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As most flavour components develop during roasting, coffee is almost always decaffeinated in the green bean form, before roasting. Decaffeinated beans, roast and ground and instant coffees are now widely available. The first successful extraction of caffeine from coffee beans was achieved by a German chemist, Runge, in 1820. His friend, the poet Goethe, had suggested that Runge analyse the constituents of coffee to discover the cause of his insomnia - and the history of decaffeinated coffee began. The real breakthrough, however, didn't come until the turn of the century when Ludwig Roselius, a German coffee importer, turned a batch of ruined coffee beans over to researchers. They decided to pre-treat the coffee beans with steam before bringing them into contact with a caffeine-removing solvent. Steaming swells the beans, increasing their surface area and making the caffeine easier to remove. The discovery made it possible to produce decaffeinated coffee on a commercial scale for the first time. He founded Kaffee Hag in Bremen in 1906 with his brand Sanka. Pre-treatment with steam is still the first stage of many modern decaffeination processes, but significant changes have taken place in the technology and in the solvents used. Defacceination processes basically involve treating the green coffee beans with a solvent, then removing the caffeine-laden solvent from the beans. The three main methods of decaffeination in commercial use today are: a) chemical solvents b) supercritical gases or c) water and caffeine-free extracts. After the decaffeination process, processing companies no longer throw the caffeine away; they sell it to pharmecutical companies who use it in a number of different products. Chemical solvent decaffeination: Firstly, the green beans are treated with steam, under pressure. This treatment swells the beans, increasing their surface area and making the caffeine easier to remove. The next stage is extraction of the caffeine by a solvent, again under pressure, at a temperature close to the boiling point of the solvent. Ideally, the solvent should remove caffeine selectively, without affecting the coffee in any other way. After decaffeination, only minute traces of the solvent are left in the coffee. Nevertheless, the chemical used must be sage, so that these traces do not affect the health of anyone drinking decaffeinated coffee. The safety of solvents used in decaffeination is tested in animal and human studies and reviewed by government scientific authorities. Solvents in current use which pass these stringent criteria includ methylene chloride (dichloromethane) and ethyl acetate. The caffeine which is removed from the solvent by distillation has many commercial applications, for example in pharmaceuticals and as a flavouring agent. Traces of solvent still adhering to the beans are forced out by further steaming and the coffee is then dried. Decaffeination by supercritical gas: At temperatures above their 'critical point' under pressure, gases behave rather like liquids and can be used as s olvents. Supercritical carbon dioxide is used as a selective solvent for caffeine. It is applied to previously steamed green coffee at temperatures of about 70 degrees C and at high pressure. The caffeine is separated from the gas by rinsing or by absorption and the gas recirculated. In this method the wax layer of the coffee bean is retained and nothing but the caffeine is removed. Methods using water and caffeine-free extracts: Various processes have been devised in which caffeine is removed, not from the bean, but from an extract of water-soluble substances produced by steeping the coffee in hot water. If the caffeine is removed by a solvent, this is known as an 'indirect solvent' method; otherwise, the caffeine may be separated from the extract by absorption onto the substance such as activated carbon (charcoal). The caffeine-free extract is then used to decaffeinate the green coffee, as caffeine passes readily from the beans into the extract. However, these methods also result in the loss of some other water-soluble components of coffee such as carbohydrates and chlorogenic acids. In the 'Swiss water process', the green beans are immersed in water and the resulting extract passed over activated carbon to remove the caffeine, as above. The caffeine-free mixture is then added to the partially dried coffee beans before they are fully dried and roasted. Regulations concerning decaffeinated coffee: EC regulations state that the caffeine content of decaffeinated coffee should not exceed 0.1% in the case of green beans or 0.3% in the case of coffee extracts (instant coffee) - dry matter basis. All decaffeination methods in use today remove at least 97% of the caffeine naturally present in the coffee bean. A cup of decaffeinated coffee contains about 1-5 mg of caffeine - depending on the strength of the brew. Beans are also shipped in bulk using bulk containers with plastic liners. On arrival in the destination country, the shipments are sent to warehouses or direct to the roaster. The tasting of coffee is a ri gorous and disciplined process. It is slurped by an expert for the purpose of evaluating the brew and determining its characteristics. The taster first assesses the green beans for their appearance. A small quantity are then roasted in a laboratory roaster and tested for their flavour and aroma. After the coffee has been infused in water, the brew is 'nosed'. After approximately three minutes the brew is lightly stirred and smelled again. The resulting foam is removed and the tasting begins. A small spoonful of coffee is taken into the taster's mouth and it is 'chewn' around before being spat out. The procedure is repeated with all of the samples and notes are made as each one is sampled. The taster would be looking for criteria such as acidity, body, aroma and flavour. Acidity: This is a desirable characteristic in coffee. It is the sensation of dryness that the coffee produces under the edges of your tongue and on the back of your palate. The role acidity plays in coffee is not unlike its role as related t o the flavour of wine. It provides a sharp, bright, vibrant quality. Without sufficient acidity, the coffee will tend to taste flat. Acidity should not be confusedwith sour, which is an unpleasant, negative flavour characteristic. Body: Body is the feeling that the coffee has in your mouth. It is the viscosity, heaviness, thickness or richness that is perceived on the tongue. A good example of body would be that of the feeling of full cream milk in your mouth, as compared to water. Typically, Indonesian coffees will posess greater body than South and Central American coffees. Coffees with a heavier body will maintain more of their flavour when diluted with milk. Aroma: This is a sensation which is hard to separate from flavour. The aroma contributes to the flavours we discern on our palates. Subtle nuances, such as 'floral' or 'winy' characteristics, are derived from the aroma of brewed coffee. Flavour: Flavour is the overall perception of the coffee in your mouth. Acidity, aroma and body are all components of flavour. Describing the tastes and flavours of different roasts is as subjective as putting a wine into words. In both cases there's no subsitute for your own personal tastes - so sample away! Coffees of various origins are usually blended in the trade in different proportions so as to make a cup with varying acidity and taste characteristics. Also, as different batches of coffee are likely to taste different to each other due to the fact that it is a natural product, blending is one way in which constant quality can be achieved. With more than 100 coffee growing regions in the world, each producing beans with distinctive characteristics, proper blending is obviously essential to balance the flavours needed to create a superior espresso. A single coffee bean will generally not possess the complexity necessary for great espresso. Many espresso blends will contain three to seven different types of beans. Argument still exists among roasters as to which should occur first, the roasting or the blending. Some people believe that roasting each varietal separately, to maximise it's flavour characteristics, and then blending, will produce the best result while others believe that if roasted together, the aromas of the different beans are homogenized during roasting. Blending before roasting certainly has its difficulties in that the homogeneous roasting of beans of different size, weight and country of origin has to be achieved. When green, coffee keeps for a long time, provided it is protected from damp; keeping it, in fact, improves it. It is entirely devoid of smell. To release the aroma, coffee has to be roasted, an operation which many coffee lovers insist on performing themselves. A good roaster must be part artist, and part scientist, to maintain quality and consistency. In the development of flavours, roasting is probably the most important of the steps considered so far. Well roasted coffee should be brown, of varying degrees of darkness, but never black. If not sufficiently roasted, it produces a colourless infusion, and is rough and astringent. If over-roasted it produces a black drink, bitter and unpleasant. In the roasting process coffee beans undergo many pyrolytic reactions which lead to the formation of the substances responsible for their sensory qualities, accompanied by important physical changes. It is during the roasting that the sugars and other carbohydrates within the bean become caramelised, creating a substance which is known as coffee oil. Technically, this fragile chemical is not actually an oil, but it is what gives the coffee its flavour and aroma. The modern machines used for roasting evolved from crude stone vessels used around 1200AD, through the first cylindrical design about 1650, to computerised roasters now used by major coffee companies. Yet in the 900 years or so that coffee has been roasted, the basic concept remains the same: create a flavourful, evenly roasted bean from the green coffee of the fields. During the industrial roasting process a small quantity of sugar molasses, or various other products is sometimes added, to 'coat' the berries. This coating, which is permissible by law, gives the berries a better colour and more shiny appearance, prevents the loss of aroma and has the further advantage for the merchant of increasing the weight.
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