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Troubleshooting Wine Kits and Instructions, Prevention and Measurements


Troubleshooting, Wine Kits and Instructions, Prevention and Measurements 

If your wine kit suddenly and unexpectedly does something it never has before, or progresses very differently from the way it is supposed to, what has happened to it? And what can you do? Do you have to throw away your entire batch, or is there some way to fix the problem? When you face something like this, do not feel bad, and do not discard the wine. Regardless of how strangely your wine may behave, you are not the first person to experience the problem.

The good news is that the failure rate of kits is very low. 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, the chances are that you will make good wine 99.9% of the time.

However, failures do occur. That is when it is time for troubleshooting. We address the major types of problems (primarily fermentation and visual and odour issues) below, but your first recourse should always be to carefully re-read your kit instructions.

Winexpert kits sometimes have instructions and procedures that contradict accepted techniques for fresh grape winemaking. There are many good reasons for these non-intuitive procedures, but they all boil down to the same thing: our numerous laboratory trials have shown that these methods best produce fermentation, clearing and stabilising. And the number one reason that our Quality Control laboratory sees for kit failure is departure from the steps in the instructions.

Logically, it seems that techniques used for grapes would work best for kits as well, but that turns out not to be the case. Not only does this apply to the difference between the instructions for kits and fresh grapes, but it also applies to instructions between different manufacturers kits. If you are used to one kind of kit, that does not mean you can apply its typical instructions to another. The best way to ensure the greatest incidence of successful kits for the largest number of users is to follow the instructions that come with a particular kit, as carefully and accurately as possible.

Keep two important things in mind. First, you will need a good floating thermometer, a test-jar, and a hydrometer. These are essential for checking temperatures and specific gravity readings under normal circumstances, but you will definitely need them to troubleshoot your wine kit problems.

Secondly, the key to the cure in most cases is prevention. So even after you have fixed a problem with a current kit, the best way to improve your winemaking in the future is to keep good, careful records. Eventually you will be able to diagnose many of your own problems or repeat your successes, and avoid future problems altogether.

Fermentation Problems

Wine Won't Start Fermenting

When yeast is pitched according to kit instructions, you should see activity within 48 hours, or at least see a nice, healthy scum of developing yeast on top of the must. If you do not, the first step is to take a specific gravity (SG) reading. If it shows a drop from the original, you are experiencing 'secret' yeast. For several complex reasons, sometimes yeast like to get quietly to work without much foaming or fizzing. In this case, the immediate solution is to wait and take another SG reading a day later, to confirm the progress of fermentation.

If the gravity has not dropped, double-check that you have actually added the yeast. On the first day, sometimes the multiple activities expected of you (adding the right amount of water at the right temperature, stirring in additives, etc.) can get confusing. If you find your package of yeast sitting inside the box, or think you may have discarded it, add yeast immediately. If you can not find the package that came with the kit, make sure you add an identical strain to the one originally in the kit; it is the only way to be sure that your kit turns out the way it was intended to. Check your gravity for the next three days to make sure that fermentation is proceeding correctly.

If you know you added yeast, and it still is not fermenting, check the temperature of the must. Kit wines are all designed to ferment at room temperature, generally in a range of 18 to 23°C (65 to 75°F). If it is above 40°C (104°F), you may have added too much hot water to the must, and the yeast is likely dead. Cool the must by freezing a couple of bottles of water, sanitising them on the outside, and dropping them into the fermenter. Alternately, you can drape a wet towel or T-shirt around the fermenter and direct the breeze from a fan at it (this technique is great for unexpected heat waves as well). When the temperature is below the recommended maximum in your instructions, go ahead and pitch a fresh package of yeast.

If the temperature of the must is below 18°C (65°F), warm it up by wrapping the fermenter with a heating belt or by other means of direct heat. Do not set it on a heating pad or blanket: this concentrates the heat and can cause electrical damage, or even a fire (not to mention what it would do to the wine). Most of the time, the yeast will recover and begin fermenting on its own within 24 hours, but if not, double-check the temperature of the must, and pitch another package.

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 mouldy (see the sections below on clarity and odour problems), you are probably out of luck. In any case, monitor your fermentation for signs of contamination during the rest of the process.

If you have added the yeast, the temperature is fine, and it is 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 stabilisers to the kit, you may have a terminal problem on your hands.

If you have only added the sulphite, sometimes a very strong yeast starter culture can overcome moderate levels of free sulphur dioxide. Start a package of yeast in a quart of commercial apple juice heated to 24°C (75°F), along with a teaspoon of yeast nutrient. Shake 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. Do not worry about changing the flavour; any change would not be significant, and a small flavour change is less important than getting your must started as soon as possible. If you have added more than 50 parts per million (PPM) of extra sulphite (6 grams/a half-teaspoon per 23 litres/6 US gallons), there are some things you can do to lower the sulphite content. Look in the section on odour problems, below.

Another good restarting techniques is to take a wine from another kit 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. By far the best way to do this is to leave the yeast sediment in the primary fermenter and pour the non-fermenting must in 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 it is added to.

If, rather than adding the sulphite, you have mistakenly 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 have avoided all the above conditions, and your wine still would not ferment, your yeast may have been inactive; a fresh package should get things on the road. Make sure it is the same variety and type of yeast included in the kit, or you may not get exactly the results intended.

One thing that may seem like a good idea, but actually does not work with wine kits, is adding extra yeast nutrient. Winexpert adds very nearly the maximum amount of yeast nutrient a kit can handle. It is 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 will leave a salty-bitter flavor.

Wine Ferments Too Quickly/Slowly

If your wine ferments to dryness in less than half the time required in the instructions, your temperatures may be too high. Try the wet towel trick described above, 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, please wait the minimum amount of days indicated in the instructions before racking to the secondary fermenter. For example, if the instructions say to wait 5 to 7 days, until the gravity is below 1.020, and you achieve 1.020 on the third day, cool the fermentation down to the temperature specified in your instructions and wait until day 5 before racking. 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, while having a large amount of oak chips still in suspension. These can collect in the airlock and block it off, causing pressure to build up, until suddenly the whole thing bursts.

If you do find your wine shooting out of the airlock, you have racked it into the carboy too soon. Rack it back into the primary and wait for it to hit the correct gravity. Do not be fooled if it calms down immediately after racking. All that has happened is that the CO2 has been knocked out of solution by the agitation of racking, but 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. Do not rack the wine on day 7 if the specific gravity is higher than recommended in the instructions. Wait for the appropriate gravity.

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 favourable conditions. You may need to isolate your fermenter in an area with a more steady ambient temperature.

Wine Won't Quit Fermenting

Sometimes a carboy will continue to bubble and bubble, long after it should have stopped. First of all, check your specific gravity. If it is high, give the wine a good stir, make sure the temperature is at the high end of the specified range. Then practice patience yet again.

If the SG is in the right range, as listed in the instructions, you may be experiencing one of two phenomena. First, your 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 quite like active fermentation. This could be exacerbated if your wine fermented quite slowly (as in a cool fermentation), and is saturated with CO2.

How this works with temperature: CO2 is soluble in a liquid solution in inverse proportion to the temperature of the solution. When a can of soda is ice-cold, it barely hisses on opening. When it is hot, it gushes from the can as the trapped CO2 tries to exit as rapidly as possible. If your wine finishes fermenting cool, and then warms up, it may expel the gas quickly enough to mimic active fermentation.

How this works with barometric pressure: The sixty-mile deep layer of air above you presses down and keeps the pressure on you and everything around you at about 15 pounds per square inch at sea level. This pressure of air also squeezes the carbon dioxide in solution in your wine kit. Under high pressure conditions (clear skies, sunny) the CO2 stays in solution. If there is a change in the weather (dropping barometric pressure, cloudy skies or rain) then the pressure lessens, and gas comes out of solution, again mimicking active fermentation.

The other possibility is that the wine is being fermented by an organism that can continue to access nutrients long after the cultured yeast has finished. This could be random bacteria from the environment (most commonly a lactic acid bacteria, like a spontaneous malolactic fermentation) or a mutant or indigenous yeast. In this case, when the wine has hit its target gravity, and the requisite number of days have passed, it is imperative that you proceed with the stabilising and clearing procedures in the instructions. By stabilising in a timely fashion, and at the correct specific gravity, you will prevent organisms from doing any significant damage to the kit.


Wine Won't Clear

First of all, if your wine is cloudy, do not try to bottle it, because it woould not clear in the bottle. In fact, you had have wasted your time, since any extra treatment you do to clear the wine would require you to dump out all the bottles, process the wine, and re-bottle.

Secondly, do not filter the wine to clear it. Filtering is only good for clearing wines that are already almost completely clear. Fining agents still in suspension would quickly block your filter pads, and those that madke it through would simply show up as sediment later on. So this would be another waste of time and money.

Your first step, if your wine has not cleared, should be going back to the instructions and carefully reviewing them to be sure you followed the fining procedures exactly. Winexpert kits want you to add bentonite on the first day, while others want it on the 20th. Some kits must be racked prior to fining, and some must not be racked or the finings would not work at all. But you will notice that the instructions regarding fining all contain the same phrase:

Stir the wine vigorously

Which actually means, really, really, really vigorously. In order for the finings to have the proper effect on the wine, it needs to be free of carbon dioxide. If it is not, the fining particles will attach to the bubbles of CO2 and float back into suspension, over and over again, so that nothing settles out. So stir the wine until it stops fizzing. You may help this process if you warm the wine to the upper end of the specified temperature range; remember that CO2 is soluble in a liquid solution in inverse proportion to the temperature. When the wine is warm, it will be much easier to de-gas.

This leads to the next step: check the specific gravity. If the wine had not finished fermenting before you added the finings, you will have no option but to have to wait until it does. Nothing you do will influence the clarity until the yeast is finished fermenting all available sugars in the juice.

If all of the above suggestions are in order, double-check the instructions regarding temperature. While some fining agents work very well under cool temperatures (bentonite, kieselsol, etc), others (chitosan, isinglass) stop working at all below specified temperatures. Many grape winemaking textbooks advise lowering temperature to help the finings work but make sure this agrees with your instructions before you do cool the must down.

So, if your gravity is correct, and you have stirred the wine sufficiently, and you have got it at the right temperature, the best course of intervention is simply to wait an extra week and see if it clears up on its own. The principle of least intervention applies to all fining activities: try to get the most effect with the least amount of added finings and effort.

However, if weeks of patience do not seem to make a difference, you can probably add an extra dose of finings. Use the same fining agent used in the kit, at a rate of 50% of the original dose. If that turns out not to be an option, the fining agent Sparkalloid is an excellent choice. It is a little complicated to use, but the combination of carageenan proteins and diatomaceous earth makes it a very effective clean-up fining. Use sparingly and follow the package directions precisely.

If you do wind up stirring extra fining agents into the kit, be sure to increase the sulphite levels to match the extra processing and handling. As a rule of thumb, you can add an extra 1.5 grams per kit (one-quarter teaspoon) to offset any oxidation from the handling.

Wine Clears, But Goes Cloudy in the Bottle

If your wine seemed clear in the carboy, but after bottling showed a haze or sediment, you have one of three problems:

Fermentation Not Finished

You can determine if the wine is continuing to ferment in the bottle by taking a sample and checking both the specific gravity and the level of CO2. If the specific gravity is higher than that recommended in your instruction for bottling, and it has a significant amount of CO2, you will need to un-bottle all of it and let it finish fermenting.

This is especially important if your wine is stored inside your house or over a carpet. You could discover that your bottles have become a bunch of miniature wine-volcanoes popping corks and spewing red wine all over your rugs. Or, even worse, you might find that your batch become thirty glass hand grenades ready to shower your room with debris and even do you some bodily damage.

Fermentation Contamination

If the specific gravity is at or below the levels recommended in your instructions, but the wine is fizzy with CO2, and hazy, you may have a microbial infection in the form of a wild yeast or spoilage organism. There are thousands of potential culprits, from lactic acid bacteria (spontaneous malolactic) to acetobacter (vinegar) to air-breathing mutant yeast (candida vini). All will have the same characteristic, the ability to ferment your wine after it has achieved what should be your terminal specific gravity. In this case you will need to un-bottle it all, re-stabilise it with more sulphite, and filter it. It will need to remain in the carboy until you are completely sure it will not ferment again in the bottle.

Protein haze

Protein haze is by far the most common of the three scenarios. Sometimes a fining agent will fail to clear all of the big proteins in a wine kit, or in some cases, traces of a protein-based fining agent (gelatine, isinglass, etc.) will stay in solution. When the temperature of the wine changes, these proteins become visible as a haze. As it warms up again, the haze usually disappears. If you are familiar with beer making, you will recognize this as chill-haze.

Proteins are usually taken care of with the bentonite included in most kits, but if you do have a protein haze, a small addition of bentonite should take care of it. Try adding 15 grams to the kit (about three teaspoons). Follow the bentonite instructions for rehydration, and add to the kit. Wait two weeks and check again for cold stability.

Another solution to this problem is cold filtering. If the wine is mostly clear at room temperature, but it clouds when it is cold, you can chill the entire batch, and while it is still cold, filter the haze out. Note that this will not work if the wine contains significant amounts of solid material or sediment.

Something is Floating in the Wine

Lumps on Top

During the early stages of fermentation, yeast can sometimes clump together and float on top of the must. And occasionally mould can form on top of the wine, showing up as small, papery-looking dots or circles. To discern between yeast and mould, take a sample of the floating material and rub it between your fingers. Yeast smears like yoghurt or sour cream. Mould will roll up like rubbery paper, and would not smear at all, remaining discrete in your grip.

If it is yeast, ignore it. Sometimes yeast simply does float around at the top of the must this way. On the other hand, if it is mould, you need to carefully assess the wine. If the mould came out of the bag when you made the kit, you should carefully document the kit serial number, grab a sample of the mould, and call your sales rep for help. Winexpert warrants all kits against such defects, but do not skip the sample and serial number.

Because of the way the wine is packaged, through a sterile-fill pasteurising head, it theoretically goes into the bags free of organisms. But certain environmental moulds are actually thermophillic, meaning they do not bloom until after they have been heated beyond a certain point. You see this phenomenon in some trees that would not release seeds from their cones until after a forest fire has cleared the underbrush and roasted the cones to fruition.

Similarly, thermophillic organisms can survive the pasteurising process and show up in your wine a few weeks after packaging. But do not panic; the failure rate from this sort of mould is very low indeed. We track this very keenly, so take a sample and contact us with the serial number and sample.

But if you see something floating on your wine after it has been stabilised and fined, it could again be clumped yeast, meaning you had stir harder to release CO2 so the clumps will sink. Or it might be an aerobic organism, like mycoderma or acetobacter (see the sections on films below). It would not be mould in this case, though, because mould can not grow in wine once the alcohol level rises above 3%.

Film On Top Of Wine

Film organisms like mycoderma and acetobacter only grow in aerobic, or oxygen-rich environments. This points back to carboys that were probably not topped up according to instructions, or wines that do not contain sufficient sulphite. Mycoderma is actually a species of yeast (Candida vini) that breathes air. If you detect it soon enough, you can sometimes treat the wine with a measured dose of 50 PPM of sulphite (6 grams, or a half-teaspoon of sulphite powder), followed by racking to get it off of any mycoderma sediment. Top the wine up to the neck of the carboy, use a solid bung, and taste the wine after a week to see if you caught it in time.

You may wish to re-test the wine for sulphite level, and filter it to keep it stable. Then go through all of your equipment and sterilise it by soaking it in a chlorine solution, and scrubbing with plenty of elbow grease. Check all of your other wines, being careful to sanitise your wine thief and sample jars between wines. Mycoderma easily spreads to other wines, and is difficult to get rid of.

Here we should mention something about chlorine sanitising solutions: the most common one is a pink, chlorinated-phosphate detergent that Winexpert sells as Sparkle Brite. Originally a product from the dairy industry, it is also used for sanitising milk-processing equipment. It not only cleans effectively, but also destroys the physical body of a spoilage organism through the action of the chlorine. Mere sulphite or detergent can not accomplish this, and infections like mycoderma or the other ones listed below are serious enough to warrant a take-no-prisoners effort at sanitation. Be careful to follow the package instructions for use, and keep the product out of contact with metals like aluminium (which can produce irritating gases) and stainless steel, which chlorine can pit and etch.

Some people see a film on their wine and think that they have a sherry or flor yeast. This is a type of yeast that behaves as strangely as its cousin mycoderma, utilising oxygen and leaving a film (or flor) on top of the wine. As it works, it can drive the alcohol content of the wine to 20% or higher, and leaves it with a nutty, delicate flavour described as rancio by sherry makers. But it is very unlikely that the film you see is actually flor. It grows under an incredibly narrow range of conditions: temperatures in excess of 38°C/100°F, lots of dissolved oxygen, no sulphite and a huge culture of the proper yeast strain. So you will probably never see it.

Swirly Haze in Wine

Characterised by a milky, cohesive swirl in wine, acetobacter consumes alcohol and leaves you literally with a sour taste in your mouth. It breaks alcohol down into acetic acid and associated ketones, esters and aldehydes, giving wine that distinctive vinegar odour and back-of-the-throat tang, dropping its alcohol content and utterly ruining it forever. It can manifest itself as a swirly-looking ghost in the wine, known as mother of vinegar.

Unfortunately, if this is the problem with your wine, it can not be saved. Nor can you use the vinegar for anything, since the kind of vinegar that wild actobacter makes tastes more like nail-polish remover than salad dressing. Sanitise all of your equipment intensely, all at once, with chlorine-based solutions.

When making a wine kit, the solution to acetobacter is preventive: top up your carboys, make sure the airlocks and bungs are secure and full of water or a sulphite solution, and use the recommended level of sulphite in your kit.

The Culprit

The fruit fly is the primary carrier of acetobacter. But by following several rules of thumb, you can reduce the possibility that this problem will affect your wine. Start by wiping up all spilled wine and juice, treat all your surfaces with sulphite solution, and do not keep bananas in the winemaking room. If you do get a fruit-fly infestation during a warm spell, get some food-grade insecticide. This is based on pyrethrin (derived from chrysanthemum oil) and is sold by food service suppliers and sometimes by hydroponics supply shops. One popular brand is Gard-Mist. It is safe for use in food preparation areas, and it is not very smelly. Read the label before using.

Wine Looks Like Ropey Goo

Another strange phenomenon in wine's appearance is rope, or graisse. The yeast exudes a mucous-like polysaccharide compound and thickens the wine. In extreme cases, you can actually use your finger to scoop out a thick ribbon of wine that looks like rope! This condition, while fascinating, is rare even in the worst winemaking conditions. If somehow you do discover this phenomenon in a wine kit, throw your wine away, discard your equipment and start over. There is simply no cure for this condition.


Kit is Darker/Ligher Than Expected

Wine kit manufacturers are in an odd position: they make a packaged food out of a variable agricultural product. In this respect they are like producers of bread or pasta, who face harvest differences from year to year (e.g. wheat having higher or lower protein content due to local growing conditions). Both of them blend raw materials (wheat, or grapes) from different areas to try to achieve consistent quality.

However when all of the grapes in a kit come from a specific area, as they do in Limited Edition, Vintners Reserve Passport, Selection International or Selection Limited Edition, it may not be possible to completely blend away the colour and flavour differences. Commercial wineries acknowledge this, and celebrate the different harvests by doing vintage tastings. Kits, however, will vary a bit from year to year, and unless the colour change is marked by some other change (such as a loss of aroma or bouquet) you may not want to do anything to change it.

There are colouring products on the market, such as Grapeskin Extract, Oenocyanin, Exberry, etc, which can be used to darken a red wine. If you must use them, follow the package directions, but keep in mind that they are not very stable colours, and could combine with any proteins or melanoidins in the wine and fall out of suspension later on, leaving a deposit in the bottles.

Philosophically, Winexpert is opposed to darkening kit wines with exogenous colouring agents. High-quality kits will have an appropriate color that would not require fiddling, and are as dark as or darker than good commercial examples of the wine. Also, keep in mind that dark colour is not necessarily a sign of high quality. Pinot Noir kits can be a delicate ruby color and still deliver wonderful flavor and quality. Having said that, it could happen that a kit is mislabelled, and if you get a white wine out of a box clearly labelled as red, you need to contact your retailer immediately.

It hardly ever happens that a kit is darker than expected, but if it is, double check with your retailer to make sure you got what you were asking for. If it is the correct style, but still seems too dark, you may wish to blend it away into a lighter wine.

Pink Wine is Orange

Blush wines are actually quite difficult to produce, and commercial wineries have spent literally millions of dollars trying to figure out how to keep the color in their blush. The kind of color compounds that give a blush or a white Zinfandel (or Merlot) its lovely pink color are very unstable. They lose their purple-pink hue over time and change to a reddish-brick pink. The French call this color l oeil de Perdrix (eye of the partridge) and it almost looks like the color of salmon flesh. This change is not a sign that the wine is oxidising or spoiling, merely that the colours are going through their natural evolution. Red wines do the same thing, but they have much higher levels of color, and more importantly they have higher levels of tannin and polyphenolic compounds which stabilise the color. Again, unless this color is accompanied by definite off aromas and flavors, it is not a sign of low quality.

White Wine is Brown, Red Wine is Brick-Colored

While well-aged examples of white wine can be deep golden, or Icewine a gorgeous amber, or sherry a lovely tawny-toast colour, brown wine is usually a sign of advanced oxidation, and is usually accompanied by a sherry-like smell due to acetaldehyde production. When terminally advanced, this sherry smell goes from acetaldehyde to acetic acid to ethyl acetate, the vinegar and nail polish remover aromas described below.

The best treatment is prevention, so follow your kit instructions for racking, topping and sulphite use. Severe oxidation is always preventable.

But if you get caught out, in early stages you can treat the wine first with a strong dose of sulphite (50 PPM), and then with a compound that removes oxidised melanoidins (colour compounds). The best of these is Polyclar (food grade Polyvinylpolypyrrolidone or PVPP, a type of powdered nylon). Use according to package instructions, usually stirring in 1 to 2 grams per litre (one to two ounces of powder per kit). This amount may seem high to people who have used Polyclar for grape or fresh juice wines, but experience with kit wines has shown they take significantly more treatment to remove oxidised compounds. Polyclar requires repeated stirring over a period of hours, as it is only effective when in contact with the wine, and it settles out rapidly. After stirring and settling, filter the wine and adjust your sulphite to 50 PPM again.

Polyclar can diminish aroma compounds (sometimes it is used for this very purpose, to remove an undesirable aroma) and can completely de-aromatise a wine, so you may wish to do a trial on a small sample of your oxidised wine to determine if it is actually an improvement.

Polyclar can also indiscriminately remove polyphenolic compounds (tannins) and desirable melanoidins. For this reason it is much more damaging to red wines, and a dose can strip a bricky-red wine to salmon-y pink, and remove enough of the tannins to leave it flabby and soft. But a small trial will tell you if it can help the wine without stripping it too much.

It is possible to re-correct the colour and flavour of a Polyclar stripped red wine with the addition of oenocyanin (grapeskin extract, etc.) and tannin, but wines treated this way always have an unsatisfactory manipulated taste, and rarely age well.

Odour Problems

Deficiencies in aroma or faults come in the following varieties in wine kits:

Wine Smells Like Matches

Your wine may have too much sulphite, which is characterised by a 'burnt match' or 'sulphur/volcano' smell, often accompanied by a tickling in the nose. However, the true level of sulphite ca not really be determined without a proper sulphite test. Until you have had your wine accurately tested, do not attempt any correction of the sulphite level.

Minor excesses of sulphite (an extra 10 or 25 PPM) can be driven off by stirring small amounts of oxygen into the wine, effectively oxidising the free sulphite into bound sulphite, taking it out of action. You can stir air into the wine with a spoon, rack it with plenty of splashing, or bubble air into it with a brand-new, sanitised fish tank aerator for a short period of time. As always with such operations, test, adjust and test again to make sure you accomplished your goal.

Larger amounts of sulphite (up to an extra 50 to 100 PPM) can sometimes be treated with hydrogen peroxide addition. Hydrogen peroxide is a very potent oxidiser. In high concentration, it is used as part of the fuel mixture in rocket engines, oxidising the fuel so rapidly as to resemble an explosion. It does the same thing in wine, oxidising the sulphite, taking it out of action.

For every 10 PPM of sulphite to be removed in 23 litres (6 gallons) of wine, add 4.2 ml of regular drug-store hydrogen peroxide. You must use a brand-new bottle of 3% USP-grade hydrogen peroxide, measure with a syringe to get accurate results, and above all, test before and after your adjustment, to make sure you have hit your precise target.

The big problem with using hydrogen peroxide is that it is very touchy. If your calculations are off by even a few drops, you will not only reduce the sulphite but will also strip its protective power from the wine and oxidise it beyond redemption. If this does happen, your only recourse is to discard the wine.

In the case of massive overdoses of sulphite (in excess of 100 PPM) there is no answer. Hydrogen peroxide does not make the sulphite disappear, but simply shifts it into another form, and too high a concentration of the bound form is not acceptable for human consumption.

Wine Smells like Chemicals or Plastic


If you introduced any of your cleaning chemicals (chlorine, detergent, caustics, free halogen sanitisers such as Iodophor) into the wine, you should discard it immediately. While small amounts of these products may or may not be harmful to your health, there is no way to be sure, and you are better safe than hospitalised.

Equipment Taint

If you tried to ferment your wine in a non food-grade fermenter, you may have a real problem on your hands. In addition to causing odd plastic aromas in the wine, non food-grade buckets and pails use volatile chemicals and sometimes heavy metals such as antinomy, arsenic and lead, to keep the plastic pliable and soft. They may also contain UV blockers that are toxic. The alcohol in the wine will leach these out, and could seriously jeopardise your health. Discard the wine and purchase some good food-grade wine-specific equipment.

Wine Smells Like Sherry or Nuts

These smells mean that your wine is oxidised. See the treatment recommendations for browned wines in the section, above, on Color problems.

Wine Smells Like Rotten Eggs

Most yeast produces a small amount of hydrogen sulphide (H2S) during fermentation, giving off a whiff of rotten-egg smell. Certain yeast are famous for producing large amounts of this aroma, the Montrachet strain being particularly bad. However, an excess of H2S is usually a symptom of low nutrients in the must, or too high a level of solid grape material. Since these conditions do not apply to wine kits, this problem is pretty rare.

However, if you do experience the problem, it can sometimes be cured by aeration, like the treatment, above, for small amounts of excess sulphite. This will drive the aroma off. If the smell is worse than a whiff, though, the fix could be to treat the wine with copper, either in the form of metallic copper (a handful of sanitised pennies tossed in the carboy) or with a product called Cufex, which is a copper sulphate compound. But the problem with this is that even in small amounts, copper is toxic to humans, and the treatment requires laboratory testing and measurements for safety.

However, there is a brand-new treatment available that is both easy and safe. It is a product called Bocksin, which is made by the German firm ERBSLÖH GEISENHEIM. Related to the fining agent silicon dioxide (kieselsol), this product is stirred into the wine in the amount of 30 ml per 23 litres (6 gallons). It immediately bonds to the hydrogen sulphide and removes the aroma. Because it is formulated like silicon dioxide, it acts like a fining agent, bonding to proteins in the wine, settling out and leaving sediment. It may be necessary to rack and/or filter the wine after using Bocksin.

However, there may come a point where the hydrogen sulphide will chemically change to another compound called mercaptan. This is the same compound that is added to propane and natural gas to give it the distinct skunk aroma that alerts people to gas leaks. Once it has settled into a wine, there is no treatment.

Wine Smells Like Yeast or Bread

Actively fermenting wine will have a faint yeast smell, but if the wine in the carboy takes on a heavy smell like bread, or in some cases soda crackers or even brewer's yeast, you may be smelling the beginnings of autolysis.

Autolysis is the physical action of inactive yeast cells disintegrating and releasing their internal contents into the wine. Essentially, the dead yeast rots and decomposes. Because the material they release is rich in amino acids, it has a distinctive odour. The good news is that autolysis takes many months to occur at room temperature, and even longer at cool temperatures, and in any case only happens in the presence of a visible sediment of yeast.

If you follow the instructions in the kit with regards to racking, fining and stabilising, you should never see autolysis in any of your wines. But if you miss racking a kit for an extended period of time, your wine may be vulnerable. If you catch it at the first sign, quick racking and sulphiting can prevent the autolysis from overwhelming the wine, but if it has already progressed to the point where it can be strongly detected as a brewer's yeast smell, there is no cure. In addition, because of all the amino acids in suspension, the wine will be far more susceptible to infection by spoilage organisms.

Vinegar Smell

Your wine is infected with acetobacter. See the bad news in the Color and Clarity section, above.

Wine Smells Like Dead Trout/Rotting Geraniums

Unfortunately, this problem is not as uncommon as we had like to see in wine kits. When it is full-fledged, this condition can wrinkle noses at one hundred yards, and once smelled is never forgotten.

The compound Hexadienol causes the odour. It is produced when lactic bacteria consume the sorbate in the wine kit. These bacteria are present wherever human beings live, and are on virtually every surface as well as being airborne. They are easily suppressed by the sulphite included in a wine kit. However, if the sulphite level falls, either through oxidation, or because the winemaker did not add the correct amount, they can infect the wine.

Normally, lactic bacteria will produce low levels of off-odours, sometimes described as cheesy, mousy or musty. Most people will never notice them. However, in the presence of sorbate, which is included in wine kits as a stabiliser, they produce the stunning aroma of fermented trout and flowers. This is a terminal condition, and the wine must be discarded.

The best way to prevent this is to make sure you are adding the full amount of sulphite included in the kit. If you are adding extra rackings to the processing of the kit, or if you are storing the wine for long periods of time, make sure to top up your carboys and monitor your sulphite levels.

Also, if you choose not to add the sulphite to your wine kit, you must not add the sorbate either, lest disaster result. Without the sulphite to suppress them, lactic acid bacteria could have a field day with your wine, and with the sorbate.

Wine is Stinky When Poured

Bottle Stink

When young wines are put into the bottle, they sometimes carry a residual aroma of fermentation with them, often a hint of hydrogen sulphide or simply a slightly yeasty character. This usually dissipates with time, but if you are drinking your wine young, then decanting it before serving, or swirling it in the glass, will often drive off most of the aroma. If the stinkiness persists, your wine may have hydrogen sulphide or excess sulphite (see above for how to deal with these). You should also ensure that your wine is completely de-gassed before bottling. This will cut down on any off aromas carried into the bottle.

Mousey Wine

If some of your bottles of wine have an aroma like a wet mouse or maybe an old mouse nest, but others seem normal, you may have a trichloranisole contamination from your corks. Trichloranisole is a combination of a mould from the lignin, or fibrous part of the cork, and chlorine, used in bleaching and sanitising the corks after harvest. It is a persistent problem in the cork industry, and one all winemakers have to live with, even if they use the highest quality corks. There is no cure but to open another bottle.

Trichloranisole contamination can be entirely avoided through the use of synthetic corks.

The Bright Side

The good news in all of this is that most of these problems are actually very rare. Of the hundreds of thousands of wine kits sold every year, we see very few cases of real defects in processing. Winemakers generally tend to be pretty savvy and careful.

With good sanitation, accurate measurements of temperature and gravity, and detailed record keeping, you should never see most of these problems. But if you do, again, do not panic: most of the common conditions are easily fixed. Check out your options, and if you get stuck, call your retailer for back up. They should be able to help you get back on the right track.

Courtesy of Winexpert


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