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The effect of bean origin and temperature on grinding roasted coffee.

Uman E, Colonna-Dashwood M, Colonna-Dashwood L, Perger M, Klatt C, Leighton S, Miller B, Butler KT, Melot BC, Speirs RW, Hendon CH - Sci Rep (2016)

Bottom Line: Coffee is prepared by the extraction of a complex array of organic molecules from the roasted bean, which has been ground into fine particulates.We find that the particle size distribution is independent of the bean origin and processing method.Furthermore, we elucidate the influence of bean temperature on particle size distribution, concluding that grinding cold results in a narrower particle size distribution, and reduced mean particle size.

View Article: PubMed Central - PubMed

Affiliation: Meritics Ltd., 1 Kensworth Gate, Dunstable, LU6 3HS, United Kingdom.

ABSTRACT
Coffee is prepared by the extraction of a complex array of organic molecules from the roasted bean, which has been ground into fine particulates. The extraction depends on temperature, water chemistry and also the accessible surface area of the coffee. Here we investigate whether variations in the production processes of single origin coffee beans affects the particle size distribution upon grinding. We find that the particle size distribution is independent of the bean origin and processing method. Furthermore, we elucidate the influence of bean temperature on particle size distribution, concluding that grinding cold results in a narrower particle size distribution, and reduced mean particle size. We anticipate these results will influence the production of coffee industrially, as well as contribute to how we store and use coffee daily.

No MeSH data available.


Related in: MedlinePlus

The temperature dependence on the grind profile of the El Salvadorian coffee, (a). The temperatures were achieved by grinding liquid nitrogen, dry ice, freezer and room temperature coffee, respectively. The fine particulate cutoff is schematically shown, with exact values corresponding to; −196 °C = 61 ± 3 μm, −79 °C = 63 ± 3 μm, −19 °C = 73 ± 3 μm and 20 °C = 70 ± 3 μm. The mode of the number distribution, (b) shows a clear and non-linear trend of increasing mode with increasing temperature. The distribution skewness is inversely proportional to temperature. From a flavour perspective this is a favourable feature because the surface area to volume ratio becomes increasingly significant for the smaller particles. The mean particle size, (d) is discontinuous with temperature likely indicating a transition between freezer and room temperature.
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f4: The temperature dependence on the grind profile of the El Salvadorian coffee, (a). The temperatures were achieved by grinding liquid nitrogen, dry ice, freezer and room temperature coffee, respectively. The fine particulate cutoff is schematically shown, with exact values corresponding to; −196 °C = 61 ± 3 μm, −79 °C = 63 ± 3 μm, −19 °C = 73 ± 3 μm and 20 °C = 70 ± 3 μm. The mode of the number distribution, (b) shows a clear and non-linear trend of increasing mode with increasing temperature. The distribution skewness is inversely proportional to temperature. From a flavour perspective this is a favourable feature because the surface area to volume ratio becomes increasingly significant for the smaller particles. The mean particle size, (d) is discontinuous with temperature likely indicating a transition between freezer and room temperature.

Mentions: The lower the original bean temperature, the colder the produced particles will be at every stage of grinding. However colder bean fragments will absorb heat from their surroundings more quickly due to the larger temperature gradient, effectively reducing the indicated temperature difference between the samples. Therefore, the observed change in grind profile should be considered a lower limit on the effects of grinding at reduced temperatures. Given the inhomogeneous nature of the beans, it is likely that cooling the burrs (and hence further reducing the temperature of the particles as they are ground) would smoothly continue the trend observed in Fig. 4.


The effect of bean origin and temperature on grinding roasted coffee.

Uman E, Colonna-Dashwood M, Colonna-Dashwood L, Perger M, Klatt C, Leighton S, Miller B, Butler KT, Melot BC, Speirs RW, Hendon CH - Sci Rep (2016)

The temperature dependence on the grind profile of the El Salvadorian coffee, (a). The temperatures were achieved by grinding liquid nitrogen, dry ice, freezer and room temperature coffee, respectively. The fine particulate cutoff is schematically shown, with exact values corresponding to; −196 °C = 61 ± 3 μm, −79 °C = 63 ± 3 μm, −19 °C = 73 ± 3 μm and 20 °C = 70 ± 3 μm. The mode of the number distribution, (b) shows a clear and non-linear trend of increasing mode with increasing temperature. The distribution skewness is inversely proportional to temperature. From a flavour perspective this is a favourable feature because the surface area to volume ratio becomes increasingly significant for the smaller particles. The mean particle size, (d) is discontinuous with temperature likely indicating a transition between freezer and room temperature.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834475&req=5

f4: The temperature dependence on the grind profile of the El Salvadorian coffee, (a). The temperatures were achieved by grinding liquid nitrogen, dry ice, freezer and room temperature coffee, respectively. The fine particulate cutoff is schematically shown, with exact values corresponding to; −196 °C = 61 ± 3 μm, −79 °C = 63 ± 3 μm, −19 °C = 73 ± 3 μm and 20 °C = 70 ± 3 μm. The mode of the number distribution, (b) shows a clear and non-linear trend of increasing mode with increasing temperature. The distribution skewness is inversely proportional to temperature. From a flavour perspective this is a favourable feature because the surface area to volume ratio becomes increasingly significant for the smaller particles. The mean particle size, (d) is discontinuous with temperature likely indicating a transition between freezer and room temperature.
Mentions: The lower the original bean temperature, the colder the produced particles will be at every stage of grinding. However colder bean fragments will absorb heat from their surroundings more quickly due to the larger temperature gradient, effectively reducing the indicated temperature difference between the samples. Therefore, the observed change in grind profile should be considered a lower limit on the effects of grinding at reduced temperatures. Given the inhomogeneous nature of the beans, it is likely that cooling the burrs (and hence further reducing the temperature of the particles as they are ground) would smoothly continue the trend observed in Fig. 4.

Bottom Line: Coffee is prepared by the extraction of a complex array of organic molecules from the roasted bean, which has been ground into fine particulates.We find that the particle size distribution is independent of the bean origin and processing method.Furthermore, we elucidate the influence of bean temperature on particle size distribution, concluding that grinding cold results in a narrower particle size distribution, and reduced mean particle size.

View Article: PubMed Central - PubMed

Affiliation: Meritics Ltd., 1 Kensworth Gate, Dunstable, LU6 3HS, United Kingdom.

ABSTRACT
Coffee is prepared by the extraction of a complex array of organic molecules from the roasted bean, which has been ground into fine particulates. The extraction depends on temperature, water chemistry and also the accessible surface area of the coffee. Here we investigate whether variations in the production processes of single origin coffee beans affects the particle size distribution upon grinding. We find that the particle size distribution is independent of the bean origin and processing method. Furthermore, we elucidate the influence of bean temperature on particle size distribution, concluding that grinding cold results in a narrower particle size distribution, and reduced mean particle size. We anticipate these results will influence the production of coffee industrially, as well as contribute to how we store and use coffee daily.

No MeSH data available.


Related in: MedlinePlus