Ask Mr. Wizard

Blueberry Additions and Fruit Haze

TroubleShooting

James Biehle - Ballwin, Missouri asks,
Q

I recently made a blueberry Weizen. After a bit of research, we decided to add the blueberries to the secondary fermenter. We defrosted them, ran them through a blender, then poured the crushed berries into the secondary. The resulting brew is nicely bluish-purple, tastes nicely of the blueberries, and is a very refreshing beer. I like it a lot. The issue is that the beer is very cloudy, millions of tiny particles of blueberries in the liquid, in spite of draining the berries through a muslin bag to get out the solids. I suspect the particles I see are too tiny to be caught in the bag. We added Irish moss during the boil, but wonder if there’s something we should do next time for a clearer result.

A

I think the problem with this beer is that you placed your blueberries into a blender. By doing this you broke down insoluble compounds in the blueberry skins into millions of tiny bits that have a density not much greater than beer. The result is fairly stable, hazy emulsion that is difficult to filter and not effectively removed by straining or fining (Irish moss helps with wort clarity in the kettle, but has no effect on ingredients added after the boil). Some fruit beers, like Abita’s Purple Haze, are intended to be hazy and using fruit purees help achieve this sort of appearance. But if you want clearer beer, different techniques work better than the one you employed in your blueberry weizen.

I suggest taking a lesson from winemakers and begin with crushed, not pureed, fruit. Add the crushed fruit to the secondary and allow the yeast to completely ferment the fruit sugars. During this process the fruit pulp tends to break down and the insoluble fruit matter associated with the skins and pulp will sink to the bottom of the beer after activity has ceased. You are still likely to have some haze because tannins from the berries react with proteins in the beer. These hazes may settle over time, but if you want to move things on a bit finings like Bentonite, PVPP and silica gel can work quite well.

Another method that is appealing to food geeks like me is to make blueberry juice syrup from your fresh fruit. If I did this I would be very tempted to add pectinase to the juice before reducing to prevent gelling. This sort of syrup will have nice color, flavor and sweetness. Add it to your weizen for a sweeter, fruitier preparation than adding fruit to the secondary. I hope these simple tips help you out in your quest for great fruit beer.

Response by Ashton Lewis.