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

Abstract

A B S T R A C TThe 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.Conservação de café torrado e moído durante o armazenamento. Parte 1: Teor de água e ângulo de repouso R E S U M O 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.

<b>Kinetic modeling of water sorption by roasted and ground coffee

“…However, grinding promotes cell breakage and enables the release of molecular components, which can make quality preservation difficult (Corrêa et al, 2016a).…”

Farm to Consumer: Factors Affecting the Organoleptic Characteristics of Coffee. II: Postharvest Processing Factors

“…Similarly, storage period, along with the variables of roasting and particle size, significantly influences the moisture content of all coffee types at both low and high storage temperatures. During storage, ground coffee beans (coarse: 1.19 mm, medium: 0.84 mm and fine: 0.59 mm) from medium to dark roasting are more hygroscopic, with a higher moisture content than light‐ to medium‐roasted coffee (Correa et al., ; Oliveira et al., ). However, the equivalent moisture level of both light‐ and dark‐roasted ground coffee after 180 days indicates that the moisture level of roasted coffee is a function of storage time (Correa et al., ).…”

“…During storage, ground coffee beans (coarse: 1.19 mm, medium: 0.84 mm and fine: 0.59 mm) from medium to dark roasting are more hygroscopic, with a higher moisture content than light‐ to medium‐roasted coffee (Correa et al., ; Oliveira et al., ). However, the equivalent moisture level of both light‐ and dark‐roasted ground coffee after 180 days indicates that the moisture level of roasted coffee is a function of storage time (Correa et al., ). The initial difference in moisture content between light‐medium to dark‐roasted coffee beans may be due to a high degree of moisture loss during prolonged roasting to produce a dark roast (Baggenstoss, poisson, Kaegi, Perren, & Escher, , ).…”

“…The initial difference in moisture content between light‐medium to dark‐roasted coffee beans may be due to a high degree of moisture loss during prolonged roasting to produce a dark roast (Baggenstoss, poisson, Kaegi, Perren, & Escher, , ). In contrast, some authors have also deduced that roasting degree does not affect the hygroscopic ability of whole and ground coffee (Fernandes, Pereira, Borem, Nery, & Padua, ), but storage at low temperature markedly reduces the adsorption of moisture from the environment, in addition to varying other influential physical factors like ρ u , ρ ap , and intergranular porosity (Correa et al., ), because a higher storage temperature causes more excitation of water molecules, leaving sorption sites for the retrieval of moisture from the environment (Correa, Oliveira, Botelho, Goneli, & Carvalho, ). As compared to that of roasted ground coffee, storage of whole roasted coffee beans is preferable for conserving coffee constituents, moisture, and quality, without agglomeration and compactness, probably due to intact cells working as a physical barrier (Toledo et al., ).…”

Effects of Fruit Maturity, Bean Fermentation and Roasting Time on Physico-Chemical Characters of Robusta Coffee

“…Buah yang dipanen berwarna merah dan disangrai selama 10 menit menghasilkan kadar protein lebih tinggi, tetapi tidak berbeda dengan buah yang dipanen warna kuning kemerahan yang disangrai selama 13 menit (Tabel 6). Hasil penelitian sebelumnya menunjukkan bahwa semakin lama waktu sangrai, kadar air semakin berkurang karena adanya efek evaporasi (Corrêa et al, 2016). Kadar abu merupakan representasi kandungan mineral pada kopi atau seluruh bahan anorganik dalam produk yang tersisa setelah dilakukan pengabuan, sedangkan keasaman merupakan salah satu penentu citarasa kopi.…”