Wednesday, July 30, 2008

Slaked Lime

With all of the cold aging going on in my beer fridge, I haven't been brewing much beer lately. I put an end to that troubling trend this morning and whipped out a batch of amber ale that should quench the late summer heat in a flavorful way. I usually dose my brewing water with lactic acid to hit my target mash pH, but I tried something different today: slaked lime. A big thanks to fellow homebrewers and MHTG members Ted Gisske and Mark Garthwaite for turning me on to the idea. I'd heard about the process before, but didn't pay much attention to it because I assumed that Madison's water didn't have enough calcium to make it worthwhile. Not true! Basically, slaked lime reduces residual alkalinity by causing calcium and bicarbonate to form chalk and precipitate out of solution. The reaction will occur on its own as carbon dioxide in the water and air reach equilibrium, but it happens at the speed of my grandpa driving. Slaked lime speeds up the process to a "let the water sit overnight" rate. Before adding the lime, I added some extra calcium to the water via gypsum and calcium chloride. The process worked really well, but the big test will come in three weeks when the beer will be ready to drink. If you brew your own beer and want to give slaked lime a try, you can find it labeled as "pickling lime" in the canning supplies section of Woodman's. I added some usage calculations to the files at Geek Central as well.

2 comments:

Steve said...

How did the slaked lime work out? I couldn't find any posts that followed up.

Joe said...

Hey Steve, the slaked lime worked great! I like the principle of it better than lactic acid because it doesn't add any soluble byproducts to the water, but I haven't noticed any flavor differences in my beer (not that I'd be able to tell - my palate sucks). Whether or not I'll use it in the commercial brewery will depend on how well my equipment can separate the water from the precipitated chalk without excessive losses.