Brewing and Distilling Process

/Brewing and Distilling Process
Brewing and Distilling Process2016-10-27T16:01:10+00:00

The Brewing Process

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Introduction

Fundamentally beer is the product of the alcoholic fermentation by yeast of extracts of malted barley. Whilst malt and yeast contribute substantially to the character of beers, the quality of beer is at least as much a function of the water and, especially, of the hops used in its production.

Barleystarch supplies most of the sugars from which the alcohol is derived in the majority of the world’s beers. This starch is enclosed in the cell wall and proteins within the barley, and these wrappings are stripped away in the malting process (essentially a limited germination of the barley grains), leaving the starch preserved.

Mashing

In the brewery, the malted grain must first be milled to produce relatively fine particles, which are for the most part starch. The particles are then intimately mixed with hot water in a process called mashing. The water must possess the right mix of salts. For example fine ales are produced from waters with high levels of calcium. Famous pilsners are from waters with low levels of calcium. Typically mashes have a thickness of three parts water to one part malt and contain a stand at around 65 deg C, at which temperature the granules of starch are converted from an indigestible granular state into a ‘melted’ form which is much more susceptible to enzymatic digestion.

The enzymes which break down the starch are called the amylases. They are developed during the malting process, but only start to act once the gelatinization of the starch has occurred in the mash tun. Some brewers will have added starch from other sources, such as maize or rice, to supplement that from malt. These other sources are called adjuncts.

After perhaps an hour of mashing, the liquid portion of the mash, known as wart, is recovered, either by straining through the residual spent grains or by filtering through plates. The wort is run to the kettle (sometimes known as the copper, even though they are nowadays fabricated from stainless steel) where it is boiled, usually for I hour. Boiling serves various functions, including sterilisation of wort, precipitation of proteins (which would otherwise come out of solution in the finished beer and cause cloudiness), and the driving away of unpleasant grainy characters originating in the barley. Many brewers also add some adjunct sugars at this stage and at least a proportion of their hops.

Hops

The hops have two principal components: resins and essential oils. The resins (so-called a-acids) are changed (‘isomerised’) during boiling to yield iso-a-acids, which provide the bitterness to beer. This process is rather inefficient. Nowadays, hops oils are often extracted with liquefied carbon dioxide and the extract is either added to the kettle or extensively isomerised outside the brewery for addition to the finished beer (thereby avoiding losses due to the tendency of the bitter substance to stick on to yeast).

The oils are responsible for the ‘hoppy nose’ on beer. They are very volatile and if the hops are all added at the start of the boil then much of the aroma will be blown up the chimney. In traditional lager brewing a proportion of the hops are held back and only added towards the end of boiling, which allows the oils to remain in the wort. For obvious reasons, this process is called late hopping. In traditional ale production, a handful of hops is added to the cask at the end of the process, enabling a complex mixture of oils to give a distinctive character to such products. This is called dry hopping. Liquid carbon dioxide can be used to extract oils as well as resins and these extracts can also be added late in the process to make modifications to beer flavour.

After the precipitate produced during boiling has been removed, the hopped wort is cooled and pitched with yeast. There are many strains of brewing yeast (Saccharomyces cerevisiae),and brewers jealously guard and look after their own strains because of their importance in determining brand identity.

Fermentation

Fundamentally brewing yeast can be divided into ale and lager strains, the former type collecting at the surface of the fermenting wort and the latter settling to the bottom of a fermentation (although this differentiation is becoming blurred with modern fermenters). Both types need a little oxygen to trigger off their metabolism, but otherwise the alcoholic fermentation is anaerobic. Ale fermentations are usually complete within a few days at temperatures as high as 20°C, whereas lager fermentations at as low as 6°C can take several weeks. Fermentation is complete when the desired alcohol content has been reached and when an unpleasant butterscotch flavour which develops during all fermentations has been mopped up by yeast. The yeast is harvested for use in the next fermentation.

In traditional ale brewing the beer is now mixed with hops, some priming sugars and with isinglass finings from the swim bladders of certain fish, which settle out the solids in the cask.

In traditional lager brewing the ‘green beer’ is matured by several weeks of cold storage, prior to filtering.

Nowadays,the majority of beers, both ales and lagers, receive a relatively short conditioning period after fermentation and before filtration.This conditioning is ideally performed at -1°C for a minimum of three days, under whichconditions more proteins drop out of solution, making the beer less likely to go cloudy in the package or glass.

The filtered beer is adjusted to the required carbonation before packaging into cans, kegs or glass or plastic bottles.

The Distilling Process

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History

Historians agree that whisky production, albeit on a small scale actually began in Ireland somewhere around or before the twelfth century and was brought across to Scotland somewhat later. The first recorded instance of a grain spirit in Ireland dates back to 1172 and it is not till 1494 that a firm record exists of the same spirit in Scotland.
It is worth noting that until about the 1950s all malt distilleries would carry out the entire process on the site – malting, fermenting and distilling. Now only a few distilleries have their own maltings.

The whisky year

Many distilleries began their lives on farms. The distilling season began after the harvest and continued until late April. Until modern times this cycle was followed by all distilleries and even now there is a ‘silent season’, usually in August when many distilleries are closed.

The Malting Process

As has been stated above, the process of malting converts the plain barley grain into malted barley and by so doing greatly changes its chemical makeup. The barley is first soaked for between 48 and 72 hours in tanks or ‘steeps’ and allowed to germinate. Germination releases heat which has to be controlled in order to keep the temperature around 60 deg F/16 deg C and avoid the barley killing itself from its own generated heat. Traditionally the malting barley was drained and spread out over a large floor then turned regularly by hand with rakes or shovels. This was repetitious and arduous work, leading sometimes to a repetitive-strain injury called “monkey shoulder”. More recent maltings designs employed either mechanical rakes (Saladin box) or large revolving drums to achieve the same effect.

The Malt Kiln

The fully germinated malt is next transferred to the kiln for drying on a mesh over a fire containing a certain amount of peat, thus contributing to the peaty taste evident in many malt whiskies. Traditional malt kilns draw the hot air from the peat furnace through the malt by way of a chimney effect generated by the characteristic steep roofs and pagoda heads of many Scottish distilleries. The pagoda roof was introduced around the 1890s as it offered an improved air draught, fanning the peat furnace to core temperatures which can reach between 800 and 1200 deg C. In most cases, where most distilleries buy in their malt they have mostly lost their function other than a piece of visual identity. The malt is dried and roasted in the peat reek at 60 deg C for two days and is then ready for the next stage

Dressing

The malt contains much detritus or ‘combings’, principally rootlets. These are removed and used as cattle food. The malt is then coarsley ground and becomes known as ‘malt grist’.

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Mashing and brewing

The malt grist is fed into the ‘mash tun’ where it is combined with a carefully measured quantity of hot water. This completes the conversion of dextrin into maltose and produces a fermentable solution of the malt sugars caled ‘wort’ or ‘worts’. Again, after several washings to draw out the malt, the solid residue or ‘draff’ is removed and sold as cattle food. The worts are held in a receiver called an ‘underback’. This must be cooled to prevent unwanted decomposition of the maltose and to allow yeast to be introduced. The cooled worts are injected with yeast and the fermented in a further tank or tanks called ‘washbacks’. Thirty-six hours or thereabouts of sometimes violent fermentation produces a weakly alcoholic (10 degrees or thereabouts) clear liquid called ‘wash’, which will now be distilled

Distillation

Distillation takes place in pear-shaped copper vessels called ‘pot stills’. and at least two are required of different types.
The wash is first distilled in the ‘wash still’ to produce an impure intermediate product called ‘low wines’. This is then fed via the spirit safe into the low wines charger ready for the next stage of distillation. The spirit safe is a heavy glassfronted and padlocked box in which the emerging distillate may be inspected and directed onwards or back for redistillation as appropriate. When ready, the low wines are discharged into the low wines still and the process repeated. The final product – raw, unmatured whisky passes via the spirit safe to spirit receiver and spirit store, ready for filling into barrels. Early and late distillation fractions (‘foreshots’ and ‘feints’) contain impurities so are recycled back for re-distillation with the low wines. The ‘safes’ used for spirit storage are exactly that. The moment the intermediate product contains alcohol it comes under the control of the Excisemen and the safes are a necessary means of ensuring that the spirits stay where they are supposed to be and are accurately accounted-for.

Stills

The horizontal pipe from the top of the still to the worm is called the Lyne Arm (I’ve also seen ‘lye pipe’). There is a fair variation in the design of these and distilleries will vigorously defend the design of each as contributing something unique to the final product.
Further refinements include a bulge at the base of the column (the “Milton Ball”) and in particular the Lomond still which has a refluxing coil in the head which enables the still to be ‘tuned’ to produce a lighter or heavier spirit. Lomond stills have enabled several distilleries to market two distinct malts. A few stills have water cooling of the neck. Each still has a large hatch on the top of the base of the still, the ‘man door’ for inspection and cleaning. Further up the neck can be seen a small glass porthole which allows inspection of the contents of the still to ensure it does not rise too far up the neck and boil over. Before the advent of the porthole a wooden ball was swung against the neck of the still and the resulting ‘ding’ used to determine the state within.

Casks

Casks are critical to the taste and appearance of the final whisky. The need is for casks wich will impart a characteristic taste to the whisky without dominaing it or imparting a ‘woody’ flavour. Principally two types of cask are used – Oloroso sherry casks and American oak Bourbon casks. Some distilleries use intact barrels, others remake barrels from selected staves from more than one source. The barrel may be charred before use, a process which apparently assists the release of vanillin from the wood. No two casks are the same – one may produce a fine whisky and may be refilled and used again whereas its neighbour may taste woody after one filling.

Maturation

The whisky is left a minimum of three years but usually between 8 and 25 years in wooden barrels to mature. The bonded warehouses are cool and earth-floored to provide an even temperature and humidity. The barrels lose about 2% alcohol per annum – the so-called ‘angel’s share’. It is worth noting the investment tied up in each one of these modest low stone warehouses – each full-size cask can contain up to 110 gallons – easily &163;15-20,000 of spirit once it reaches the shops.

Marrying

Occasionally bottlings are produced from one single cask – the so-called ‘single single’ malts. More normally, several casks of similar ages from the one distillery will be ‘married’ by vatting them together then maturing them further for a few months.