Home roasting coffee

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Start of roast

End of roast (overroasted)

Chaff

1 Freshness
2 Bean Selection
3 Roasting Profile
4 Quality
5 Equipment
- 5.1 Hot Air Popcorn Popper Method
- 5.2 Dedicated Home Coffee Roasters
6 References
7 External links

Home roasting is the process of obtaining green coffee beans and roasting them 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 for at-home coffee drinkers to roast their coffee in their residence than it was to buy pre-roasted coffee. During the 20th century, roasting coffee in the home faded in popularity with the rise of the commercial coffee roasting companies ^[1]. In recent years home roasting of coffee has seen a revival, primarily it is a means for the coffee aficionado to get access to better quality, fresher roasted beans.

[edit] Freshness

Roasted coffee flavor improves for approximately 24-48 hours from the time it is roasted. After this brief period of improvement coffee flavor declines and within a week much of the flavour complexity lost. Grinding roast beans accelerates the rate of staling to a matter of hours. There are numerous factors involved in the decline of coffee flavor after roasting, among these are the oxidation of oils and other compounds exposed to atmospheric oxygen after the roasting process damages bean cell wall integrity, and also the loss of flavor active volatile compounds to evaporation. It is worth noting that freshly roast coffee beans produce a significant amount of carbon dioxide (CO₂) gas as a result of the roasting process. This CO₂ gas has a modestly protective effect for freshness to the extent that it prevents atmospheric oxygen from contacting the beans. Other means of extending freshness such as freezing roast beans and displacing surrounding air with an inert gas are somewhat controversial.

Because home roasters have control of the roasting quantity and schedule, they can arrange to have coffee available at or near its flavor optimum. Many home roasters insist on roasting several times per week for the sake of obtaining optimal coffee flavor.

Unroasted (green) 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. It seems that there is some regional character associated with coffee which may in part be due to plant genetics, and also in part to terroir or the regional climate. Also modest changes in growing conditions impact coffee flavor. The processing method of coffee 'cherries' into dried green beans impacts flavor and aroma of the resulting beverage. For all these reasons the selection of the beans is an important quality factor. 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 vs. temperature trajectory of the beans through the roasting process. Typical roasting profiles take the beans from ambient temperature to a peak between 205°C (400°F) and 250°C (480°F) in a period from 4 to 20 minutes. The beans are then rapidly cooled. The times spent at various temperatures as well as the peak temperature achieved greatly impact the flavor and the color of the roast. Rapid cooling of the beans is necessary to prevent substantial flavor damage to the beans. Generally the equipment available to home roasters makes accurate and repeatable profile control more difficult than with professional commercial roasting equipment which is often automated and well instrumented, though home roasters can become very good at their craft with experience.

[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

Corretto model G with thermocouple

Home coffee roasting equipment includes a variety of retail machines made specifically for this purpose and additionally a number of home built devices which have been ingeniously adapted to the purpose of coffee roasting. However the traditional and simplest way of roasting the beans is to stir the green coffee beans in a flat pan over a high heat. This method is quite acceptable for coffee drinkers who are happy to have a variety of roast levels in their beans as it's almost impossible to achieve a consistent roast while stirring.

The most common DIY roasters include hot-air popcorn poppers (side-vented models), stove-top popcorn poppers (manual stovetop), heat/hot air guns (normally for stripping paint), and barbeque roasting with home made steel drums suspended and rotated over burners. Heat guns and hot-air popcorn poppers are generally the least expensive home-use roasters available. Some home-built roasters are based on stir-arm popcorn poppers coupled with convection ovens. A recent innovation is the conversion of bread making machines used in conjunction with heat guns. The bread maker provides the agitation of the beans and the heat gun a concentrated source of heat for roasting. This method is particularly popular in Australia where it has become known as a 'Corretto', a reference to the online nickname of the developer of the method.

[edit] Hot Air Popcorn Popper Method

Home Roasting with a Popper

Start with 46 grams of green coffee beans roasting for 8 minutes and 40 seconds in a side-vented, hot air popcorn popper venting into a metal or ceramic bowl. Use a timer with a loud alarm to ensure you don't forget to unplug the roaster. A couple of beans may be expelled into the bowl along with the chaff. When done, unplug the popper, discard the chaff in the bowl, dump the roasted beans into the bowl and quickly cool the beans by pouring them between two bowls for about a minute. A wait time of about 24 hours before brewing is recommended, as the flavour improves significantly. Roasting should be done out-of-doors, in a garage, or under a stove fan exhausting outside as enough smoke to set off a smoke detector is produced.

[edit] Dedicated Home Coffee Roasters

There are a variety of consumer appliances made specifically for coffee roasting such as the Hearthware iRoast2, Swissmar Alpenrost, Zach & Dani's Home Roaster, the FreshRoast +8, HOTTOP Bean Roaster, and the Gene Cafe Roaster. These are generally more expensive than home-built options, but offer more automation of the process and avoid the potential hazards of reappropriating other equipment which may be pushed outside of its intended operating range by this unexpected use.

Most of the purpose-built homeroasting appliances are either "air" or "drum" roasters. Commonly, it is held that fluid-bed or air roasting method tends to produce more acidity in the coffee beans while the drum roasting method tends to produce more body in the coffee beans. More recent exploration into the art of roasting in the home has shown that the fast heat up times typical in many fluid bed roasters leads to greater acidity being exposed in the bean, whereas the slower heat up times in drum roasters help develop more body. As new machines come to market that allow for greater control over the heat application process, it should be possible for fluid bed air roasters to develop more body and less acidity, and vice versa for the drum roaster appliances.

Recently, there have been "hybrid" roasters introduced to market that borrow technologies and methodologies being explored in the professional roasting field; most notably the Gene Cafe roaster out of Korea. Recently introduced into North America, this roaster uses an oscillating, off-axis drum rotation to agitate and apply even roasting to the beans, and uses a sealed hot air flow to heat the roast drum chamber.

The main drawbacks with many of the dedicated home roasting appliances are their relatively small batch size (some roasters are capable of handling only 75 grams of green coffee), frequent limitations in the "roasting profile" used by professional roasters to further control the resulting coffee roast, and often slow cool-down abilities for the freshly roasted beans, which could result in a dulling or flattening of potential flavors in the coffee.

New devices coming to market are providing more control over some of these variables, including the iRoast2 which allows for programmable roasting profiles, and the Gene Cafe Roaster which allows the user to adjust both roast time and temperature at any time during the roast. 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.

These improvements, along with other developments are fostering a better understanding and appreciation for the art of roasting coffee. They are also continually improving the quality of coffee roasted in the home. Home roasting allows the coffee aficionado to be integral in the process and become more knowledgeable while enjoying better, cheaper and fresher coffee.

Coffee beans can be roasted to different levels and is usually dependent on the variety of coffee bean being roasted as well as the style of coffee being prepared. A typical roast takes around twenty minutes to complete. The images show an example of a roasting cycle, in this case utilizing a HOTTOP drum roaster.

[edit] References

^ Pendergrast, Mark (2000). Uncommon Grounds

[edit] External links

TooMuchCoffee: The European Coffee and Espresso Resource - Offers non-commercial articles and discussion about homeroasting, coffee and coffee preparations.
CoffeeSnobs - An Australian green bean co-op with a large forum of enthusiastic home roasters.
HomeRoasters.org - drink the best, learn to home roast, articles and forum
Coffeegeek.com- A large community of coffee enthusiasts featuring discussions of and opinions about purchasing, brewing, home roasting, cupping, and grinding coffee and espresso for personal consumption. With columns, equipment reviews and how to articles by coffee professionals and amateur hobbyists.
Basics of Home Coffee Roasting - An instructional overview on the basics of roasting your own beans at home.
CaffeBLOG.com - Coffee Related Blog Community Network. A free blog community centered on the culture of coffee preparation, roasting, and societies relationship with coffee.