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Coffee preparation is the process of turning coffee beans into liquid coffee. While the particular steps vary with the type of coffee and with the raw materials, the process includes four basic steps: raw coffee beans must be roasted, the roasted coffee beans must then be ground, and the ground coffee must then be mixed with hot or cold water (depending on the method of brewing) for a specific time (brewed), the liquid coffee extraction must be separated from the used grounds, and finally, if desired, the extracted coffee is combined with other elements of the desired beverage, such as sweeteners, dairy products, dairy alternatives, or toppings (such as shaved chocolate).
Coffee is usually brewed hot, at close to the boiling point of water, immediately before drinking, yielding a hot beverage capable of scalding if splashed or spilled; if not consumed promptly, coffee is often sealed into a vacuum flask or insulated bottle to maintain its temperature. In most areas, coffee may be purchased unprocessed, or already roasted, or already roasted and ground. Whole roast coffee or ground coffee is often vacuum-packed to prevent oxidation and lengthen its shelf life. Especially in hot climates, some find cold or iced coffee more refreshing. This can be prepared well in advance as it maintains its character when stored cold better than as a hot beverage.
Even with the same roast, the character of the extraction is highly dependent on distribution of particle sizes produced by the grinding process, temperature of the grounds after grinding, freshness of the roast and grind, brewing process and equipment, temperature of the water, character of the water itself, contact time with hot water (less sensitive with cold water), and the brew ratio employed. Preferred brew ratios of water to coffee often fall into the range of 15–18:1 by mass; even within this fairly small range, differences are easily perceived by an experienced coffee drinker. Processes can range from extremely manual (e.g. hand grinding with manual pour-over in steady increments) to totally automated by a single appliance with a reservoir of roast beans which it automatically measures and grinds, and water, which it automatically heats and doses. Another common style of automated coffee maker is fed a single-serving "pod" of pre-measured coffee grounds for each beverage.
Characteristics which may be emphasized or deemphasized by different preparation methods include: acidity (brightness), aroma (especially more delicate floral and citrus notes), mouthfeel (body), astringency, bitterness (both positive and negative), and the duration and intensity of flavour perception in the mouth (finish). The addition of sweeteners, dairy products (e.g. milk or cream), or dairy alternatives (e.g. almond milk) also changes the perceived character of the brewed coffee. Principally, dairy products mute delicate aromas and thicken mouthfeel (particularly when frothed), while sweeteners mask astringency and bitterness.