Brewing Process

The production of beer must be a carefully planned operation going through specific stages to ensure a successful result. The methods described below cover the brewing process using dry ingredients and can be split into 5 main stages.

1. Mashing.   2. Sparging.   3. Boiling.   4. Cooling.   5. Fermentation

Mashing
In order to obtain the fermentable materials needed for brewing, the starch in the malted barley must be converted into sugars, and extracted. This process is known as 'mashing'. This is done in a mash tun, an insulated tank which has a perforated false bottom inside, which acts as a filter.

The mash tun is filled with about half of the total brewing liquor (water), at a temperature of about 72'C.
The weighed malt and any other cereals to be used is called grist. The grist is added to the mash tun, and mixed with the water.
The colder grist takes up some of the heat of the mash liquor, which has the effect of bringing down the mash temperature to around 65-66'C.

This is the ideal temperature for the mash, as it is the optimum temperature for enzyme activity in the grains - enzymes convert starch to sugars through 'saccharification'. The mash is conducted for between 1 and 1 hours .

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Running off & Sparging
At the end of the mash stage, the liquor has taken on the sugars and colour from the malt, and is known as wort.

A tap at the bottom of the mash tun is opened, and the sweet wort is run off. To begin with, these runnings are cloudy, or turbid, and are returned to the mash tun.

Once the wort has been run-off, the mashed grains are rinsed of the sugars which are still coating them - this is known as sparging. Rotating spray arms, called sparge arms, are fitted under the lid of the mash tun. The remaining brewing liquor, which has been heated to about 80'C is used for the sparge. As well as rinsing the grains of residual sugars, sparging acts to halt the saccharification process - the higher temperature of the sparge liquor halts the enzyme activity.

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Boiling
When the run-off and sparging is complete, the wort is run into the copper, where it is boiled for a period of about 1 hours.

Once the wort has started to boil, hops are added. Some of the flavour, and much of the aroma of the hops are driven off during the boil, and so we add a small amount of hops about ten or fifteen minutes before the end of the boil, to restore this lost aroma. This practice is known as late-hopping.

The boil has the effect of sterilising the wort, and also precipitating haze-forming proteins out of solution. About 15 minutes from the end of the boil, copper finings are added - usually this is a substance known as Irish moss, which is derived from a seaweed. Copper finings coagulate the proteins which have come out of solution, and so contribute to a clearer finished beer.

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Cooling
After boiling, the wort must be cooled to about 20'C so that yeast may be pitched (added). The cooling must be undertaken as quickly as possible; this has two benefits - the wort is safeguarded against bacterial infection, and proteins do not get the opportunity to go back into solution.

Cooling is effected by means of a heat exchanger, or paraflow. Before the wort is run through the paraflow, it is either directed to a hopback, which removes the hops and other matter from the wort, or a hop-seed filter is attached to the tap of the copper.

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Fermentation
The wort is pumped directly from the heat exchanger to the fermenting vessel, where it will have cooled to about 20'C.

The wort is aerated, either by injecting oxygen or air, or by being vigorously agitated by hand during the filling of the fermentation vessel. This is done because yeast needs oxygen in order to grow. During the boiling most of the dissolved oxygen has been driven off from the wort.

After aeration, the yeast is pitched into the wort. Within a few hours of pitching, the yeast will begin to collect on the surface. About 18-20 hours after pitching, the yeast will have developed a large, craggy head like fluffy clouds.

About 48 hours from the time of adding the yeast, the yeast head will have subsided, and the production of alcohol will be underway.

As the fermentable materials are used up during fermentation, the gravity of the wort will fall, until it reaches final gravity, which is where most of the sugars have been used, and the yeast is almost inactive.

The beer is then ready to be casked or bottled.

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