Malting and the Brewing process.
It is said “he who brews knows of hard labor and good cheer, for when one brews many drink.”
Welcome back for part – 2 of the Chemistry of Beer. In part – 1 we looked at the basic ingredients used in brewing beer and what they bring to the table, in this the second installment we’ll be having a look at how Grain becomes Malt and we’ll jump into the brew house for a lesson in brew science and the brewing process. Once again this is not intended to be an in depth article but more of an overview that all levels of knowledge can take something way from.
Malt
In part – 1 we looked at how grain provides the carbohydrates used by yeast to create alcohol in beer. For grain to do this it needs to go through a process called malting. In the malting process grain is germinated by being soaked in water, this is called the “wet side.” Once the grain starts to germinate the Maltster (person responsible for malting grain) will then stop it from germinating further by drying it with hot air. Doing this develops the enzymes required for modifying the grain’s starches into carbohydrates during the mashing process. At this stage it’s referred to as “green malt” it is then taken to be kiln-dried to the desired colour and specification in what’s referred to as the hot side. Malts range in colour from pilsner or pale, through crystal and amber, to chocolate and black malts with many varieties in between. Our malt is now ready for making beer.
The brew house
When the grain arrives at the brewery it is taken to the milling room to be cracked. Cracking the grain releases the starches from the husk although the gains are not pulverised like wheat for bread, instead they are for the most part left intact but cracked, doing this helps to release the carbohydrates after mashing and allows the grain and husk to work as a natural filter during the sparge process. The brew house traditionally consists of three brewing vessels and they are-
- The hot liquor tank or “HLT”. This is essentially a very large boiling vessel used to heat the water used in the brewing processes.
- The Mash Tun. This is where our Milled Malt is mixed with heated water to form the mash that produces the wort.
- The Kettle or Copper. This is where the wort is boiled and hops are added for bittering, flavour and aroma.
The mash
Water is heated to a specific temperature in the HLT in readiness for mixing with the Malt. The temperature of the mash is dependent on how much body is needed for the style being brewed. The reason behind this is related to the enzymes living on the grain we talked briefly about earlier. The two main enzymes active during the mash are alpha and beta amylase. Alpha amylase, is most active around 67-74C and creates longer sugar chains that are less fermentable, this results in a beer with more body and malt sweetness. The Beta amylase, is most active between 55-66C produces single maltose sugar units which are more fermentable, this helps with a more complete fermentation (higher attenuation) and a cleaner beer with a thinner, dryer body. These temperatures are referred to as Saccharification rests. The mash can be stepped up gradually through different temperatures called “rests” in what is known as a step mash or held at one temperature known as a single infusion mash for a time period from 60min to 90min or more but for the most part with today’s highly modified malts, 60min is all that is needed to convert the starches into sugars.
The Sparge
Once the conversion is complete the temperature of the mash is lifted to around 75.5C and held for around 10min to stop the enzymes and increase the viscosity of the mash. Its now time to draw off the sweet sugary liquid to the Kettle this is now called “Wort” (pronounced Wert). As this is happening we also want to wash all the excess sugars from the grain. To do this 75.5C water is slowly sprayed over the top of the grain as wort is drawn from the bottom of the grain bed, the brewer is very careful not to disturb the bed of grain as it naturally acts as a filter for the wort being drawn off. The brewer will stop sparging when he has collected the correct volume and by measuring the specific gravity of the wort collected in the Kettle.
The Boil
Once the collection is complete the wort is then brought to the boil and hop’s are added. Typically hop’s that are added at the start of the boil are for bittering, the longer hop’s are boiled the more Alpha acids isomerized into our wort but the more volatile aroma and flavonoid oils boil off so its for this reason that hop’s that are added at different times and intervals give different things to the beer. Hop’s added near to the end of the boil add their flavors and those added at the end and after the boil give their aroma to the finished product. The boil typically lasts for between 60 and 90min, after which the brewer will again measure the specific gravity to obtain what is known as the “opening gravity”. The wort is now rapidly cooled to a temperature the yeast being used will ferment best at, oxygen is also added as it’s transferred to the fermentation vessel.
Fermentation
This is where our wort becomes beer! After the wort has been transferred from the Kettle to the fermenter it’s time to add our yeast. Once in our wort the yeast quickly multiply and get to work converting the sugars into alcohol (ethanol) this can take from two to six weeks depending on style, yeast strain and alcohol content of the finished beer. The brewer once again measures the gravity and this is known as the “final gravity” he can now determine the alcohol content by using the opening and final gravity. We can now call it beer for the first time. The beer or “green beer” is now chilled close to freezing temperatures to help drop the yeast out of suspension before being transferred to a “bright tank” (large cooled holding tank) for lagering and carbonation, this further filters and conditions the beer and can take up to three months for Pilsner’s but usually around two to three weeks for Ales. After this the beer is then ready for packaging and consumption.
Beer is many things to many people, from quenching a hard earned thirst to having fun with your mates or even making a living. To me beer is the beautiful coupling between science and art, it’s about understanding how and why so you can stand in front of the canvas and express yourself freely. It’s about watching others enjoying your heart and soul, it’s about taking people to new places and letting them experience new things. I truly love beer and the journey it’s taken me on and I hope with some knowledge I impart here over the coming months, it helps you on your journey in beer.
Well there you have it my brethren, a quick insight into the Chemistry of Beer. So next time your lifting that glass… spare a thought for the Water, Malt, Hop’s and Yeast and drink something that “doesn’t” spare the Water, Malt, Hop’s and Yeast!
Cheers, Swannie
The Alechemist
