Author: Matt Del Fiacco

As any all grain brewer is well aware, sweet wort is created during the mash in what is termed the saccharification rest. When crushed malted grain is steeped with water at temperatures ranging between about 131°F/55°C and 165°F/74°C, diastatic enzymes are activated that convert the dry starch into a fermentable liquid consisting largely of maltose and some unfermentable dextrines.

Modification is a term used to describe the how much of the endosperm in grain has been broken down during the malting process– the higher the modification, the less work the enzymes activated during the mash have to do. Given the higher modification of modern malts, single infusion mashing has become incredibly common among brewers, not only because of its simplicity, but because it works. But this hasn’t always been the case.

In the early days of brewing, malts weren’t as well modified as they are today, which meant that even a long rest at saccharification temperatures wasn’t enough to break down certain proteins, which had detrimental effects on head retention, body, and appearance. Moreover, the use of non-malted grains contributed to the problem. To combat this, brewers relied on techniques that involved holding the mash at temperatures known to activate other enzymes. One such example is the protein rest, which occurs when the mash is held between 113°F/45° and 131°F/55°C for 15 to 30 minutes. During this rest, proteolytic enzyme is activated and begins to break down larger protein molecules into smaller amino acid chains, making the starch more accessible to the diastatic enzymes activated during the saccharification rest.

Despite the availability of highly modified malt and claims protein rests can actually hinder body and head retention, some brewers continue to rely on this traditional method under the belief it contributes something positive to their beer. As someone who frequently uses adjuncts in my brewing and has employed the many protein rests without issue, I decided to test it out for myself!

| PURPOSE |

To evaluate the differences between a beer made using a protein rest and one made using a single infusion mash, the grist of which was comprised entirely of well modified malted grains.

| METHODS |

I went with a very simple American Wheat Ale for this xBmt.

Protein Spirit

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5 gal 60 min 19.6 IBUs 4.3 SRM 1.053 1.014 5.1 % Actuals 1.053 1.007 6.1 % Fermentables Name Amount % Wheat Malt, Red (Rahr) 5 lbs 55.17 Pale Malt, 2-Row (Rahr) 3.625 lbs 40 Vienna Malt (Weyermann) 7 oz 4.83 Hops Name Amount Time Use Form Alpha % Cascade 15 g 60 min First Wort Pellet 6.5 Cascade 28 g 5 min Boil Pellet 6.5 Yeast Name Lab Attenuation Temperature American Wheat Ale (1010) Wyeast Labs 76% 58°F - 74°F Notes Water Profile: Ca 68 | Mg 0 | Na 10 | SO4 70 | Cl 65 Download Download this recipe's BeerXML file

I started my brew day by collecting RO water, adjusting it to my desired profile, then kicking on the electric controllers to heat it up.

While waiting, I weighed out the kettle hop additions.

As strike temperature neared, I weighed out and milled 2 identical sets of grain.

The protein rest batch was ready first, so I added the grains and stirred before checking to ensure it was at my target temperature of 126°F/52°C. After a 25 minute rest, I raised the temperature to 155°F/68°C for saccharification rest, which took about 10 minutes, then let it rest for another 25 minutes for a total of 60 minutes.

The single infusion batch sat at the same saccharification temperature for 60 minutes.

When the mashes were completed, I removed the grains and boiled each for 60 minutes, added hops per the recipe. At the end of each boil, the worts were quickly chilled with my counterflow chiller and ran directly into identical fermentors.

Hydrometer measurements showed the protein rest batch had a slightly higher OG than the single infusion batch.

The worts were allowed to chill to my intended fermentation temperature of 64°F/18°C before I returned to pitch equal amounts of yeast starter into each. I observed fermentation activity from both beers within several hours and left them alone for 12 days before confirming FG had been reached.

The beers were then transferred to serving kegs.

The filled kegs were placed in my cool kegerator and burst carbonated before I reduced the pressure. After a few days of cold conditioning, they were ready to serve to participants!

| RESULTS |

A total of 22 people of varying levels of experience participated in this xBmt at the CHAOS Brew Club 2018 Summer BrewBQ. Major cheers to the organizers for allowing me to collect data during this incredible event!

Each participant was served 1 sample of the protein rest beer and 2 samples of the single infusion mash beer in different colored opaque cups then asked to identify the unique sample. At this sample size, 12 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, though only 7 (p=0.64) made the accurate selection, indicating participants in this xBmt were unable to reliably distinguish an American Wheat Ale brewed with a protein rest from one brewed using a single infusion mash.

My Impressions: I attempted 4 semi-blind triangle tests with these beers and selected the unique sample only twice, both times were guesses. To my palate, the protein rest had no impact at all on the body of the beer, I perceived the same mouthfeel in both. The beers had a really pleasant raw dough character in the flavor and the hop character was virtually absent. It wasn’t bad, though not my best work, in future iterations I may tone down the bittering bit.

| DISCUSSION |

Many publicly available recipes, some of which come from respected brewing authorities, list a protein rest as a step in the brewing process. It’s possible this is for historical purposes, cases where a protein rest would have been used in the earlier days of the style, or it could be because the beer is made with a large portion of unmalted adjuncts. While such a rest may very well serve a purpose in certain situations, some contend it can lead to poor head retention and negatively impact the body of the beer when used with grists consisting of all modified malts. It’s for this reason I brewed a beer using all well modified grains for this xBmt, and the fact tasters could not reliably tell them apart suggests the protein rest did not have a noticeably strong impact on flavor, aroma, or mouthfeel.

But what about foam? I poured equal sized samples of each beer and let them sit out for 3 minutes to observe any differences in head formation and retention.

To my eyes, the head on the beers looked more similar than different, though the protein rest version did retain a larger foam raft, which counters the claim that performing a protein rest when the grist consists of highly modified malts leads to poorer foam quality. Furthermore, I noticed no differences in clarity between the beers. While I don’t see myself using a protein rest in future batches, these results have left me feeling pretty confident that doing so even when it isn’t necessary likely won’t be detrimental.

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

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