Troubleshooting Homebrew

Modern homebrew has improved greatly since I first began brewing in the mid-1990s. Better ingredients, equipment, and information has led homebrewers to avoid many of those formerly commonplace mistakes and produce commercial-quality amateur craft beer. Yet there are some common mistakes that still show up, even among good brewers. However, by focusing on a few fundamental habits, homebrewers can learn to control and ultimately avoid these issues.

This is a look at troubleshooting homebrew that starts with good brewing habits and discusses what kinds of faults can occur when they aren’t followed. Since many brewing faults are inter-related, it’s often misleading to approach troubleshooting by looking at the cause-and-effect of each individual fault. Getting to the root cause of the problem is the quickest way to implement a solution.

Several of the faults mentioned have common solutions, and unfortunately, some cannot be fixed. So the first thing you should do when troubleshooting your beer is basic triage; assess the beer to determine if the batch should be dumped, whether it can be fixed, or if it can be just somewhat improved. In all cases, the best answer is to learn from the mistake in order to avoid it in the future.

Habit 1: Select Good Ingredients

Brewing ingredients should be fresh, clean, and properly prepared for brewing. Ingredients should be stored appropriately before brewing. Hops are best stored in a freezer with no oxygen. Malt should be in an airtight container and kept cool. Yeast should be refrigerated. Water from municipal water supplies should be filtered to remove chlorine and contaminants.

Always select and use fresh ingredients that aren’t oxidized. Oxidized hops can have a cheesy or sweaty character. Oxidized malt extract can have a cidery or tangy flavor (what we used to call “homebrew flavor”). Oxidized malt can be stale and papery. In extreme cases, old malt stored warm and unsecured may be infested with weevils or other bugs.

Prepare fresh, healthy yeast that isn’t infected. Wild yeast can introduce a number of negative flavors and effects, typically causing a clove-like flavor, sourness, cloudiness, plastic-like or smoky flavors, and a number of other problems. Detecting all of these faults simultaneously almost always points to a wild yeast infection. Old yeast can be sluggish to reproduce, and not contain sufficient viable cells for a healthy fermentation.
Obtain water that does not contain iron, chlorine, heavy metals, or other unwanted compounds. If brewing water contains chlorine, the element can react with phenols from the malt or yeast to produce medicinal chlorophenolic flavors. Brewing water can be run through an activated carbon or charcoal filter, pre-boiled, or treated with Campden tablets to remove chlorine.

Take care that your malt is crushed properly, avoiding pulverized husks. Over-crushed malt can lead to harsh astringency in beer.

Troubleshooting Tips

Oxidized ingredients: Cannot be saved. Depending on the severity of the oxidation, the effects might be ignored or blended with other beer.

Infected beer: Cannot be saved. Depending on severity, might be ignored, blended, or dumped. Will get worse, so consume quickly.

Chlorophenolic: Cannot be saved. Dump the batch.

Astringency: Astringency is caused by tannins, which can soften over time (like in red wine). Finings that target tannin (such as PVPP/polyclar or egg white) might help reduce the problem. Astringency has a bitter component, so balancing with sweetness can also help mask the problem.

Habit 2: Monitor and Control the Brewing Process

While there are many aspects of the brewing process that can be monitored and controlled, I’d like to focus on three key aspects of the wort production process in all-grain brewing: The pH of the mash, the sparging process, and the vigor of the boil. The goal of wort production is to produce wort with the desired flavor profile, sugar composition, and gravity for the recipe in question.

Hitting a proper mash pH (5.1 to 5.3, measured at room temperature) is a function of grist composition and water chemistry. There are spreadsheets and computer programs that can assist with this, or you can use a technique of mine that removes the need for those calculations. I use reverse osmosis (RO) water treated with phosphoric acid to a pH of 5.5 as my brewing liquor. I only mash pale grains in this water, and I use light mineral treatments to reach a calcium content of about 50 ppm in my mash. I add dark grains and crystal-type malts after the mash is complete, while I am recirculating.

The sparging process should avoid reaching a pH of 6.0 or higher at the same time as the temperature is 170 °F (77 °C) or higher. This temperature-pH combination can extract unwanted polyphenols (tannins) from grain, which causes astringency or harshness in beer. I find that limiting the contact time of dark and crystal malts with hot water reduces the overall harshness in my beers. Starting with lower pH water means that I can’t introduce harshness during the sparge.

Astringency is often confused with bitterness. I find that astringency accentuates bitterness but not in a good way. It creates a harsh bitterness rather than a clean bitterness, something I describe as the quality of bitterness. By limiting tannins, I reduce astringency and harshness, which gives me a cleaner-tasting final flavor profile in my beer.

A rolling boil of 60 to 90 minutes is typical. I like to use the 90 minute boil for most recipes, especially those with a large percentage of Pilsner-type malts. Since these malts have a higher concentration of the precursor to DMS (dimethyl sulfide, a cooked corn or cooked vegetable flavor), I like the longer boil to drive off more of those compounds.

Harshness and astringency can also come from hops. If I am trying to reduce these in a recipe, I often reformulate the recipe to use first wort hopping (adding hops to the kettle before running off), hop bursting (adding all the hops in the last 15-20 minutes of the boil), and whirlpool hopping (adding hops after the heat has been turned off). All of these approaches can reduce hop-derived harshness in beer. I also find that using low mineral water can also reduce harshness, particularly by avoiding excessive carbonates.

Troubleshooting Tips

Astringency: See Habit 1.

DMS: As a volatile sulfur compound, might be able to be stripped out with CO2 scrubbing in a keg. Chill the keg, overcarbonate it, then warm it and vent the CO2. Do this repeatedly over a few days, and the action of the CO2 coming out of solution will take sulfur with it. Otherwise, see if cold aging helps reduce the character over time.

Habit 3: Conduct a Healthy Fermentation

Beer needs to have completed fermentation before moving on to conditioning and packaging. Prematurely separating the beer from the yeast can result in a number of off-flavors, as yeast in a healthy fermentation tend to clean up after themselves fairly well. On the other hand, finished beer should not be left on the yeast so long that autolysis flavors develop.

Fermentation is an indirect process, since the brewer is really just creating the conditions for yeast to ferment the beer. Keys to a healthy fermentation are having a sufficient quantity of healthy, active, clean yeast, providing sufficient oxygen to support yeast growth, providing adequate nutrients for the yeast, and regulating the temperature to be in a suitable range for the yeast strain.

Many things can go wrong during fermentation, often with noticeably negative effects on the finished beer:
• A beer that gets off to a slow start fermenting often shows evidence of wort spoilage bacteria, which can have a vegetal flavor.
• Fermenting a beer too warm may result in a number of off-flavors, such as the solventy, hot, headache-inducing fusel alcohols, excessive and inappropriate fruity esters, and many different kinds of spicy phenols (including clove and smoke). Many of these off-flavors are yeast strain-dependent, and different strains have different preferred temperature ranges. Check the yeast manufacturer’s specifications.
• Separating the beer from the yeast too soon, or having an unhealthy fermentation due to inadequate nutrients (free amino nitrogen created during the mash), insufficient oxygen for growth, or underpitching can lead to issues with intermediate fermentation by-products not getting adequately reduced. Diacetyl (flavor of artificial butter or butterscotch) and acetaldehyde (green apple skins) can often be found.
• Leaving the beer on the yeast too long after fermentation has completed, particularly if at warmer temperatures, can produce autolysis flavors which can seem meaty, brothy, glutamate, or (in extreme cases) like burnt rubber. Autolysized beer can also have a higher finished pH, which leads to dull flavors.

Good yeast management practices can greatly reduce the chances of these problems occurring. The best tips for yeast management include buying fresh yeast, storing it cold before using it, making a starter, and oxygenating the wort. Combined with good wort production practices, these techniques should create the conditions for fermentation to begin rapidly. Keeping the fermentation temperature under control will help keep more of the bad off-flavors from forming. Remember that yeast generates heat during fermentation, so start the fermentation cooler than your desired fermentation temperature. I often begin ale fermentation around 64 °F (18 °C), but that will vary by yeast strain.

I normally leave my beer on the yeast until the yeast flocculates and the beer is bright. If I know a yeast strain is powdery or is a poor flocculator, I will often cool the beer to encourage the yeast to settle. If I intend to warm-condition a beer (as with some Belgian strains), I will use a secondary fermentation to remove the bulk of the yeast mass. Likewise if I intend to lager the beer.

Troubleshooting Tips

Vegetal: You could possibly blend or mask the character with a stronger flavor. However, you should probably go ahead and dump the batch and appreciate the importance of sanitation and yeast pitching rate. Blending good beer with bad beer almost always results in a bigger batch of bad beer.

Fusels: Cannot be ignored. The only hope is that aging will cause them to oxidize into esters. Dump the batch if it’s not a bigger beer that will hold up to extended cellaring.

Esters: Esters tend to fade with time, so possibly age longer. Aging on yeast will also tend to reduce these. Add fruit to the beer and pretend you wanted the character.

Phenols: Depends on the type of phenol. Some are always negative (plastic, band-aid, smoke) and should be dumped. Some (clove, pepper) might be acceptable if not with other problems. Possibly mask through blending or sweetening. Or, see if aging will reduce them, along with other flavors.

Diacetyl: If the beer is still on the yeast, leave it there, possibly raising the temperature to allow the yeast to fully reduce the diacetyl. If using a diacetyl-prone strain, rack first and use a more neutral strain. Kräusening is a traditional German brewing method of adding freshly fermenting wort to finished beer to speed the conditioning process, including reducing yeast by-products. Use 5-10% of the volume of finished beer.

Acetaldehyde: Same as diacetyl; try to get the yeast to finish the job.

Autolysis: If subtle, might be ignored. Reducing the pH (add acidity to the finished beer) can help mitigate the palate effects, but the flavor will persist. Extreme examples (burnt rubber) are dumpers.

Habit 4: Handle the Finished Beer Properly

Finished beer should be packaged in bottles or kegs without oxygen, and then stored in cool cellar conditions (if bottle conditioned) or at cold refrigerator temperatures (if not). The finished beer should not be exposed to sunlight, temperature extremes, mechanical vibration, or changing temperature conditions, as all of these can cause negative effects.

The most common problem from improperly handled beer is oxidation. As there are hundreds of chemical compounds present in beer, the sensory profile of the finished product can change significantly when these compounds oxidize.

While most brewing literature describes oxidation as papery, wet cardboard, or Sherry-like, these are actually less common forms of oxidation. The changes that occur in finished beer that oxidizes due to packaging problems can be style-dependent, but most frequently has dull, muted, stale flavors that lack the intensity and vibrancy of fresh examples. The color of the beer actually picks up more brownish tones, and loses color saturation and intensity.

Bitterness becomes more harsh and astringent, and flavors like black currants may be noticed. Sweeter flavors develop, which can take on flavors like honey in paler beers or caramel in amber or copper colored beers. Darker beers can develop dark or dried fruit flavors. Some of these flavors may be perceived as a positive in small amounts, but the dull character and harsh bitterness tends to quickly overcome these qualities.

Darker beers tend to survive better due to natural anti-oxidants in the darker grains. Malty beers with considerable Maillard reaction products can actually taste better with a light amount of oxidation, giving that elusive “German malty character” to amber and darker beers. Belgian beers can pick up more esters and richness. But paler and hoppy beers tend to just start tasting dull and lifeless; they do not hold up to aging as well, and thus are best consumed when fresh.

When investigating oxidation, look at the entire cold-side process for unwanted oxygen uptake. Pay particular attention to racking and transfers, as well as the integrity of seals on airlocks and bottle caps. If kegging, purge containers with CO2 first, and avoid splashing. Transfer the beer under a blanket of CO2, blow some CO2 on top of your beer if you ever open a carboy or keg, and always cap on foam when bottling.

Beer that is exposed to direct sunlight can become lightstruck, which has a characteristic skunk-like aroma and flavor. Clear or green bottles offer very little protection against sunlight; brown bottles are about eight times better at stopping light.

The lightstruck condition can occur at any time after hops are added to the wort. Specific wavelengths of visible light cause molecular rearrangement of hop compounds to cause this fault. So avoid having your beer in direct sunlight at any time after hops are added.

Troubleshooting Tips

Oxidation: Oxidation cannot be reversed. If you note the character developing, make sure your remaining beer is stored cold (low temperature slows the oxidation process) and consume it quickly. Adding a little acidity can also counter the developing sweetness, but don’t do this if the beer is also picking up sourness.

Lightstruck: Cannot be corrected, and is highly objectionable to most beer judges. However, Heineken, Stella Artois, Becks, etc. have done quite well selling lightstruck beer to Americans for decades. Some consumers even associate this aroma with high-priced imports. If you’re entering your beer into competition, I say dump it. If not, stick a lime in the bottle and give it to your hipster friends.

Habit 5: Serve Beer at a Proper Age

Patience is a personality trait that serves homebrewers well. Many issues can come from rushing to serve a beer prematurely, especially higher-gravity beers or lagers. Some problems have already been mentioned if beer is separated from the yeast too soon during fermentation. But beyond fermentation, the conditioning phase lets the new beer mature, lose its green, unfinished flavors, and become ready to drink.

Bigger beers need time to allow the alcohol flavors to smooth out. Many brewers rush to drink or enter their big beers, which does not do them justice. If your last bottle or pint from a keg is your best one, then you likely consumed it too soon. Big beers that are too young can have a hot or burning alcohol flavor and mouthfeel, and often taste sweet or the flavors are not well combined.

Lagers often taste sulfury or yeasty (bready or nutty flavors) if not lagered sufficiently. Separating the yeast by fining can help with the yeasty flavors, as can more age. Sulfur can reduce with time, but if you keg and are in a hurry, you can use CO2 scrubbing to lower it. Chill the keg, overcarbonate it, then warm it and vent the CO2. Do this repeatedly over a few days, and the action of the CO2 coming out of solution will take sulfur with it.

For packaged beer, failing to consume it in a reasonable amount of time can also lead to problems as the beer slowly degrades. This problem can be exacerbated if oxidation is present, but very old beers can also begin to develop sourness. This can be perceived as vinegar if oxygen is present, since acetic acid forms in the presence of oxygen. Sometimes this can be detected before sour flavors develop; the beer begins to taste thinner as the pH drops.

Troubleshooting Tips

Hot alcohol: Age the homebrew in cellar conditions until it is smooth and drinkable.

Sulfur: Sulfur can reduce with time, but if you keg and are in a hurry, you can use CO2 scrubbing to lower it (see Habit 5). Try kräusening (see Habit 3).

Sourness: Balance sourness with sweetness, or neutralize acidity with an alkaline substance like pickling lime. Possibly blend or mask the flavor, including adding additional ingredients where sourness might be perceived as a positive (such as fruit).

Habit 6: Understand Beer Styles

Beer styles are a convenient shortcut for describing types of beer, and for communicating information between the brewer and the consumer. If a brewer calls a beer by a confusing name, the beer may not be recognizable by the drinker. But the problem can also be that a brewer doesn’t understand what a style should be, and uses a name improperly. Or simply that a certain name is fashionable (IPA, anyone?) so it winds up being attached to beers that lack the recognizable stylistic character.

I think the most important aspects about referring to beers using well-known beer style names is that you get the overall balance and essential characteristics correct for that style. You may think this is an obvious statement (and it is) but determining the actual correct profile for a beer style may be harder than it seems. This is particularly true for imported beer styles that are pale, lower-gravity, lightly hopped, or otherwise fragile.

If you still don’t believe this is true, consider some actual examples. Many people in the US believe that English bitters have a high level of caramel flavor because that’s how bottled imported examples taste. However, some of that caramel flavor is due to oxidation, and isn’t present in fresh examples in the UK. For a long time, Bière de Garde was considered to be musty, but that was due to old corked bottles. Popular recipes for schwarzbier often produce something resembling a roasty porter.

In South America, I’ve tasted many IPAs that are caramelly and sweet, and with only moderate bitterness. Go back and review the section on oxidation — that’s exactly what happens to an older beer. Many brewers are accurately cloning an inaccurate sensory profile based on old samples. The beers may taste the same in the local area, but when the true examples of the style are tasted, the difference can be readily seen.

The 2015 Beer Judge Certification Program (BJCP) Style Guidelines attempt to describe world beer styles as they exist when fresh, which may not be the case in the US import market. If brewers learn how to read and apply the guidelines, they may be able to accurately reproduce a beer style without having tasted good examples.

In general, style understanding, beer evaluation skills, and recipe formulation can address most style-related issues in beer. Just remember that if you start with an incorrect target, it doesn’t matter how skilled you are — you will always be limited by that original concept.

Troubleshooting Tips

Out of style: Taste the finished beer. Regardless of original intent, call it by whatever style it most closely resembles. Try not to laugh or fidget when naming the style.

Habit 7: Focus on Balance and Drinkability

Good brewers know that drinkability is ultimately what matters in brewing. Beer that is impressive in small sips but cannot be finished when served a pint at a time is problematic. Balance is a style-specific concept that means that the proportion of components in a specific beer exemplify the beer style well, and result in a pleasantly drinkable experience. Some people assume that balance means that all components are of equal intensity — that is not the case when discussing beer. The important concept is the proper balance for a given style.

Assuming the general aspects of a beer are appropriate for a specific style, there are several areas that can be investigated for possible improvement for balance and drinkability.

I often find body and sweetness of a beer to be too high in an otherwise well-made sample. A heavier body and a sweeter finish will make a beer harder to drink. Sweetness can be measured in final gravity (FG), while body is a measure of dextrins and other heavier molecular proteins in solution. Body is a tactile sensation, and can have a thickness, creaminess, silkiness, or fullness to it.

I think the fermentability of the wort is more important than the attenuation level of the yeast strain used when addressing body and sweetness in beer. Mashing at lower temperatures, step mashing, and adding sugar are all ways of reducing body and sweetness. A complete fermentation and proper conditioning time appropriate for the yeast and the beer style should be conducted.

The relationship between bitterness (measured in IBUs) and sweetness (measured in FG) is worth exploring. Sweet balances bitter, so a sweeter beer can take more bitterness than a drier beer of the same strength. Keep in mind that maltiness is often confused for sweetness, so the impression of sweetness can exist even in a well-attenuated beer. The absence of bitterness often makes a beer seem sweet.

When troubleshooting the bitterness level of a beer, just remember that you might not need to add more IBUs — you might just need to have the beer finish at a lower gravity to achieve the desired balance. While bitterness balances sweetness, the absolute level of sweetness also has a palate impact. A beer that is both bitter and sweet can seem raw and unfinished, and also difficult to drink.

Troubleshooting Tips

Body and Sweetness: If the beer seems underattenuated, try kräusening (see Habit 3). Unless the beer is already too bitter, adding some acidity can also help cut the body and sweetness. Blending the beer with a drier, more bitter beer is a straight-forward approach, and can often be done at service (think of the “three threads” story of the origins of porter).

The carbonation level of beer can also affect the balance. Increasing the carbonation in beer balances maltiness and sweetness, and can make a slightly sweet beer seem in balance. Carbonation adds both carbonic acid (which thins the beer and balances sweetness) and a prickly sensation on the tongue that helps lift off heavier-feeling malt flavors. For a beer that is slightly out of balance, tweaking the carbonation level is often a quick solution (particularly for kegged beer).

Serving temperature is another parameter that can be used to balance beer. Warmer temperatures enhance maltiness, while colder temperatures suppress it (but not bitterness). So a beer that seems too bitter may seem in balance if allowed to warm a bit.

Be a Better Brewer

When you notice a problem in your beer, think through the proper brewing practices. The more you understand about the end-to-end process, the easier it is to find the causes of your issues and make the changes necessary. For a helpful chart of common homebrewing problems and their solutions, visit our online troubleshooting guide.



Issue: October 2015