The science of brewing
By: Marisa Sloan
Science may be the last thing on your mind when sitting down to enjoy a craft beer, but it’s always on the minds of the brewers who make it. Whether you prefer pilsners, stouts, or IPAs, there’s some crazy science happening from the moment the grain is harvested to when the final product comes out of the tap. To learn more about the brewing process, several brewers in the Triad offered to share their expertise and knowledge.
Dan Morgan is the owner and head brewer at Leveneleven Brewing (1111 Coliseum Blvd.) in Greensboro. He has also owned a homebrew shop called Big Dan’s Brew Shed for the better part of eight years. Don’t make the mistake of calling him a “master brewer,” however, because he said there’s no such thing.
“I [brewed for] the first time in ‘83 or ‘84 right after I dropped out of high school,” said Morgan, reminiscing about an old record store that used to sell beer kits in the back. “It was pre-hopped extract syrup, so you would buy that and three to five pounds of corn sugar. You’d boil those and use the little dried yeast pack on the lid that was horrible. We sanitized with chlorine. I actually made one batch that tasted a little bit like bleach. It didn’t kill me. It was cool; I made five batches of really bad beer.”
Morgan was living with his aunt and uncle, who at the time, had no idea what was happening while they were at work.
“I would brew in the kitchen at night,” Morgan said. “They thought it was weird that a 16-year-old boy suddenly got really passionate about cleaning and bleaching the kitchen on a Wednesday night. Then exploding bottles in the attic gave me away. Yep, the whole batch.”
A lot of things have changed since Morgan’s first brush with homebrewing — there’s even a Walgreens where the old record store used to be on the corner of Spring Garden and South Josephine Boyd Streets — but his love of both beer and brewing remains the same. He’s “always kind of approached this more as cooking than anything,” starting with a recipe and the same four main ingredients: malt, water, hops and yeast.
Malts are produced by steeping grain, usually barley; until just before the seeds begin to sprout. After grain growth has begun, the seeds are heat-dried in a kiln, and then ground up. The heating process stops the growth and also preserves enzymes such as amylase and protease that will later be used to catalyze the breakdown of starches to sugars.
“Probably the smartest people, the biggest scientists in the food chain, are the maltsters,” Morgan said. “The people who take a barley seed and trick it into thinking it’s going to become a plant. Barley out in the field is just starch, pretty much useless for making beer. But if you get the barley wet and it’s around 100 degrees, you start the germination process. The inside of the seed thinks it’s going to become a plant, so it grows up energy reserves in the form of starch…. Then just as [the maltsters] start to see some sprout they get them into a kiln which raises them to about 115 degrees. Then that heat rise kills the enzyme that says ‘you’re going to become a plant,’ and it stabilizes. That germination and malting process builds up the starch which is eventually gonna become sugar, and we’re gonna make alcohol out of that.”
After the malt is ground and the insides of the seeds exposed, it is ready to be used for brewing. Jeff Thompson, owner and head brewer at Goofy Foot Taproom and Brewery (2762 NC-68 Ste. 109) in High Point, gave me a personal tour and walked me through the life cycle of a beer.
“I was a software engineer for the last 20 years, and I did brewing on the side,” he said. “Computer science gave that to me for a while — its problem-solving, its creativity, its math. Then toward the end, we weren’t as busy on the creative side, we weren’t creating things. That was another reason I did this. I thought it would give me an outlet to be creative to a certain extent, within boundaries.”
For Thompson, brewing gives him that freedom and creativity, and the science part comes into figuring out how to brew it. Goofy Foot is a one-barrel nanobrewery, meaning Thompson uses a three-vessel system that he fondly dubbed “glorified homebrewing.” The first vessel is a hot liquor tank, which, contrary to its name, is used to heat water.
The second vessel is called a “mash tun,” and is where the ground malt is mixed with hot water to convert starches to sugar. The temperature varies depending on what kind of beer Thompson is making that day.
“Your alcohol by volume (ABV) is directly impacted by how much grain you put in there,” Thompson said. “The more grain, the more sugars you get. The more fermentable sugars you get, the more the yeast can [turn into alcohol].”
At the bottom of the mash tun is a metal filter. As starches are converted to sugars by enzymes in the malt, a sweet solution of sugars called “wort” is filtered out. Thompson said the temperature is increased to 168 degrees after about an hour to stop the extraction of sugars. Then, hot water is very slowly added to the mash tun in to drain the wort into the third vessel, called the boil kettle.
At this point, Thompson takes a pre-boil gravity reading that tells him how much sugar is in the wort, then boils it at approximately 190 degrees for 60 to 75 minutes. When the wort is boiled, it acts as a canvas for hops to work on.
Hops are a cone-shaped flower that comes from the same plant family as cannabis. While there is a misconception that hops contribute most to the flavor of beer, Thompson said there are generally two types of hops that each serve different functions: first addition and late addition hops.
First addition hops, or “bittering hops” are added at the beginning of the boiling process. These hops release higher alpha acids that are responsible for the beer’s bitterness and preservative quality. Late addition hops, on the other hand, are added at the very end of the boil and contribute to most of the tastes and aromas that people traditionally associate with hops. There are over 250 different types of hops in total, each containing their own essential oils, flavors and aromas.
After about an hour of boiling, the wort is cooled down again and transferred to a fermenter. During fermentation, yeast is added to break down sugars in the wort to glucose, which is then transformed into alcohol and carbon dioxide. Yeast is living organisms, however, and sometimes things can go wrong when dealing with them.
“When it’s too cool, the yeast is going to fall out and go dormant,” Thompson said. “When it’s too hot, it won’t activate.”
For this reason, the fermenter must be kept at a temperature somewhere between 55 and 70 degrees, depending on the type of yeast being used and the type of beer that is being brewed. Ales typically ferment at a higher temperature and for shorter periods of time than lagers. It must also be a closed system — that means no oxygen allowed after the yeast has been added. Yeast loves oxygen, but too much oxygen will make the beer flat and damage the stability of the flavor.
There are also side reactions occurring during fermentation that can form unwanted organic compounds which strongly influence flavor. For example, the type of yeast strains used to make ales will typically undergo side reactions that produce byproducts with fruity fragrances. Ryan Jackle and Sam Victory, the head brewers at Wise Man Brewing (826 Angelo Bros Ave.) in Winston-Salem, know more than anyone about the complications that come with fermentation.
“Sam, being a Ph.D. chemist, he brings to the table a whole other level of research and development,” Jackle said. “Bringing his chemistry background to the table is just great. He is basically a big kid. He likes to play with as many different microbes and yeast and hops and different ingredients, different techniques, different styles. We are almost like a research and development lab…. We always have at least a dozen to two dozen experiments going on somewhere.”
Jackle said it only takes a few days for the yeast to consume all the sugar available and for the beer to be considered technically “done.” But alcohol and carbon dioxide aren’t the only things being made, and after only a few days, the beer doesn’t taste quite right yet. Somewhere on its journey toward becoming alcohol, the sugar makes a quick pitstop and is transformed into pyruvic acid. Pyruvic acid is very reactive, and can sometimes be changed into another organic compound before the yeast can help it become alcohol.
“Some of those compounds are good, and some of those compounds are bad,” Jackle said. “One of the ones being bad would be diacetyl. The diacetyl is kind of a buttery flavor; it’s a slickness in your mouth…. What happens is the yeast produce this diacetyl compound, and if you give it time after the yeast is done fermenting it reabsorbs that diacetyl along with some other off-flavors. So, they reabsorb that stuff and put it back out as good stuff.”
Other off-flavors include acetaldehyde, which is a green-apple flavor, and hydrogen sulfide, which has the unmistakable smell of rotten eggs.
“When the beer is ‘done,’ that’s when we do a diacetyl rest,” Jackle said. “We jack up the temperature a few degrees for at least four to five days. That really kind of whips things up and makes sure the yeast are staying active and are able to clean up all that mess.”
After the diacetyl rest, the fermenter is set to a much lower temperature in order to force the yeast to go dormant and fall out of the solution. Then the finished beer is filtered out and packaged with the addition of extra carbon dioxide under pressure. The final step? Taste-testing.
“We have a sensory panel that consists of me and my two cellarmen,” said Jackle, laughing. “And we all taste the beers. It’s a tough job, but someone’s gotta do it!”
The job may be tough, but that hasn’t deterred many brewers. North Carolina is home to the largest number of craft breweries in the South, with over 300 breweries and brewpubs. North Carolinians love beer, and if the growing number of breweries is any indication, the Triad is no exception. In fact, the only thing stronger than the Triad’s love of beer is the community of brewers who make it — a community described by Jackle as “awesome,” and which Morgan could only shake his head and describe as “somewhat incestuous” due to how often the brewers partner up to collaborate.
While living in Asheville, Thompson originally planned for Goofy Foot to be a six or eight-tap brewery that sold his own beer exclusively. That changed, however, when he moved to High Point and was introduced to the brewers of the Triad.
At the time, Jackle worked at Big Dan’s Brewshed. While frequenting the shop for supplies, Thompson became good friends with Jackle, whose advice helped Thompson to develop many of the recipes that he continues to brew today. Thompson said it was Jackle’s kindness and knowledge that really pushed him to start up Goofy Foot.
“We kind of changed our model a little bit to be a taproom first and foremost, and all these buddies of mine around, we wanted to support them because a lot of people don’t even know they’re here,” he explained. “So we kind of wanted to be a tasting room for all the local North Carolina breweries.”
It seems that whether you’re looking to get into the science behind homebrewing or just looking for a good craft beer, the brewers of the Triad are a great place to start.
Marisa Sloan is a senior at the University of North Carolina at Greensboro. She is majoring in chemistry with a minor in English, and her work has also appeared in her school’s newspaper The Carolinian.