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BREWING YOUR OWN BEER: WHAT YOU NEED TO GET STARTED
So you want to make your own beer. How hard could it be, right? Really, it's not that hard, and I'll have a nice home beer brewing equipment for you soon that outlines every aspect of the process.
Before you get all fired up about it, though, let me be the voice of reason and point out that you're going to have to spend a pretty nice chunk of change before you can even make your first batch.
While the actual process of brewing is simple, it is pretty time consuming, and when you first get started, there is quite the long list of equipment and ingredients that first need to be bought.
Not all of these are cheap, either, but after your initial investment, the home brewing process is actually much more affordable than buying beer at the store. Let's take a look at what all you'll need to get ready to brew.
Every single article or guide that I have read is sure to emphasize this one key point: sanitize like a maniac. Every item that will have even the slightest contact with your beer at any phase of the brewing process needs to be as clean as you can get it.
You can, of course, use a mixture of bleach and hot water to soak everything, and then rinse everything thoroughly. This can add additional time to the process that you don't necessarily have to spend.
Many sanitizers do not require rinsing and most are on the inexpensive side, costing less than $5 on average and up to $15 for a large container. One package or bottle will last you through many brewing sessions, so they are a fantastic deal. I would definitely make the small investment in a good no-rinse sanitizer if I was planning to brew on a regular basis.
I suppose that you could use any old stock pot for making your wort, but I wouldn't recommend it. First, when you're boiling your wort (pronounced wert- see my guide to beer for more on that), you will need plenty of extra room to avoid overflowing the pot.
Most home beer recipes make five gallons, so you need at least an 8 gallon pot to have enough additional space during the boiling process. This is not your average-size stock pot.
Additionally, brew kettles are made specifically for making beer (obviously), which means that they have nice heavy bottoms for even heat distribution.
You can also get them with built-in temperature gauges to easily keep an eye on that, which is really important for the step that follows the boil- adding the yeast (if you add it when the wort is too hot, it kills the yeast, and dead yeast=no beer).
You can even get a kettle with a built-in spigot, which will come in super handy. These two features cost more, but even a basic kettle will be a bit pricey, with the price climbing upwards for the extra features and larger sizes.
Known in the beer fermentation equipment as a carboy, a fermentation vessel is simply the place where the wort and yeast are combined and allowed to sit for several days to turn into beer.
Whatever you use for this fermentation process needs to be 100% airtight so that not even one airborne microbe can get in to alter the taste of the batch.
Keep in mind also that you will need at least two containers for this part of the process, because you will siphon the beer out of the first fermentation vessel into a second one after a few days (more on that part of the process in my next article).
A plastic carboy will run you around $30, which isn't too bad, and these won't be nearly as heavy to try to move when they are full of liquid as a thick glass fermenter (also referred to as a fermentor).
On the other hand, a good glass carboy will last forever, with proper care and handling, and they start around the same price point.
You can get away with buying a simple food-grade plastic bucket for under $20, but I haven't seen one that has a gasket on the lid to make for a truly air-tight seal, whereas all the better carboys and other actual fermenters will have a gasket.
AIR LOCKS
During the fermentation process, as the yeast eats up the sugar in the wort, there are two byproducts- alcohol and carbon dioxide. As the CO2 builds up inside the fermentation vessel, you're going to need a way to release that gas without letting outside air into the container to possibly contaminate your brew.
This is where an air lock comes into play. These fit securely into the top or, in some cases, onto the lower side of any vessel made specifically for brewing.
The air lock allows all the built-up gas to escape, which will hopefully prevent any explosions from happening. Yes, you read that correctly- explosions.
Whenever you have any situation where pressure is building within an enclosed area, explosions can occur, and the fermentation period is no exception. Not using an air lock pretty much guarantees you'll end up with beer pouring out of a broken carboy, and with them only costing a couple of bucks, there's no reason not to buy one.
LONG-HANDLED SPOON
Remember, you're going to be dealing with at least an 8-gallon brew kettle, so we're talking about a really long handle on this spoon, an item you're not likely to have on hand.
You'll use the spoon for stirring during the boiling process, and you will need to be able to reach all the way to the bottom of the pot. You can also lay the spoon horizontally across the top of the kettle, which will help prevent the wort from boiling over.
I recommend going with the stainless steel option on this for durability, which only costs a few dollars.
HYDROMETER
Before I go into what a hydrometer does and why you need one, we need to talk about gravity. No, I'm not talking about the kind of gravity that keeps your feet on the earth.
I'm talking about specific gravity, which, according to Wikipedia, is "the ratio of the density of a substance to the density (mass of the same unit volume) of a reference substance," with the substance being your fermenting beer and the reference substance being water.
Specific gravity in beer is important because it's how you can determine the percentage of alcohol in the final product. When you first start the process, the density of the liquid will be higher, closer to that of plain water.
As the yeast in the fermentation vessel consumes the sugar in the malt and converts the liquid into alcohol, the specific gravity inside the container will drop, because alcohol is considerably denser than water. Once the gravity stops dropping, you know that the yeast has finished its work.
A hydrometer is a device that measures the specific gravity of your brew, so it's useful for determining the aforementioned readings. Also, by taking the measurement of the final gravity inside the container and subtracting it from the original gravity of the brew, you can determine the percentage of alcohol your product contains.
A hydrometer looks like an oversized, old fashioned, mercury thermometer, and costs around the same amount, so it's not an expensive tool to buy and is pretty useful to have around. You just don't want be measuring non-stop during fermentation since you'd be letting air into the container.
You can simply measure before putting on the lid or stopper and then again when you siphon the beer filling machine out for the secondary fermentation that I mentioned before. We recommend this one.
SIPHONS
As I said, at some point you will need to siphon out the liquid from one fermentation vessel to another. In the same place where you attach the air lock to the container, you will need to attach a siphon.
Now, once the yeast has done its job, all the dead yeast will settle on the bottom of the container, along with the used up malt and hops. You need to remove the liquid from the container while at the same time getting as little of those bits and pieces as possible.
You could always just pick up the ridiculously heavy carboy or bucket and slowly and carefully pour the beer from one container to the other, but you will end up with more of that sediment in the second container, which will result in a hazy final product. You don't want that. Instead, make sure to purchase a siphon.
Alternatively, you can even buy a ported fermenter that has a valve on the side to transfer the liquid, no siphons required.
BOTTLES, ETC.
Once you finish the brewing and fermenting, you will of course need to bottle up your brew. Invest in a good set of glass bottles that you can use time and time again. Go with brown glass since they will block out the most UV light, which can cause spoilage.
To make things easy on yourself, I would also say to buy the bottles with the attached swing caps. Expect an investment of around $2.50 per bottle.
The kicker is that you will probably need about 4 packs to bottle all of the beer from a standard recipe, which is for 5 gallons.
If you want to save some money here, you can always opt for capping the bottles yourself. You will spend about half the amount on the bottles themselves going that route.
You will spend another couple of bucks on a pack of bottle caps and a little more for a bottle capper. This will ultimately result in some savings. And considering the amount of money you will have invested already, this seems like a pretty good idea!
INGREDIENT STARTER KITS
Assuming you fall in love with the whole home brewing process, at some point you will probably want to buy your own malt and hops to really customize it to your taste. To begin with, though, it will be so much easier for you to buy a recipe kit.
There are tons of websites including Amazon that offer these if you don't have a home brewer's store in your neck of the woods. Just decide what kind of beer you want to make (ale or lager) and the style that you prefer, and you'll be able to find a kit for that.
This really simplifies the brewing process, which is awesome when you're a beginner. And they're affordable, too.
READY TO MAKE SOME BEER?
I bet you would have never thought that it can take so much stuff to actually make a few bottles of beer, not to mention an initial investment of at least $300.
Now that you know, though, it's easy to set about buying what you need. Stay tuned for my follow-up article where you'll get a step-by-step guide to the actual beer-making process.
Although the equipment needed to brew beer traditionally was fairly simple, large commercial breweries today use equipment that does everything from crack the grain to seal the cases and a multitude of chores in between. These are the basics:
Most folks visiting a brewery immediately recognize the large, round brew kettle that usually dominates the brewhouse. Somewhere nearby is usually a second, sometimes smaller, similar-looking vessel called a mash tun, and if the place is big and brews lagers, it has yet another one, called a lauter tun. These vessels are vented through stacks that carry the steam out of the brewhouse, consequently treating the whole neighborhood to the intoxicating, malty-sweet aroma of beer in the making.
Traditionally, these vessels were made of copper and were often referred to simply as the coppers. Nowadays, the term has fallen out of use, mostly because modern brewing equipment is fabricated from the relatively cheaper and easier-to-obtain stainless steel.
After the first three vessels are used, the wine filling machine is pumped (and cooled at the same time) into a big tank called a fermenter. For sanitation purposes, fermenters are usually airtight vessels that allow only for the escape of the carbon dioxide pressure built up inside. However, some traditionalists in the industry, particularly in Britain and Belgium, still allow their beer to ferment in open vessels, and some even encourage spontaneous fermentations caused by wild, airborne yeast (Belgian Lambic brewers, for example).
At this point, each brewery uses different kinds of tanks and does different things to its beer. For example:
Most breweries allow beer to go through a short aging process after the initial fermentation, using additional vessels cleverly named aging tanks for this purpose.
Next, breweries transfer the aged beer from aging tanks into finishing tanks to prepare them for their introduction into society.
Beer would not exist without microbes. During fermentation, yeast cells convert cereal-derived sugars into ethanol and CO2. Yeast also produces a wide array of aroma compounds that influence beer taste and aroma. The complex interaction between all these aroma compounds results in each beer having its own distinctive palette. This article contains all protocols needed to brew beer in a standard lab environment and focuses on the use of yeast in beer brewing. More specifically, it provides protocols for yeast propagation, brewing calculations and, of course, beer brewing. At the end, we have also included protocols for analyses that can be performed on the resulting brew, with a focus on yeast-derived aroma compounds.
Beer brewing is intrinsically a biotechnological process: the conversion of raw materials into beer relies on many different enzymatic reactions and microbial activity. Beer is traditionally made from four key ingredients: malted cereals (barley or other), water, hops, and yeast. Each of these ingredients contributes to the final taste and aroma of beer.
Beer production starts with the malting of barley (or other cereals, such as wheat, sorghum, rye, or oats). The main goal of malting is to activate enzymes within the grain. These enzymes will hydrolyze starch and other compounds within the kernels during mashing (Goldammer, 2008; Kunze, 2004). During malting, barely kernels are soaked in water and periodically aerated, the so-called steeping and germination phase. During germination, three important groups of enzymes are activated: (i) amylases, (ii) proteases/peptidases, and (iii) beta-glucanases. Each of these enzymes have an important function during the malting and downstream brewing process: (i) amylases convert starch, present in the barley kernels, into fermentable sugars; (ii) proteases and peptidases break down proteins and release free amino nitrogen (FAN), while (iii) beta-glucanases degrade the endosperm cell wall, allowing other enzymes access to the endosperm. Next, in the drying and kilning phase, kernels are dried and heated. This stops germination, arrests enzymatic activity within the kernels, reduces spoilage risks, and determines the impact of malt on the final aroma and color of the beer.
The actual brewing process consists of five steps. The main goal is to convert insoluble malt or grain material into a soluble and fermentable extract.
Milling of malted grains (i) and mashing (ii)
In this step, milled grains are mixed with warm water. This mash is kept at specific temperatures and pH to ensure proper enzymatic conversion of starch and proteins. Traditionally, a starting temperature of 45°C is used. At this temperature, proteases are activated and degrade proteins to short peptides and amino acids, that will form the major nitrogen source for yeast during fermentation. The mash is then heated to 62°C-64°C, at which starch will gelatinize and become accessible to amylases. Beta-amylases will cleave off maltose from starch molecules. The mash is then heated to 72°C for 15-25 min, allowing further breakdown of long chain polysaccharides by alpha-amylases. Finally, the temperature of the mash is raised to 78°C, stopping nearly all enzymatic activity.
Modern, highly modified malts allow mashing in directly at temperatures >60°C since the protein breakdown has already been completed by the maltster.
Filtering/lautering (iii)
During this step, the insoluble fraction (spent grains) is separated from the soluble extract. The remaining extract (wort) is transferred to the boiling vessel.
Boiling (iv)
During boiling, hops and other spices are added. These contribute to bitterness and aroma of the final beer. More specifically, hops contain alpha acids and during boiling, these acids will isomerize into iso-alpha acids, the major bittering substances in beer.
Bitter hops contain high concentrations of alpha acids (6%-16%) and are often added at the beginning of the boil. Aroma hops have a high hop oil content (>1%), which contains 200-250 different compounds that contribute to the characteristic aroma of hops (e.g., myrcene, linalool, and nonenal) (Kunze, 2004). Aroma hops are typically only added towards the end of the boil, or in the dry-hopping of green beer to reduce the stripping of aroma-active compounds.
Other major effects of wort boiling include protein denaturation and aggregation, concentration of the wort, stripping of off-flavors such as dimethyl sulfide (DMS), and sanitization of the wort. The boiled wort is then transferred to a whirlpool to remove the aggregated protein and insoluble hop components (hot trub). Finally, the wort is cooled, aerated, and transferred into the fermentor, where yeast is added.
So you want to make your own beer. How hard could it be, right? Really, it's not that hard, and I'll have a nice home beer brewing equipment for you soon that outlines every aspect of the process.
Before you get all fired up about it, though, let me be the voice of reason and point out that you're going to have to spend a pretty nice chunk of change before you can even make your first batch.
While the actual process of brewing is simple, it is pretty time consuming, and when you first get started, there is quite the long list of equipment and ingredients that first need to be bought.
Not all of these are cheap, either, but after your initial investment, the home brewing process is actually much more affordable than buying beer at the store. Let's take a look at what all you'll need to get ready to brew.
Every single article or guide that I have read is sure to emphasize this one key point: sanitize like a maniac. Every item that will have even the slightest contact with your beer at any phase of the brewing process needs to be as clean as you can get it.
You can, of course, use a mixture of bleach and hot water to soak everything, and then rinse everything thoroughly. This can add additional time to the process that you don't necessarily have to spend.
Many sanitizers do not require rinsing and most are on the inexpensive side, costing less than $5 on average and up to $15 for a large container. One package or bottle will last you through many brewing sessions, so they are a fantastic deal. I would definitely make the small investment in a good no-rinse sanitizer if I was planning to brew on a regular basis.
I suppose that you could use any old stock pot for making your wort, but I wouldn't recommend it. First, when you're boiling your wort (pronounced wert- see my guide to beer for more on that), you will need plenty of extra room to avoid overflowing the pot.
Most home beer recipes make five gallons, so you need at least an 8 gallon pot to have enough additional space during the boiling process. This is not your average-size stock pot.
Additionally, brew kettles are made specifically for making beer (obviously), which means that they have nice heavy bottoms for even heat distribution.
You can also get them with built-in temperature gauges to easily keep an eye on that, which is really important for the step that follows the boil- adding the yeast (if you add it when the wort is too hot, it kills the yeast, and dead yeast=no beer).
You can even get a kettle with a built-in spigot, which will come in super handy. These two features cost more, but even a basic kettle will be a bit pricey, with the price climbing upwards for the extra features and larger sizes.
Known in the beer fermentation equipment as a carboy, a fermentation vessel is simply the place where the wort and yeast are combined and allowed to sit for several days to turn into beer.
Whatever you use for this fermentation process needs to be 100% airtight so that not even one airborne microbe can get in to alter the taste of the batch.
Keep in mind also that you will need at least two containers for this part of the process, because you will siphon the beer out of the first fermentation vessel into a second one after a few days (more on that part of the process in my next article).
A plastic carboy will run you around $30, which isn't too bad, and these won't be nearly as heavy to try to move when they are full of liquid as a thick glass fermenter (also referred to as a fermentor).
On the other hand, a good glass carboy will last forever, with proper care and handling, and they start around the same price point.
You can get away with buying a simple food-grade plastic bucket for under $20, but I haven't seen one that has a gasket on the lid to make for a truly air-tight seal, whereas all the better carboys and other actual fermenters will have a gasket.
AIR LOCKS
During the fermentation process, as the yeast eats up the sugar in the wort, there are two byproducts- alcohol and carbon dioxide. As the CO2 builds up inside the fermentation vessel, you're going to need a way to release that gas without letting outside air into the container to possibly contaminate your brew.
This is where an air lock comes into play. These fit securely into the top or, in some cases, onto the lower side of any vessel made specifically for brewing.
The air lock allows all the built-up gas to escape, which will hopefully prevent any explosions from happening. Yes, you read that correctly- explosions.
Whenever you have any situation where pressure is building within an enclosed area, explosions can occur, and the fermentation period is no exception. Not using an air lock pretty much guarantees you'll end up with beer pouring out of a broken carboy, and with them only costing a couple of bucks, there's no reason not to buy one.
LONG-HANDLED SPOON
Remember, you're going to be dealing with at least an 8-gallon brew kettle, so we're talking about a really long handle on this spoon, an item you're not likely to have on hand.
You'll use the spoon for stirring during the boiling process, and you will need to be able to reach all the way to the bottom of the pot. You can also lay the spoon horizontally across the top of the kettle, which will help prevent the wort from boiling over.
I recommend going with the stainless steel option on this for durability, which only costs a few dollars.
HYDROMETER
Before I go into what a hydrometer does and why you need one, we need to talk about gravity. No, I'm not talking about the kind of gravity that keeps your feet on the earth.
I'm talking about specific gravity, which, according to Wikipedia, is "the ratio of the density of a substance to the density (mass of the same unit volume) of a reference substance," with the substance being your fermenting beer and the reference substance being water.
Specific gravity in beer is important because it's how you can determine the percentage of alcohol in the final product. When you first start the process, the density of the liquid will be higher, closer to that of plain water.
As the yeast in the fermentation vessel consumes the sugar in the malt and converts the liquid into alcohol, the specific gravity inside the container will drop, because alcohol is considerably denser than water. Once the gravity stops dropping, you know that the yeast has finished its work.
A hydrometer is a device that measures the specific gravity of your brew, so it's useful for determining the aforementioned readings. Also, by taking the measurement of the final gravity inside the container and subtracting it from the original gravity of the brew, you can determine the percentage of alcohol your product contains.
A hydrometer looks like an oversized, old fashioned, mercury thermometer, and costs around the same amount, so it's not an expensive tool to buy and is pretty useful to have around. You just don't want be measuring non-stop during fermentation since you'd be letting air into the container.
You can simply measure before putting on the lid or stopper and then again when you siphon the beer filling machine out for the secondary fermentation that I mentioned before. We recommend this one.
SIPHONS
As I said, at some point you will need to siphon out the liquid from one fermentation vessel to another. In the same place where you attach the air lock to the container, you will need to attach a siphon.
Now, once the yeast has done its job, all the dead yeast will settle on the bottom of the container, along with the used up malt and hops. You need to remove the liquid from the container while at the same time getting as little of those bits and pieces as possible.
You could always just pick up the ridiculously heavy carboy or bucket and slowly and carefully pour the beer from one container to the other, but you will end up with more of that sediment in the second container, which will result in a hazy final product. You don't want that. Instead, make sure to purchase a siphon.
Alternatively, you can even buy a ported fermenter that has a valve on the side to transfer the liquid, no siphons required.
BOTTLES, ETC.
Once you finish the brewing and fermenting, you will of course need to bottle up your brew. Invest in a good set of glass bottles that you can use time and time again. Go with brown glass since they will block out the most UV light, which can cause spoilage.
To make things easy on yourself, I would also say to buy the bottles with the attached swing caps. Expect an investment of around $2.50 per bottle.
The kicker is that you will probably need about 4 packs to bottle all of the beer from a standard recipe, which is for 5 gallons.
If you want to save some money here, you can always opt for capping the bottles yourself. You will spend about half the amount on the bottles themselves going that route.
You will spend another couple of bucks on a pack of bottle caps and a little more for a bottle capper. This will ultimately result in some savings. And considering the amount of money you will have invested already, this seems like a pretty good idea!
INGREDIENT STARTER KITS
Assuming you fall in love with the whole home brewing process, at some point you will probably want to buy your own malt and hops to really customize it to your taste. To begin with, though, it will be so much easier for you to buy a recipe kit.
There are tons of websites including Amazon that offer these if you don't have a home brewer's store in your neck of the woods. Just decide what kind of beer you want to make (ale or lager) and the style that you prefer, and you'll be able to find a kit for that.
This really simplifies the brewing process, which is awesome when you're a beginner. And they're affordable, too.
READY TO MAKE SOME BEER?
I bet you would have never thought that it can take so much stuff to actually make a few bottles of beer, not to mention an initial investment of at least $300.
Now that you know, though, it's easy to set about buying what you need. Stay tuned for my follow-up article where you'll get a step-by-step guide to the actual beer-making process.
Although the equipment needed to brew beer traditionally was fairly simple, large commercial breweries today use equipment that does everything from crack the grain to seal the cases and a multitude of chores in between. These are the basics:
Most folks visiting a brewery immediately recognize the large, round brew kettle that usually dominates the brewhouse. Somewhere nearby is usually a second, sometimes smaller, similar-looking vessel called a mash tun, and if the place is big and brews lagers, it has yet another one, called a lauter tun. These vessels are vented through stacks that carry the steam out of the brewhouse, consequently treating the whole neighborhood to the intoxicating, malty-sweet aroma of beer in the making.
Traditionally, these vessels were made of copper and were often referred to simply as the coppers. Nowadays, the term has fallen out of use, mostly because modern brewing equipment is fabricated from the relatively cheaper and easier-to-obtain stainless steel.
After the first three vessels are used, the wine filling machine is pumped (and cooled at the same time) into a big tank called a fermenter. For sanitation purposes, fermenters are usually airtight vessels that allow only for the escape of the carbon dioxide pressure built up inside. However, some traditionalists in the industry, particularly in Britain and Belgium, still allow their beer to ferment in open vessels, and some even encourage spontaneous fermentations caused by wild, airborne yeast (Belgian Lambic brewers, for example).
At this point, each brewery uses different kinds of tanks and does different things to its beer. For example:
Most breweries allow beer to go through a short aging process after the initial fermentation, using additional vessels cleverly named aging tanks for this purpose.
Next, breweries transfer the aged beer from aging tanks into finishing tanks to prepare them for their introduction into society.
Beer would not exist without microbes. During fermentation, yeast cells convert cereal-derived sugars into ethanol and CO2. Yeast also produces a wide array of aroma compounds that influence beer taste and aroma. The complex interaction between all these aroma compounds results in each beer having its own distinctive palette. This article contains all protocols needed to brew beer in a standard lab environment and focuses on the use of yeast in beer brewing. More specifically, it provides protocols for yeast propagation, brewing calculations and, of course, beer brewing. At the end, we have also included protocols for analyses that can be performed on the resulting brew, with a focus on yeast-derived aroma compounds.
Beer brewing is intrinsically a biotechnological process: the conversion of raw materials into beer relies on many different enzymatic reactions and microbial activity. Beer is traditionally made from four key ingredients: malted cereals (barley or other), water, hops, and yeast. Each of these ingredients contributes to the final taste and aroma of beer.
Beer production starts with the malting of barley (or other cereals, such as wheat, sorghum, rye, or oats). The main goal of malting is to activate enzymes within the grain. These enzymes will hydrolyze starch and other compounds within the kernels during mashing (Goldammer, 2008; Kunze, 2004). During malting, barely kernels are soaked in water and periodically aerated, the so-called steeping and germination phase. During germination, three important groups of enzymes are activated: (i) amylases, (ii) proteases/peptidases, and (iii) beta-glucanases. Each of these enzymes have an important function during the malting and downstream brewing process: (i) amylases convert starch, present in the barley kernels, into fermentable sugars; (ii) proteases and peptidases break down proteins and release free amino nitrogen (FAN), while (iii) beta-glucanases degrade the endosperm cell wall, allowing other enzymes access to the endosperm. Next, in the drying and kilning phase, kernels are dried and heated. This stops germination, arrests enzymatic activity within the kernels, reduces spoilage risks, and determines the impact of malt on the final aroma and color of the beer.
The actual brewing process consists of five steps. The main goal is to convert insoluble malt or grain material into a soluble and fermentable extract.
Milling of malted grains (i) and mashing (ii)
In this step, milled grains are mixed with warm water. This mash is kept at specific temperatures and pH to ensure proper enzymatic conversion of starch and proteins. Traditionally, a starting temperature of 45°C is used. At this temperature, proteases are activated and degrade proteins to short peptides and amino acids, that will form the major nitrogen source for yeast during fermentation. The mash is then heated to 62°C-64°C, at which starch will gelatinize and become accessible to amylases. Beta-amylases will cleave off maltose from starch molecules. The mash is then heated to 72°C for 15-25 min, allowing further breakdown of long chain polysaccharides by alpha-amylases. Finally, the temperature of the mash is raised to 78°C, stopping nearly all enzymatic activity.
Modern, highly modified malts allow mashing in directly at temperatures >60°C since the protein breakdown has already been completed by the maltster.
Filtering/lautering (iii)
During this step, the insoluble fraction (spent grains) is separated from the soluble extract. The remaining extract (wort) is transferred to the boiling vessel.
Boiling (iv)
During boiling, hops and other spices are added. These contribute to bitterness and aroma of the final beer. More specifically, hops contain alpha acids and during boiling, these acids will isomerize into iso-alpha acids, the major bittering substances in beer.
Bitter hops contain high concentrations of alpha acids (6%-16%) and are often added at the beginning of the boil. Aroma hops have a high hop oil content (>1%), which contains 200-250 different compounds that contribute to the characteristic aroma of hops (e.g., myrcene, linalool, and nonenal) (Kunze, 2004). Aroma hops are typically only added towards the end of the boil, or in the dry-hopping of green beer to reduce the stripping of aroma-active compounds.
Other major effects of wort boiling include protein denaturation and aggregation, concentration of the wort, stripping of off-flavors such as dimethyl sulfide (DMS), and sanitization of the wort. The boiled wort is then transferred to a whirlpool to remove the aggregated protein and insoluble hop components (hot trub). Finally, the wort is cooled, aerated, and transferred into the fermentor, where yeast is added.