High gravity lagers
I am interested in how many of you have experience in brewing high gravity for lagers.
Any comments, process techniques, experiences, ideas, issues,... are welcome.
To get things started:
- What OG do you propose and how to get there?
- What is the impact on fermentation, fermantation time and temperatures?
- Do you add just plain water, demineralized water, ...
Looking forward to this...
Last edited by BelgianBrewer; 04-04-2008 at 05:35 PM.
I don't have any experience with high gravity lagers, per se, but I do plenty of High Gravity light ale brewing. I would think that the overall premise is the same. We have 1 serving tank dedicated to dilution water. We boil our filtered water for 30 minutes and run it through our heat exchanger into a clean, CO2 purged serving tank and bubble CO2 through the tank for about 30 minutes. When we are ready to filter the high gravity beer, we run the water through our plate and frame filter and fill our serving tanks to a pre-determined volume and then blend the high gravity beer with the water.
As far as OG, that is up to you and the strength of the beer you wish to make. We brew a 1.055 beer and after blending it is 1.032. You can use the blending formula Aa+Bb=Cc where "A" and "B" are the different quantities of the materials being mixed and "a" and "b" are the different conditions of those quantities. "C" is the sum of the 2 quantities "A" and "B" and "c" is the equilibrium point for the two conditions "a" and "b". Example: (2 bbl"A"*6.0% abv"a")+ ("B" bbls H20*0%abv)=(2 bbl + "B" bbl) * final alcohol content (3.2 abv).
As far as impact on fermentation, it takes a day or two (for an ale) longer to ferment our high gravity light ale than the regular gravity beer. There are slight flavor discrepancies as well with regard to ester formation and hop profile, however these differences seem to vary system to system.
In Sweden where I used to live they make a beer called "light beer". Which is not a low calorie beer but an low alcohol brew. The mashing method is called "Spring mashing". The grist is mashed in at 73 C. This kills off alot of the a-b amylase leaving alot of unfermentable dextrins and just enough sugars to make a 2.5 % by vol beer. This shit sells like hotcakes in Sweden. Anyway back to high gravity. The gravity of all the beers when brewed is approx 1.060 / 14.7 plato. Then after fermentation (13 C) the beers are run through a filter and mixed with "light beer" to the recipes original gravity.
I'd also be interested to hear how people handle hop additions for high gravity brews.
I have a 7bbl pub system, but my fermenters are 9bbl and 15bbl.
I'd like to try and stretch one of my lagers to 9bbl to make it more economical, especially if it is going to take up my tank space for best part of 2 months.
I figure with a low temp bottom fermentation, the relative lack of headspace in the unitank will be less of an issue than for my hefeweizen.
I've heard that hop utilisation is less for higer gravity wort boils. Any thoughts?