STiR coffee and tea magazine

STiR coffee and tea 39 20+ Major Systems For Immediate Sale Coffee & Soluble Drinks Production formerly of Nest le Mainz, Germany Many More Systems for Immediate Sale at m.maynards.com/nestle hot metal in the roaster." As the roasting proceeds, flakes of chaff released from the bean builds up in the chaff compartment, affecting the airflow in the roaster. "The convective heat of the airflow is the primary heat source. About 70% of the heat medium is from hot air. As chaff builds up, it inhibits the airflow, so that affects the heat of the roaster, which affects how the coffee is cooked. That's why periodic maintenance is so important," says Whitley. "It affects the quality of the coffee because suddenly your ratio, your mix between the three heat mediums, changes from less hot air to more convective heat, so now you're actually using a different roast pro- file. You're trying to duplicate the same result in a different environment." Thornton points out, "when residue starts building up, your piping becomes a different size, in essence. In order to maintain the roast profiles you need it to be clean." Further, poor cleaning will negatively impact the cooling process, says Whitley. "Targeted cooling times range from three to four minutes. What we often see in the field is that the screens in the cooling bins aren't cleaned often enough, so the holes plug with residue. Without daily maintenance on both the top and the bottom of the screen, the cooling process actually slows down which means the roasting process ex- tends," further disrupting the roasting profile. He advises roasters to clean the screen on both sides after about every four hours of roasting using a cooling bin roller or by pressing a wire brush into the holes. Fire safety Regular cleaning is vital to diminish the risk of fire. Built-up residue presents a risk. "It can take a while to light, but once it lights it's like a grease fire," says Hoos. He notes that buildup varies. "When you are roasting dark or roasting a lot of volume through a small machine, then you're going to see buildup a lot faster. If you tend to roast light- er—we're talking pre-second crack―then you're going to see less buildup and have to clean less frequently." When onboarding a new roaster, Hoos recommends you "check fans and ventilation monthly until you figure out exactly how quickly it builds up. Stray bits of chaff accumulate in every part of the roaster. The chaff compart- ment should be emptied after every four hours of operation. Photos by Rob Hoos, Nossa Familia

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