My Brewing Log

After last year's Maibock, this is the 2^nd experiment where I compared a beer brewed with decoction mashing and a beer brewed with infusion mashing.

This time I wanted to see if there is a more pronounced flavor difference if the majority of the grist was composed of highly kilned base malts. This is one type of grist for which decoction mashing is still fairly common in Germany. test test test . So I chose a basic Dunkel recipe and the brewing process is outlined after the mash diagram for the 2 beers (click the diagram for a larger version).

It should be noted that the Dark Munich malt caught me by surprise and the mash for Dunkel II resulted in a rather unfermentable wort (attenuation limit 71%) which was compensated for during the mash of Dunkel III (see longer maltose rest). As a result the wort for Dunkel III was more fermentable. But both beers finished with a similar attenuation (67% and 69%). The poor fermentability was attibuted to the enzymatic weakness of the Best Malz Dark Munich which took a long time to convert (see the 40 min 70C rest of the decoction) and showed similar attenuation problems in subsequent beers.

3 ½ months after brewing Dunkel II and 3 months after brewing Dunkel III I tasted the beers side-by-side. It should be noted that at the time of this tasting I was not aware that I brewed one with decoction and the other one without. I had brewed quite a number of other beers in between and actually forgot how I mashed these beers and thought that they were both brewed with decoction until I checked my notes.

As you can see I did notice differences berween the beers but it is difficult to tie them to the decoction alone. I contribute the better clarity, lower head retention and thinner mouthfeel of the more intensely mashed Dunkel III to the stronger protoelytic activity in the mash. Its increased sweetness stems from the larger amount of residual fermentable sugars (see attenuation delta) compared to Dunkel II. I even considered Dunkel II (the non-decocted, more precisely only 3 min thin decoction boil) to be the more malty of the two beers.

Conclusion: This experiment was not as conclusive as the Maibock experiment and I would even call it inconclusive. There were too many differences between the analytic parameters (in particular the attenuation numbers) of the two beers to tie their slight taste differences to the more intensive mashing (including a 35 min decoction boil) of the Dunkel III. A future experiment needs to increase the decoction boil time to 60 min and attempt to keep the original extract, attenuation limit and attenuation and fermentation the same.

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