Ask the Experts Gearhead: Sour Union

Homebrew expert Brad Smith, author of the Beersmith homebrewing software and the voice behind the Beersmith podcast, tackles questions about saving a batch of beer gone wrong, beers that finish overly bitter, and stuck fermentations.

I just finished fermenting and bulk aging my beer, but it did not turn out well. Is there anything I can do to “save” it?

It depends on what is wrong with your beer. Some off-flavors (e.g., from serious infections) really can’t be easily corrected or covered up. However there are a significant number of flaws that can be corrected by adjusting the bitterness levels or blending your beer. You can even use the same techniques to change the style of your beer after fermentation.

First, let’s talk about hops-malt balance. If you have a beer that is too malty, you can adjust it by adding more bitterness. The easiest way to do this is using an isomerized hops extract. Isomerized extracts are “pre-boiled”—that is, the alpha acids have already been put in a final “isomerized” form. So you can, quite literally, add tiny amounts of isomerized extract “to taste” until you achieve the hops balance you want.

If the beer is too hoppy, then blending your beer with a much less hoppy beer is probably your best option. In fact, blending is often the best way to correct a mediocre beer. Blending is used extensively in the production of wines and distilled spirits because it can, in many cases, provide a finished product better than the sum of the blended parts. With proper blending, you can not only cover up minor flaws but even change the style—say from an English ale to a brown ale—after fermentation is complete.

If you have a beer that is flawed or out of balance, one approach is to brew a blending beer that is the “opposite” of your flawed beer. Blend a hoppy beer with a low-hops beer. For a light beer with a slight off-flavor, blend it with some dark beer to hide the flaws. If your beer is weak on body, blend it with a higher-body beer that uses more adjuncts. You can also dilute your beer with water to reduce the final gravity and alcohol or fortify the beer with a stronger beer for more alcohol. Some mead makers even use small amounts of vodka to dilute a cloyingly sweet mead. The same technique could be used on an excessively malty beer.

Finally, you can blend using the beers you already have on hand. I enjoy dark beers and usually have a few on tap and find they are great at covering minor flaws in lighter beers. To achieve the right blend, start with a measured quantity (say, 100 ml) of your base beer and then slowly add measured amounts of the second beer until you achieve the balance you want. If you’ve measured both the base beer and the addition, you will have a blending ratio. I’ll then pull a second sample and mix at that ratio to do a final check of taste. Once you have your ratio, just scale it up to your batch volumes to get the proper blend. While a finishing gravity of 1.025 is quite high, the combination of a high mash temperature and high percentage of crystal malt can lead to very low yeast attenuation, particularly if you use a low-attenuating English yeast such as White Labs WLP002 English Ale. You could consider pitching more yeast or, if that fails, blending the beer with a lighter bodied beer. Short of blending, there is not much you can do to correct the beer at this point. It will probably be quite malty when it finishes—perhaps more like an English cask ale.

It is worthwhile to take a look at the contributing factors in the recipe that led to the very high finishing gravity. First, you probably do not need a large percentage of crystal malts in an English ale. Crystal malts add body because they have a high percentage of non-fermentable complex sugars. However, adjuncts of any kind in your grain bill are really used to accent certain flavors and should make up a small portion of the grain bill. Most adjuncts have low fermentability, and if you use an excessive percentage of adjuncts, it will throw off the malt-hops balance of your beer. The vast majority of your grain bill should be pale malt or another base malt, and adjuncts in most cases should be 10 percent or less. I’ve had discussions with several yeast manufacturers who tell me that the percent of adjuncts used has the largest impact on overall yeast attenuation, so this factor alone is probably the driving factor in your high finishing gravity.

Next, consider the mash temperature you used. Yeast attenuation goes down as mash temperature goes up, so if you mash at the low end of the range (around 148°F/64°C), you will get higher attenuation than mashing at the high temperature range (156°F/69°C). This is due to the active temperature range for the major mash enzymes, which produce more fermentable sugar chains at the lower temperature. So mashing at a lower temperature would have reduced your final gravity by at least a few points.

I brewed an English pale ale and purposely added a high percentage of crystal malt and also mashed at a high temperature (158°F/70°C). Now the fermentation seems to be stuck at 1.025. Is this normal?

The final significant contributor is the yeast strain you used. While you did not mention which strain you used, you can look at the yeast data sheets for a variety of English ale yeasts and see that there is quite a range of possible attenuations. For example, White Labs WLP002 English Ale yeast has an attenuation range of 63–70 percent. White Labs WLP005 British Ale yeast, a similar strain, has a much higher attenuation of 67–74 percent. So if you are making a high-gravity, full-bodied English pale ale, it might be better to use a higher attenuating yeast than you might use for a low-gravity bitter. I’ll cover two possibilities. Based on your description, the most likely cause is excessive tannins, though it is also possible you used an excess of grains from the “harsh zone,” which I’ll describe in a minute.

Tannins are a form of polyphenol that naturally occurs in malted grains and is derived primarily from the grain husk. During the mashing and lautering process, some tannins are extracted from the grain husks, although in most cases the tannin level remains below the flavor threshold that most people can detect.

Excessive tannins can be extracted in your beer if you allow the ph to be driven too high (above 6.0) either when steeping grains in an extract brew or when lautering an all-grain brew. In the extract case, the usual cause is using too much water when steeping your grains. For extract brewers steeping grains, I recommend keeping your water/grain ratio below about 4 qts/lb (8 l/kg), as higher ratios can result in the ph above 6.

For all-grain brewers, tannins are most frequently extracted near the end of the sparge/lautering process when the last runnings rise above a ph of 6. To counter it, first you want to manage your mash ph and keep it in the 5.2–5.6 range while mashing. For most batches, I end up adding some lactic acid to bring the ph down close to 5.2 when brewing, and you can use software or an online calculator to estimate your mash ph acid adjustment both for the mash and sparge water. Second, you want to avoid very long sparges, especially on light colored, low-gravity beers.

While tannins are one potential cause of your problem, the other problem could be use of too many grains in the “harsh zone.” The “harsh zone” is a concept Randy Mosher introduces in his recent book, Mastering Homebrew. In the book, Randy notes that very few grains are malted and produced in the color range from roughly 80 to 250 Lovibond. The reason for this is that malts produced in this “harsh zone” have many harsh flavors including strong tannic, coffee, burnt marshmallow flavors that can easily overpower other malts.

That’s why malts such as Special B, very dark caramel malts, dark brown malts, aromatic malts, and even light chocolate malts should be used very sparingly. Some even come in “debittered” or “dehusked” versions to try to soften their flavor. Using more than a few percent of malts from the harsh zone can give you excess tannins and other harsh burnt flavors that could ruin your beer. I use them only in small percentages and only when I have a specific purpose, such as to add depth to a complex porter or imperial stout. You should avoid using grains in the “harsh zone” when brewing most beer styles.

My last beer has a sharp harsh bitter finish to it. It’s not a hoppy flavor but tastes more like a harsh tea or overdone coffee finish. What did I do wrong?