Troubleshooting Homebrewed Beer

by Brad Smith on September 21, 2008 · 66 comments

This week we examine the topic of troubleshooting homebrewed beer. Despite the best laid plans of mice and men, not every beer you brew is going to be a homerun. Homebrewing beer is a combination of both art and science, and sometimes the art or science goes wrong.

Fortunately all is not lost, for each bad batch is an opportunity to learn how to diagnose and improve your next batch. Assuming you’ve already taken the time to carefully design your beer and match the target style, the next thing to examine is the taste of your beer. Beer troubles each have their own unique signature which you can evaluate using the guide below.


Excess bitterness in your beer is usually perceived on the back of the tongue, and often manifests itself as a bitter aftertaste. If bitterness is too low the beer often will have a very malty, sweet or grainy profile. Some beers such as IPAs require high bitterness, while others such as Scotch and many German ales require a malty profile.

Excess bitterness is created by overuse of boiling/bitterness hops, long boil times, the use of black or roasted malts, and the use of alkaline water or water with excess sulfates. Conversely low bitterness can result from a low bitterness to gravity ratio, too little hops, malty grains such as Vienna and Munich malts, short boil time or high fermentation temperatures. Filtration can also reduce the bitterness of your beer in many cases.


Body is often referred to as mouth-feel or the thickness of the beer. Full bodied beers have a well rounded thick feel to them while light bodied beers have a thin profile.

I recently wrote a complete article on how to enhance the body of your beer. Some techniques include adding caramel, crystal or carafoam malts, lactose, malto-dextrin, adding more malt overall, adding wheat, increasing the mash temperature of your beer and fermenting at a lower temperature. Conversely thin beers can be created by reducing additives, adding rice or sugar, decreasing mash temperature and fermenting at higher temperatures.

Diaceytl Flavors

Diaceytl flavor comes through as a buttery or butterscotch flavor. It is most often caused by incomplete fermentation. Potential causes include an old or undersized yeast starter, lack of oxygen in the wort before fermentation, lack of yeast nutrients, bacterial contamination or use of excessive adjuncts such as corn or rice that lack proper nutrients. Finally, if you prematurely halt fermentation by suddenly raising or lowering temperature, adding finings too soon or choosing a yeast with very high flocculation you can get a distinct butterscotch flavor in your beer.

You can counteract diceytl by starting with an appropriately sized yeast starter, making sure your wort is properly oxygenated before fermentation, avoiding contamination and making sure a majority of your grain bill contains fresh barley malt. Barley malt naturally has the nutrients needed for proper yeast growth.

Alcoholic Profile

The alcoholic profile of a beer is most often perceived as a warm sensation in the mouth and throat. Different styles obviously require different alcohol profiles as indicated by the starting and ending gravities in the BJCP Style Guide. Ideally a beer should have a balanced profile that compliments the overall flavor.

Fusel alcohols leave a solvent like flavor in the beer and are most often produced by fermentation at excessively high temperatures. Fermenting in the recommended range for your yeast can mitigate any solvent-like fusel flavors.

Overall alcohol balance can be controlled by adjusting your original gravity to match the style of beer as well as taking proper care in fermentation to make sure the wort is properly aerated, pitched and kept within the recommended temperature range during fermentation. If there is a significant mismatch between the alcohol content and body of the beer, you can also look at adjusting the body of the beer (described above) to better balance your recipe.


An astringent flavor comes across as grainy or a raw husky flavor. In some cases it may be dry or similar to the flavor of grape skins.

Astringency is most often caused by oversparging your grains or boiling your grains. It can also be caused by sparging with excessively hot water (over 175F), excess trub in the wort, and overmilling of your grains. You can minimize astringency by proper milling, sparging and a good rolling boil when brewing your beer.

Phenolic Flavors

Phenolic flavors are perceived as a medicinal or band-aid like flavor that can be quite harsh. It also sometimes is perceived as plastic, smokey or clovelike. Strong phenolic flavors can make the beer harsh or even undrinkable in some cases.

Phenolic flavors, like astringency, can be caused by oversparging or boiling your grains. In addition the use of chlorinated tap water or presence of bacterial contamination can also cause phenolic flavors. Excessive use of wheat malts or roasted barley malts can also lead to clovelike flavors. Check your equipment and bottle caps for leaks and potential contamination, carefully control your sparging process and use an alternate water source if needed to mitigate phenolics.

Dimethyl Sulfide (DMS)

DMS flavors and aromas come across as cabbage, rotten eggs or a sweet cornlike aroma. Excess DMS can spoil your beer.

DMS has many potential causes. These include high moisture malt (especially 6 row), bacterial contamination, oversparging at low temperature (below 160F), and underpitching your yeast. Covering your pot during the boil can also create DMS. Storing malt in a cool dry place, care when sparging and boiling, and a proper yeast starter can help to mitigate the ill effects of DMS.

Sour/Acidic Flavors

Sour and acidic flavors may be perceived as a bitter, cider-like, lemon-juice or sour candy flavors usually at the side of the tongue.

One primary cause of sourness is contamination due to inattention to proper sanitation. The use of excessive sugar, particularly refined sugars used by many beginners can also introduce a sour cider-like flavor. Other causes include the addition of excessive ascorbic acid, introduction of bacteria or contamination, excessively high fermentation temperatures and storage of the beer at very warm temperatures.

I hope this week’s beer troubleshooting guide will help you diagnose common brewing problems and their causes. Portions of this article were derived from the troubleshooting page on BrewWiki. Thanks again for visiting the BeerSmith Home Brewing Blog. Please consider subscribing for weekly delivery and keep your comments and emails coming.

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{ 46 comments… read them below or add one }

Geoff October 31, 2008 at 1:00 pm

I am new to home brewing but have done two very drinkable brews so far (a porter and an amber) got a bit cocky on my thrid attempt and rushed thing burning the malt extract. I continued and had hopes that the end result would not be too bad with no luck and the batch is helping my compost pile.

dave in norway February 19, 2010 at 12:11 pm

Have brewed beer for almost 30 years and for the most part the brews have won appreciation. However every now and again there is created a sort of thin ‘waxy’ film onthe surface of the brew after fermentation has finished but before tapping into bottles. This occured on 3 different brews during the last 2 weeks. I am very perturbed as to what it can be – obviously some sort of bacterial attack due to a slip in hygiene most likely but it would be nice to hear from an expert so as I have peace of mind. If you can help I would be extremely grateful – Thanks, Dave, Norway

Brad Smith February 20, 2010 at 8:04 am

Actually the presence of a thin film is not always an indication of bacteria. Often the CO2 from the fermentation will lift some light particles/proteins in the solution and leave them at the surface of the fermented beer. If you actually do have a bacterial infection, in most cases you can immediately taste it in the beer as it will either taste sour or just plain spoiled.

Bart November 29, 2010 at 8:17 am

Finished brewing an IPA (extract) and within 12 hours fermentation had begun. However, within another 12 hours it had virtually stopped. Any cause for alarm? Should I do anything? Thanks.

Brad Smith November 29, 2010 at 8:20 am

Bart – I would not worry – give it some time as it may not have completed, but some fermentations can be rapid. If you are concerned, try taking a hydrometer reading to see where the specific gravity is now. Also make sure you have a good seal with the airlock and especially the lid of the bucket if you are using a bucket to ferment – sometimes gas can escape your fermeter through the seals. — Brad

Ishan grover February 12, 2011 at 7:19 pm

I just brewed lager beer at home for the first taste sour,colour is dirty yellow i assume it got contaminated. I dnt want to waste 40 pints so can u gimme advice how to fix the issue. Imhave already bottled the beer..
Waiting for reply

Brad Smith February 12, 2011 at 7:24 pm

My best advice is if it is already bottled, give it some a week or two to carbonate, then store it in the fridge for a month or two. Likely the color will clear over time and the flavor will improve. Young beer (just brewed) is neither clear nor particularly good – so you may not have contaminated it at all.

Have some patience and crack a bottle in a few weeks to see if it is better. If it is still bad, give it a month or two to settle out – just about anything gets better with age.


Evan February 13, 2011 at 6:41 am

I brewed my second batch of red ale yesterday and at 6:00 AM my lid blew off my ferminter. The air gap pluged up with foam. I cleaned everything but the foam keeps pouring out the hole. Is this a lost cause or is there still hope?

Brad Smith February 13, 2011 at 7:17 pm

Keep it going – if the fermentation is still active the beer will have a layer of CO2 over it, so even if your airlock failed it is unlikely you have spoiled the beer. I’ve had it happen a few times and it has always turned out for the best. In fact many commercial breweries still use open air fermenters.


Lenzy February 17, 2011 at 1:08 pm

Hi, I made my first batch of beer, tastes great, problem is, its not very carbonated?? what happened? It sat for 2 weeks before we opened the first bottle.

Brad Smith February 17, 2011 at 6:04 pm

There are several reasons you could have carbonation problems. The yeast could be inactive, you may not have used enough sugar, and you may not have given it enough time. Fresh ingredients are very important so I would probably start there – did you use fresh sugar to prime it?


Lenzy February 18, 2011 at 11:35 am

the recipe I used said to use dry malt extract 1 1/4 cup to 1 cup boiled water for bottling. so that’s what I did. so sounds like next time I will use the sugar.

Austin February 26, 2011 at 2:18 pm

Have brewed two batches of beer. One is a lager and the other a Yorkshire bitter. Two issues the Yorkshire has an apple flavor to it after one month in the kegarator. The Lager is an all grain and has a slight smoke taste. What is wrong and how do ya fix it.

Brad Smith February 27, 2011 at 10:03 pm

Hard to tell but the lager could have problems due to aging at high temp – did you ferment and age it at lager temperatures (around 54F?)


Sjakk Matt May 17, 2011 at 9:48 am

We have brewed two beers; Brown Ale and Bayer. Both beers had an OG = 35 Ö and FG = 12Ö. How do we get an increase in the OG value?

Brad Smith May 19, 2011 at 8:31 am

To increase your FG, just add more grains or extract to the beer!


valtco June 22, 2011 at 9:29 pm

I have just brewed an all grain American brown and added 8 oz maple syrup in the last 20 minutes of the boil. I am wondering if I can add about 4-6 oz maple syrup for the carbonation I want in the keg? Want yo have a distinct maple essence but don’t want the beer to be dry or off flavored!

Michele January 17, 2012 at 6:46 pm

I purchased everything to brew beer over the holidays. I started with a Brewer’s best Continental Pilsner. Paid careful attention to instruction & sterilization procedures. After 48 hrs at 55 degrees there was no sign of fermentation. I went on the manufacturers website & was instructed to take a hydrometer reading being assured if the gravity was decreasing, fermentation was occurring. The readin was 1.000. Original gravity was 1.044. It is 5 days later & still nothing. I contacted a local brew supply co. & was instructed to take another reading. It was 1.050. an increase of 6/1000? I was instructed to take it out of the chiller and bring it to room temp to see if fermentation started, and, if not, maybe the yeast packet was bad & to re-pitch tomoro. Have I been given the correct information? I would hate to fail on my first attempt.

Brad Smith January 19, 2012 at 2:19 pm

I would look for signs of active fermentation (bubbling airlock, head on the fermenting wort, etc). Its possible you have a bad hydrometer or your procedure for measuring is not quite consistent yet.


Andy February 1, 2012 at 10:59 am

I’m having an issue similar to Michele, over 3 days since yeast pitched and no activity. A friend who is more experienced suggested that yeast is dead, advised that I buy more yeast and try adding again. My question is will this work, and what will happen w/ dead yeast, ie will it affect taste?

Brad Smith February 4, 2012 at 2:53 pm

Yes – if something happened to the original yeast, pitching more might revive your fermentation.

Gary February 6, 2012 at 9:38 pm

I bottled a Brewers Best holiday ale two weeks ago and it has not carbonated yet. The gravity was spot on with the recipe and the flavor is good. Is this just a matter of more time in the bottle, or do I have a problem?

Spumoni March 12, 2012 at 3:52 pm

Brewed a pilsner yesterday and added the yeast around 3:30pm. Today at 11am it is fermanting hard and foaming up. The temp seems to be rising to. We keep the house at 73 and the primary reads 75 and rising. Is there something wrong and if so wha can be done.

Kara May 25, 2012 at 1:19 pm

I tried my first experimental all-grain Belgian Wheat by adding corriander and apricot. I racked the beer to remove the apricot after 9 days, and now at 2 weeks of fermentation the color is a dirty yellow with a rotton smell and a lasting spice taste. Is there anyway to fix this and make it more like the spicey apricot good tasting wheat that we wanted.

sam hudson June 9, 2012 at 7:39 pm

Hi Brad

I have my first all grain in the fermenter. It’s an IPA and tastes delicious, SG was 1.56 after boiling. 7 days later it is 1015. Looking good with beersmith program est. Did not use finings. It is very cloudy, not just IPA cloudy. Fermentation is still occuring, is there anything I can do to help before bottling? I really don’t want bottles with lots of sediment.


Brad Smith June 10, 2012 at 12:36 pm

You can certainly add finings in the fermenter near the end of fermentation a few days before bottling. This will reduce the sediment.

John July 11, 2012 at 8:06 pm

just opened a 22 oz bottle of a batch that I bottled with several 12 oz bottles, the 12 oz were great, no problems … the larger bottle pretty much exploded when opening any thoughts

Brad Smith July 13, 2012 at 1:58 pm

Not sure why it would explode – I’m assuming you primed them both with the same amount of sugar?

Mike July 25, 2012 at 11:02 pm

Hi Brad, I made a cream ale all grain. My first one turned out great, but only 2.7% abv. So on the next batch I mashed at 150 to try to get my fermentable sugar higher to up the abv. Well I got 6.6% abv nice and clear but a BAD taste at the end, like strong almost alcohol or bitter yeast taste. What did I do? I did a hef, a my version of mirror pond and that bad cream ale all in 3 days of each other, using the 150 mash temp. And the other 2 where great. Please help!!! I am your biggest fan!! Thank you!! Mike

Graham August 1, 2012 at 9:37 pm

Hi Brad,I have put down 2 home brews now which have stopped fermentation at 1010 and 1012 respectively. The one at 1010 had stabilised for 3 days before I put it in a keg and it tasted pretty good. The second a Dutch Larger is still in the fermenter. It fermented for 8 days and stopped yesterday with an SG of 1012 and 1012 again today. Do you have any advise on what I should be doing with it now?

Bill O'Connor August 9, 2012 at 3:08 am

Recently brewed a Cooper’s Pale Ale and bottled it 2 weeks ago. Crystal clear and good carbonation, decent body but it does seriously lack flavour. Realise it’s still very young but will it do any harm if I empty it back into the fermenter, add hops and rebottle?

Brad Smith August 11, 2012 at 1:20 pm

You could certainly dry hop or add a hop tea to taste (make a hop tea by boiling some hops and then add it as needed until you get to the flavor desired).

Brad Smith August 11, 2012 at 1:22 pm

I would let it age a few more days and see where it falls out.

Brad Smith August 11, 2012 at 1:25 pm

It could be fusel alcohol – possibly from fermenting at too high a temperature? I’m just guessing, but this is certainly one possible cause.

Toni August 26, 2012 at 10:08 pm

For all the experts out there. We have made 4 batches of various beers with no problems and awesome beer. The last one was brewed a week ago, its a honey cream ale. We put it in the primary fermenter and nothing happened for about 36 hours, then it started bubbeling. We opened it today to put it in the carbo and sampled it. It tasted weird, like old yeast, not sour, not acidic. There was also about 1/4″ of growth on the bottom. Will this get better? is it bad? any advice would be helpful.

Ben August 31, 2012 at 9:04 am

Hey Brad, i just had my first attempt at brewing a pilsner from a beer kit, i pitched the yeast when the wort was 22 degrees Celcius ( thats as cool as i can bring it down to as i live in a warm climate) and after about 24 hours fermentation started but seemed very slow, about 1 bubble every 30 seconds. i waited a further 24 hours with no change so i gave the wort a gental stir and it seemed to pick up a little bit but still slow.. in the past ive always brewed ales and draughts so i was wondering if this is normal for this type of beer

Brad Smith September 6, 2012 at 4:14 pm

Slow fermentation starts are not than unusual, especially if you don’t use a yeast starter. I would let it go and see what happens. If you still have nothing after several days then it is time to consider pitching new yeast.

Bluett September 8, 2012 at 4:18 am

Hallo I have just brewed my second batch of home brew beer. The first one was a great success. My second one I left for 7 days in the fermentor and the airlock stopped bubbling. I took my SPGR readings and it was stable at 1.015 for 2 days. I then proceeded to add my beer finnings and about 1 hour later the airlock started bubling again. Will my beer be ruined if i opened and added my finnings to early?


Brad Smith September 12, 2012 at 4:21 pm

Its unlikely you ruined it by adding finings. They will help drive the suspended yeast out earlier, but will not force all of it out so your beer should finish up fine. Also, when adding the finings you can release CO2 from the beer which might have caused your bubbler to start again.

Alan Farley September 30, 2012 at 7:51 pm

I made my first batch of October Feist home brew.Made it from malt extract.Followed all the instructions.Its a dark cloudy beer.Made four gallons of it.Let it furment for 21 days.Put the beer in 2 quart jars.Put sugar in each jar.
Beer tasted bad.So i added more sugar.Even put some surp in the beer.Tried a taste a while ago ,still taste bad.Real hate to just poor it out.Do u know of anything i can do to save the beer.It taste ruined to me

Thanks Alan Farley

Brad Smith September 30, 2012 at 8:25 pm

Alan – Not sure you can do much at this point. The key point would be how does it taste (is it sour, grainy, too bitter, etc) which might help pinpoint what went wrong for the next batch. You might want to check my series on off flavors in beer which I’ve been running over the past few months on the BeerSmith blog main page (

Joe October 1, 2012 at 12:53 pm

I’ve had two beers not carbonate. One is an ipa the other is a pale ale. They are both bottled now. Is there anything that could be done to save them. They both taste great but just flatt. HELP!! They where both pretty expensive beers to brew so I don’t want to just throw them away.

Brad Smith October 9, 2012 at 4:42 pm

I’m not sure you can do much once they are bottled to increase carbonation. Emptying the bottles would just expose them to air and spoil the beer. All I can say is that you could store them at room temp for a while to see if the yeast will activate and carbonate it a bit more. Obviously if you had kegged them you would have the option of adjusting the carbonation, but with bottles there is not much you can do.

For the next batch make sure you add enough sugar and also that you store them at fermentation temp for a few weeks before taking them cold so the yeast can act on the sugar and full carbonate them.

Tony November 18, 2012 at 8:44 pm

I’m kind of a beginner, and working on a Honey Ginger Lager. During bottling, I tasted a sample and the flavor was perfect…could be my best yet. Anyway, I used corn sugar pellets for the first time on this batch, and now I seem to have small but visible particles floating in most of the bottles near the top. The beer was bottled 1 week ago, and 24 hours after bottling I upturned the bottles to better mix the dissolving pellets, which had seemed to be sitting on the yeasty bottom. Will these dissolve over time, and will the clarity improve? Was it a mistake to upturn the bottles? Thanks in advance for any help…

T.G. Fisher November 23, 2012 at 2:03 pm

I have been brewing beer in my home for 20 years. Occasionally I still get a batch that is clear in the bottle when room temperature but cloudy when chilled. How do I avoid that?

jerry January 26, 2013 at 11:29 pm

I started brewing over a year ago and have made over 23 5 gallon batches. Most have been from kits , Im now using the beer smith proram and the beersmith cloud for recipe’s Howerver the last few beers are all starting to taste the same. I was wondering because Im a extract brewer have I gone as far as I can in extract and will I have to go to the next level to find the taste I seek BIAB or all grain

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