Adding fresh fruit to beer fermenters

Many craft breweries and homebrewers enjoy incorporating fruit flavors in one form or another, into their beer fermenting tank, especially during the hot summer months. Beer is good, fruit is good… Beer with fruit in it is even better! Every spring and summer season, we get lots of questions about how to safely add fresh fruit to a brew, during fermentation but after high Krausen has passed, without introducing unwanted infection.

Sure, you can always use store-bought or pre-pasteurized purees, but if you have access to fresh, local, fruit, you would surely be crazy not to use them in your beer! Luckily, preparing fresh fruit to add in post-boil, is pretty easy! Chances are, you have heard us discuss the “vodka tincture” method for things like citrus zest, but what about larger quantities of fleshy, “bulky” fruits like peaches or strawberries? Well, that is what we will discuss today!

Allow me to paint you a picture, it is a beautiful weekend day and you just picked yourself several pounds of juicy, fresh peaches with every intention of adding them to your beer. Now you are wondering, “How do I handle these peaches so that they don’t spoil my beer?” There are a couple of ways to get the job done, so here goes!

Heat pasteurization

This is a great low-heat pasteurization method that you can do in a double boiler. First, wash pit and puree your fruit. In a double boiler, hold the mashed fruit at around 150-170°F for about 15 minutes, while stirring the fruit occasionally with a sanitized spoon so that you maintain the heat consistently throughout the mixture. This method should rid the fruit of most unwanted bacteria. Let this cool a bit before adding it into your fermenter.

In my opinion, this is the most “reliable” method, but be careful not to “overdo” it, as your goal is not to “cook” the fruit, but only to sanitize it. If you overcook fresh fruit, you can lose some of the wonderful flavors, that make using fresh fruit so desirable. Overcooked fruit also expresses more fruit pectin’s which can contribute to something called “chill haze”.

Freezing

In my opinion, this method is slightly less ideal, as it is not quite as reliable, and it requires a bit more “work” and patience. The advantage to using this method over the low heat method is that some feel it maintains even more of the fresh fruit flavors than the low heat method. I, personally, find the difference to be negligible in most cases. If you wish to use this method, start by prepping the fruit the same as you would if you were using the heat method. I like to add an ounce or two, of very high-proof alcohol to the fruit in the blender. This helps to add a little extra sanitation power without causing dilution of the flavor. Once blended, you will need a sealable container or back that can tolerate being frozen and thawed, several times over. Transfer the pureed fruit to your container and place it in the freezer until frozen solid. After it is completely frozen, remove the container and allow it to thaw, then place it back in the freezer and repeat this process at least 4 times. This method is said to damage the cell walls of bacterial organisms, rendering them weak and unable to reproduce. Once you have completed this freezing and thawing process, the fruit can be added to the brew during fermentation.