Fruit Brewing Techniques

Over the years, many beer styles have developed a reputation among homebrewers as being hard to brew. Many homebrewers worry that adding fruit will contaminate their beer with microorganisms from the fruit, leading to off-flavors. This has a basis in fact. Careless use of fruit can contaminate batches. I once made a cherry beer that developed a horrible, tongue-coating, phenolic flavor that was so bad I was afraid to even open the fridge door. However, armed with a little knowledge, you can easily make a fruit beer — full of fruit flavors and aromas — without any worries of contamination. In the last issue of BYO, I discussed the flavors in fruits and how they interact with beer flavors. In this article, I’ll explain how to go from the idea of a fruit beer in your head to a glass of fruit beer in your hand.

Choosing Fruit
Fruit comes in many forms. Some brewers prefer fresh fruit because none of its taste or aroma have been lost or altered during processing. In addition, many regions have varieties of fruits that are not available in any other form. In general, the best fruit beers are made from fresh fruits. However, there are several disadvantages to using fresh fruit.

Most fruits are seasonal, so the brewer will be limited to making his beer only when the fruit is in season. The brewer may have to do a lot of processing (washing, pitting, etc.) depending on the kind of fresh fruit he chooses. And, of course, all fresh fruit harbors wild yeasts and bacteria. On properly washed fruit, the level of microbes is not high enough to hurt you. However, when submerged in wort, these microorganisms can potentially multiply and add off-tastes and aroma to your beer.

Some brewers prefer the convenience of using fruit concentrates, purées or juices. These fruit products are not seasonal and they save you time because you can simply open the can or jar and use the fruit as you would use any liquid sugar source (such as liquid malt extract, honey or molasses). In addition, these products are packaged sterile. If contamination is your biggest concern when considering a fruit beer, using sterile fruit products is an option to consider.

Brewers should avoid fruit products that contain anything other than 100% fruit. Some fruit products contain added sugar. This sugar won’t harm your beer — it’ll just boost the alcohol content slightly — but you’ll need to add more of it to get enough flavor. Some fruit products contain added acids, such as citric acid. In the concentrations they are present at, these probably won’t adversely affect your beer, but may add a slight “tang.” More problematically, some fruit products contain preservatives, which may interfere with your brewer’s yeast. Don’t use jams or jellies. These contain pectins (either naturally or added), which can cause haze in your beer.

You can also use frozen fruit in a fruit beer. Buying frozen fruit — or freezing your own fruit when it’s at its peak — allows you to brew your fruit beer when the fruit is not in season.

Amount of Fruit
The amount of fruit to add to a beer depends on many variables — the type of fruit, the amount of fruit flavor desired, the beer style and many others — and so there is no simple answer to this question. As a first approximation, add one half of a pound of fruit per gallon of beer for strongly flavored fruits such as raspberries. So, for a five-gallon batch of raspberry wheat, you would add 2.5 pounds of raspberries. For lighter-flavored fruits, such as cherries or peaches, you may need to add up to two pounds of fruit per gallon of beer. Your peach ale would thus need 10 pounds of fruit. Processed fruit is usually more concentrated, so you need to add less of it. Sometimes, the label will give some indication of how concentrated the fruit is. If not, add a small amount of processed fruit to a finished beer and estimate an appropriate rate of addition.

One simple way to get the right balance is to brew a test batch. Once the test batch is ready, taste it and determine if there is too little or too much fruit flavor. Adjust the amount of fruit (and perhaps other ingredients) and brew the beer again. Make note not only of how much fruit you added and the taste of the beer, but also how flavorful the fruit itself was before you added it to your beer.

Another way to get the right balance is to blend your beer. To do this, brew two batches of your base beer and add fruit to one but not to the other. To the “fruity” batch, add about one and a half times the amount of fruit you expect you’ll need. Either keg both beers or bottle a few bottles from each batch and leave the remainder in your secondary fermenter. Blend the two beers in a glass until you find the balance you’re looking for in the finished beer, then blend the rest of the beer according to that ratio.

In the Mash
For all-grain brewers, fresh fruits can be added to the mash. To do this,  cut the fruit into pieces and stir the fruit into the grains while mashing in. The sugars and fruit flavors will dissolve into the mash and be drained along with the wort. A benefit of adding fresh fruits to the mash is that the wort will subsequently be boiled and any yeasts or bacteria on the fruit will be killed. Simply finish brewing as usual after the mash.

The drawbacks of adding fruits to the mash are that the extracted sugar and flavoring from the fruit will be boiled and then subjected to primary fermentation. Most of the fruit aromas will be lost in the process. In addition, the fruit flavor may seem “cooked” rather than fresh. So, although adding fruit to the mash is safe and convenient, it is not the way to go for most fruit beers.

Pumpkin ales are the only fruit beers typically made by adding this fruit — which is commonly referred to as a vegetable — to the mash. The pumpkin flavor desired in the beer is that of cooked pumpkin, and much of the flavor in a pumpkin ale comes from pumpkin pie spices.

If you are using pasteurized fruit concentrates, purées or juices, these are already sterile so the mash is not the best place to add them.

In Hot Wort   
Fruits can be steeped in hot wort before, during or after the boil. For fresh fruit, whole fruit or pieces of fruit are placed in a nylon bag. Submerge the fruit bag in the hot wort and tie the string of the nylon bag to the handle of your kettle. Once you’re done steeping the fruit, lift the bag into a sanitized colander and let any wort run into the kettle. The fruit will absorb some wort and lower your volume slightly. To counteract this, you can boil a slightly larger volume of wort or add water to your fermenter to make up the volume. The amount of wort absorbed by the fruit will, of course, depend on how much fruit you steep.

Fruit can also be added directly to the wort and the fruit solids left behind as the wort is siphoned to the fermenter. You may want to use a sanitized kitchen strainer to clear most of the fruit solids from the wort before racking it your fermenter.

The heat from boiling wort will kill any yeasts or bacteria on the fruit. However, pectins in the fruit can be extracted and may cause clouding in the beer if the fruit is placed in boiling wort. To sanitize the fruit, but avoid extracting pectins, you can steep the fruit in hot wort after boiling. At lower temperatures — between 160–170° F — pectins from the fruit will not be extracted but the heat will still kill any microorganisms on the fruit. The fruit itself will cool down the wort, so you may need to heat the wort to keep it above 160° F while you are steeping. For all-grain brewers, a drawback of not immediately cooling the wort is that DMS production continues in hot wort and may lend a cooked corn flavor to the beer. The amount of DMS production will depend on the type of malt you use. Extract brewers do not need to worry about DMS.

When steeping fruit in hot wort, you should allow at least a half-hour to extract as much fruit flavor and sugar as possible. Swirl the fruit bag or stir the wort every five minutes or so to disperse fruit-derived sugars and fruit flavors into the wort. Since steeping involves shorter contact times than other methods of fruit use, you should increase the amount of fruit used by at least 15–20 percent.

For fruit concentrates, purées and juices, simply add the fruit product after the boil but before the wort is cooled below 160° F. Then, finish your brew as you normally would.

Using Fruits in Secondary Fermentation
For most fruits, the best time to add them is in secondary fermentation. When added at this time, the fruits are not subjected to heat, their flavors do not end up tasting cooked and their aromas are not lost. The drawback, of course, is that adding fruits in the secondary fermenter runs the risk of contaminating the beer. However, green beer generally has enough alcohol and a pH low enough to discourage the growth of contaminating organisms.

For fresh fruits, remove the stems, leaves and pits or seeds. Wash the fruit thoroughly. If you want, you can use commercial produce-washing products such as Fit, although this isn’t necessary. You should reduce the fruit to small pieces by one of several methods: Mash the fruit with a potato masher, chop it with a food processor or cut it up with a knife. Place the fruit in your secondary fermenter and siphon beer on top of it. It is also important that the fermenter is sealed tightly. If air can get in, microorganisms can grow on the top of the floating fruit. (This is what happened to my ill-fated cherry beer.) It is usually best to use a large bucket — one with some headspace — as a secondary fermenter, as some foaming may occur when the yeast begins working on the fruit sugars.

One way to minimize the risk of contamination from fresh fruits is to take a page from the winemakers’ handbook and sterilize the fruit with sulfur dioxide. Winemakers do not sterilize their “wort” by boiling it. They sterilize their “must” by treating it with SO2 (often in the form of Campden tablets). To sterilize a “mini-must,” mush your fruit into a slurry in a sanitized bucket. Add enough water so that it’s basically a thick liquid. Add one crushed Campden tablet for every gallon of your “mini-must” and let sit, loosely covered, overnight. During this time the SO2 will kill any microorganism in the “mini-must,” then diffuse away. The SO2 also acts as an antioxidant, preventing browning of the fruit. The next day, add the now-sanitized “mini-must” to your fermenter.

Adding fruits during secondary fermentation increases the volume of the brew, but some of this volume is lost when beer is racked from the remaining fruit solids. You can plan for this by making less volume of your base beer, but making it somewhat more concentrated. The degree you need to change your base beer depends, of course, on how much fruit you plan to add. (Alternately, you can choose to simply not worry about it and end up with a couple extra beers in your batch.)

To add concentrates, purées or juices to your secondary fermentation, begin racking the base beer to the secondary fermenter. Slowly pour the fruit into the secondary fermenter as the beer is racked so that the fruit and beer mix well. You may want to stir with a sterilized spoon.

The beer can be left in contact with the fruit for varying amounts of time. One week is long enough to extract most of the fruit flavors, but not prolong the batch interminably. If you want to get the most out of your fruit, let it sit longer. Keep in mind, however, that flavor extraction decreases over time. Letting the fruit sit for two weeks will not give you twice as much fruit flavor as letting it sit for one week.

After secondary fermentation with the fruit, siphon the beer away from the fruit solids into a keg or bottling bucket. You may want to use a sanitized kitchen strainer to remove floating fruit solids before racking. Bottle or keg the beer as you usually do.

Conditioning and Clarifying

Part of the appeal of most fruit beers is their color. In order to best enjoy the color, the beer should be as clear as possible. There are a few ways to achieve this. First and foremost, you should store your fruit beer cold for at least a couple of weeks — but preferably a month or so — after kegging or bottle-conditioning. During this time, much of the yeast and chill haze (if present) will sediment out of the beer. In addition, the fruit flavors will have time to blend more completely with the base beer flavors.

One of the biggest enemies of beer clarity is chill haze, caused by protein/polyphenol (tannin) complexes in the beer. Although aging will help, minimizing chill haze to begin with will speed the development of the beer. Most fruits contribute tannins to a beer. The tannins are mainly confined to the skins of the fruits and these tannins contribute to the flavor of the fruit. Although you can fine for tannins using PVPP (Polyclar AT), this will lessen the fruit color and flavor in your beer. A better method is to minimize the protein level in your base beer.

There are a few easy ways to reduce protein levels in your beers. First of all, use an appropriate amount of Irish moss — between 1.5 and 2 teaspoons of Irish moss per 5 gallons — in the boil. This will reduce protein levels in your beer, but should not affect head retention (which is also related to protein levels). You can also fine with silica gel, which targets proteins of the size that cause chill haze, but not those of the size involved in head retention. I usually rely on the Irish moss and have had good results in my yearly raspberry porter (although the dark malts also help the clarity of this beer).