Issue link: https://read.dmtmag.com/i/491371
42 STiR tea & coffee industry international The roasters Uniformity is prized by roasters. Constant air temperature and humidity are ideal. Uniform drum speed in the roaster, surface temperature, and a uniform first crack is ideally fol- lowed by uniform cooling Uniform bean size and density are critical. Out- liers that are too small or too light end up charred. Beans too large or dense roast to a lighter color than desired. "Roasters try to match a profile so that the line plotting temperature over time line up, the changes in color and the audible reaction from the first crack happen at the same time and at the same temperature every time, everything as close to mimicking the ideal roast as possible," said Rob Hoos, a roasting consultant and head roaster at Portland's Nossa Familia Coffee. The roaster is owned by Augusto Carneiro whose family has grown coffee in the Sul de Minas and Mogiana re- gion of Brazil since the 1890s. Optical Sorting Optical sorting is the essential technological breakthrough for separating green coffee by color. The newest machines can dif- ferentiate between 16 million shades to sort the most chaotic batch of beans, first by eliminating defects and then sorting the near-perfect beans by color. Technicians in Houston first passed the coffee sample through an Evolution RGB (red-green-blue) using a pre-programmed de- fect detecting camera. The coffee is illuminated by bright LEDs and a high-resolution color image is briefly stored in memory. As the bean proceeds the image is compared to a three-dimen- sional ideal calibrated to meet SCAA's defect-free standard. Major and minor color defects and other foreign matter are diverted to the waste bin by carefully timed jets. Every green bean that pass- es inspection drops into the accepted product bin. Dale Svatek, applications manager at Satake USA, said that it takes 1.5 hours to run a 37,500 pound lot of coffee through the sorter. Selections are made in miliseconds at processing speeds from 7 to 14 metric tons (31,000 pounds) per hour. Once the coffee is cleaned, the multi-colored batch of beans can be immediately run through the sorter for the hue color sort. For this pass the machine is programmed to look for dark green beans chosen by eye. Beans of this hue pass quickly through the machine while light and medium colored beans are eliminated by jets of air. The air does not damage the bean, said Svatek. A second pass, calibrated to identify medium hue beans leaves only the lightly colored beans. The three sorts can easily be done in an eight hour shift, said Svatek. Peter Cawthorne, Satake USA v.p. marketing, estimates the cost of a sort at $100 per hour for labor with 25% of that time for operating the sorter. Add to that a machine operating expense of $10 per hour which includes maintenance and electricity. Setup and handling is no different than a defect sort. Sorting a lot of cof- fee costs $35 per hour or $52.50 for a sort that takes 1.5 hours. Total additional cost: $105. Satake invented the rice milling machine and developed a rice color sorter. In 1992 Satake acquired Electric Sorting Machine Company (ESM) which had invented the optical sorter in 1931. ESM invented the two-color sorter in 1941 and prospered sorting beans and peanuts. In 1947, ESM installed its first green coffee sorting equipment in Colombia. Satake applied ESM's technology to sort many other prod- ucts in addition to rice.The company today is a perfect hybrid of Western ingenuity and Eastern precision. Satake demonstrated the expense of sorting rice can be easily recovered by the higher price customers were willing to pay for perfectly shaped uniform- ly colored grains. The same may prove true for coffee. "When it comes to color, coffee beans are a lot more chal- lenging than rice," said Svatek. "Sorting rice amounts to removing the red or brown and yellow grains. There are quite subtle hues in coffee. You need the very latest full-color technology to find de- fects in the green range like green sour," he said. "Sorting coffee is an art, not science." Satake USA sorted the green beans by color. Photo courtesy Satake USA