas dissolved in the wine.”
In order to accomplish this, you need to stir hard — much harder than you will ever stir anything else in your kitchen. It helps to think of it less as “stirring” and more as “agitating.” You really need to beat the wine to show it who’s the boss. The trick is to tear the spoon through the wine, jostling the CO2 and whacking it out of solution.
If you stir hard enough, you can actually get cavitation, which contributes greatly to the degassing process.
cav•i•ta•tion \ kav’ i ta’ shun \ n.
[1. the rapid formation and collapse of vapor pockets in a flowing liquid in regions of very low pressure. 2. such a pocket formed.] — (Webster)
Remember the movie “The Hunt for Red October?” Sean Connery, a Russian submarine commander with a bizarre Scottish lisp, has a problem when the submarine’s propellers spin too suddenly and huge gouts of bubbles come off them, showing up clearly on the sonar of the enemy ships. If you ever wondered where the bubbles came from underwater, it wasn’t actually air or oxygen: it was steam. The propellers moved fast enough to flash the water at the tip of the prop into vapor (this effect is properly called “tip vortex cavitation”), which expanded to form bubbles that subsequently collapsed, hammering the water and triggering the sonar images. In kit wine, this hammering effect also blasts dissolved gases out of solution, including our CO2 gas.
Cavitation Aside: Okay, I can never resist a science trivia aside. By far the coolest thing about cavitation is the fact that it can actually generate light, in a phenomenon called sonoluminescence and when the cavities in a liquid collapse the energy generated can create heat in the range of 20,000 Kelvin! Some scientists contend that there may even be nuclear fusion effects in cavitational collapse. Of course, because all of these things take place in a few billionths of a second, not only can’t you see the light, but the heat and radiation pass so quickly that they have no effect on our perception. But think of it! A little big-bang in a carboy! Whee!
. . . Or, Whip It, Whip It Good!
It can be pretty hard to stir strongly enough to get all of the fizziness out, especially if you have some issues with upper body strength or your grip. Most home-winemaking shops sell drill-mounted stirring whips that can take much of the effort out of the task. There are several models of stirring whip, but they are all essentially a long rod with a hook, a set of paddles on the end that goes into the wine and a shank that fits into a drill. Once the whip is sanitized, it’s easy to use. You secure the shank in the chuck of a 3⁄8-inch drill, stick the business end into your wine and pull the trigger to stir with a lot of vigor. It helps to use a little finesse. Place the head of the stirring whip all the way to the bottom of the vessel and give the drill a one to two-second stir. If the wine is heavily saturated with carbon dioxide and very foamy, this will give you a chance to test the waters without decorating the ceiling with Cabernet — if you charge in full-bore you might get a violent evolution of CO2. When you’re sure it’s safe, proceed with full-speed stirring. Next, read the fining and stabilizing procedures. Wherever they direct you to stir, use the drill in one direction, clockwise or counter-clockwise for 60 seconds. When they require you to make an addition and stir again, change the direction of the drill and go for another 60 seconds, until all the additions are in.
If you have a whip that specifically instructs you not to reverse the stirring direction, obey it. These whips can’t take the counter-rotation and may be damaged by reverse stirring. For such whips, wait a couple of minutes to allow the wine to slow down on its own before moving on to the next stirring procedure.
There are a couple of things to note here. CO2 saturation is a tricky business and depends on two factors. First, CO2 is soluble in a liquid solution in inverse proportion to the temperature of that solution. In other words, colder wine will hold more gas and be harder to stir well enough to get all the fizz out. Keep your wine in the specified temperature range (usually 65–75 °F, 18–24 °C) and you’ll have a much easier time of it.
Second, barometric pressure can play a large role in degassing. This may sound surprising, but if you think about it for a minute, it makes sense: The barometric pressure is a measurement of the weight exerted on everything by the column of air above us. We actually swim around at the bottom of a sea of air sixty miles deep and sometimes the pressure of that air is higher and sometimes lower.
If the pressure is high, as it often is on bright, sunny days and clear nights, the CO2 in your wine will be highly compressed and will want to stay in solution as opposed to coming out as a bubble of gas. On the other hand, if the pressure is low, like on a cloudy, rainy or overcast day, the gas will be able to come out of solution much more rapidly, with less stirring.
Another side-note here: This is where the old-country wisdom of racking your wine on the night of the bright full moon comes from. If there’s a high pressure system — so you can see the moon, naturally — there will be less chance that the CO2 will fizz up and disturb the sediment in the wine being racked. With this knowledge, you can achieve clearer wine through observing the weather!
If all of the stirring and worry about the weather forecast sounds less than fun, there’s another twist to degassing. Some home winemakers swear by vacuum degassing with their wines. Using a device to pump air out of the carboy, they lower the pressure inside, causing the CO2 to rapidly boil out of solution, in only a few minutes, after which the fining agents can be stirred in with much less work and whipping. For details on vacuum degassing see the next page.
Vacuum degassing only works with intact, full glass carboys. Applying a vacuum to a plastic carboy doesn’t work (it just collapses and crumples) and if your carboy is only partly filled, the vacuum inside could cause it to implode, breaking the glass and causing a (potentially dangerous) mess. With the carboy quite full, the liquid inside supports the glass walls, preventing breakage, while the much stronger neck can take the vacuum pressure.
While some folks can afford an electrical vacuum pump, at over $200 they’re not for everyone. Other people have cleverly adapted wine saver vacuum units for this purpose. They consist of a stopper with a one-way valve that fits into the neck of a bottle and a small pump-unit that slips on to the top of the stopper. When you have a partially empty bottle of wine, you slip the stopper into the neck, attach the pump unit and evacuate most of the air from the bottle.
I’m told this will help an unfinished bottle of wine stay fresh for several days. I haven’t been able to check this out personally, as I haven’t experienced an unfinished bottle of wine yet — maybe some day.
Some of these wine saver units will fit right into the neck of a glass carboy, while others require a bit of adapting with a bung or a stopper, but the people who use them often gloat about the great results they get with very little effort.
What If it’s already bottled?
If you’ve gotten to the end of the process, and just like in the introductory paragraph, you’ve wound up with unintentional Champagne, don’t panic: there are a couple of things you can do to help your wine out.
First, you could simply decant it. If you read the article on decanting in the later section on “Storing And Enjoying Your Wine”, then you’ll know that I’m a strong proponent of decanting your kit wine in any case. By opening the wine, pouring it into a decanter and waiting half an hour or so, the CO2 can escape, the wine can breathe and nobody ever has to know about your bubbly little problem.
The other thing, surprisingly, goes back to the vacuum wine saver units. If you haven’t got a suitable decanter, or you can’t wait a half an hour to serve the wine, open the bottle, pour off half a glass of wine, attach the vacuum stopper and pump the gas out of the bottle. You’ll see a rush of bubbles come up to the neck. Then comes the tricky part. Without removing the stopper, give the bottle several really vigorous shakes. This will help the bubbles come out of solution and you’ll see a lot of rapidly evolving foam. Vacuum it again, and this time it should be relatively gas-free and ready to go.
You could leave your kit wine for a year or two in bulk and avoid the complications of stirring to degas, but one of the great things about kit wines is that they can be enjoyed after only a few months. With a bit of vigorous stirring — or maybe a drill, a whip or a good vacuuming — you can avoid any gassy problems and wind up with smooth, ready-to-drink wines sooner than you might think!
The ultimate luxury ride for vacuum degassing is an electric vacuum pump. Costing over $200 a piece, these units are sturdy, fast and powerful, running off 110V wall current. In only moments, they develop vacuum as high as 29 inches (740 mm) of mercury. Pre-fitted with 1⁄4 inch hose barbs, they can be ordered through scientific supply catalogues, from the internet or through a local school/college laboratory. Or, you might get one used.
My own vacuum pump is a vintage model, built in the 1930s by a company called Gomco. It’s a beautiful unit, of crackle-finished lacquered iron and stainless steel, with hand-blown glass vacuum reservoir, leather seals and the weight of an anvil, a real piece of vintage Art-Deco engineering and design. I got it for free when a friend of mine, a mortician, bought himself a new unit. You see, it is intended for pulling the fluids out of corpses. But don’t worry; I rinsed it out before I started using it.
There are a couple of points to keep in mind with electric vacuum pumps. First, wine and electricity don’t mix, so you’ll need to be careful to isolate the unit from contact with liquid, or even significant amounts of wine vapor. To do this, you’ll need a vacuum reservoir. This is simply another sealed vessel used as an intermediate unit between the pump and the carboy. If your pump comes with one, you’re golden. If it doesn’t, they’re not too difficult to make.
You’ll need to use a small, extremely sturdy glass or metal vessel as a reservoir. Just about the all-around best container for this purpose is a 1-gallon (3.8 L) glass jug in good condition. Large enough for liquid spill-over, but small enough to be fairly robust against vacuum pressure, most of them also accept a #6 or #6.5 bung. The key to adapting it is a double-drilled bung. The first hole accepts the hose from the vacuum pump. The second hole gets fitted to another hose, which goes into a single-hole bung that fits into the degassing carboy. The hose running from the degassing carboy to the vacuum reservoir should be pulled right through the hole, until it nearly rests on the bottom of the gallon jug — when it’s all set up, you can see why: flip the switch and the vacuum pump begins removing air from the gallon jug. Naturally, atmosphere from the degassing carboy races through the hose to the area of lower pressure. As the lowered pressure increases in both vessels you’ll see the evolution of gas out of the wine. This will happen very quickly, and often with a lot of foaming and rising wine. If some liquid does get sucked from the degassing carboy it will flow through the hose to the bottom of the reservoir, well away from the second hose leading to the vacuum pump, preventing you from ruining a $200 investment by trying to electrocute your wine.
Some units, such as my vintage Gomco, have vacuum adjustment valves, allowing you to dial-in the amount of vacuum you want. Others simply keep pumping until they hit their maximum limit. Usually, hitting 29 inches (740 mm) of mercury isn’t going to crack a nearly-filled carboy in good condition, but you may wish to dial it back.
You can leave the vacuum on for a few minutes, but most of the action will be over in less than 30 seconds after achieving a good pressure differential: it’s really quite impressive, foaming, bubbling, rushing and gushing and then, poof! It all settles quietly, with no further activity — now that’s good degassing! You can proceed with the rest of your winemaking steps with nary a bubble or a fizz.
Whither Goest the Gas?
A couple of points for the curious: while hard vacuums have some interesting properties, you needn’t worry about most of them when using your home degassing unit. I’m speaking of the fractional volatilization of different substances in the wine. Theoretically, a hard enough vacuum will cause the liquid inside the carboy to boil — even at room temperature. To understand this, think about the instructions for cooking at high altitudes: they sometimes say things along the lines of “boil for an extra ten minutes for every 1,000 feet above sea-level.” This is because under lowered pressure water boils at a lower temperature. The opposite is true as well, of course. Inside pressure cookers things get hot, fast, as water boils at much higher temperatures.
So, will your wine boil? Nope. The vacuum you’ll be able to develop won’t actually be strong enough to boil water at room temperature. But what about alcohol? Alcohol already boils off at a much lower temperature than water, and most people have heard of vacuum stills. Can you de-alcoholize your wine under vacuum? Again, nope — or at least nope in terms that you can measure. While you may lose a few alcohol molecules to the vacuum process, it won’t be enough to affect the actual percentage of alcohol in your wine. Finally, what about sulfite? It can be pulled out of solution by the action of vacuum. In this case, the answer is actually “yep, but.” You can lose one or two parts per million (ppm) of free SO2 to a strong vacuum over a period of hours. However, a couple of parts per million are beneath the ability of most home tests to measure, and not enough to warrant the addition of any extra sulfite to your kit wine.
That’s pretty much all there is to it: if you want a fast, very effective, and permanent solution to your degassing worries — and you aren’t afraid of a little work adapting some non-traditional gear to your home winemaking tools, or perhaps spending a bit of cash on a cool commercial vacuum pump — you can be the first on your block to give up vigorous stirring for languid repose, saving the strength in your arms for hoisting a sample of your latest batch!
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