They may be light and fluffy confections, suited for a summer garden, or profound and brooding—worthy of, as the Italians say about their greatest red wines, meditatazione. Added casually for centuries, fruit has now come into its own in the family of contemporary craft beers.
Truly great examples can be found, but they are uncommon. People love fun and fruity beers—but because fruit is expensive, such beers are often a little short on flavor. The demand for super-intense, wine-like fruit beers has yet to reach the fever pitch of pastry stouts, so market support for them is restrained. Yet more than ever, fruit beers are worthwhile endeavors.
They are tricky to get right. Beer is already highly complex in its flavor, chemistry, and process; fruit adds another world of difficulty, merging two separate elements into a single glass, hopefully finding ways to bridge them and make sure that each plays nicely with the other. Fruit intensity inevitably takes a hit because a typical fruit beer contains maybe 10 percent fruit, meaning you’ll never quite match the mouth-tingling impact of real, whole fruit. Plus, some flavors and fruit colors are unstable in beer, changing or fading over time.
Beer might seem an odd partner for fruit, but a little chemistry shows it makes more sense than you might think. First, a few malt flavors, such as the lightly caramelized furanones, are actually signature aromas in some fruits—strawberries and pineapple, for example. The full range of Maillard flavors, from caramel to cookie to toast and roast, are the same as any pastry or confectionary context in which you often find fruit. Second, the vast majority of beer’s fermentation aromas are fruity, a result of esters, alcohols, lactones, and other chemical classes. Finally, hops contribute abundant terpene alcohols and polyfunctional thiols—that is, thiols attached to other functional groups, such as alcohols—which are shared not only by citrus, but also by many kinds of tropical fruits.
So, beer actually is a pretty good matrix for fruit flavor.
Where to Start?
You may have a germ of an idea or possibly have found a fruit you’d like to showcase. First, do a little research. How is this fruit used in cooking? What flavors are harmonious with it? What other foods share odorous molecules with it?
Besides cookbooks, there are some great resources for this kind of homework. Y.Y. Ahn’s influential “Flavor Network” article is available online as an interactive graphic, so you can find your fruit and zero in on other foods or ingredients that are chemically similar. The Flavor Matrix, a book resulting from the adventures of IBM’s Watson supercomputer in flavor chemistry, does something similar in print. A crowd-sourced book called The Flavor Bible simply compiles ingredients that chefs like to mix and match. All of this research can help determine what kind of beer and fermentation might be suitable and what other fruits or seasonings might be harmonious additions.
Next, start jotting things down—random bits and pieces are fine. See if anything coalesces or catches your imagination. If an idea starts to solidify, close your eyes and try to imagine it, from appearance to a sniff, a taste, and the finish. This does not come naturally to us, but experienced brewers, perfumers, and flavorists learn to get quite good at it. Try to picture the beer. Jot down some notes as if you were actually tasting the beer: appearance, aroma, taste, texture, retronasal (the smell you breathe out through your nose after swallowing), and aftertaste.
Then, choose your best idea. The “tasting” notes can be parsed out into the beginnings of a recipe: intensity/gravity, signature malts, hop bitterness and aroma, fruit character, acidity, mouthfeel, and fermentation. This takes some practice, but at this point it’s only a sketch.
Prototyping
The next step is to put together a tabletop prototype using available beers, adding fruit in purée or other liquid form, tinctures of spices, acid, and anything else you think you’ll want in the beer.
This takes just a bit of preparation. You’ll need a small beaker or graduated cylinder along with a syringe or pipette for measuring a milliliter or less, plus another small beaker (100–200 ml) for the trial mix. This can be very basic and inexpensive; lab-grade equipment is not needed here. If you’re using spices or herbs, it’s best to mix known quantities into cheap vodka and allow them to soak for a day or so before straining them through a coffee filter. I like a 1:5 ratio for spices and a 1:10 ratio for leafy herbs, which tend to absorb more liquid. For dry acids such as citric, I typically use a 1:5 mix with water because measuring tiny amounts of dry ingredients is challenging. A small gram scale is helpful.
Start with the base. I usually like to have commercial beers available that represent the ends of the range—in color, gravity, hoppiness, and fermentation character—of the desired blend. Take a stab at a blend and taste. Too weak? Add a stronger beer. Too toasty? Add a paler beer. How’s the hop level and character? Will your fruit fit nicely into this? Repeat this until you have a good base. Then add some fruit. If, for example, your frozen guava purée comes in a 14-ounce package, then one bag per five-gallon (19-liter) batch would translate to 2.1 g/100 ml, or about 2 percent—pretty weak. Taste the base with the fruit. Is it enough fruit? Is the base still appropriate now that the fruit is in, or does it need changes? We usually like to go too far and then back off.
Once you have the fruit level right (for now), does it need some acidity? Different acids are not identical in their flavor characteristics, and they vary by fruit type. (For more on this, see Flavor Fever: Fruit for the Senses.) Citric is short and sharp; malic is less sharp and more lingering, with a raspy, slightly astringent edge. Lactic is very soft, with a kind of creamy, dairy aspect, good for something that will eventually have vanilla added. Some tannic mouthfeel also can help sell the fruit. Grape tannins are available for home winemakers.
After you get the acid level where you want it, add seasoning if you wish. These can be really overt, such as with vanilla, which can turn the whole mix into a kind of fruit ice-cream flavor. Or they can be subtle, just to enhance or warp the fruit. For example, I like very small amounts of Ceylon cinnamon with Montmorency pie cherries, where the cinnamon perks up the spicy aspect the fruit brings. Juniper or rosemary with mango, tarragon with pear, and basil with strawberry are good combinations, but there are countless others. Fruit top-note extracts are sometimes helpful in enhancing aromas, especially with vague or problematic fruits such as blueberries or peaches, so have those available. They’re good for augmentation, but they are not substitutes for real fruit.
Color has a high psychological impact on fruit beers, actually enhancing sweet and fruity perception. Various things can be used, but none are perfect in every situation: beets (earthy), hibiscus (fleeting, with some acidity and tannin, pH sensitive), elderberry, black currant, chokeberry (fruity flavors of their own). At Forbidden Root, we use coloring from purple carrots, but I have not seen this available in homebrew quantities.
For various reasons, this prototype is not a perfect preview of the finished beer, but it’s enough to help you make some decisions and even get some feedback. This is a fun exercise to do with a club or at a party, with varying degrees of scientific rigor.
Scale Up & Brew
Now it’s time for a real recipe. With commercial beers, you probably know the alcohol percentage, from which you can guesstimate the gravity, then calculate a base beer recipe based on the percentage of each beer used. Sometimes brewery websites have details about malts and hop types and IBUs. Just do the grade-school math, and you can figure out a starting point. Fruit scales pretty directly. If you added 0.5 ml of a 1:5 tincture of spice to 100 ml of base beer, that’s 5 ml per liter or 0.8 gram of spice, or about 15 grams per five-gallon (19-liter batch). For now, you just want to use whatever quantities of fruit and other flavorings will get you close without being too much. You’ll have the opportunity to tweak after fermentation.
In my experience, it’s best to add fruit after fermentation slows down but while it’s still active. Most fruits have a low percentage of sugar that needs to ferment out to prevent over-carbonation in the package. The exception to this is thicker slushy-type beers, but without pasteurization these must be kept chilled from the time they’re carbonated onward, or there could be real damage. If you want some residual sweetness, you can mash hotter and use more malt for a less attenuated beer. Lactose in small amounts can help, but it can taste artificial when there’s more than a hint. Light-colored malts such as crystal/caramel 10 or Vienna will have a fair amount of maltol, a proven sweetness enhancer. While not appropriate for every fruit-beer combination, licorice root has a similar effect.
Once the fruit has fermented out, have a taste. Now’s your chance to add more of anything—even fruit. Any spice tinctures can be added at this point; the same is true for acids, tannins, and top-note products. Then, the beer just needs to drop clear, and it’s on to packaging and carbonation.
Followed, naturally, by the drinking and the adulation of your fruit-loving friends.