Home roasting coffee
From Wikipedia, the free encyclopedia
Home roasting is the process of roasting green coffee beans on a small scale for personal consumption. Personal roasting of coffee has been practiced for centuries, and has utilized numerous method of roasting the beans. Until World War I it was more common to roast coffee at home than to buy pre-roasted coffee. During the 20th century commercial coffee-roasting companies became common and home-roasting decreased[1].
In recent years some people have returned to home-roasting of coffee to get the freshest possible coffee with aroma undiminished by storage.
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[edit] Freshness
Depending on the origin and method of storage, coffee flavor can peak from 4 to 24 hours after roasting.[2] Subsequently flavor declines at a rate which depends on origin and storage. The flavor of ground coffee deteriorates much faster, sometimes in a matter of minutes[citation needed]. Many factors cause the decline of flavor after roasting, including the oxidation of oils and other compounds exposed to atmospheric oxygen after roasting damages bean cell wall integrity, and the evaporation of flavor-active volatile compounds. Roasting coffee beans produces a significant amount of carbon dioxide (CO2) gas; this CO2 preserves freshness to the extent that it excludes atmospheric oxygen. Other means of extending freshness such as freezing roasted beans and displacing surrounding air with an inert gas are somewhat controversial.[citation needed]
Home roasters can roast the amount of coffee they want when they need it, so that the roasted coffee is not stored for long enough to lose flavor or aroma. Green (unroasted) coffee beans can have a shelf life of one year or longer if properly stored.
[edit] Bean selection
Green coffee beans vary in quality due to many factors. The origin of the beans makes a notable difference in the resulting flavor. There appears to be some regional character associated with coffee which may be due partly to plant genetics, and partly to terroir or the regional climate. Also modest changes in growing conditions affect coffee flavor. The method of processing coffee 'cherries' into dried green beans affects the flavor and aroma of the resulting beverage. For these reasons the selection of the beans is important. In recent years Internet retailers and home roasting co-operatives have made a very wide selection of beans available to home roasters.
[edit] Roasting profile
A roasting profile describes the time the beans spend at each temperature during roasting. Typical roasting profiles take the beans from ambient temperature to a peak of between 205°C (400°F) and 250°C (480°F) over a period of 4 to 20 minutes. The beans are then rapidly cooled. The times spent at various temperatures and the peak temperature greatly affect the flavor and the color of the roast. Rapid cooling of the beans is necessary to prevent substantial loss of flavor. Professional commercial roasting equipment is usually automated and well instrumented; the simpler equipment available to the typical home roasters makes accurate and repeatable profile control more difficult, though they can become very good with experience. [3]
[edit] Quality
Because the unroasted beans are relatively stable, and roast coffee is quite unstable, the home roaster has a decided freshness advantage over all forms of commercially roast coffee, together with the ability to formulate exact roast times to taste. The recent hobby interest in home roasting and particularly the advent of home roasting co-operatives and internet green bean vendors have made a very wide selection of high quality green beans available to home roasters, comparable to or exceeding the variety available in the best commercial shops. In addition home roasters have reasonable control of the roasting profile and can with modest equipment, experience, and skill produce results comparable to commercial roasting systems.
[edit] Equipment
[edit] Improvised equipment
The simplest way of roasting green coffee beans is to stir them in a flat pan over a high heat. This method produces coffee beans with a variety of roast levels as it is almost impossible to achieve a consistent roast merely by stirring. Equipment designed for other purposes can also be adapted to roast coffee.
Common DIY roasters include hot air popcorn poppers (side-vented models), stove-top popcorn poppers, heat guns normally used for stripping paint, and barbecue roasters using home made steel drums suspended and rotated over burners. Heat guns and hot air popcorn poppers are generally the least expensive home roasters available. Some home-built roasters are based on stir-arm popcorn poppers coupled with convection ovens. Modified home bread-making machines have been used to agitate the beans with the high temperatures needed for coffee roasting provided by heat guns. This method is particularly popular in Australia where it has become known as a 'Corretto' after the online nickname of its developer.
[edit] Hot air popcorn popper
Popcorn poppers which use heated air can be used to roast small quantities of coffee. These machines are inexpensive and require only minimal setup. Their lightweight construction can cause machines to fail sooner when roasting coffee rather than popcorn, as the heating element is used for longer periods of time.
[edit] Dedicated home coffee roasters
There are a number of consumer coffee roasters including the Imex CR-100, Hearthware iRoast2, Swissmar Alpenrost, NESCO Professional Coffee Roaster (formerly Zach & Dani's Home Roaster, the FreshRoast +8, HOTTOP Bean Roaster, and the Gene Cafe Roaster. The Behmor 1600 is the newest entry into the homeroaster market. They are more expensive than home-built equipment, but automate the roasting process and avoid the hazards of using equipment not designed for high temperature operation. The HOTTOP is notable as having one of the best cooling cycles of any purpose-built home roasting appliance, coming close to the ability of small professional roasters.
Most of the purpose-built home roasting appliances are either "air" or "drum" roasters. Fluid-bed or air roasting is believed to produce more acidity in the coffee beans, while drum roasting tends to produce more "body". Recent studies have shown that the fast heat-up times of fluid-bed roasters lead to greater acidity being exposed in the bean, while the slower heat-up times of drum roasters help develop more body[citation needed]. Recent "hybrid" roasters use techniques being explored in the professional roasting field; most notably the Gene Cafe roaster from Korea, which uses an oscillating, off-axis drum rotation to agitate the beans and roast them evenly, and a sealed hot air flow to heat the roasting drum chamber.
The main drawbacks with many of the dedicated home roasting appliances are their relatively small capacity—some can only roast 75 grams of green coffee, limitations to the "roasting profiles" available, and often slow cooling abilities for the freshly roasted beans, which can dull or flatten flavor. Coffee roasting produces smoke and fumes and should be done in a well-ventilated area, problematical indoors at home. If coffee is roasted outdoors the ambient temperature needs to be monitored because it can affect the roast temperature. The appropriate degree of roasting depends upon the variety of coffee bean being roasted and the style of coffee required. A typical roast takes around twenty minutes to complete.
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[edit] References
- ^ Pendergrast, Mark (2000) Uncommon Grounds
- ^ Sweet Marias. Storing Your Roasted Coffee
- ^ Davids, Kenneth. Home Coffee Roasting: Romance and Revival. St. Martin's Griffin; revised edition, November 2003. ISBN-13: 978-0312312190
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