How To Make Beer

The 1-2-3 of brewing beer

Making beer is a pretty simple process – composed of 4 basic ingredients; water, malted grains, hops and yeast. It’s really just cooking but with some fancy words.

A very simple summary of ALL GRAIN brewing can be described in 3 steps:

1. Extracting sugars from malted grains to produce sugary liquid (called sweet wort). 2. Boiling this liquid with flavourings (hops and sometimes other additions such as fruit and spices) and finally 3. Fermenting it with yeast to make it alcoholic.

A more complex explanation follows:

Traditional methods, as used by breweries, involve 3 vessels; a Mash Tun, Hot Liquor Tank (HLT) and a Boiler.   In traditional home brewing, the same techniques and processes are used, just on a smaller scale.  At HomeBrewtique we use a simplified method which uses a brewing bag.  This method is true to the traditional brewing craft but the addition of a mesh bag makes the process quicker and less equipment-intensive. We will describe this process but have included some notes about the traditional methodology for your information.

It all starts with a recipe for a chosen beer.  The grains chosen will contribute the colour and the final mouth-feel as well as the background flavour (such as biscuit, toast, crackers, caramel, toffee, nutty, chocolate).  Malted grains are measured out and milled (crushed just enough to crack open every grain).

The mash

Brew in the bag (BIAB) brewing uses what is known as a “full volume mash”.  All of the water required for the brew is used in a large pot (mash tun) and heated to the required temperature (strike temperature) before a mesh brewing bag is added to the pot.  The crushed grains are then added to the bag-lined pot and maintained at the desired temperature for 60 minutes.

In comparison, the traditional brewing method uses approximately half of the total brewing water required for the mash.

This process, scientifically termed “saccharification” is known in brewer’s terms as the mash.  By adding heat and liquid to the malted grains, we wake up the enzymes (amylases) and allow them to do the hard work of converting the starches in the grains into short sugar chains which can be eaten by the yeast (known as fermentable sugars). If the water is too hot the enzymes will be denatured and will not be able to convert the sugars.

The temperature of the mash is very important for the final beer product; different enzymes are activated at different temperatures.  In a low temperature range (54-65oC) the Beta Amylase enzymes are more active resulting in a more complete conversion of fermentable sugars.  This creates a higher alcohol, lighter bodied beer.  At higher temperatures (68-74oC) the Alpha Amylase enzymes are more active and result in a mix of fermentable and un-fermentable sugars.  This creates a more full bodied beer but with less alcohol.

In many recipes, the mash is held at a mid-range temperature (65-67oC ) where both enzymes are active, creating a medium bodied beer.

The style of beer being brewed determines the desired mash temperature.  As noted above, precise temperature is desirable as the temperature does affect the final product, but in practise, approximate temperatures are fine (and the norm for home-brewers).  Ultimately better control of mash temperature leads to more predictable, consistent and refined beer.

Depending on the beer style, the mash stage will last 60 – 90 minutes.  Sugar conversion takes longer at lower temperatures.  In most cases, the majority of the sugars are converted after 30 minutes.  Some recipes will call for a 90-minute mash stage, in practice, a longer mash stage will not do your beer any harm – ultimately there is a finite amount of starch present and once all the starch is converted to sugar nothing more can happen – so leaving the grains in the water longer will simply mean a longer brew day!

Mash out

After the mash comes the mash-out.  This is where the grains and water are heated to 76oC.  This higher temperature deactivates the enzymes and prevents them from converting any more sugars.  A mash-out also has the effect of making the sugary liquid more fluid – which can help it to flow more easily. Once the wort reaches 76 oC the bag of grains is removed and drained. The mesh bag acts as a filter to catch any particles in the wort.  (Note that at temperatures above 76oC, unwanted astringent tannins may be extracted from the grain hulls)

Traditional brewing methods require  the wort to be slowly drained out of the mash tun and into another vessel known as the boiler (a third large pot which can be heated either using an internal element, or by placing on a direct heat source) . By draining slowly, the grain bed can settle and act as a filter, catching any particles floating in the wort. 

The sparge

This step is eliminated in BIAB as the full volume of water has already been added at the beginning of the process.

In traditional brewing methods, as the liquid wort is draining out of the mash tun, heated water is gently sprinkled over the top in a process known as the sparge.  This is essentially a rinsing process and ensures all the sugar on the outside of the spent grain husks is dissolved and washed into the wort. By using sparge water at 76oC a simultaneous sparge and mash out can be performed.

The boil

The next stage is the boil.  The wort is heated to boiling point and hops are added at varying times as determined by the recipe. As the wort reaches boiling point, an occurrence known as the hot break can be seen.  This is where the clear wort becomes chunky as proteins come out of the wort and the sugars will froth up producing thick pale brown foam.  The boiling wort “breaks” through the thick foam – giving rise to the term, and providing the starting point for hop addition timings.  Different hops have different characteristics and lend a variety of differing aromas and flavours (such as fruity, citrus, grassy, floral, earthy, woody, pine, spicy) to the beer.

Hop additions are timed for their final influence on the beer.  Hops added at the beginning of the boil phase add bitterness only – as the flavour and aroma are boiled away. A boil time of 90 minutes may increase the effectiveness of the bittering hops but only by approximately 5%.   Hops added during the middle of the boil phase (approximately 30minutes) will contribute a small amount of bitterness but mostly flavour.  Hops added at the end of the boil time add aroma.  A great beer will balance the alcohol content, body, bitterness, flavour and aroma.

Note that once hops have been added, it is important to keep the pot uncovered.  As the hops are boiling they release sulphur compounds which need to escape.  If they condense and fall back into the wort, they can form dimethyl sulphide (or DMS) and result in undesirable off-tastes in the final beer (often described as cooked cabbage flavours – blah!).

A boil stage will last at least 60 minutes but can be longer.  A longer boil time may increase the bitterness level obtained from the bittering hops by a small percentage.  It will also lead to more concentrated wort – resulting in a higher alcohol percentage in the final beer volume.  At the end of the boil time the heat source is removed – known as flame out and the wort may be left to sit for a while depending on the recipe.


The wort now needs to be chilled – thoughts on this stage vary with some believing that a rapid chill is not necessary, while others insist that chilling as quickly as possible is the best way to achieve a cold break and minimise the risk of bacteria infecting the wort.  Much like the hot break described earlier, the cold break is when more proteins come out of the liquid and sink to the bottom.

Once the wort has cooled to 21oC, it can be transferred to the fermentation vessel – ideally leaving behind any protein sediment.

primary fermentation

At 21oC the yeast can now be added (pitched).  Note: temperatures above 21oC can shock – or at worst, kill the living yeast cells.

Yeast needs oxygen to thrive so agitating the wort to introduce as much oxygen as possible will assist the yeast to wake up and start the fermentation process.

The fermentation vessel must be closed off to prevent bacteria from infecting the beer, yet the by-product of fermentation – CO2 – needs to escape.  This is achieved by the addition of an airlock – a simple one way system whereby CO2 gas can escape by bubbling out through water or sanitiser, yet no bacteria can get in.

Primary fermentation – when the yeast converts the fermentable sugars in the wort into alcohol and CO2 –  takes approximately 14days.  After this point the wort has become flat beer.

secondary fermentation

Natural carbonation is achieved by adding some more sugar and closing the beer in a sealed container – such as a bottle or a keg.  The yeast will then eat the added sugar creating a bit more alcohol and more CO2.  This time the CO2 cannot escape so dissolves into the beer, resulting in carbonation.  This process takes another 2 weeks and results in a ‘bottle conditioned’ beer.


It is possible to “force carbonate“ beer.  In this process, no further sugar is added to the beer, rather the flat beer is sealed in a pressure resistant container (such as a keg) and then CO2 gas is added to the container.  The CO2 cannot escape so is “forced” into the beer, resulting in carbonated beer.  This method saves on time as the carbonated beer can be consumed immediately after primary fermentation.  Because of the time-savings, most commercial breweries use this method of carbonation.

real beer

Real beer, like that made by home brewers, contains living yeast, and as such is a living product.  Much like wine, real beer will change over time.  Depending on the style of beer, flavours will mature and develop over differing periods of time, peaking and then ultimately declining.  Some beer styles will peak quite soon after fermentation – usually the paler beers and especially those with hops used for aroma.  Other beers, notably darker or stronger beers, can be matured for months or even years and the flavour will mellow and mature.



How to Brew – John Palmer