Physical Changes During Coffee Roasting in Rotary Conduction‐type Heating Units

Mwithiga, Gikuru; Jindal, V. K.

doi:10.1111/j.1745-4530.2003.tb00655.x

Cited by 19 publications

(14 citation statements)

References 5 publications

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“…This effect was previously observed in several studies on coffee (Illy & Viani, 1995;Singh et al, 1997;Mwithiga & Jindal, 2003;Mendonça et al, 2009;Vargas-Elías, 2011 roasting results in greater weight loss and increased coffee volume and, therefore, lower ρ ap . The change in volume is related to the increase in internal cell pressure that occurs during heat transfer and in pyrolysis reactions, which are more intense during longer roasts (Borges et al, 2004).…”

Section: Resultssupporting

confidence: 49%

“…Roast level has been reported to determine the final quality of the beverage (Melo, 2004;Baggenstoss et al, 2008), and significant changes to coffee's physical properties have been observed to occur during roasting (Mwithiga & Jindal, 2003). Grinding results in powdery products that can have different particle sizes according to the market's needs (Schmidt et al, 2008) and affect the physical properties of coffee (Geldart et al, 2009;Langroudi et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Preservation of roasted and ground coffee during storage. Part 2: Bulk density and intergranular porosity

Corrêa

Oliveira

Vasconcelos

et al. 2016

Rev. bras. eng. agríc. ambient.

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A B S T R A C TThe determination of physical properties is an important factor in the design of machinery and the scaling of post-harvest operations. The present study evaluates the influence of the level of roasting and the size of grinding on the physical properties of coffee during storage. The following physical properties were evaluated: true and bulk density, and intergranular porosity. 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 grinded into three different 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 medium light roast had higher values for each of the measured physical properties. Finely ground samples had higher true and bulk densities, and porosities. It is concluded that the size of grinding, level of roasting and duration of storage significantly affect the physical properties of coffee.Conservação de café torrado e moído durante o armazenamento. Parte 2: Massa específica e porosidade R E S U M OA determinação das propriedades físicas é fator importante na formulação de projetos de maquinários e dimensionamento de operações pós-colheita. De forma a permitir o dimensionamento correto e o uso desses maquinários, objetivou-se avaliar e determinar, durante o armazenamento, as propriedades físicas: massa específica unitária e aparente e porosidade intergranular, além de avaliar a influência dos níveis de torrefação e moagem sobre essas propriedades. Grãos de café cru (Coffea canephora e Coffea arabica) foram utilizados, descascados e secados e só então torrados em dois níveis: média clara (SCAA#65) e moderadamente escura (SCAA#45). Os grãos foram 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 de armazenamento (0, 30, 60, 120 e 180 dias). A torra média clara permitiu maiores valores das propriedades físicas; já as amostras de granulometria fina apresentaram aumento das massas específica unitária e aparente e porosidade. Conclui-se que a granulometria, o nível de torrefação e o tempo de armazenamento, afetaram as propriedades físicas do café.

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Section: Resultssupporting

confidence: 49%

Section: Introductionmentioning

confidence: 99%

Preservation of roasted and ground coffee during storage. Part 2: Bulk density and intergranular porosity

Corrêa

Oliveira

Vasconcelos

et al. 2016

Rev. bras. eng. agríc. ambient.

View full text Add to dashboard Cite

show abstract

“…Accordingly, green beans with a high moisture content will exhibit a greater dehydration rate and a faster increase in RL than drier beans, while organic roast loss (ORL: defined as the percent loss of organic dry matter) may be only slightly affected. 5,48 Fast roasting generally produces coffee with a lower density due to the larger volume. As an approximation, a 7.0% of ORL is equivalent to medium roast degree.…”

Section: Moisture Content Roast Loss and Densitymentioning

confidence: 99%

Physicochemical Characteristics of Roasted Coffee

Wang

Lim

2015

Coffee in Health and Disease Prevention

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“…Roasting is an essential step in the production of high-quality instant coffee, because this process produces the desired aroma and taste of the beans (Farah et al ., 2006;Mwithiga et al ., 2003). During the roasting process, physical, chemical, structural and sensorial changes in the coffee beans are induced by pyrolysis at temperatures of between 160 ° C and 260 ° C for different periods of time (Hern á ndez et al ., 2007;Pittia et al ., 2001).…”

Section: Roastingmentioning

confidence: 94%