Unless the malt is not well modified it makes little sense for me to perform a triple decoction mash nowadays. In my brewhouse, the double decoction mash and it’s variations are the de facto default.
However, on recipe forumlation I noticed that there is a difference in mash efficiency (ie the amount of sugars extracted from the same grist) pending on the type of double decoction used.
Here is the classic double decoction schedule.
Both decoctions are thick (1:2 – 1:2.5 grist to water ratio – about 33% of the total mash) and the mash-in at 50C emphasises protease activity, but not excessively and is thus suited for normal to well modified malts (like most German malts available today). A long rest at 65C creates the necessary maltose, whereas the mash itself is converted at 70C. It achieves a nice round taste with a lot of mouthfeel and good foam. The mash efficiency I usually expect from this schedule is at 62% – 64% (note that this is not the brewhouse efficiency, that’s something else).
The other type is more intense.
Here the first decoction is at a very low grist to water ration again, but instead of the usual 33% it now contains 60% of the mash volume. It is almost the entire grain bill.
Mash-in is around 35C – which improves the extraction of starch particles and provides for a high enzymatic content in the mash. Because the first decoction is so large, a protein rest at 52 – 55C is usually employed. For wheat malts, this rest is usually stepped for 10 minutes at 48C, 50C and 52C (wheat malt contains double the protein than barley malt). The saccharification is also more intense. First the maltose is made in the range of 62 – 65C, then the dextrins are made around 70 – 74C (the choice of temperature depends on the desired final attenuation). Mid-way during the boil, part of the decoction is returned to the main mash in order to submit it to a protein rest. The remainder is then returned to raise the total mash to a temperature around 62 – 65C. The final decoction is then like in the schedule before. Here the mash efficiency is a whooping 72%!
The explanation is quite simple. As the grains are boiled at temperatures above 80C, the walls inside the grain are further broken down, releasing more starches which otherwise would not be available to the mash. The much higher grain content means that a much larger part of starches are now available for conversion in the next temperature step. This has a huge impact on the colour of the beer since one needs about 10% less grain in order to make the same drink.
For Bavarian Helles, methods like these are important in order to achieve a bright beer but with plenty of mouthfeel and malty taste. It also brings down the cost of my malt down by 10% – which is not so much an issue for me, but as the batch sizes increase this can be of notable interest. In my opinion, this is well worth the extra 10 minutes waiting time!
However, real Bavarian Helles, is mashed in a very different way. The technique is called Endosperm mashing and it is very labour intense. I haven’t tried it yet, but my gut feeling is that it won’t be long before I do.
Either way, both methods deliver great results.