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.
You may want to read the 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 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.
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 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 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