Below is an overview of the process to make beer. There is a fair bit of information covered, so it might be worth sitting back and taking your time as you go through it; perhaps with a home brew of your own as company!
You may want more information to quench your thirst for brewing knowledge, so I would suggest getting some good books on the subject or you could follow the “Weekly Mash” page on this website which will cover a number of topics in more detail over time.
No matter if you are a home brewer churning out a couple of batches of a year or working in a massive brew plant there are three main stages in making great beer:
- Brewing
- Fermenting and storage
- Packaging
With our four important ingredients:
- Malt
- Hops
- Yeast
- Water
In a nutshell you could summarise all the process in one sentence.
“Brewing is the process where the sugars from malt are extracted in hot water while the hops are added, fermentation is where yeast converts the sugars to alcohol and other flavour components, while storage is where the beer clears of haze and matures in flavour”.
Pretty well there is not too much more to the process, however, there is a fair bit to learn about each step if you want to become a good home brewer. The brewing story has a few chapters and interesting characters involved so settle in for a great thriller!
Brewing Basics
Ok, so how do home brewers get the sugars out of the grain, I can hear you thinking? This is where we initially rely on our great friends the Maltsters. If it wasn’t for them, we would not be brewing at home or anywhere else for that matter.
There are a wide variety of grains that we can use for brewing, each having its own type of flavour profile that you will taste in your home brew. The predominate one is barley.
Malting
The sugars you get in your brew kits or the grains purchased in a brewing supply shop have all come from the malting process. What happens is the plants in the field grown by the farmers are harvested and processed to separate out the grains, for example barley grains. Each grain is a seed with the intended purpose to make more barley plants, unfortunately for the barley plant, its seeds also make great beer. Barley comes in either two row or six row varieties, depending how the seeds are arranged on the plants. Two row barely tends to have a higher sugar content so it is generally better for brewing.
Each grain has a number of parts including the bran (the outer covering), the embryo (the germ cell which grows) and the endosperm (the nutrients including carbohydrate, proteins and some vitamins) that the embryo uses for nourishment when the conditions are right and it germinates to grow.
Unfortunately, the sugars stored in the barley are no good for brewing. They are complex carbohydrates, being too big to go through the wall of the little hero of brewing, our yeast cells. This is why we need out maltster friends.
Fundamentally, what the maltsters do, through a great deal of trickery involving temperature and moisture, is fool the barley grains into thinking the conditions are right to commence growing, so they start to germinate. The whole process takes several days with some specialised steps. Enzymes within the grain are produced being the little catalysts in the grain that help convert the sugars. Once the grains start to germinate, the grains enzymes start to convert the long chain storage carbohydrates into short chain sugars like maltose, which the embryo could use for energy to start growing.
There is one more little twist to the process. The maltsters can control their kilning profile to determine the characteristics of the malt produced. They use this to produce different types that they sell. The longer the malt is left in the kiln at a higher temperature, the darker it gets. Generally speaking the darker the colour of the grain, the less fermentable sugars it has, as the extra heating burns them to oblivion and the enzymes which do the sugar conversion are denatured (they won’t work anymore). So malt colour ranges from our the straw coloured pale malt, to our crystal malts, roasted malts and right up to our black barley.
Incidentally, I worked once with a gentleman who use to get black barley and grind it up to make what he called his “coffee equivalent”. I tried it, an interesting burn ‘t flavour, but I don’t think Starbuck’s has anything to worry about.
So why would the maltsters want to roast these malts and destroy the beautiful sugars our yeast needs to feed them? It all comes back to flavour. The darker a malt is, the less fermentable it may be, but the greater the effect it will have on the colour or tint of the beer as well as its flavour. So that’s how we can make anything form a pale ale to a dark stout, by what types of malt we use in combination.
So it is really a balancing act, pale malt has more fermentable sugars, with more enzymes ready to convert them, but less colour and body to add to the final product. While darker malts have less fermentable sugars and enzymes but add colour and body to the beer. That’s why you will find a lot of home brewers use a mix of grains to get the alcohol, flavour, tint and body of the beer they want.
Milling
The maltsters have done their job and can head out for a well-earned break. The modified grains, now called malt can be handed over to the brewers to work their magic.
Once a brewer receives their malt, the first task to get it ready for brewing is to mill it. The milling is generally done just before the start of the brewing process as this way the sugars in the malt are protected inside the husk of the grain until they are needed.
The aim of milling is to crack open the grain so the sugars inside can be extracted for fermentation later on. Milling is a very important step for if you get it wrong, your beer will suffer. Generally, the malt is milled through a series of spinning rollers set at a precise distance apart to get the perfectly milled malt. If the rollers are too far apart the grain will not be crushed enough meaning you may get some whole grains getting through. This will mean there will be less sugar extracted later in the process for the yeast to ferment. Not a good thing at all.
Alternatively, if the rollers are too close, the malt will be ground up into a fine flour which can block up the process later, by causing what is a stuck mash.
This is why brewers always check their mills and pay particular attention to make sure they have “goldilocks” milled grain, not too finer and not too thick- just right!
Mashing
Mashing is simply where the milled malt is soaked or “steeped” in hot water to extract the soluble sugars needed for brewing. The “dough-in” is where the dry malt is mixed with the water to start the process. The temperature and the acidity (pH) of the water is very important during this process to gain optimal results. In fact, it is the temperature that brewers primarily use to determine how fermentable the wort they produce will be. There are also a range of enzymes in every grain of malt that are required to continue the job the maltsters started converting the remaining storage sugars in the malt such as starch to fermentable sugars such as maltose.
Brewers will also add salts to their water to create an optimal pH during mashing in. They target between 5.1 to 5.4 to ensure they get the best conditions for the enzymes to work to convert the sugars.
The different enzymes that are required to do a job during the mashing each has a different optimal temperature which is why brewers accurately control and ramp up the temperature during the mashing cycle. Some enzymes are there to remove beta-glucans, others for protein, while the rest are for sugar conversion. The process of enzymes turning storage sugars into soluble fermentable ones is called saccharification. The key enzymes are:
Beta glucan: Is active between 46.1oC and 47.2oC and is used where a malt has a high beta glucan content which will cause the mash to be sticky and hard to run off.
Proteolytic Enzymes: break up proteins in the grain that cause haze. They do their best work between 50oC and 57.2oC. The time within this temperature range is called the protein rest.
Beta Amylase: Works well between 60oC to 65 oC and converts complex non-soluble storage sugars into short chain simple fermentable sugars. The longer the mash stays in the dryer the beer will be.
Alpha Amylase: Is most active between 65oC and 71.1oC and this is the range most brewers use to convert the storage sugars to the simple fermentable ones they want. These enzymes convert the storage sugars into longer chain simple sugars than the Beta amylase enzymes and give more mouth feel to the beer.
The final phase is where the temperature is raised to 76.6oC which “denatures” the enzymes or kills them for want of another term. There is no more sugar conversion.
Generally speaking, due to the good quality malt we have now, most brewers tend to use the high-end alpha amylase rest temperature for around 45 minutes to do their conversions. However, there are times depending on the malt you may wish to use a glucan, protein or beta amylase rest at the right temperature.
Recirculating or Lautering
Ok, we now have this wonderful mixture of water with dissolved sugars and lots of grain husk. The next thing we do is to recirculate the liquid, generally within a vessel with a false bottom called a lauter tun. This is done using a mesh at the base of the vessel which the broken the husks of the malt cannot fit through, but the sugary water can. By collecting the liquid at the bottom of the vessel and pumping it over the top (recirculating), the grain husks create a bed sitting on the mesh, which helps collect more husks until the liquid starts to clear up. In effect the broken grain husks become a filter bed for cleaning up the liquid. Big breweries also have set of rakes set up that move through the grain to help it spread evenly across the lauter tun and give a good even run off of the liquid.
One it has been decided the liquid is clear enough, the recirculation is stopped and the liquid once is pumped to another vessel to be collected. There can still be fair amount of those wonderful fermentable sugars sitting in the broken grain filter bed which is where sparging comes in.
Sparging is where the brewer trickles clean water through the grain bed to wash out and collect any remaining sugars. The volume of sparge water is calculated so enough of the remaining sugars are collected, but the sugary liquid is not diluted too much that the taste of the beer will be adversely affected.
We can now call the sugary liquid that has been collected its traditional brewing term- “wort”. Pronounced as “wert” if you want to sound authentic! The left over broken up malt sitting in the lauter tun is called spent grain, but don’t worry it is not wasted, big brewers often sell it to farmers as it makes great nutritious feed. Home brewers can give it away to neighbours with chickens for example or find a great recipe on line to make dog biscuits!!
Boiling
Here comes the next stage, quite often where the brewers can get a bit of a break in the process. The boiling! The collected work must be boiled and this is done for a number of key reasons:
- Sterilisation- if you boil wort for long enough, no known nasties that will spoil your beer will survive. You must remember, that the malt was grown in a field open to all forms of natural bugs and bacteria. Despite the fact it has been malted and mashed, it has not been sterilised so it is possible some nasties have survived in the wort waiting to cause havoc with our beer if were to ferment it without boiling it.
- Enzyme denaturing- the high temperature destroys all the enzymes left from the mashing stage, meaning they cannot convert anymore sugars from storage to fermentable.
- Boil off volume- The boiling process helps to start concentrating the liquid we now call wort as some of the water is boiled off. This can be up to around 10 percent of the volume depending on how long and how vigorous the boil is. It can
- Hotbreak- this is where the proteins in the wort coagulate and form clumps or flakes. You generally see it when your wort comes to the boils and you will see a white foam forming which will need to be patted down with a brewing paddle to stop a boil over. The proteins in the foam clump together and slowly sink to the bottom. These proteins can cause a chill haze in your beer if you don’t have a good hot break. One of the reasons we boil for an hour is to have a good hot break to get rid of as many of the proteins as we can in the bottom of the vessel.
- Hops are added during the boil. Depending on the type of hop and how long you leave it in the boil, will determine the flavours and aromas passed onto your beer. Simply put if you put your hops in at the start of an hour-long boil, most of the aromatic components are quite volatile and will boil away, but you will be left with the bitterness in the taste. Alternatively, if the hops are added towards the end of the boil, they will pass on less bitterness in the taste, but you will keep much more of the hoppy aroma in the beer. There are some other tricky biochemical reactions that are going on, but fundamentally that is how it works. So, your choice of either bittering or aromatic hops and how long you add then into the boil can have a significant effect on the final outcome.
Boil Time
The amount of time you should boil depends on the type of beer you are making. Generally, I would suggest going below 60 minutes for good sterilisation and hot break. Some people do get away with 30 minutes for an IPA but this is pushing it. In some cases, a 120 minute boil is required for beers with a large Pilsner malt loading. This extra time helps boil off a component in the malt called dimethyl sulphide (DMS), which is found in all malts but particularly in Pilsner and gives your beer a smell like cabbage if it remains!
Additives
We now know we add hops to the boil, but they are not the only additives added by brewers to the boiling wort. Whirfloc comes in a tablet formand can be added towards the end of a boil. These tables are are a blend of purified Kappa carrageenan and Irish Moss. It helps aid the precipitation of haze causing materials such as proteins and Beta glucans.
Whirlpool
After boiling we now head for the whirlpool. Some big commercial brewers transfer the hot wort form the kettle to a designated whirlpool vessel for this task, but most home brewers can do this in the boiling vessel before transferring the wort out. It simply involves getting a whirlpool effect going in the kettle by using the paddle or any other instrument to move the wort around in a circular motion until you get enough momentum that you can see a whirlpool effect. Clockwise or anti clockwise, it doesn’t matter! What this does is to separate the waste material of the hop pellets and “trub” (left over protein material from the hot break) from the wort after the wort boil. This tends to settle down the bottom centre of the vessel as a sediment which you need to be careful not to transfer when you send your wort to the fermenter.
Transfer to Fermenter
Now we have to undertake one of the most important tasks of a brewer, getting the beautiful hot wort cooled and transferred into a lovely clean fermenter while making sure the wort is oxygenated to help the yeast start fermenting when we add it later on and the trub is left behind!.
There are a whole range of methods used to do this from picking up the kettle and tipping in into a fermenting vessel which is sitting in an ice bath (not my favourite), using a siphon system, through to having a designated pump collecting the wort from the kettle and sending it through a heat exchanger to the fermenter (my favoured method). In addition, having an air pump with a sterile line and diffusing stone (like in a fish tank) to oxygenate the wort in the fermenter is quite often used.
Whatever way you choose to get the wort into your fermenter be it a stainless steel vessel or carboy, there a few thing we need to do:
- Leave the trub in the kettle
- Cool the wort
- Aerate the wort
- Put the wort into a sterile fermenting container.
When cooling the wort it is best to do it as quickly as possible to get a good “cold break”, which is why I prefer some form of heat exchanger system which could be running the wort through a coil in an ice bath or a counter flow system with running water. The cold break consists of another group of proteins that precipitating out of the wort when it is cooled quickly. These proteins cause chill haze and will not precipitate out if the wort is cooled slowly.
One last thing to remember is to take a sample of the wort before pitching to measure the gravity with a hydrometer (which will be the original gravity) prior to pitching the yeast. This will be handy when determining how well your brew has fermented over time as well as working out the alcohol volume in your final product.
Once in the fermenter it is time to pitch (add) the yeast to the wort. Homebrewers can obtain their yeast in a granular or liquid state ready to pitch. They are a pretty hardy organism yeast cells, dedicated to creating a lovely brew for us. They don’t ask for much in return but really need five things to do their job well:
- A good wort mixture for food
- Being pitched in the wort at the right temperature- too hot or cold can have dramatic effects
- A good level of oxygen in the wort to start with the help the yeast. This will get consumed by the yeast and we will want to keep oxygen away from the process after this.
- A nice clean fermenter
- The correct temperature to ferment at which will vary depending on the yeast
It is important to follow the instructions that came on the packaging with your yeast as best you can. Some yeast may require a starter to be done, which is doing a small controlled fermentation a day or so before your brew is ready, so the yeast is very active when pitched. The yeast packaging will all have information on the temperature you should try and keep the fermentation at (lager yeasts are much lower than ale yeasts).
Fermentation
Now comes the time of patience, waiting for the fermentation to run its course. Straight away, it is important to remember that yeast is not like a tardy child running late for school that you can hurry up. It needs time to do its work, all you can do is give it the best conditions to work in with regards to temperature and try not to disturb it too much.
The yeast is working away to convert sugar into alcohol and CO2 with all the other lovely associated flavours we associate with a good beer!
The fermentation will go through several stages where it will most likely be quite dormant to begin with and build over the first day or so until it becomes very active. You can tell how active the fermentation is by hearing the CO2 bubbles coming through the water filled airlock in the top of the fermenter. It is during the active stage that if you have a clear fermenter you will see a creamy foam substance forming on the top of the wort which tends to stick to the sides. This is called “krausen”, and consist of wort proteins and yeast cells. Quite often you can spot darker patches in it which has left over hop resin in it. This is quite normal and nothing to worry about.
Commercial brewers will check the gravity and temperature at least every 12 hours over the course of a brew. As home brewers we don’t have to check that often. I know some people that like to do a gravity check each day and see how it is progressing, I tend to wait towards the end of the fermentation to take a sample. This is not due to just pure laziness and indifference but trying to minimise any change of introducing a potential infection into the batch via the sample point (generally a tap). The more samples you take, the more chance you have of causing a problem is my theory.
It is important to take a careful hydrometer reading and don’t forget to note it down. It is also a good idea to have a taste of the sample you test. Even though it will not be carbonated you will still be able to pick up some important characteristics of the beer including its mouthfeel and bitterness. Also, you can check it for any off flavours or signs of infection to ensure it is going well.
Once you have reached your target gravity and the fermentation is finished, it is always best to give the fermenter a couple of days to rest before packaging it into a bottle or keg. This will help give time for the yeast to settle and reabsorb diacetyl which is a ketone (for those chemically minded) produced as a bi product. The yeast will consume it again in what is called the diacetyl rest at the end of fermentation. This is particularly important for lagers fermented at colder temperatures. Diacetyl has a smell like butterscotch if it is still in the beer in large amounts when drinking it.
You can use your final gravity reading to compare the the original gravity reading at the start of the fermentation to determine the alcohol content of your beer. There are numerous tables on line you can use to do the conversion for you.
Take care to know how long the wort should take to ferment. For some beers including some kits it can be just over in a week or so, with some lagers taking up to a month or two depending on the yeast, raw materials and temperatures. The key is to make sure you don’t try and rush it, let the yeast do its work.
Once the fermentation is over, quite often there may be a storage phase (cellaring) required to help the beer mature and clarify as haze particles fall out. Once again this will depend on the type of beer you re brewing and the conditions.
Packaging
Once your beer has finished fermenting and cellaring, it is ready to drink, well almost. The beer will need to be carbonated. There are two distinct pathways to do this depending if you are packaging your beer into a bottle or keg (generally a 19 litre Corny keg).
If transferring your beer into a bottle, it will need to be primed with some sugar just before putting the cap on the bottle. This gives the residual yeast left in the bottle enough sugar to undertake a small secondary fermentation to add CO2 to the beer, so when you open it after storing it for a couple of weeks, you will hear the glorious hiss of gas escaping from well carbonated beer. Beer kits generally come with a scoop to make sure you add the right amount of sugar for the volume of your bottlr. There are also some special sugar drops which can be purchased which do the same job when added to the beer.
Carbonating a keg, offers some different challenges and will need some more equipment. The beer in the keg will need to be force carbonated. This means an external CO2 source from a gas bottle will need to be hooked up to the keg via a regulator. There are two distinct methods to use, the slow and steady and the quick and rough method.
The slow and steady requires hooking up the CO2 to the keg at a set temperature and pressure for around a week and slowly allow the beer to absorb CO2 until it is carbonated to the correct level. There are numerous tables available that you can refer to which give the combinations of temperature and pressure to use. This method, although slower than the alternative, is quite an accurate way of carbonating.
The quick and rough method is much faster and is a bit of a gym workout. It involves hooking up the CO2 gas to the key at a much higher pressure up to 40psi and vigorously agitating the keg for a few minutes. You will actually hear the CO2 bubbling and dissolving into the beer as you rock the keg. The beer is then allowed to settle for an hour or two and it will be ready to pour. The problem with this method is that until you become practiced at it, you can easily over or under carbonate your beer. It all depends on what pressure you set your CO2 at and how vigorously you shake your keg and for how long. It is much harder to get a consistent result until you can figure it out and do it the same way under the same conditions each time.
An interesting point (well I think it is anyway) is that each time you notice a bubble coming through the airlock during a fermentation, the gas is predominately CO2, after all of the air has been pushed out of the fermenter. Apart from the a fact we are adding to the greenhouse effect (only joking, it is only releasing CO2 that was taken out of the atmosphere when the grain was growing so there is no net effect), the CO2 is quite a valuable commodity. So much so that commercial brewers collect it off their fermentations. They put it through scrubbers and reuse it in their plants for things such as carbonating their bright beers. I am yet to find a homebrewer with their own CO2 collect system, but no doubt there is some engineering genius out there with some great system that I would love to hear about.
Well that is it. My not so brief summary of brewing. I hope it makes sense and you have got some benefit from it if you read this far to the end!!