Inside the Seed: The Enzymatic Voyage from Malting to Mashing

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Inside the Seed:

The Enzymatic Voyage from Malting to Mashing

Written by Mark || 12/20/16

Some people brew just to have a steady supply of their own fresh beer, but I would argue that most home brewers are nerds at heart. We get overly excited about hitting a target mash pH or building the perfect yeast starter. Whereas most people were happy to be done with science after high school chemistry, we willingly pick it back up.

Why? For one, because our beer gets better.

At first, this didn’t seem worth it. My initial attempts at learning the biochemistry behind beer were no fun at all. I did not see how understanding the difference between alpha-amylase and beta-amylase would do me any good. That is, until I actually understood the difference between the two enzymes.

I’m sure you recognized the protein structures of alpha-amylase

and beta-amylase. I definitely (cough) did.

My stumbling block was that the names of these enzymes meant nothing to me without the larger context of what was happening to the grain every step of the way. For me, this meant going back to the beginning of the story, well before the mash, when there was just a little seed waiting to be malted.

As stand alone subjects, malting biochemistry and brewing biochemistry didn’t make sense to me, but when I started thinking about the process as a whole, it all came together. By tracing the enzymatic thread through malting and brewing, I learned an important lesson: malting and mashing are part of the same story. Mashing is not the start of something new – it merely continues the enzymatic progress that started during malting.

Once I had the full story, I no longer felt like my mash was just a nice hot bath for my grain – now it’s a nice hot bath with a purpose.

Putting the Bio in Biochemistry

Many brewers primarily consider themselves to be chemists, but we should not forget that we’re all also biologists. At a fundamental level, we are transforming plants and bacteria into beer.

It might feel unnatural to talk about it this way, but we are working with living organisms. Of the four main ingredients in beer–malt, hops, yeast, water–it is easy to see that the yeast are still alive and the hops (if fresh) were recently picked off a living plant, but the malt tends to be a bit farther from its growing days. It has already been chemically altered in the malting process, and has probably sat in some silo for a matter of months or years. We tend to forget that it’s a plant, and think of it merely as an ingredient.

But obviously, malt started as a plant, in most cases as a barley seed. Through malting and brewing, we are attempting to squeeze sugars out of this tiny seed. Then we feed this sugar to our yeast so that they can make us alcohol. Pretty simple, right?

Brewing can indeed be simple if we want it to be. If we brew with extract, all the sugar squeezing has been done and we’re good to go on to the next step. It’s easier, but perhaps less interesting. We make the leap to all grain brewing because we have a burning desire to squeeze those sugars ourselves. We want to have a larger role in this beer opera.

I started malting for the same reason. I thought it was an interesting biological process in itself, but it became way more intriguing and relevant to my brewing when I understood the enzymatic connection between the two. On brewday, I was picking up where my malting left off. It wasn’t a new story, just a return from intermission.

If one key to making outstanding beer is figuring out how to manipulate that seed’s enzymes to work for me, then I’d like to be involved in Act 1 of this great enzymatic drama. So as I said before, it begins with a seed…

The Journey from Seed to Wort

Grains are fixed on a biological loop: seed → root → shoot → leaf → flower → seed. They will keep cycling in this way for unlimited generations under suitable conditions. A grain farmer participates in this loop by trying to provide those ideal conditions. Farmers are benevolent gods, and they have reason to be – it’s to their advantage and profit that the seed they planted completes the loop and produces more seeds.

The maltster and brewer have other plans for the seed. They make their dollar bills by disrupting the loop. They will work together to squeeze every last drop of sugar out of the seeds. They are cruel gods.

Of the two of them, the maltster is the trickster. They send the seed down a familiar path at first: germination. This means providing the ideal conditions of springtime to coax the grain into growing. As a result, the seed will do the hard work itself – it will break down the structures surrounding its starchy energy reserves and make them accessible. This energy would go towards helping the plant build its roots and shoot, but the maltster has already laid claim to those sugars. The maltster dries the seed back down so that the grain can’t use up the sugars to grow any more.

That’s the short version. Let the seed start growing, then abruptly stop it. When the brewer is ready, they pick up where the maltster left off. In order to understand how mashing is really just a continuation of the malting process, we need to look inside the seed at what the enzymes are doing.

Introducing… Enzyme Squad

Like I said before, I had a terrible time trying to understand malting and brewing biochemistry. Without the context of a story, the technical terms kept me from making any sense of what was happening. In an effort to keep your brain from shutting off immediately because you saw the word “arabinoxylan,” I’m going to make this real basic and relatable. I know this is corny as hell, but bear with me. It’s story time.

Let me introduce you to Enzyme Squad (ES for short). They’re a mining crew made up of the most badass enzymes around. They do all the work of malting and brewing – you are merely their puppet master.

Enzyme Squad lives inside the seed, waiting to be called into action. They work deep in the inner reaches of the seed, in a place we call the endosperm, which is made up of many individual cells. Inside the endosperm cell walls, there is a dense protein matrix with treasures buried inside. These precious treasures are called The Starch. It is Enzyme Squad’s life purpose to mine The Starch and refine it down to its simple sugars. These sugars will power the fledgling seed’s quest for world domination!

As powerful as ES is, they need some help to get started. Each member of the crew works best at different temperature ranges, but they all need a wet environment to move around and do their work. This is where the maltster steps in.

The maltster’s job is to make sure each seed germinates at the same rate. Some seeds have more efficient Enzyme Squads than other seeds, a difference that is accentuated if the maltster allows for a rapid germination. So rather than starting off at any enzymes’ optimal temperature range, the maltster provides a very cool environment to slow all the Enzyme Squads down to the same sluggish pace.

Enzyme Squad Takes on Malting and Brewing!

(The maltster/brewer’s tasks are described briefly in italics, followed by a dramatic retelling of the events unfolding inside the grain…I took liberties in personifying the actors, but in truth, enzymes have no feelings or motives)

STEEPING: You submerge the grain in cool water for a couple days to hydrate it. It is common practice to interrupt the steep with one or two long air rests. This entails draining the water to keep the grain from drowning, allowing several hours for it to breathe.

The steep signals the beginning of the work season. It feels like springtime has arrived. ES has been stuck inside their homes all winter, bored out of their minds, unable to go anywhere. With the water rushing in and hydrating their world, they can finally move around the seed again.

Cross-section of a barley seed. Not anatomically perfect, but close enough.

Water enters the grain at one end, the tip that contains the embryo. Consequently, this is where activity initially takes place. There are some stores of fats and sugars in the embryo that power the early action.

The first actors called into play are the gibberellins. They are a group of hormones that live in the scutellum. They’re not officially part of ES as they are not enzymes, but they get everything rolling. The gibberellins move out to the aleurone layer, which is located close to the outer surface of the seed. The aleurone surrounds the deep inner recesses of the endosperm. Thus, it’s the perfect launching point for ES to embark on their mining expedition.

When the gibberellins get to the aleurone, they find that Enzyme Squad has fallen apart during the long dry season, quite literally. Each enzyme needs to be synthesized before it can be of any use to the mission at hand. And synthesized they are: alpha-amylase, beta-glucanase, xylanase, and the proteases – a ragtag group of champions! Off to go retrieve The Starch!

GERMINATION: Once the moisture content inside the grain is high enough from steeping, you allow the grain to germinate for several days. Germination will happen most consistently in a cool, moist environment. Rootlets will emerge from the embryo and an acrospire (the first shoot) will start to lengthen inside the husk.

Once germination starts, Enzyme Squad’s work season really gets underway. They eagerly begin to mine for The Starch, a process known as “modification.” The enzymes closest to the embryo were roused by the gibberellins first, so they are the first to get to work. Thus, the mining/modification progresses from the embryo to the opposite tip of the seed, and from the aleurone layer inward.

Diagram of an endosperm cell. Again, not anatomically exact, but you get the picture.

ES is a great team, so they all play to their strengths to get the job done. For example, beta-glucanase is a brute – ES sends it in first to break down the endosperm cell walls. Once beta-glucanase puts a hole in that wall, the proteases can enter the cell to break down the next line of defense. They chip away at the protein matrix until they can see the glimmer of The Starch.

But that is not the proteases’ only amazing discovery: they also uncover beta-amylase! Their invaluable teammate from Enzyme Squad had been trapped in the protein matrix this whole time! Beta-amylase is ecstatic to be freed and to see its pal alpha-amylase. With impressive vigor, the two amylases set to work on breaking The Starch down into its simple sugars. They’re one step away from completing their mission! Then the sugars will be transported to the embryo, where they will be used to build deeper rootlets and a taller acrospire than the world has ever seen, and then nothing will stand in the way of…

KILNING: You’ve decided that the germination process has progressed to your liking, so you start to dry the grain. This is usually done by blowing warm dry air through the grain until its moisture content has dropped considerably, then ramping up the air temperature to develop some flavor in the finished malt.

Whoa, hold on… this wasn’t supposed to happen. Enzyme Squad’s work grinds to a halt as their world dries up. They are rendered powerless and immobile – their tools are water-powered and their transportation channels need to be wet to function. Beta-glucanase and the proteases had all but wrapped up their work, but the amylases hadn’t finished breaking down The Starch.

To make matters worse, the high heat at the end of kilning kills off some beta-amylase. If it gets much hotter (say, while roasting malts), this destroys a significant amount of both amylases. What a horrible turn of events.

STORAGE: When the finished malt has reached a very low moisture content, you remove its dried rootlets and store in a cool, dry environment until it is ready to be brewed.

There is nothing that Enzyme Squad can do – it’s too damn dry.

MASHING: It’s brew day! You mill your malted grains, heat up your water, and combine the two to make wort. You can leave the wort at a set temperature for an hour, or “rest” it at different temperatures for allotted times. At the end of the mash, you sparge the grain with extra hot water to rinse the remaining sugars from it and to raise the temperature of the wort to end enzymatic activity.

After the interminable dry spell, the situation progresses quickly. Enzyme Squad’s world has been broken open by the grist mill, and they are surrounded by water again. Plus, the temperature is significantly warmer than it was during germination, much more to their liking. The amylases set to work at a feverish pace, breaking down The Starch faster than ever before. To add to their speed, the hot water causes The Starch to swell up and burst – this gelatinized mess is even more accessible to the amylases. All of the restraint of germination has gone out the window.

Alpha-amylase and beta-amylase are an unstoppable duo. Alpha-amylase breaks the complex starch structure down into dextrins, which beta-amylase then snips into maltose. This pace is surely unsustainable. Some maniac starts heating the wort up again, and…

Smmooosh… the sound of enzymes denaturing. The wort has gotten so hot that the last members of Enzyme Squad fall apart. A tragic end to such a heroic journey.

THE REST: You got your sweet wort, are you happy? You bring the wort to a boil, add some hops, cool the wort back down, then throw some yeast in there. End of story. You exploited everyone from Enzyme Squad, making them work so hard to get those sugars, then you killed them all and stole the sugars. And all for what? So you can drink some beer? You’re a monster…

The Final Word

You’re not really a monster. It’s OK to kill enzymes. I didn’t write the Enzyme Squad story to make you feel bad about yourself – I wrote it to share how I understand malting and brewing biochemistry to hopefully give you a better understanding too.

Malting and brewing are part of the same story that begins when the seed leaves its loop. The maltster and brewer collaborate in beer making, but they’re cut off from each other. They think they’re each doing their own thing, but from an enzymatic standpoint, it’s all the same long process. They’re really co-puppet masters, both in control of Enzyme Squad, both working to steal The Starch for the sake of beer.

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