Home roasting coffee
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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 such as heating over fire coals, roasting in cast iron pans, and rotating iron drums over a fire or coal bed. 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 with the creation of instant coffee in 1901, home-roasting decreased.[1]
In recent years an increasing number of 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 peaks from 24 hours to 7 days after roasting.[2] Subsequently, flavor declines at a rate which depends on origin and storage. The flavor of ground coffee deteriorates much faster. 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 have unproven success.
Home roasters are able to roast smaller volumes of coffee to match consumption 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 or more years if properly stored.
[edit] Bean selection
The origin of beans makes a notable difference in the resulting flavor. There are regional character associated with coffee which are due to plant genetics, soil composition and terroir[vague] or the regional climate. Modest changes in growing conditions can also affect coffee flavor. The method of processing coffee 'cherries' into dried green beans affects the flavor and aroma of the resulting beverage. In recent years internet retailers and home roasting co-operatives have made a very wide selection of beans available to home roasters, including crops from small plantations that produce too little volume for commercial 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 color of the roast. Rapid cooling of the beans is necessary to prevent the roast continuing from retained heat. 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
The home roaster is generally able to consume fresher coffee than typical commercially roast coffee. Additionally, the home roaster can formulate exact roast times to suit individual taste. The recent hobby interest in home roasting and particularly the advent of home roasting cooperatives 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.
[edit] Equipment
[edit] Improvised equipment
The simplest technique for 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. The opportunity to automate and better control various aspects of the roasting process has led to innovative reuse of equipment intended for other purposes.
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 vented from the sides of the popping chamber 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 and subject to higher temperatures than it was designed for.
[edit] Dedicated home coffee roasters
There are an increasing number of consumer coffee roasters including the Imex CR-100, Hearthware iRoast2, Swissmar Alpenrost, NESCO Professional Coffee Roaster (formerly Zach & Dani's Home Roaster), FreshRoast +8, HOTTOP Bean Roaster, Gene Cafe Roaster, and Behmor 1600. 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.[peacock term]
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".[citation needed] Newer "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—varying from 75 grams (2.6 oz.) to 300 grams of green coffee, limitations to the "roasting profiles" available, and often slow cooling abilities for the freshly roasted beans, which can lead to dull or flat flavor. Coffee roasting produces smoke and fumes and should be done in a well-ventilated area which is often difficult to obtain in a home environment. Coffee roasted outdoors is affected by variation in the ambient temperature, requiring more complex adjustments to the roasting process to produce repeatable results.
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[edit] References
- ^ Pendergrast, Mark (2000) Uncommon Grounds
- ^ AllExperts Fresh Coffee
- ^ Davids, Kenneth. Home Coffee Roasting: Romance and Revival. St. Martin's Griffin; revised edition, November 2003. ISBN-13: 978-0312312190
[edit] External links
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Wikimedia Commons has media related to: Home roasting coffee |
- Homeroasters Association - Information and discussion on how-to roast coffee at home.
- CoffeeSnobs - A large and busy coffee forum with a focus on home roasting devices and processes.
- Absolute Beginner's Guide to Home Coffee Roasting
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