As spring fades into summer, the produce department at my local supermarket fills with fruits and vegetables. As the summer progresses, the selection gets wider and the colors get brighter. As a homebrewer, I look at all this bounty and think, “Hmmm . . . I wonder if I could ferment any of this?”

Historically, fruit has been absent from breweries in most major brewing centers. The use of fruit in beer was banned in Germany from 1516 to 1987 when the Reinheitsgebot (the German Beer Purity law) was in effect. English brewers use adjuncts in some of their beers, but there are no traditional British fruit beers. The use of fruit does, however, have a long history in Belgian brewing. Belgian brewers flavor their lambics with cherries and raspberries to make kriek and framboise, respectively. More recently, lambics have been flavored with peaches (Peche) and black currants (Cassis).

In the U.S., neither law nor tradition has restrained the use of fruit. Most brewpubs and many microbreweries offer fruit beers, often as summer seasonals. A sampling of American fruit beers includes: Sam Adams Cherry Wheat, Pete’s Strawberry Blonde, Magic Hat’s #9 (apricot), Buffalo Bill’s Pumpkin Ale, New Belgium’s Two Cherry Ale, Cave Creek Chili Beer, Leinenkugel’s Berry Weiss (loganberries, elderberries and blackberries) and Sea Dog Raspberry Wheat. Among homebrewers, raspberries and cherries are the two most popular fruits used in brewing.

Making a good fruit beer doesn’t require any new equipment and the procedures for using fruit are simple. The most common fear homebrewers have when contemplating their first fruit beer is contamination of the beer with microorganisms from the fruit. In practice, this rarely happens. To make a good fruit beer, you first need to examine the flavors of fruit and how they can be used in brewing. That is the subject of this month’s installment of “Techniques.”

Fruit

The biological definition of a fruit is the mature ovary from a flowering plant. (The fruit may also contain some flower parts in addition to the ovary.) This definition includes most of what we think of as fruits as well as many fruits that we commonly call vegetables (such as tomatoes, peas and peppers). This definition further includes many plant structures that are not typically eaten, such as the “helicopters” from maple trees, the white fluffies on a dandelion and the sticky burrs of many plants. Hop cones, incidentally, are fruits. Interestingly, the biological definition of a fruit excludes juniper berries. These “berries,” used in the manufacture of gin, come from the ovary of a non-flowering plant.

The culinary definition of fruit is a sweet, edible part of a plant, often containing seeds. I’ll use this more utilitarian definition, since the only fruits of interest to brewers are the sweet, sugary fruits that can easily be used to add flavor, color and fermentable sugars to fruit beers.

Sweetness

Most fruits contain between 10 and 15 percent sugar when they are ripe. The least sugary fruits are limes, which contain less than one percent sugar. The most sugary are dates, which contain up to 60 percent sugar. Most fruits contain a mixture of fructose, glucose and sucrose. See Table 1 for the percent sugar content of many brewing-relevant fruits.

The sugars from fruits will raise the specific gravity of your beer. For large additions of fruits, you may want to calculate how much the specific gravity will increase.

You can calculate how much a fruit addition will affect its specific gravity by using the following formula:

SG = [Wfruit X (Psugar/100) X 45]/Vbeer

In the equation, SG is the specific gravity increase due to fruits. It is given in “gravity points,” or the decimal portion of a specific gravity number. Wfruit is the weight of the fruit in pounds. Psugar is the percentage of sugar in the fruit. The number 45 is the extract potential — in gravity points per pound per gallon — of simple sugars (such as fructose, glucose and sucrose). Vbeer is the volume of beer in gallons. For example, if you use 10 pounds of cherries in your five-gallon batch of cherry wheat, you would calculate the specific gravity addition like this: SG = [10 (14/100) 45]/5 = 12.6, or about 13 gravity points. If your wheat beer weighed in at 1.048 before the cherries were added, it would now have a specific gravity of 1.061.

Most fruits are sweeter than the beer they will end up in. So, when a beer drinker tastes a fruit beer, the fruit flavors are experienced in a background that is less sweet than in the fruit. This may explain why the most popular brewing fruits are low in sugar. The fruit flavor in high-sugar fruits may not taste quite right.

If you wish to add sweetness to a fruit beer, you can add a non- fermentable sugar such as lactose when you bottle or keg the beer. The amount of sugar you add will depend on how much “sweet” you want in the beer. Your best bet may be to slowly sweeten a pint of your fruit beer until you reach a level of sweetness you enjoy. From that basis, calculate how much sugar you will need to add for five gallons of beer. (There are 40 pints in five gallons of beer.) In five gallons of beer, 6.4 ounces of sugar will raise the sugar percentage by one percent. Lactose, however, is not very sweet. That’s why commercial brewers sweeten their sweet beers with fermentable sugars followed by pasteurization.

The sugars in fruits come from the breakdown of starches during the ripening process. There are two main forms of plant starch, amylose and amylopectin. Fruits also contain carboxymethylcellulose, which is commonly called pectin. In cooking, pectins help jams and jellies thicken. When heated, such as when boiled in wort, pectins can be extracted from fruit and cause haze problems in beer. Fortunately, most common brewing fruits — including raspberries, cherries, strawberries, blueberries, apricots and peaches — are low in pectin. (When making jam or jellies from these fruits, cooks must add pectin to get them to gel.) Most winemaking stores sell an enzyme that degrades pectins, called pectinase. In beers in which high-pectin fruit is heated, this enzyme can be used. To do so, add pectinase at a rate of 1/4 tsp. per five gallons during primary fermentation.

Acidity

There are many types of acids found in fruits, including malic acid, citric acid and tartaric acid. Malic acid is the primary acid in apples, apricots, cherries and peaches. Raspberries and all citrus fruits are high in citric acid. Tartaric acid is found in grapes.

As fruit ripens, the acid content of the fruit declines. However, even ripe fruits have pH values well below neutral (pH 7). Table 1 also gives the pH values of various fruits commonly used by homebrewers. These pH values do not have direct, quantitative use in brewing as the numbers for sugar content do. However, some qualitative considerations are worth discussing.

The pH of most fruits is lower than that of most beers, which usually have a pH of 4.0–4.6. So adding fruits to beer will lower the pH of the beer and may make it more tart. Conversely, the beer drinker will experience the fruit flavoring in fruit beers at a higher pH than in the native fruit. It is interesting to note that the most historically successful fruit beers — lambics — have a lower pH than most beers. The pH of fruit lambics (3.3–3.5) overlaps the pH range of fruits used in lambics.

Some brewers attempt to make their fruit beers more acidic so that the beer pH is closer to the fruit’s natural pH. You can do this by adding food- grade acid. If you make a lambic, acidity will come from lactic acid produced by bacteria. When adding acid, your best bet might be to draw off a small sample of your fruit beer and add acid to see if the flavor improves, and if so, what rate of acid addition to apply to your beer. For five gallons of beer, you will probably end up adding only a few teaspoons. Most winemaking shops sell malic acid and citric acid, so you can add the appropriate acid for your fruit if you desire.

Color

Many fruit beers exhibit the color of their added fruit. Lambics and wheat beers are light-colored beers that allow the color of the fruit to show. Fruit can also add a pleasing reddish cast to darker beers, such as stouts and porters. Few fruit beers fall in between these color extremes.

The color in fruits and other plant parts comes from three major pigment families: chlorophylls, anthocyanins and carotenoids. The green color in plants comes from chlorophyll, the molecules that absorb light energy from the sun. Chlorophyll is not, however, a major pigment in most fruits.

Anthocyanins are responsible for most of the red, purple and blue colors in plants. These molecules give cherries, raspberries and blueberries their color. Unlike chlorophyll and carotenoids, anthocyanins are water-soluble. So adding red fruit to a beer will make a reddish-colored beer. Anthocyanins are also pH sensitive; they are more reddish at low pH values and bluer at higher pH values. In beer, the pH is low enough that they will always be on the reddish end of the spectrum. As a consequence, blueberry beers will turn out red.

Carotenoids are responsible for many of the yellow and orange colors found in plants. (They are also responsible for the red color in tomatoes and bell peppers, although most red colors in plants are due to anthocyanins). Carotenoids are fat-soluble. Thus fruits rich in carotenoids will transfer relatively little color to your beer. Pumpkin beers, for example, are not bright orange in color.

If you wish to adjust the color of your fruit beer, you could add food coloring. It will take a little experimentation to find the right amount to add. In general, however, the natural color of the fruit should be sufficient to get a pleasing color. Artificial colors tend to look, well . . . artificial.

Astringency, Bitterness and Death

Fruits are edible, but any associated plant parts are likely inedible or unpalatable. The majority of plant parts are chemically defended to prevent animals (especially insects) from eating them. The leaves and stems of most plants taste bitter or astringent, depending on the plant species and plant parts. Trim off other plant parts from fruits that you use in brewing.

The pits of some fruits, including cherries and peaches, contain cyanogens. Plant cyanogens are broken down to release hydrogen cyanide (HCN) when the plant is damaged. Cyanide is a potent and deadly poison. Yet it occurs naturally in tiny doses in many food products. (Lima beans, for example, contain cyanide.) It is highly unlikely that you could add enough fruit to a beer to cause cyanide poisoning. However, many brewers remove fruit pits, just to be safe. Pits can also impart a tannic, almond-like taste to beer, so removing them will also improve the flavor.

Choosing a Beer Style

Many people’s only exposure to fruit beers are the fruit beers made by many brewpubs. In these fruit beers, the brewer mixes fruit with a light ale or lager. The rationale is that the “blank” background lets the flavor and color of the fruit show through. This is perfectly true, but it’s also why most beer drinkers don’t like these beverages — they don’t taste like beer!

The best fruit beers are, in my opinion, those in which the flavors of beer and fruit co-exist. There are many beer flavors that can successfully interact with fruit flavors, and these are outlined below in the discussion of various fruit styles. There is, however, one characteristic beer ingredient that does not mix well with fruits — hops. Hop bitterness and aroma just doesn’t mix well with fruit flavors. When making a fruit beer, it’s best to choose beer styles that are lightly hopped or to decrease the amount of hops used in brewing the beer. Don’t eliminate the hops, but their presence should be secondary to the fruit flavor. The amount of hops a fruit beer can support is a matter of taste, but I’d recommend keeping the beer under 18 IBUs.

Lambics

Historically, the most successful fruit beers are lambics. In lambics, the flavor of the fruit is balanced by the acidity of the beer. Lambics are typically made from 65 percent pale malt and 35 percent unmalted wheat. They are lightly hopped with aged hops. Lambics are fermented with a mix of yeasts and bacteria. Lactic acid bacteria in the lambics convert sugar into lactic acid, leading to a tart flavor. The light color of base lambic allows the color of the fruit to be exhibited. Lambics are great beers, but they take a lot of time and patience to brew. In addition, many homebrewers are reluctant to purposely introduce bacteria and wild yeasts into their brewing equipment. See Jean-Xavier Guinard’s book “Lambic” (1990, Brewer’s Publications) for more information.

Wheat Beers

Wheat beers provide an excellent base for a fruit beer. In wheat-based fruit beers, the characteristic “tang” of the wheat blends with the fruit flavor. In addition, the characteristic yeast aroma from German wheat yeast mingles with the aroma of the fruit. (Of course, German brewers would never add fruit to a wheat beer.) American wheat beer — brewed with a “clean” yeast rather than traditional wheat yeast — can also be used as a base. However, you should use enough wheat malt (in my opinion, at least 50%) to get a good wheat flavor in the beer. Light-colored wheat beers also provide a good background for fruit colors.

Raspberry wheat is a particular favorite of homebrewers. The tart taste and sharp aroma of raspberries mix quite well with the flavors and aroma of a traditional wheat beer. In a good raspberry wheat beer you can clearly taste the fruit and the beer. The Internet is a good source for raspberry wheat beer recipes.

Stouts and Porters

The dark, roasted grain flavor of stouts and porters can also provide an excellent complement to fruit flavors. Fruit porters and stouts can also be more highly hopped than more lightly-flavored fruit beers. However, to make a good fruit stout or porter, you need to get enough fruit flavor into the beer to compete with the dark grain flavor. This means you should only use fruits with lots of flavors, such as raspberries and cherries. How much more fruit you need is, of course, a matter of taste. But I recommend using at least 25 percent more fruit than you would in a lambic or wheat beer.

Of course, with dark beers the color of the fruit is less visible. In stouts, color from the fruit may not be seen at all. In porters, you may have to hold the beer up to the light to reveal the color contribution of the fruit. However, the deep red of a fruit porter can be very appealing. Next to kriek (cherry-flavored lambic), raspberry porter is my favorite fruit style. A good raspberry porter has a full beer flavor accentuated by the tart raspberry flavor. See the sidebar on page 47 for my recipe for raspberry porter.

High-Gravity Beers

One other beer flavor that could be matched with fruit flavor is alcohol. This is an underexplored option, but it seems to me that many milder fruit flavors — such as peaches or apricots — could complement the flavor of alcohol in a strong ale or barleywine. The elevated ester levels that accompany very strong beers would also add complexity to this beer. Since the hopping rate would have to be low, the resulting beer would be very sweet. This would not be a session beer, but might make a nice after-dinner drink to sip on.

Using fruit

Brewers have the choice of many different fruits, both in fresh and processed form and there are many ways you can add fruit to your beer. Fruit can be added at many different brewing stages. The type and amount of fruit you add, along with when you add it, will affect the extraction of sugar, flavors, aromas and color from the fruit. The risks of contamination from fruit microorganisms will also vary with the technique you use.

Recipe

Raspberry Porter

(5 gallons, partial mash)

OG = 1.052 FG = 1.014

SRM = 30 IBU = 21

Ingredients

4.5 lbs. pale dry malt extract

1 lb. pale malt (2-row)

6 oz. chocolate malt

5 oz. roasted barley

3 oz. black patent malt

3.75 lbs. raspberries (frozen)

1 tsp. Irish moss

7.5 AAU Northern Brewer hops (1.0 oz. of 7.5% alpha acid)

Wyeast 1056 (American Ale) or White Labs WLP001 (California Ale) yeast (make yeast starter)

0.75 cup corn sugar (for priming)

Step by Step

Put pale malt and dark specialty grains — both crushed — in a large grain bag. Heat three quarts of water to 165° F and submerge grain bag. Steep grains between 154 and 158° F for 30 minutes. Rinse grains with three quarts of water at 168–170° F, then set bag and grains aside. Add water to steeping water to make at least three, but preferably four, gallons and bring to a boil. Remove from heat and stir in extract. Resume heating and boil wort for 1 hour. Add hops for final 45 minutes of the boil. Add Irish moss for final 15 minutes of boil. Cool wort and transfer to sanitized fermenter. Add cold water to make 5.5 gallons. Aerate wort and add yeast starter (wort temperature 78° F or below). Ferment for one week at 68° F. After the first week, add frozen raspberries to a sanitized fermentation bucket and crush with a potato masher. Rack beer onto raspberries and let ferment for an additional week. Bottle with 3/4 cup of corn sugar. Let bottles condition at room temperature for two weeks, then refrigerate for one week. To serve, pour beer into a tall glass, such as a wheat beer glass. Examine the color by holding glass up to light, inhale the aroma and then drink.