There's an Enzyme for That!
ARTICLE BY EMILY TIETJE-WANG, FOUNDER/LEAD SCIENTIST AT FERMLY
Cure to what ales you!
We all look to the big-name medals when going to a brewery. How many GABF medals do they have? Which styles? Is that what they are known for? What about World Beer Cup? All that shiny hardware with pictures of the brewer biting it plastered on social media around those events. In the midst of all of the drama of these national competitions for professionals, it is easy to not consider the roots of all of these dreams that have come true: homebrewing.
Before there were multiple official programs on fermentation, there was Michael Jackson and Charlie Papazian inspiring people to explore what they could make at home and arguably the beginning of the brewing boom. In all of that trial and error, skills were honed, discussions of iingredients and yeast became fuller, more vibrant. For some people though, why bother with homebrewing now when there is perfectly good beer in town or within a reasonable drive?
The presence of many professional breweries has not dampened the aspiring brewer spirit! Homebrewing competitions are alive and well. In fact, there may be several new homebrewers participating as a result of the pandemic since many people found themselves with ample time and a great deal of curiosity about how some of their favorites were made. But what makes now different than the naissance for homebrewers?
Enzymes are here to save the brew!
In creating a beer, it seems completely straightforward but what if there is a problem. What if there is an undesirable off-flavor? Was there not enough fermentable sugar? Is this not the right mouthfeel for the style? What about the clarity? What if it just isn’t quite right?
All of these problems can possibly be solved by using the right enzyme! But what enzymes are out there? It turns out, more than even some professional brewers are aware of!
Before we swipe right for an enzymatic brew...
Let’s have a science review! Enzymes are essentially complex proteins designed to break down other molecules (including other proteins). Some need to be properly wined and dined in a protein rest of the correct temperature and pH to become active proteolytic enzymes.
The proteolytic enzymes are proteinases and peptidases. Proteinase breaks down proteins, which affect head retention and haze, into smaller amino acid chains. Peptidase breaks down the amino acid chains from the ends inwards to release nutrients for the yeast. We then get to the stars of brewing: the enzymes breaking down carbohydrates. They snip sugars off of starches and other long-chain or complex molecules, creating the sugars that yeasts feed on for alcohol production. There are other byproducts, but those can be discussed later after understanding the enzymes that are already at work before brewing even starts.
Perhaps a little restraint?
Enzymes first become active upon germination of a seed. It is through this process that enzymes begin to break down the hard cell walls (made of cellulose fibers) to access starch reserves for growth to begin. There are two main classes of carbohydrate hydrolases that are already in the seed: ones to break down the cell wall into glucose, and others to convert the starch into smaller sugars once the walls are down. Cell wall hydrolases consist of β-glucanase, cellulase, and xylanase which break down glucose, cellulose, arabinose, and xylose. Starch hydrolases are familiar to most brewers and therefore will be discussed in that section: ɑ-amylase and β-amylase.
Maltsters have mastered the process of germination in controlled conditions so that enzymes are produced and released to start working on accessing the starch, but is then halted when the malt undergoes kilning. Excessive heat is not kind to enzymes since this causes the protein to unfold, a process called denaturing. After this, it is up to the brewers to make the malt into beer.
Brewers receive the malt and begin furthering the process of access to sugars by physical means through milling the grain. The goal is to crack open the grain to allow access to the starches, not to pulverize it since the size of the grist particle has a huge impact on the finished beer. The milled grain is mixed with water, heat is applied according to the recipe, and the cell walls continue to be destroyed and any enzymes that survived kilning continue the breakdown of starch. The purpose of mashing is to solubilize nearly a quarter of the malt matter, gelatinize the starches and convert them into fermentable sugars as appropriate for style and gravity, as well as release additional proteins and nutrients useful for the yeast. But which enzymes are at work during this step?
● ɑ-amylase and β-amylase: These enzymes both have the same goal: break down starch by adding water to produce usable sugar molecules. The ɑ-amylase has the advantage of breaking off larger chains of sugar molecules and is therefore credited additionally with improving clarification since larger molecules participate in haze creation. The β-amylase breaks off shorter chains of sugars to increase fermentation yield.
● β-glucanase: Glucans are polysaccharides made of glucose and this enzyme focuses specifically on breaking down the links between these molecules with the addition of water. This enzyme improves wort viscosity and increases fermentability of adjuncts by continuing to also work on the cell wall materials inconjunction with proteases which can clog the mash and interfere with filtration.
● Xylanase: β-glucanase’s sidekick that works on longer sugars, further improving extraction and can be helpful later in filtration.
● Amyloglucosidase: Glucose is broken from starch with this enzyme towards the ends, resulting in an increase in fermentability. This is great for creating lower calorie and lower carb beers, but providing glucose before other fermentable sugars can stall fermentation since the yeast will focus on it, not the other fermantables. This is known as glucose suppression/repression.
● Limit-dextrinase and pullulanase: Cleaning up sugars left behind by amylases isn’t an easy job, but an enzyme hs to do it! Limit-dextrinase is active in the mash for a short period of time before it is inhibited, but it focuses on breaking apart the highly-branched core of the starch fragments after the other hydrolase enzymes have had their way. This increases fermentability. Pullulanase can be used for the same function without the concer of inhibition.
● Proteases: Proteins need to continue to be broken down not just for their sugar content, but also their opportunity in increase free amino nitrogen which is important for yeast growth. These should also be considered for reducing protein haze in the finished beer. Chemistry Fun Fact: When referring to ɑ (alpha) and β (beta), it is a descriptor for the structure of the molecule’s position of hydrogen and the hydroxyl (OH) groups. These positions affect the linkages between the sugar molecules, and not all enzymes can work on every linkage. This is why multiple enzymes are necessary to adequately break down starch. This concept can be applied to many digestive processes!
My kink is not your kink, and that’s okay.
Heat can create a great environment for enzymes to do their work, but unfortunately, they begin to unfold when the heat is turned up during the boil. Enzymes are carefully folded and kinked together to do their job, so even if one ɑ-helix or β-pleated sheet moves out of place, some enzymes are using their safeword to stop. Starting off with β-glucanase at 140 oF (60 oC), enzymatic activity begins to drop off. In some brews, it may be desirable not to boil to temp so the enzymes can carry through to the fermenter.
Fermentable sugar-seeking yeast. Must have own fermenter.
Since pretty much all of the enzymes were denatured during the boil, it may be necessary to add a few to help along towards a particular style while the yeast do their work. We have some old friends, but who doesn’t love a little guest appearance to keep things interesting (and tasty)!
● ɑ-amylase: Carried in originally with the malt, adding this enzyme again will continue to increase maltose and glucose content, thereby adding to the plentiful fermentable sugar by the same method it did so in the mash. This enzyme is particularly useful when it comes to light beers.
● β-glucanase: This enzyme continues to clarify the beer as well as lower the carbohydrate value for lighter beers. As it continues to hydrolyze sugars, it lowers the maturation time of the beer and improves filtration.
● Alpha-acetolactate decarboxylase: Also know as ALDC, this enzyme is sometimes mandatory to reduce fermentation time but also avoid one of the most well-known off-flavors: diacetyl. This enzyme catalyzes the conversion of ɑ-acetolactate, a natural byproduct from yeast during primary fermentation, to acetoin. This is accomplished by cleaving the carbon-carbon bonds to the carboxyl group, making it no longer a precursor to diacetyl. Although yeast can clean up diacetyl on its own, this requires time and temperature, which may be limited on a brewing schedule. It is something to consider that less of this enzyme needs to be added if it is later in fermentation since the hope is that the yeast has already done a significant amount of clean-up and may just need an extra bump to avoid any further presence of diacetyl. Keep in mind that this off-flavor is acceptable or expected in some styles.
Enzymes can be a game-changer in addressing the gluten content of beer. Multiple companies produce endopeptidases, proteases that target cleaving around the proline amino acid, which can be added post-fermentation to break apart the proteins that trigger reactions in gluten-sensitive individuals and those dealing with Celiac disease. These beers are considered gluten-reduced or gluten-removed and must measure below 20 ppm to qualify for specific labeling requirements. All of that being said, these proteases do not necessarily break down the parts of the protein that can trigger a reaction in an individual and therefore can open up the possibility of lawsuits. It is important to consider this aspect when marketing a beer because enzyme usage is an imperfect alternative to a beer brewed with gluten-free ingredients.
Terms and conditioning.
Protein can still be present in the beer, continuing to present a haze or causing trouble with filtration. Breaking the proteins down into smaller bits will help reduce turbidity that may form in the beer by adding proteases during conditioning. In proper conditioning of the beer, it is also hoped to improve the storage quality of the beer.
Did you even read the bio?
Many enzymes, as discussed, are already in the malt and are released during the malting and mashing processes. However, for ones that may be added in addition to or for some extra, let’s say oomph, in the brewing process, they may be sourced from elsewhere.
● ɑ-amylase: From bacteria Bacillus licheniformis and Bacillus subtilis or the fungus Aspergillus sp.
● β-amylase: From bacteria Bacillus licheniformis.
● β-glucanase: From bacteria Trichoderma sp. and Orpinomyces sp
● Proteases: From bacteria Aspergillus sp. or pineapple latex.
● Alpha-acetolactate decarboxylase: From bacteria Bacillus subtilis recombinant.
● Amyloglucosidase: From bacteria Aspergillus niger.
Many of these bacteria and fungi are common and may cause concern if found during plating or PCR analysis, but most are harmless to a beer and will not tremendously affect the final product.
Enzymes sent you a message!
Brewing is a process that takes time, patience, temperature, and by no doubt some talent and training, but enzymes can be used to help in many of these aspects. Starting at the malt through storage, fermentable sugars to weakening the seemingly indomitable gluten monster, these hard-working compounds can ease many a brewing woe by reducing variability in ingredients and addressing unexpected changes from adjuncts. It is easy to judge the process when using enzymes, but at the end of the date, wouldn’t you rather judge the final product?
Still have your doubts? How about a background check done by Zac Rissmiller, head brewer/co-owner of 1623 Brewing and multiple Great American Beer Fest medal-winning brewer:
“ The understanding of enzymes and what they do biologically can really set your beer apart in the fermentation process. They have the potential to shorten run-off times where haze is not a factor. With the use of β-glucanase, rice hulls can be eliminated and may significantly increase your yield of wort in run-off. Alpha acetolactate decarboxylase enzymes can prevent diacetyl from forming. Enzymes are, quite frankly, in everything we do, including when to inactivate them. Learning about what enzymes do and how they work can really increase the quality of your beer. “
About the Author
Emily received her Bachelor of Science in Biology and Chemistry from Le Moyne College in 2009. Having always nurtured a passion in microbiology and chemistry, Emily has always enjoyed being in a laboratory environment. Her altruistic nature and desire to care for others gave her eight years of success in the medical field and acceptance into medical school. After choosing to forgo medical school, Emily moved to Colorado looking to rekindle her passion for the laboratory sciences. After a hard weekend of enjoying craft beers, Emily decided to grab life by the pint glass and founded Fermly in 2018. Emily is a Certified Beer Server in the Cicerone program and a provisional BJCP judge.