Inside an aging industrial park, a nutty, sweet aroma wafts through the air. Smoke billows out of one particular shophouse in a row of red-brick, one-story factories. Inside, four men clad in polo shirts, hair nets, masks, and heavy-duty gloves emerge from the smoke. With metal rods, they repeatedly slam a mound of caramelized coffee beans inside a tub, breaking them apart. These are employees of Kim Guan Guan, one of the last traditional coffee roasters in Singapore. Jason Soon founded Kim Guan Guan in 1988. Initially, he saw coffee…