Preservation of roasted and ground coffee during storage Part 1: Moisture content and repose angle

Abstract

The present study evaluates the influence of the level of roasting and the grind size on the moisture content and repose angle of coffee during storage. Raw coffee beans (Coffea canephora and Coffea arabica), hulled and dried, were roasted to two different levels: medium light (SCAA#65) and moderately dark (SCAA#45). The beans were then ground into three different grind sizes: fine (0.59 mm), medium (0.84 mm) and coarse (1.19 mm). An additional coffee lot was kept whole. Following grinding, samples were stored at two different temperatures (10 and 30 oC) and analyzed after five different storage durations (0, 30, 60, 120 and 180 days). The moderately dark roast was found to have a lower moisture content. Finely ground samples had higher angles of repose. It is concluded that the grind size, level of roasting and duration of storage significantly affect the moisture content and angle of repose of coffee.Objetivou-se, com este trabalho, avaliar a influência dos níveis de torrefação e moagem sobre o teor de água e ângulo de repouso de café, durante o armazenamento. Foram utilizados grãos de café cru (Coffea canephora e Coffea arabica), descascados e secos e torrados em dois níveis: média clara (SCAA#65) e moderadamente escura (SCAA#45). Os grãos foram então moídos em três granulometrias: fina (0,59 mm), média (0,84 mm) e grossa (1,19 mm) além do lote de café inteiro. Realizada a moagem as amostras foram armazenadas em duas temperaturas (10 e 30 oC) e analisadas em cinco tempos distintos (0, 30, 60, 120 e 180 dias). A torrefação a nível moderadamente escuro proporcionou menores valores de teor de água. Obtiveram-se, com amostras mais finas, maiores valores de ângulo de repouso. Conclui-se que a granulometria, o nível de torrefação e o tempo de armazenamento afetaram significativamente o teor de água e o ângulo de repouso do café.