Beer Fruit Without Fruit?
When it comes to getting fruit flavor into beer, you have a wide range of options that involve adding no fruit whatsoever. Here’s how. By Josh Weikert
QUESTION: What do bananas taste like? ANSWER: Bananas. This oh-so-obvious “Who’s buried in Grant’s tomb” answer is, in practice, incorrect. Banana flavor (or rather, the flavor we most strongly associate with bananas) is actually an ester called isoamyl acetate. It just so happens that bananas have significant amounts of it, and so we’ve trained ourselves to think of it as the smell and flavor of bananas.
Now imagine that you want to brew a beer that tastes like bananas. One option, of course, is to add bananas, but in doing that you’re adding a lot more than just isoamyl acetate—see “Fruit (Not Fruity) Flavors,” page 73. Adding actual fruit to your beer introduces all kinds of secondary non-fruity fruit flavors and also adds an additional step (or multiple steps) to your brewing process. When it comes to brewing, I virtually never recommend adding a step or process or ingredient that doesn’t need to be there, and when it comes to getting fruit flavor into beer, we have a wide range of options to do so that involve adding no fruit whatsoever.
In this article, I describe the range of fruit flavors you can add by using traditional brewing ingredients (yeast, hops, and grain), and we’ll wrap up with a discussion of the difference between fruit as a flavor and fruit as an off-flavor.
Fruit from Yeast
If we want to generate some fun fruity flavors using yeast, we can approach it from two directions. First, we can choose a yeast strain that is more likely to produce the fruity flavors we want. Second, we can manage the fermentation process (and equipment) to produce a more noticeably fruity product. Whether you choose a highly active strain and try to manage the fermentation to cap esters or choose a more-modest strain and really push it to produce as much as it can is up to you and will likely depend on your process, capabilities, and the specific flavor profile you’re trying to produce.
Yeast-strain selection is one of the most important decisions you make as a brewer. The old saying that “brewers make wort, yeast makes beer” is true in many ways, and one of the things you can ask your yeast to do is produce esters. Esters are compounds formed by the combination of alcohols and acids, and many of them impart fruity flavors. Those flavors can include banana (obviously), cherry, a wide variety of berry flavors, apple and pear, citrus fruit, and stone fruit such as peaches and apricots. Esters are more common in ale strains than in lager strains, but that certainly doesn’t mean that you can’t produce fruity lagers!
As we discuss below, ester production is largely a function of fermentation temperature. Consult reviews of different yeast strains for specifics on that strain to help you choose, but generally speaking you’ll find that German wheat strains tend to produce higher levels of banana, English strains produce significant berry esters, Belgian strains produce almost everything, and American ale strains tend to be cleaner and produce minimal esters. And, for the more-adventurous among you, yeast/bacteria “bug” blends can be used to produce everything from rich cherry, raspberry, and grape flavors (for something like an oud bruin) to the crisp, zippy, acidic flavor we associate with lemons (in strains that introduce Lactobacillus). Get creative—just because a strain says it’s for a specific style, there’s no reason you can’t use it to get your fruit profile!
Modulating the level of ester production in your yeast can be accomplished in a variety of ways. First, and most importantly, is temperature. Higher temperatures will, on average, produce more esters. Where you need to be careful, though, is that at higher temperatures we’re producing a lot more of everything, including precursors and off-flavors that might overwhelm your flavor profile. Temperature can also result in the production of different esters than the specific fruity tones you’re looking for. This isn’t like turning up the volume dial. If you want to increase the level of a specific ester, then ferment on the higher side of the recommended temperature range, but if you go far beyond it you might not like the results!
You can also increase ester production by changing your overall treatment of the yeast. The short version is that the more stress the yeast cells are under, the more esters they’re likely to produce. Pitching on the low end of the pitch-rate scale is
the case, but when there are numbers to compare, they can be hard to resist. What is needed, Kara Taylor of White Labs pointed out during a presentation at the 2015 Craft Brewers Conference, is more research related to “sourness in beer on the sensory side.” Her presentation—appropriately titled “Sour Beers: It’s more than just ph”—illustrated just how complicated sour can be. She provided details about an experiment in which eleven trained panelists at White Labs tasted eight beers and rated the level of sourness from zero to three (see chart above). Many times individuals ranked some of the beers off the charts (over three).
The results illustrate that while ph and TA are most often correlated (i.e., TA will be higher when ph is lower), that is not always the case. In addition, different organic acids have different flavors. They also have different thresholds of perception. Of the four acids Taylor measured, lactic acid has the lowest, followed by malic, acetic, and citric. Of course several other acids—tartaric, succinic, butyric, ascorbic, etc.—may add to the flavor matrix. Other factors that change perception included carbonation levels, alcohol levels, flavors from fruit or barrels the beers aged in, and how hard it was to distinguish between super sour and super, super sour beers.
Consider Beer D, for instance. It had the lowest ph (3.35) but was not perceived as the most sour. Instead the TA was a better predictor, although the higher finishing gravity and lack of acetic acid should also be considered. In contrast, the beer rated the most sour (Beer A) did not have the highest TA but had the second lowest ph, contained acetic acid, and had a relatively low finishing gravity.
More recently, Urban Chestnut Brewing Company in St. Louis gathered information from a broader audience: 355 of its customers. UCBC invites consumers to sample beers (for a nominal price) at its Urban Research Brewery across the street from its production brewery and offer detailed feedback. In February, the lineup featured three Berliner weisse beers with varying levels of acidity. One had a ph of 3.8 and TA of 6.1; another 3.5 and 7.2; and a third 3.2 and 12.1.
The results provide plenty of fodder for future studies—for instance, the third beer rated much higher for umami/savory, and it was easily the most divisive of the three (drinkers liked it first or third). But what was also apparent is that even though a majority of drinkers still rated drinking the most acidic beer pleasurable, as the level of sourness increased, they were less likely to buy it on tap.
Drinkers “Are Ready”
By the time Schmidt starts blending, he has checked the numbers many times. He regularly takes readings on gravity and ph for all the barrels. He may simply be looking for a drop in ph to signal that what he has added to a barrel, for instance Pediococcus, is doing its job. There are other variables that he can’t carefully put calculated numbers to—like the size of the barrels or how long they’ve been aging.
Fruit is an important ingredient in many of his beers. Fruits obviously have different flavors and varying levels of sweetness and acidity, and those acids may be converted into still other acids during fermentation. Consider citric acid, which obviously is found in citrus fruits as well as berries and tropical fruits. It is a relatively weak acid that is easily converted into lactic acid—which is relatively mild— or by lactic acid bacteria into acetic acid— which is much stronger and often one drinkers requesting “more sour” look for.
Schmidt measures the TA of each of the individual components, but he decides how he will get to the final blend based on what he tastes, his experience, and what he knows beyond relatively simple numbers. “Finding the balance, finding the barrels, it’s part of the game,” he says. “It’s a definite
challenge to find the ones that taste good. To find the ones that have a characteristic the others don’t, that isn’t desirable alone, but when you put them together…”
The process is not done until bottling day, when he will measure TA again and put the number to the label. He understands TA may change if a customer decides to age that bottle for several months. A beer that contains 12 g/l when it is packaged could be 14 g/l by then. “But that’s the world we live in,” he says. He initially used TA simply as an aid when blending, but Jeffers Richardson at Firestone Walker convinced him to add the number to his labels. Firestone Walker was the first brewery in the country to publicize its TA and Toolbox the second.
“People are ready for this. They want to know what they can expect,” he says. “This is what a 14 is versus a 10. In the future, other breweries are going to be talking about this.” He doesn’t want the conversation to be only about acidity, but he does want customers to understand it. In the Toolbox tasting room, customers may learn that freshly squeezed orange juice has a TA of between 8 and 10 g/l. They also may try blends of Toolbox beers that are much more sour than those it packages. “Something for everyone,” Schmidt says.
The next conversation isn’t about what comes after acidity but what works alongside it. Schmidt is constantly searching for “stuff I can make beer with” pretty much anywhere he can find it around San Diego. “Too many people can call [a lab] and get the same blend,” he says. He sometimes leaves wort outside the brewery at night to see what lands in it. He keeps a jar in his car because he never knows when he may come across a potential flavor source. That could be bacteria or yeast, although he has a sense that wild yeast adds a level of complexity.
Acidity is a complicated topic; beer is an even more complex one.