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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When reading up on brewing Weissbier (also known as Bavarian Wheat) one of the suggestions is a ferulic acid rest. This rest around 43 C (110 F) works best at a pH > 5.7 and liberates ferulic acid into the wort. This ferulic acid is the precursor to 4-Vinyl-Guajakol which is responsible for the the clove flavor produced by Weissbier yeats. The more ferulic acid there is in the wort the more 4VG should be produced by the yeast and the more clove character the beer should have.

This is what I wanted to test. So I brewed a Weissbier recipe twice. Once with a simple Hochkurz mash and another one with an additional 30 min 43C rest at a pH > 5.70. For the second beer acid malt was added at 61C. This is above the optimal range for protoelytic activitry since I also wanted to limit the protein degradation during the time the mash spent in the 45-55C range.

The following table lists the process steps taken for the 2 beers:

Note that the fermentation for the 2nd batch slowed down signficantly after it reached a gravity of 6 Plato. At this point I decided to pitch a lager yeast and I cooled the beer for the time it took to propagate that yeast. This was to drop out most of the original yeat and limit autolysis. This was unplanned and I hope it is not the reason why the results of the experiment are like they are.

Tonight I tasted the two beers:

Conclusion: For the chosen yeast holding the ferulic acid rest didn't make any noticeable difference in the clove flavor that was produced during fermentation. While additional experiments should be made to confirm these findings it is very much possible that this rest is not worth the additional work.

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