by Randy Mosher and Martin Lodahl (Brewing Techniques)
When adding fruit to a beer, the brewer must make sure the beer will work with the character of the fruit. In home brewing competitions, judges like to be able to detect “a beer in there somewhere,” but drinkers of commercial fruit beers make no such demand. In general, lighter-bodied beers do work better with most fruits, and excessively bitter beers seem to fight the sweet and sour character of most fruit. As for color, again, lighter beers meld more easily with fruit, but cherry stout reveals the reality of exceptions. In general, sharp roasty flavors from malts like chocolate fight with the fruit. Smooth caramelly notes from Munich, Vienna, and pale crystal malts will usually blend beautifully, though they may up the ante in terms of the required quality of the fruit, which in turn extends the maturation time. Very little work has been done with very strong fruit beer, even on a homebrew scale, although I feel this is an area worth exploring.
Fruit beers require a modified concept of beer balance. We usually think of the big players as malt sweetness versus hop bitterness. Balance in fruit beers is more of a sweet/acid thing, with bitterness and sometimes tannin supplying a bit of toothy background. The crucial point is that without enough acidity, fruit loses its luster, a condition wine experts refer to as “flabbiness.”
Acidity can be easily adjusted, right up to bottling time, by the careful addition of various acids. Citric and malic acids are often used in wine and mead-making and work well in beer, malic (the acid of apples) being the softer of the two. Lactic acid may also be used for a yogurty tang. I recommend testing various quantities using a shot glass and syringe or pipette to dose beer with acid until the right quantity is determined by taste, then scaling up to full batch size. Once this is done for a particular recipe, the acid may be added to the fermentor without having to repeat the dosing test.
The perfect fruit, perfectly ripe, added in sufficient quantity will produce a profoundly complex beer. Unfortunately, these conditions rarely exist for any brewer, large or small. It is therefore necessary to find ways of getting the best, most complex flavor from the ingredients at hand. For example, since sour, dark cherries don’t really exist in the North America, U.S. brewers can use a mixture of sour pale cherries and dark sweet ones to create a reasonable facsimile of a kriek. When extracts are used, sometimes a small amount of real fruit may add a fresh fruit taste without a lot of fuss. If real fruit is not an option, then at least blend a couple of different extracts for a better taste than either alone could provide.
Sometimes a small quantity of a different fruit altogether may be used — adding cherries to raspberry beer, for example. Fruits may be added strictly for color; the Belgians add the inky purple elderberry (you might try a jar of jam, along with some pectinase enzyme) to cherry beer to intensify color without adding any detectable flavor.
The best way to incorporate fruit into your beer is to add it to the secondary fermentor. By this time the crop of yeast should be strong, and conditions should be acidic, alcoholic, and nutrient-depleted enough to keep invading microbes at bay.
A covered open container is the preferred vessel for secondary fermentation with fruit. Avoid glass carboys. If you must use them, be sure to leave at least a couple of gallons of headspace to avoid clogging the outlet and blowing up the whole jug, which can be an unforgettably unpleasant, not to mention dangerous, event. I acquired an 8-gal stainless steel milk can from my local junkyard and am now brewing 5 gal of cherry beer in it.
Try to maintain a blanket of carbon dioxide over the fruit at all times to discourage mold and the vinegar-causing acetobacter. Purging the empty container with carbon dioxide before racking should help, as should a tight-fitting (but not airtight) lid. And remember, the more you open it to look, the less secure the gas blanket will be.
When using whole fruit, I like to freeze it first. Outside of the obvious benefit of keeping it stable until I’m ready to brew, freezing ruptures the cell walls and allows the fruit to mush up and release its flavors into the beer more rapidly. Freezing does not kill the microflora on the fruit’s surface, though it may reduce them a bit. Thaw the fruit in a sanitized container before adding to avoid shocking the yeast from a sudden drop in temperature.
Fruit concentrates must be treated in the same manner as fresh or frozen fruit, but they are stronger on a per-weight basis. The packaging for a concentrate usually states what the fresh fruit equivalent is. As with fresh fruit, adding to the secondary fermentation is the preferred method.
Concentrated juice is available for some fruits and when available it can be an excellent way to add a lot of fruit flavor with zero fuss. I have had especially good experience with black cherry juice concentrate, available at natural food stores. As with all concentrates, the flavor can be a little one-dimensional, so the beer may need a little something else — a different concentrate, fresh fruit, or fruit extract perhaps — to deepen and richen the flavor. As always, taste your fruit beer before kegging or bottling and add acid if you think you need it.
Fruit extracts, which lack fermentable sugars, can be added directly to serving tanks or just before bottling. Fruit extracts are particularly amenable to trial-dosing of small samples using a pipette or syringe. As with acidity adjustments, once the optimum quantity and mixture has been decided the test can be scaled up to full batch size by simple multiplication.
Extracts can give very intense flavors but may be somewhat flat in taste. Acids, especially, are missing; beers flavored with fruit extracts almost always need some acid to bring out the fruit character. Extracts are also a good way to turn up the volume on a beer fermented with real fruit — a little extra fruity kick.
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