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A Taste of the Season

Brewing with fruit can add amazing depth, flavor, and aroma to your beer, but fruits also present significant challenges. Selecting the correct fruit, understanding its fermented flavor profile, the practical considerations of fermenting fruit, and getting the right overall flavor balance is difficult but also rewarding when you get it right.

Back in 2015 I authored a BYO article on fruit beers that explained some of the challenges of brewing with real fruit. In the intervening years, I’ve dived into making meads, wines, and ciders as well as beer with fruit and gained a more in-depth understanding of fruit including both design and practical considerations.

So in this article, I will share a more in-depth treatment of fruit from a recipe design perspective as well as a practical brewing perspective, which should help you brew some truly fantastic fruit beers!

Fruit Beer Challenges

To begin, let’s discuss the fundamentals of fruit beer flavor and balance. When you enjoy fresh fruit like a mango or blueberry you taste a combination of the simple sugars in the fruit and also its flavor compounds including acidity and tannins. It is the combination of the sugar and flavors that you associate with a fruit. Fruits also have aromatic esters you smell as you taste the fruit. Your brain matches the pattern of flavors and aroma almost instantly and tells you “that’s a mango” or “that’s a blueberry.”

The challenge with fermented fruit is that all of the sugars in the fruit are completely fermentable. The two main sugars in fruit are fructose and glucose, often in roughly a 50–50% split. While glucose ferments faster, given enough time the fructose will also ferment out leaving almost no residual sweetness from the fruit.

So the sugary sweetness literally disappears, which means a large flavor component of fruit is no longer in your beer. To further compound things, fermentation often strips the fruit of its aroma. The net result is that your brain tastes the fruit beer, senses none of the sweetness or aroma it expects, and fails to register the fruit as a mango or blueberry anymore.

A final complexity is that adding fruit to a beer generally will thin the body of the beer out. This seems counterintuitive, but if you consider the fact that fruit is almost completely composed of sugar and water it starts to make sense. The sugar will ferment down to alcohol, which has an original gravity below 1.000, and the rest is water. So adding a large amount of fruit can significantly lower the final gravity (FG), also lowering the body and upsetting the malt-balance of the beer.

Fruit Beer Strategies

Given the challenges outlined earlier, what are some ways we can create great fruit beers that still maintain a proper fruit flavor balance? The technique you choose depends very much on the effect you are trying to achieve.

For example, many lighter beers lend themselves to a sweeter overall full fruit balance. To achieve this you would want to use either fruit extract or backsweetening, which are both described later. These techniques preserve the sweetness of the fruits and complement beers with very light profiles such as wheat beer, light lagers, and light ales.

In contrast, a more complex beer like a stout or porter will do better with fruits that are higher in acidity and tannins, which provide structure that is strong enough to still influence the flavor in these already flavorful beers. In this case you can still use certain extracts, but can also be successful fermenting out the fruit even without backsweetening.

The three basic techniques for adding fruit flavor to beer are flavor extracts, backsweetening, and fermenting fruit. 

Fruit Flavor Extract

The easiest method to add fruit flavor to your beer is to use a fruit flavor extract or artificial flavoring. These are available from many homebrew suppliers and are typically a concentrated artificial fruit flavor in liquid form. Typically only a few ounces (10s of mL) are needed for a homebrew batch, and it will add both color and flavor to your beer. Another technique some brewers use is to add very small extract additions as top notes to accentuate the aroma of a beer in which the primary fruit character comes from other fruit addition methods discussed later.

Since extracts are not fermented, they can be added to a finished beer “to taste.” This is a major advantage over fermented fruit, as you can adjust the amount of extract to exactly match the amount of fruit flavor you want in your beer. Also, fruit extracts often include artificial sweeteners and color so they can restore some sweetness and color from the fruit to give you a better flavor balance than fermented fruit.

To estimate how much extract is needed, first pour a small sample size of 100 mL of your finished beer and then add a measured amount of extract, starting with perhaps 5 drops (0.25 mL) of extract. If that does not provide enough flavor, add drops until you get to your desired level, or start with a new sample and cut down the number of drops if the flavor was stronger than desired. Each drop is approximately 0.05 mL. 

Once you achieve the correct flavor balance, pour one more sample and dose it to your measured rate to verify. Then scale the amounts up to your batch size. So if you had 100 mL of sample beer, you need to scale by a factor of 190 to match a 19-L (5-gallon) batch. So a dose level of 0.25 mL in 100 mL of beer would scale up to be (0.25 x 190) = 47.5 mL (1.6 oz.) in a 19-L (5-gallon) batch. In this scenario, to achieve the same flavor balance for the whole batch I would add 1.6 oz. (47.5 mL) of extract.

The only downside of using fruit flavor extracts is the flavor itself. While some extracts are nearly indistinguishable from backsweetening, many people can tell the difference between a beverage made from extract and real fruit. Some people say the artificial flavorings have a more soda-pop or artificial flavor than real fruit. Keep in mind that some extracts are better than others.

Backsweetening With Fruit Juice

A second simple method to add fruit flavor to your beer is backsweetening. This technique, widely used in cider and mead production, involves first stabilizing your beer by adding sulfites and sorbates, which together work to inhibit further fermentation. After the beer has been stabilized, you add fruit juice to achieve your desired fruit flavor. Because sulfites and sorbates inhibit fermentation, the sugar you added in the fruit will not ferment and you will be left with the complete sweetened fruit flavor in the finished beer as well as the fruity aroma. As a result this can be a great technique if your goal is a sweet fruit beer that captures the entire flavor of your fruit.

To backsweeten your beer, you first add a small amount of potassium metabisulfite to your finished beer after fermentation is complete. While you can actually measure your free sulfites using a test kit and adjust to achieve a lower sulfite level, most brewers just add a sufficient amount to prevent fermentation. Roughly 100–200 ppm will inhibit fermentation. Each 1⁄2 tsp. of potassium metabisulfite adds about 100 ppm of sulfite for a 5-gallon (19-L) batch.

After the sulfite, then add potassium sorbate (also called sorbates). Potassium sorbate is used at a 125–200 ppm dose rate, which is roughly 0.5 to 0.75 grams per gallon. This works out to 2.5–3.75 grams for a 5-gallon (19-L) batch. The combination of the sulfite and sorbates is sufficient in most cases to inhibit fermentation.

Backsweetening is typically done on finished beer, so as with flavor extracts you can backsweeten your beer “to taste.” This is most easily done with fruit juice. My preference is for pure (unsweetened) juice if you can find it, but in the case of very acidic fruits like cranberries, some sweetening can help. Much as with fruit extract, you start with a premeasured amount of finished beer and then add varying amounts of the fruit juice until you achieve the flavor balance you want before scaling up.

You can also backsweeten with whole fruit by adding the fruit to the finished beer, but you do run a slight risk of kicking off additional fermentation from wild yeast or bacteria. Stabilizing your beer with sulfites and sorbates will help to inhibit this, but it might be a good idea to bump up the sulfites/sorbates levels to reduce the risk of infection from the fruit. Steeping your whole fruit in the beer for a few days is usually sufficient to impart most of the fruit flavor. I prefer to use a grain bag to make it easier to separate the fruit at the end of steeping.

Finally, I do need to mention that the addition of sulfites and sorbates to inhibit fermentation when backsweetening always involves some risk of future fermentation. While stabilizing your beer significantly inhibits new yeast cell growth, it does not kill off the yeast cells themselves, and also sulfite levels will drop as your beer ages. For this reason you should not bottle your backsweetened beers, and instead they should be maintained in a keg where you can release pressure if needed.

Design Considerations in Fermenting Fruit

Fermenting fruit with the beer is the most challenging option, but it can also be the most rewarding. The first thing to consider when fermenting fruit with the beer is that, unlike using flavor extract or backsweetening, fermenting your fruit will result in almost all of the sugars in the fruit being fermented into alcohol, which will significantly change the perceived flavor of the fruit. So no matter how much fruit you add it won’t result in the same flavor profile of the original fruit.

As mentioned earlier, the CO2 action of the fermentation will drive a lot of the fruit aromatics out. This is especially true if you add the fruit to the primary fermentation, but some loss of aromatics will occur even if you add your fruit to the secondary. If you are working with a fruit that is light and aromatic then adding to the secondary is probably a better approach.

The main counter to loss of aromatics and sugar balance is something mead and winemakers call “structure.” Technically, structure is the major elements of a beverage that can be assessed when tasting the final product. These include things like acidity, tannins, body, sweetness, and alcohol. Each of these becomes very important when creating a balanced fruit beer.

Let’s first look at acidity and tannins, as these form the backbone of most fermented fruit beers. Acidity, which drives the pH down, will make your beer appear tart, sour, and in some cases lighter or drier in flavor. At extreme levels it can truly make your beer sour. However, acidity counters sweetness, so it can be used to add structure to your beer.

Tannins, which are polyphenols found in many fruits or fruit skins like grapes, berries, and currants are a powerful component of fruit beers and create fuller lasting flavors that don’t ferment away. Tannins, in a word, create structure in your beer.

Sweetness obviously comes from residual sugars or unfermented starches in your finished beer. In most beers it comes from malt though some adjuncts like lactose can also add sweetness. Sweetness often works hand in hand with body, which is the perceived mouthfeel of the beer and not surprisingly a beer with more residual starches and a higher finishing gravity will be perceived as both sweet and full of body.

Acidity and tannins tend to create structure in your beer, but sweetness and body are the counterpoint to them. The key is to balance your acidity/tannin level with the sweetness and body of the beer. If I ferment a fruit like black currants, with their high level of both tannins and acidity, then I will also need a high level of residual sweetness and body to balance the beer. Achieving this balance is really what designing fruit beers is all about.

Alcohol is a bit more complex. Excessive alcohol levels will lower your final gravity, which reduces the perceived body of the beer. However you can counter some of the bite of alcohol with increased structure from tannins and acidity, so a highly structured beer can stand up to more alcohol.

Because fruit is almost all sugar and water, you do need to design any fruit beer to have a bit more body, residual sweetness, and higher final gravity than you would for a normal beer. Keep in mind the fruit addition will always lower your final gravity. This can be done in a number of ways — for example wheat beers are a popular base because the wheat provides proteins that give the beer a bit more body without adding a lot of flavor. You can select lower attenuation yeasts to raise the final gravity. You can use more adjuncts or specialty malts that are not as fermentable to add body and raise the FG as well.

I want to mention how to properly measure the sugar content of your fruit or juice. For juice, simply drop a hydrometer in a sample of the juice and measure the gravity in either specific gravity, °Plato, or °Brix. Once you have the sugar density, enter that into your software along with the fruit volume. For whole fruit, extract some of the fruit juice and follow the same process to measure its sugar content. For hard fruits you can often look up the sugar percentage, which corresponds directly to its Brix value.

Which Fruits to Use

Now that we’ve discussed the basics of structure we can have a meaningful discussion about various fruits and how well they hold up in a fermented beer. As always, this decision is heavily influenced by the style and flavor profile you are trying to create. The main factors to look at when evaluating a fruit are the acidity, tannins, and aroma, and how it fits in with your beer style.

Many fruits that we enjoy have very low levels of tannins and acidity. For example many soft, sweet fruits like peaches, plums, apricots, sweet cherries, nectarines, strawberries, watermelon, pineapple, mangos, and other tropical fruits have relatively low levels of acidity and almost no tannins. These fruits will not provide any real structure to your beer, so your strawberry beer may completely lose any strawberry flavor once the sweetness and aroma ferments away. They are most appropriately used in a very light beer like a wheat or lager where some of the flavor might survive fermentation. These fruits should also be used in the secondary, as they tend to have more aromatics. Some, like apricots, hold up better than others.

I’ve personally started using fruits in my beer that have real structure – either high levels of acidity or tannins. Two of the most extreme examples are black currants and cranberries. Both of these have a very low pH, very high levels of acid, and a large amount of tannins, so they will come through even in something like a stout, though your beer needs to have enough residual sweetness and body to counter the sourness and strength of these fruits.

Other well-structured fruits include raspberries, blackberries, boysenberries, loganberries, gooseberries, sour cherries and red currants. Acidic citrus fruits like limes and lemons can also work, though they are quite sour and can overwhelm the beer. These fruits have enough structure to survive fermentation and in larger quantities can also be used for dark, rich styles like porter and stout. These structured fruits can be used in the primary, which creates a more aged-wine, less aromatic profile than using fruits in the secondary.

In between you have moderately structured fruits like apples, red grapes, pears, and blueberries. Some of these, like blueberries and grapes, have most of their tannins concentrated in the skin, so you need to keep the skins intact. Others, like apples, have huge varietal variation. The most prized apples for cidermaking, for example, the rare Kingston Black variety, have both high acidity and high tannins. Unfortunately, many of these varieties were dropped during Prohibition and are no longer grown in the US.

Practical Considerations

How much fruit to use is largely driven by the beer style and choice of fruit. Light fruits with little acidity or tannins are best used in large quantities in the secondary of very light profile beers to maximize aroma and flavor. You will also need a high dose rate of around 3–5 lbs. per gallon (0.35–0.6 kg/L) to generate much fruity flavor. Because of the high fruit usage you will also need a base beer with some body to it.

Moderately structured fruits can be used in a wider variety of styles at a dosage rate of 2–4 pounds per gallon (0.25–0.5 kg/L). Again, you would use a higher dose of fruit with a darker beer, and you still need a base beer with good body to provide residual sweetness to counter the alcohol and thinning effects of the fruit addition. Many of these like tart cherries can also be added in the primary if you are looking for a more aged flavor, though this will strip most of the fruit aroma.

Highly structured fruits like currants and cranberries are used more sparingly, perhaps 1–3 pounds per gallon (0.12–0.35 kg/L). Using too much will drive the acidity of the beer way up and create a sour beer, and excess tannins can also create bitter teabag flavors. Again, very dark or high-body beers can hold up to more structure. I prefer to use these fruits in the primary, as the acidity and tannins will carry forward into the finished beer and aroma is not as important on these fruits.

If you are brewing with large amounts of fruit in the primary I recommend adding a small amount of pectic enzyme. Pectic enzyme aids in breaking down the pectins in the fruit and the release of aromatics, particularly fruits like grapes and apples, and can also aid in extraction of tannins from fruit skins. For a fruit beer a typical dose rate is around 1.25 tsp. per 5 gallons (19 L).

Another important consideration is what form of fruit you are using. Fruit juice, by far, is the easiest to add to your beer and many excellent fruit juices are available for just about any type of fruit. You do need to take care to select only fruit juices that are free of preservatives, as juice with preservatives will inhibit fermentation.

While many brewers use them, most fruit puree is extremely difficult to separate once you get it into the fermenter, which is the reason I stopped using it. An exception to this is the Amoretti Craft Purees, which are filtered and super concentrated to avoid this issue. Another option is canned fruit wine base, which works well and can be added to a grain bag for easy separation.

Whole fruit provides the best fresh fruit flavor. Wash the fruit first and dry it. If you are working with soft fruit you can often cut it up and add it directly to the fermenter. Cellular fruits like berries are more easily fermented if you freeze them first to open up the cell walls. Clean it, freeze it, and then thaw it out before using. I also highly recommend using a grain bag to contain the fruit and make it easier to separate after fermentation. Most whole fruit I will leave in the primary or secondary for about a week or until the fruit starts to turn white. You also need to “punch down” the fruit or turn it over once to twice a day to prevent dry fruit from sitting on the top of the fermenter and developing mold.

The final topic I want to cover is blending. A significant disadvantage of using fruit in the fermenter is that you may not get the amount of fruit right the first time, as you are often guessing as to the proper flavor balance between acidity, tannins, sourness, body, sweetness, and alcohol when creating a new recipe. So if your fruit beer balance did not come out perfect, why not blend it with another beer? You can brew another beer to precisely blend in or even resort to backsweetening or fruit extract if you need a flavor boost. 

Issue: September 2020