Weißbier #1

Decoction Mash

To kick of my blog, here is my first serious attempt at a German weissbier. There have been others in the past, but they have all been disappointingly neutral, very similar to Erdinger. I’ve cobbled together a few ideas for this latest attempt, mostly from tips picked up in Eric Warner’s book in the Classic Beer Style Series, German Wheat Beer, and also from Ray Daniels’ Designing Great Beers, as well as various wisdom gained from brewing forums. The latter book, and the Classic Beer Style series in general are both excellent resources for anyone serious about beer recipe design. My tentative plan is to brew this recipe several times, altering one variable at a time until it’s to my taste. I have a particular beer in mind – Weihenstephan hefe-weissbier – which is one of my favourites. While i’m not looking to replicate this beer per se, I am looking for the kind of balance of flavours this beer exhibits.

In the picture above you can see the decoction mash being tipped into the main mash. More on this soon. The recipe is here.

I added a few interesting variables to this batch of beer, which i’m hoping will get me closer to the classic Bavarian weizen flavour:

  • A mash rest at 44C. Warner mentions that the flavour compound most commonly associated with the classic German weissbier flavour and aroma is the phenolic compound 4-vinyl-guaiacol. This is produced during fermentation by the unique strain of yeast used, whereby the yeast converts ferulic acid created in the mash. Normally, ferulic acid is bonded to the pentosanes in the grains with ester bonds – these bonds are broken down most effectively at a mash temperature of 44C, hence the rest.
  • A decoction mash. Warner mentions here that this is required to maximise the breakdown of proteins and achieve a high level of starch breakdown. Now, I believe this is no longer necessary with todays highly modified grains, and the increase in maltiness can be achived by malts such as Munich and Cara-Munich. I primarily did it as an experiment, and as the most effective way to raise the mash from 44C to 67C – I would have needed to infuse 20L of boiling water otherwise.
  • Slightly under-pitching the yeast and under-aerating. In Slide 8 of this presentation by Warner for an AHA conference, under-pitching and under-aeration are the two key variables influencing the ester formation during fermentation. According to the Mr Malty pitching rate calculator, I pitched just under half the amount required of a typical ale fermentation of that gravity. I did not oxygenate the wort directly, but the wort did get some splashing on its way to the FV. The key ester is Isoamyl acetate, responsible for the banana aroma in classic German weissbiers.
  • The ’30 rule’ of fermentation for German wheat beer brewing. According to Warner, this is an old weissbier brewing rule of thumb: the pitching temperature and fermentation temperature should add up to 30. This is probably to stress the yeast in the initial stages of fermentation. Apparently, a common fermentation schedule is to pitch the yeast at 12C, and ferment at 18C. Daniels comments that he has won a Best of Show award for his weizen using Warner’s suggested fermentation temperature, so this is what I went with too. I am using the White Labs yeast, WLP300 Hefeweizen Ale.

I now have several variables I can now alter, in particular the easiest for me are the pitching rate, level of oxygenation and fermentation temperature. I will taste the results, and probably first alter the pitching rates to get closer to what i’m after in my next  batch. I’ll post the results when they’re ready!

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One comment

  1. Pingback: Weißbier #2 « Hop Topic

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