Author: Phil Rusher

On the style of Weissbier, there are more than just a few descriptors used for this much beloved German wheat beer. Its most prominent and characteristic characteristics are typically perceived as banana and clove, which are more often than not viewed as undesirable in most other styles of beer. The ester associated the banana character is isoamyl acetate, while clove is said to come from a compound whose IUPAC name is 2-Methoxy-4-vinylphenol, though it’s more commonly known as 4-vinyl-guaiacol (4VG).

4VG is produced by the decarboxylation of ferulic acid, a compound found in varying concentrations in malted brewing grains including barley and wheat. Armed with the understanding that certain enzymes are more active at specific temperatures, brewers of styles known for their spicy clove character have relied on what’s colloquially known as a ferulic acid rest, which involves holding the mash between 104-122°F/40-50°C for about 15 minutes before warming it to the saccharification temperature. The increased level of ferulic acid then gets converted to 4VG during fermenation, thus resulting in a noticeably more phenolic finished product.

My wife is a fan of Weissbier, so I make it relatively often. While I’ve known what a ferulic acid rest is for awhile, I hadn’t performed one largely due to my belief that phenols and esters in such styles could be modulated by fermentation temperature. With a refreshing Weissbier on the docket, I figured it was a good opportunity to test it out for myself!

| PURPOSE |

To evaluate the difference between a Weissbeer made using a ferulic acid rest and one made using a single infusion mash.

| METHODS |

For this xBmt, I went with a rather traditional Weissbier grist including more than 60% malted wheat with the remainder being mostly Pilsner malt and a dash of my newest secret ingredient from Mecca Grade Estate Malt.

Bananaphone

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 12.2 IBUs 4.7 SRM 1.048 1.011 4.8 % Actuals 1.048 1.009 5.2 % Fermentables Name Amount % Mecca Grade Shaniko White Wheat Malt 5 lbs 46.51 Mecca Grade Pelton: Pilsner-style Barley Malt 4 lbs 37.21 Mecca Grade Wickiup: Red Wheat Malt 1.5 lbs 13.95 Mecca Grade Opal 22: Graham and Cocoa Malt 4 oz 2.33 Hops Name Amount Time Use Form Alpha % Mandarina Bavaria 15 g 60 min Boil Pellet 7.4 Yeast Name Lab Attenuation Temperature Stefon (G01) Imperial Yeast 75% 63°F - 73°F Notes Water Profile: Ca 50 | Mg 0 | Na 28 | SO4 75 | Cl 60 Download Download this recipe's BeerXML file

I started things off by collecting the proper volume of RO water a couple days ahead of time.

On brew day, I adjusted the water to my desired profile while it was heating up then weighed out and milled identical sets of grain for each batch.

Once the water for the ferulic acid batch reached 110°F/43°C, I incorporated the grains then set the Grainfather controller to hold that temperature while recirculating for 15 minutes.

With the ferulic acid rest complete, I set the controller to continue heating the mash to my desired saccharification rest temperature of 148°F/64°C.

Following each 60 minute mash rest, the grains were removed and sparged.

While waiting on the wort to heat up, I weighed out the kettle hop additions.

Both worts were boiled for 60 minutes with hops added at the times stated in the recipe.

At the completion of each 60 minute boil, the worts were quickly chilled then I took refractometer readings showing both achieved the same OG.

After racking equal volumes of wort from either batch to identical fermentation vessels, I pitched a single pouch of Imperial Yeast G01 Stefon directly into each.

I then placed the beers next to each other in my chamber controlled to 68°F/20°C and connected blowoff tubes… which clearly weren’t enough for the crazy kräusen Stefon produced just a day later.

After cleaning up the mess, I replaced the blowoff tubes and let the beer continue fermenting. Hydrometer measurements taken after a week showed the ferulic acid rest beer finished about 0.001 SG points lower than the single infusion mash beer.

I proceeded with transferring the beers to separate CO2 purged kegs.

The filled kegs were placed in my cool keezer and burst carbonated. After a couple weeks of cold conditioning, both were ready to serve.

| RESULTS |

A total of 24 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of the beer made with a ferulic acid rest and 2 samples of the beer made with a single infusion mash in different colored opaque cups then asked to identify the unique sample. While 13 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, only 6 (p=0.86) made the accurate selection, indicating participants in this xBmt could not reliably distinguish a beer made with a ferulic acid rest from one made using a single infusion mash.

My Impressions: Out of the 6 triangle tests I attempted, I chose the unique sample just 3 times, and even those were largely guesses. I perceived both beers as having equally high levels of fermentation character that one would expect in a Weissbier– spicy phenolics and banana esters. Interestingly, to my eyes, the beer made with a ferulic acid rest appeared a shade darker and a bit hazier than the single infusion beer.



| DISCUSSION |

When designing a beer recipe, there are many things to consider, and in doing so the best choice might seem to defer to the communal wisdom for guidance. A frequently repeated bit of advice to brewers looking to increase the perceptible clove character in their German wheat beers is to perform a ferulic acid rest, a method that seems to have solid scientific support. For this reason, tasters’ general inability to tell about beers made with and without a ferulic acid rest is pretty surprising.

Both beers in this xBmt exhibited perceptible levels of spicy phenolics, though neither seemed to have more than the other. Aesthetically, however, the ferulic acid rest beer did seem somewhat darker and hazier than its single infusion counterpart. I’m not exactly certain what to attribute this to, but it seems reasonable to assume the prolonged time the grain was exposed to the water with increasing temperatures from ferulic acid rest to saccharification temperature may have been a factor.

With the Grainfather, I have the ability to program mash steps that automatically adjust, and even so, I have no plans to regularly perform ferulic acid rests in the future. As a new father, my time is limited, so employing such a method only serves to extend my brew day. While the ferulic acid rest beer in this xBmt may have contained more 4VG than the single infusion beer, it wasn’t enough to be noticed by blind tasters or myself. Despite using a popular Weissbier yeast, it’s possible this particular strain is the reason for these results, hence I do look forward to exploring the impact a ferulic acid rest has when fermenting with different yeasts.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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