Using fruit in beers
by Phrak on 08-07-2007 at 12:20 pm

This article is designed to guide the brewer with using fruit in a brew. The article is still heavily under construction. Please add/edit if you can.

Many brewers have experimented with adding fruit to their beers. The most commonly added fruit to beer is raspberries, but many others have been tried at some point or another. Depending on what fruit you use, and what base beer you use, you will need a decent amount of them- a 20L batch will generally need at least 1kg worth of fruit for a flavour change that is noticeable.

If you want to add them in Primary, it would be best to wash the fruit in cold water first to get rid of the majority of surface crap, then cool the wort to 70-80C and use a hop-bag to dunk the cherries in for 2mins. Once this is done, put them in a sealed container while the wort no-chilled overnight and then dump the cherry bag in the fermenter and rack the wort in on top. However, adding the fruit to primary is believed to 'scrub' a lot of fruit flavour, so it is not recommended.

Putting the fruit into secondary is largely considered to be the better way to have best extraction of the fruit flavours. Before putting them into the fermenter, wash them in cold water then pasteurise at 80C for 1min, or use a Sodium Met. solution to sanitise.

Below is a quick list of do's and dont's of using fruit in a batch of beer-

DON'T boil, you'll lose all your fruity goodness and risk leaching pectic acid into your wort, causing a haze in the final beer.
DON'T pulp. Don't bother - This will just make it harder to rack your beer off the fruit. See "Freezing" below.
DON'T use in primary, you'll ferment-out all your flavour and aroma.

DO sanitise in water at 80C for 1min or 70C for 2mins. Use a hop-sock or muslin wrap to allow the hot-water to touch all the fruit. Using a zip-lock bag is mostly pointless.
DO freeze your fruits for a few days or weeks before you use it. This will break-down the cell membranes and make the fruitiness easier to extract into your beer.
DO use in secondary.
DO use a sediment reducer in your fermenter, if only so your fruit bits don't clog your tap-hole.

If you're worried about pectic haze, you can use a pectic enzyme to break-down the acid. Should be available from your LHBS.

Unless you grow them yourself, don't bother with strawberries - you need a truck-load of them to make any impression on the beer. Or alternatively buy a large box of 'jamming' strawberries from a market.

Sanitation:
This research paper [1], studied various hot-water treatments vs various chemical treatments for sanitising citrus fruits.

Note: a 5 log reduction is the FDA's 'rule' for the reduction of bacteria to what's considered a safe level. From memory, it represents a 100,000x decrease.

QUOTE

<extract from paper>
Both hot water and chemical treatments reduced the presence of E. coli. However, a 5 log reduction was observed from immersing the fruit in hot water at either 80 [degrees] C for one minute or 70 [degrees] C for two minutes, while there was only a 1.8-3.1 log reduction from the sanitizing solution. No significant flavor differences were found between juice extracted from non-heated fruit and fruit heated for one to two minutes. However, differences were observed between juice extracted from non-heated fruit and fruit that had been heated for two to four minutes.

The positive results of the study show that a rapid hot-water immersion technique may be used on raw fruits and vegetables to reduce fruit surface and initial juice microbial loads. To rectify the problem of taste changes, the temperature treatment should be controlled to limit the amount of time necessary that will still reduce the microflora.<snip>

Steven Pao and Craig L. Davis
Florida Dept. of Citrus, Citrus Research and Education Center
Enhancing Microbiological Safety of Fresh Orange Juice by Fruit Immersion in Hot Water and Chemical Sanitizers
Journal of Food Protection, 62(7): 756-760 (July 1999)

Another effective method that's been suggested is to soak for 24hrs in Sodium Metabisulphite, aka Campden tablets. Although I've also read that Sodium Met is not a sanatising solution, so I'm not sure who to believe.

I guess it also comes down to if I was using the fruit during Primary or Secondary fermentation.

There's empirical evidence to suggest that adding watermelon makes your beer taste... less than desirable [2]

And use twice as much berries as you think you'll need.

[1] Journal of Food Protection, 62(7): 756-760 (July 1999)
[2] ///, http://www.aussiehomebrewer.com/forum/inde...st&p=232648
[3]Frozberries website - Hornsby based supplier of frozen fruit - great prices