Preservation of roasted and ground coffee during storage Part 1: moisture content and repose angle/Conservacao de cafe torrado e moido durante o armazenamento. Parte 1: teor de agua e angulo de repouso

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°C) 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. Key words: Coffea arabica Coffea canephora post-harvest Objetivou-se, com este trabalho, avaliar a influencia dos niveis de torrefacao e moagem sobre o teor de agua e angulo de repouso de cafe, durante o armazenamento. Foram utilizados graos de cafe cru (Coffea canephora e Coffea arabica), descascados e secos e torrados em dois niveis: media clara (SCAA#65) e moderadamente escura (SCAA#45). Os graos foram entao moidos em tres granulometrias: fina (0,59 mm), media (0,84 mm) e grossa (1,19 mm) alem do lote de cafe inteiro. Realizada a moagem as amostras foram armazenadas em duas temperaturas (10 e 30°C) e analisadas em cinco tempos distintos (0, 30, 60, 120 e 180 dias). A torrefacao a nivel moderadamente escuro proporcionou menores valores de teor de agua. Obtiveram-se, com amostras mais finas, maiores valores de angulo de repouso. Conclui-se que a granulometria, o nivel de torrefacao e o tempo de armazenamento afetaram significativamente o teor de agua e o angulo de repouso do cafe. Palavras-chave: Coffea arabica Coffea canephora pos-colheita