Double Decoction Brewing for Hefeweizen

This post supplements the video “Hefeweizen Double Decoction Brewday”: https://www.youtube.com/watch?v=drnP5PY8DqY

My bible for all things Hefeweizen has long been the book German Wheat Beer by Eric Warner (Boulder: Brewers Publications, 1992). Warner studied at the Technical University of Munich in Weihenstephan, and then brought his valuable knowledge to the English-speaking world (his volume on Kölsch is also excellent). Warner takes a studiously professional approach to brewing wheat beer, but over the years I’ve found several shortcuts and modifications that can simplify things for the homebrewer.

 

WATER

In his book (pp. 55–56), Warner claims that any water can be used for wheat beer. His argument is that there is huge variation in the hardness of waters in different areas of Germany where wheat beer is brewed, and the chemical composition of the alkalinities is also diverse. I have been taking him at his word on this, and just using our—very hard—tap water. But on comparing my most recent brew with Franziskaner, I’m struck by the zesty, clean edge of the latter. I suspect that purer water is one element of this, creating a cleaner flavour and a more acidic profile. For future brews, I will be using purer water, to see where that takes me.

 

STEPS AND DECOCTIONS

In my experience, the banana and clove flavours (esters and phenols produced by the yeast during fermentation) are easily achieved and can often be excessive. Nevertheless, the first stage of a Hefeweizen mash is traditionally an acid rest around 50°. I have the technology (and patience) to do this, so I always do. Rests around 61° and 71° are appropriate, plus a final mashout around 77°.

Decoctions can be incorporated at several stages in this process, the question is how many, and even if it is worth bothering at all. Warner (p. 58) writes of three advantages of decoction mashing, especially for Hefeweizen:

1) It supplies the yeast with more amino acids

2) It breaks down higher proteins and aids runoff

3) It reduces chill haze

From a practical point of view, that second point is particularly important. Sparging with high proportions of wheat is always difficult, but decoction improves the runoff, and the more decoctions the better it is. Just as importantly, the decoctions change the character of the finished beer. With each decoction, the beer becomes slightly darker, not necessarily a goal with Hefeweizen. The malt profile becomes more intense (which is good) but also more complex and grainy (arguably not so good). My last two beers were both Hefeweizen, the first single decocted, the second double. The single-decocted beer had a simpler, cleaner profile, which I think is more appropriate to the style. The double-decocted was darker and more grainy. I also suspect a hint of tannin on the finish, again not good. So, in sum, I’d recommend single-decoction mashing for Hefeweizen.

 

FERMENTING

Pitch the yeast cold. Warner (pp. 72–3) recounts a Bavarian rule of thumb that the pitch temperature added to the ferment temperature should equal 30°. Interestingly, he doesn’t say why this should be. It may be to avoid diacetyl precursors, i.e., if you ferment warmer, you are encouraging diacetyl production, but if you have anticipated this by reducing the precursors (with cold pitching), you will get away with it. My guess is that the science on this has moved on considerably since the book was published in the early 90s.

An interesting appendix to Warner’s book is titled ‘Some Classic Weissbier Breweries and The Beers that Made Them Famous’. Warner consistently recommends brands that have lower esters and phenols. He is particularly fond of Huber Weisses, saying that this is the preferred drink of the students at Weihenstephan. It is a very smooth type of Hefeweizen, and the banana is finely balanced against the malt profile.

That balance is my aim when brewing Hefeweizen. Fermentation temperatures between the mid-teens and the mid-20s are regularly proposed for Hefeweizen, but I’d suggest staying below 20°. My previous two brews have been at 18° and 19°, and have produced excellent results.

 

YEAST HAZE

The texture and consistency of wheat beer are surprisingly difficult to stabilise. Where Warner advises that decoction mashing reduces chill haze, many would argue that such a haze is exactly what you are looking for. But no, to create the kind of texture you find in commercial Hefeweizen, you must crash and chill the beer, then introduced a new yeast culture at bottling/kegging. In Bavaria, lager yeast is often used, as this does not flocculate as readily, and can be relied on to sit in suspension for the lifetime of the beer.

I’d like to propose a shortcut for homebrewers. Don’t crash or chill the wort. As soon as it hits target gravity, just keg or bottle straight away. There are two possible disadvantages here, but both are surmountable. First, it is important to make sure that you do actually reach a low final gravity. There is a dry edge to the finest Hefeweizens, and you are not going to get that if the beer is too sweet. But don’t leave it on the yeast too long either—daily gravity readings from about day five are in order.

The other problem is that the Hefeweizen yeast tends to drop out of suspension. For bottled beer, the sediment can be roused, maybe don’t add it all though. In kegs it is a bit more tricky. I find that you can give the keg a swirl when the beer starts running too clear. Be vigorous with this, because the sediment can be quite firm. The next glass might look like a pint of milk, but it will be delicious.

One last point about Hefeweizen: drink it cold. Higher alcohol German beers tend to benefit from slightly warmer serving temperatures, but the crisp, clean character of Hefeweizen is best enjoyed colder, around 6°. Then there is the issue of the hangover ... perhaps that is down to those higher proteins that Eric Warner so studiously avoids.