Let’s talk about enzymes. This is a blog about enzymes used in brewing. At this point we know much more about enzymes and the working of enzymes than back in the day. To make this message as comprehensible as possible, I want to put it out through a number of questions.
What is an enzyme?
First of all, enzymes are not alive like microbes are, therefore enzymes are not microbes. But what are enzymes then? Enzymes are macromolecular biological catalysts that enable chemical transformations into organisms or organic material. The molecules on which enzymes work are called substrates, and the by enzyme converted substrates (into various other molecules) are called products. Almost all metabolic processes in the cell require enzyme catalysis to be able to take place quickly enough to sustain life.
Fig. 1 Example of enzyme, substrate and product
Enzymes are generally recognized by the suffix -ase, such as in protease, an enzyme that degrades proteins, and amylase, an enzyme that degrades proteins. They are a class of proteins that evolution has built to serve specific but different functions. Exactly how enzymes work is rather complicated. But I will try to explain the very basics of enzymes. Enzymes are extremely picky, not every enzyme can work on every substrate. They are even so picky that each enzyme can only act on one specific substrate. They leave all other substrates alone. When the enzyme has found its right substrate, they can cut long substrates into shorter, workable products.
Enzymes work the most efficient in a warm and fluid environment, generally speaking. But when you heat the enzymes too high they become inactive and then they no longer function.
How do we already use them?
For brewing we wouldn’t be anywhere without enzymes. They are at the very beginning of the brewing process. And actually, we love enzymes. We even love them so much that we create a perfect environment for them to do their job. We call it the mash! When we make a mash we work with certain parameters; pH, temperature and time. That’s all what it takes to make sure that the enzymes are happy and do the job that we want them to do. Converting all that starch into fermentable and unfermentable sugars.
With different mash-steps we activate different enzymes;
|Phytase||30-52°C||Lowers the mash pH|
|β-glucanase||20-50°C||Breaks down the gum in unmalted grain|
|Proteases||20-65°C||Solubilize insoluble barley storage proteins|
|Peptidases||20-67°C||Produce free amino nitrogen (FAN) from soluble proteins|
|α-glucosidase||60-70°C||Cleave maltose and larger sugars into glucose|
|Limit dextrinase||60-67°C||Cleave limit dextrin|
|α-amylase||60-75°C||Produces a variety of sugars and dextrins, including maltose|
Source; How to Brew, John J. Palmer
Since we know what these enzymes do to our mash and eventually to our beer it’s possible to help the mash a little bit and add some extra enzymes during the mash.
What else can we do with it?
In addition to using all those enzymes that are naturally present in the mash. We can even add some more enzymes during the mash or we can also apply them in a different way. Think about the Brut IPA that is getting more popular over time. The Brut IPA is a IPA that is fermented to a gravity of 0° plato. Not because of the yeast in most cases but because of enzymes. The more fermentable sugars, short sugar chains, the more a yeast can ferment. And therefore we can get a really dry beer. It’s because of enzymes that we can have this new beer style that we call Brut IPA.
Let’s stick with IPA’s because not only Brut IPA’s can profit from the use of enzymes. Think about β-glucosidase, which is already present in yeast, especially during fermentation when cells are highly active. We can use this enzyme during fermentation, especially with dry-hopped beers. Because β-glucosidase breaks down the bonds from a glycoside compound, which are present in hops. By breaking this compound down, it releases a fermentable sugar (glucose), an linalool (an aromatic hop oil) and a molecule of water. This is also the reason why there can be some refermentation after dry hopping. It may be clear that some yeast strains have more enzymatic activity than others. There are also some other examples of this interaction, between β-glucosidase and glycoside compound, like the transformation of geraniol into citronellol or linalool into terpineol. These transformations give a more complex hop profile to the beer.
Fig. 2 Mechanism of aroma release.
For a brewer it is also important to know and understand that this beautiful interaction can cause unfavorable effects when we dry hop our beers during active fermentation, also known as primary fermentation, will lead to the reduction of hop oils by:
– CO2 stripping (hop oil can evaporate since they are very volatile)
– Masking (compounds that are present during fermentation can mask the hop oil aroma)
– Adsorption (hop oils adsorbed by yeast membrane)
When your dry hopping takes place at the very end of the fermentation, where there is lower CO2 production, but your yeast is still active, the following benefits occur:
– Less CO2 stripping
– Reduction of DO by active yeast during dry hopping
– More solubility of hop oil, because of the presence of ethanol
– More solubility, because of a higher temperature, thanks to fermentation
– Mixing effect due to beer turbulence, thanks again to fermentation
|Enzyme||where to add||Function|
|Proline-specific endoprotease||fermentation and/or brite tank||Used for gluten reduction and chill haze reduction|
|Amyloglucosidase||fermentation||Amyloglucosidase used to increase the breakdown of dextrins to glucose|
|Pectinase||secondary fermentation||Reduce the hazing effect of pectins when using real fruit in your beer and speeds up the extraction of fruit juice|
|alpha‐acetolactate decarboxylase||primary- or secondary- fermentation||Prevents the formation of diacetyl in beer during fermentation and storage|
All these enzymes may sound new to you but we are using them already in our brewing process. These enzymes are getting more widely available as we speak. And I’m wondering what enzymes are still to be discovered for the use of making beer.