Adding Fruit to Beer
When adding fruit to a beer, it is generally the intent to have its flavor evident in the character of the base beer. Fruit flavors in beer are typically enhanced when the bitterness is low and there is some degree of residual sweetness and good body. The addition of crystal and dextrin malts as well as high temperature mashes will contribute the sweetness and body.
How to sanitize fruit and when to add it are issues of controversy when producing fruit beers. First let’s discuss sanitizing the fruit. Wild yeast and bacteria are on the skins of all fruit. Boiling fruit to kill those unwanted yeast and microorganisms will set the pectins resulting in a pectin haze that is slow to clear or permanent. Another method of preparing the fruit is pasteurization. This can be accomplished by turning the heat off and adding the crushed fruit to the boiled wort or heating the fruit in a small amount of water to 140-150 degrees F for 15 minutes then cooling as quickly as possible. Heating the fruit will drive off much of the delicate fruit flavors and aromas.
Our preferred method is to treat the fruit much like a winemaker would by adding ½ crushed Campden Tablet and 1 teaspoon Pectic Enzyme Powder to 5-10 pounds of crushed fruit 24-36 hours prior to adding the fruit to the partially fermented wort. The addition of the Campden Tablet will kill those unwanted wild yeast and bacteria while the Pectic Enzyme Powder will degrade the pectin in the fruit resulting in more juice extraction and reduction of pectin haze.
The next question is when to add the fruit. Adding fruit to the initial fermentation will result in reduced fruit character because the carbon dioxide gas produces by the yeast will scrub the desirable fruit volatiles out of the wort. Adding the fruit to the secondary (glass carboy) once the fermentation is complete will restart the fermentation. It is challenging to remove fruit in a glass carboy.
We recommend fermenting in a bucket when using fruit and adding the fruit which has been placed in a nylon straining bag to the nearly complete fermentation (when the specific gravity reaches approximately 1.020-1.025). The rate of the slowed fermentation will increase a bit, but it will not be vigorous enough to drive off the volatile aromatics of the fruit. By placing the fruit in a straining bag, its removal when racking to a carboy once fermentation is complete will be much easier. Simply pull out the bag of fruit and squeeze out the juice (after sanitizing your hands of course). Once the beer has been transferred off the fruit, gelatin finings may be added. Then allow the beer to clear for about 8 days, then rack, add priming sugar and bottle or keg as usual.
The addition of fruit will increase the original gravity of the wort, but it really doesn’t contribute that much. The sugar content of fruit varies depending on the type of fruit and ripeness. For example, the addition of six pounds of cherries (one of the higher sugar content fruits) to a five gallon batch is the equivalent of adding only .84 pounds of sugar which will increase the gravity by .007. So, I really wouldn’t worry about making gravity adjustments. One to two pounds per gallon of most fruit is sufficient in pale medium bodied (around 1.050) beers. The amount of fruit for porters, stouts and high gravity beers (1.080+) should be doubled.
With many fruit in season now, seize opportunity to make a wonderful beer that is unlike any commercially available product; one that no brewer will be able to replicate. The flavors of fruit beer mature and develop over time much like a wine. Serve your fruit beer for the Thanksgiving feast and then again at Christmas and the same beer will present itself as a totally different product.