How to choose a coffee roaster machine?
A coffee roasting machine is essential, if you own a coffee roastery or cafe shop, or plan to start a small roasting business from home. Choosing a new coffee roaster may be quite challenging, especially if you haven’t followed the coffee market. Nowadays you can choose from a huge variety of products that use advanced technologies. Every commercial coffee roasting machine should be made of robust materials that guarantee reliability of the roaster for many years. If you need some help in choosing the best commercial coffee roaster machine for your business, you can read the article below.
First, consider how much you can afford to spend on a roaster. When calculating your budget, don’t forget to include the cost of necessities such as chimney ductwork, pollution-control equipment, initial green-coffee inventory, a laptop for logging roast data, and various supplies. A budget should also include the costs of installation, permits, and architectural drawings for the permit process. If buy from overseas, then you should also consider the shipping cost, import duty etc.
With your budget and the above costs in mind, consider how much you can spend on the roasting machine. If you can afford it, please buy a larger roaster than you think you need. I’ve never known a roaster to regret buying a machine that was a bit too large, but I’ve known many roasters who regretted buying machines they quickly outgrew. Once you’ve estimated the startup costs of your roasting operation, prioritize your wants and needs.
To choose the proper machine size, it’s important to estimate how much coffee you expect to roast each week over the next two years. Note the weekly amount of coffee you expect to roast two years from today. When performing these calculations, remember that a machine’s real capacity is likely less than its stated capacity, and that beans lose 14%–20% of their weight during roasting. You can easily define the amount of coffee you produce by using this simple equation. Multiply the number of batches and kilograms per batch with the 15% weight loss, for example, 5 * 7kg * 0.85 = 29.75 kg. This should help you choose the most suitable coffee roasting machine.
Coffee Roaster Type
There are four main types of roaster machines based on the configurations and roasting mechanisms. These types are as follows.
- Classic drum roasters: in these machines a drum rotates above a gas flame, and a fan pulls hot air from the burner through the drum and out of the roaster. This process will provide some convective heat to the coffee beans to roast them evenly. Most coffee roaster machine we selling here belong to this type.
- Recirculation roasters: these machines recirculate a portion of the roasting exhaust air back through the burner and roasting chamber. Such machines are energy-efficient but often run the risk of imparting smokey or polluted flavors on coffee. To avoid smoke taint, it’s important to heat the recirculated air to a sufficiently high (afterburner-level) temperature before passing it through the drum.
- Indirectly heated drum roasters: in these machines the burner chamber is separated from the drum and hot air passes from the burner chamber through the drum. The design allows the drum’s surface to remain cooler because the flame is not in contact with the drum. Indirectly heated roasters are more difficult to control than classic drum roasters, because they require skillful management of airflow, while classic drum roasters rarely require much, if any, airflow adjustment.
- Fluid bed roasters: these machines rely on a bed of rising hot air to circulate the beans and keep the beans aloft. Fluid-bed roasters eliminate the risk of conductive-heat damage, and are usually capable of developing beans well in short amounts of time. While there is no theoretical downside to fluid-bed roasters, in practice their control systems are usually too simplistic to fulfill the machines’ potential. Given the current, rapid evolution in roast-control and data-logging software, I expect the utility and popularity of fluid-bed roasters to grow rapidly in the near future.
Every roaster will work using a different mechanism providing unique tastes to the beans. In this article, let us see the working of these types of roasters.
None of the features listed below are necessary to roast a good batch of coffee, but each may contribute to improved roast quality or repeatability.
- Double drum (applies only to classic drum roasters) and powerful burner: the foundation of a good classic drum roaster is its burner and drum. Burner output determines a machine’s true capacity. Double drums allow for faster and hotter roasting with less risk of tipping or scorching.
- Variable-speed-drive (VSD) fan: as long as your roaster’s fan provides a reasonable amount of draw, you don’t need a variable-speed fan to produce good roasts. But without a VSD fan, it’s impossible to maintain consistent airflow levels day to day. The combination of a digital air-pressure manometer and a VSD fan is essential for expert-level roast repeatability.
- Air manometer (aka drum-pressure manometer): a manometer in the duct between the roasting drum and exhaust fan is a relatively new, worthwhile addition to a roaster. The manometer reads pressure, not flow, but that pressure reading correlates with airflow. Using the same fan setting every day does not ensure consistent roasting because airflow may vary day to day with the weather and other factors. Having an air-pressure manometer helps one know how to adjust the fan to provide consistent airflow every batch. (Note: directly measuring airflow requires installing probes in the exhaust duct, but the probes get dirty too quickly during roasting to work effectively. Using an air-pressure manometer is the best current option to monitor and maintain consistent airflow batch to batch. However, the relationship between pressure and flow will shift slowly as the ducts get dirty, so frequent chimney cleaning is critical.)
- High-resolution gas manometer: Most roasting machines come with small, cheap analog manometers that offer imprecise gas-pressure measurements. I recommend replacing your stock analog manometer with a high-resolution digital manometer. Analog manometers may be aesthetically pleasing, but they make discernment of precise readings too difficult.
- Proper probes and probe locations: To be a great roaster by today’s standards, one needs better green, lighter roasts, quality data collection, precise controls, and software to track and analyze the data. To ensure adequate data collection, insist on having a bean probe and an environmental probe, each with diameters of 2.5 mm– 4 mm. An inlet-temperature probe is helpful but not critical.