Brewing process
The ingredients
At the very base level, beer is made up of 4 simple ingredients, water, malt, hops and yeast. But what are these ingredients and how do they combine to create such a wide variety of colours, aromas and flavours? Let’s have a look at each one in turn!
Water
Water is the single largest ingredient used in making beer – to give you an idea, for a basic 500 litre batch we use approximately 650 litres of water. At a minimum, the water must come from a potable supply, however water from different areas will have different characteristics. There are different salts dissolved in the water and the water may be hard or soft, this will all depend on the local environment. These dissolved salts and the level of hardness have a major impact on the resulting beer. So it is not uncommon for brewers to adjust salt levels and hardness in their brewing water.
Malt
Malt is the carbohydrate source for beer. Generally it is barley, but can also be wheat, oats, rye – pretty much any grain can be malted. The process of malting is to take the grain and get it to germinate and as soon as there are signs of growth to stop the process. This is done by first steeping the grain in water until signs of germination are seen and then immediately transferring the grain to a kiln to stop any further growth. The grain can be kilned to various colour intensities from vary pale straw colour through to very dark roasted colours. The malting process not only provides colours to the grain it also activates enzymes within the grain that will be important during the beer making process.
Hops
Hops are the flower of the hop plant. The plant itself is a vine which grows to about 7 metres tall. They are an annual and grown from a rhizome which remains dormant during winter, but grows vigorously during summer. The plant itself needs a long day to yield commercial quantities so grows best in the southern parts of Australia, primarily Victoria and Tasmania. There are literally hundreds of hop varietals that all have different characteristics that they provide to the beer.
Yeast
There is a saying in brewing ‘brewers make wort, yeast makes beer’ and this is absolutely true! It is the yeast that turns the bittersweet wort that the brewer makes into the beer that we all love. Yeast itself is part of the fungus family, they are microscopic single cell organisms that occur naturally in all environments. There are many different types of yeast but only some are suitable for brewing.
The Process
Milling
The first stage in the brewing process is to mill the grain. This is done in a simple roller mill, the objective being to break each seed open to expose the starch within but to as much as possible keep the husk of the grain intact, this will act as a filter bed in the mashing process.
Mashing
The mashing process is the where the milled grains are steeped in hot water. The objective being to break the starches in the grain down into simple sugars. This is done by enzymes within the grain itself being the alpha-amylase and beta-amylase enzymes. The steeping in hot water acts as a catalyst for the reaction and speeds up the breakdown of the starch. Full conversion of the starch to sugar takes about 1 hour.
Sparging
Once the mash is complete, the liquid and the grain bed need to be separated this done by using a false bottom in the mash tun to allow liquid through, but leave the grain bed behind. The liquid is then pumped to a separate vessel for later boiling. There is still quite a lot of sugar locked up in the grain bed and to ensure this is captured we do what is called a sparge. This is simply running hot water over the grain bed to wash the sugars through. Sparging generally takes about 45 minutes.
Boiling
At the end of the sparge we have collected what brewers call ‘sweet wort’. We now need to boil the sweet wort and there are a variety of reasons for this:
– It will sterilise and concentrate the wort.
– It will precipitate haze causing proteins out of the wort
However, the primary reason for boiling is to extract hop bitterness, hop aroma and hop flavour. The longer the hops are in the boil, the more bitter components are extracted, so bittering hops are added at the start of the boil. Hop aroma and flavour are achieved by extracting the essential oil from the hops, these are quite volatile and are lost in a long boil so flavour and aroma additions are made at the later stages of the boil. Boiling generally takes about 1 hour.
Fermentation
The final stage in brewing beer is the fermentation, this is the where we add the yeast. For a 500 litre batch of beer we will add somewhere around 300 billion viable yeast cells. Their job is to consume the sugar that was created during the mash and excreting alcohol and carbon dioxide. Fermentation (depending on the style of beer) typically takes about 10 days at which point the beer is ready to be put into kegs and consumed.