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Effect of Roasting Conditions on Carbon Dioxide Degassing Behavior in Coffee
As an observation.
Over my years of roasting I've noticed that darker roasts tend to degass at a much faster rate than lighter.
I have tended to stop all of my roasts over the last couple of years at the first few snaps of SC or 225° whichever happens first, these roasts degass at quite a slow rate, in fact over a few days the bag barely inflates.
Yesterday by way of a change decided to roast 750 grams of Yirg 10 seconds past SC, all went to plan, yep the beans were decidedly darker than usual, so, into a one way valve bag, expelled as much air a possible before sealing it, 2 hours later the bag had inflated considerably and by this morning had almost reached balloon proportions.
Wonder if others have experienced this?
This short article was all I could come up with after a brief search on Google.
Xiuju Wang, Loong-Tak Lim
Department of Food Science, University of Guelph, Guelph, On, N1G 2W1, Canada
Food Research International 01/2014;
ABSTRACT CO2 is one of the major gases formed during coffee roasting, which has important implications on coffee’s quality and packaging requirements. In this study, the residual CO2 content and CO2 degassing behavior of an Arabica coffee processed using a fluidized bed roaster, as affected by the roasting temperature-time conditions, were investigated. The results showed that positive correlations existed between the degree of roast (expressed as lightness value) and residual CO2, implying that lightness could be used as an indicator of initial CO2 content in roasted coffee. At the same degree of roast, coffee roasted with high-temperature-short-time process had significantly higher CO2 degassing rate than those with low-temperature-long-time process. Moreover, the CO2 releasing rate increased with the degree of roast. The degassing rate of CO2 in ground coffee was highly dependent on the grind size and roasting temperature, but less dependent on the degree of roast. The different degassing behaviors observed between roasted coffee samples were explained on the basis of chemical composition and microstructural differences.
As an observation.
Over my years of roasting I've noticed that darker roasts tend to degass at a much faster rate than lighter.
I have tended to stop all of my roasts over the last couple of years at the first few snaps of SC or 225° whichever happens first, these roasts degass at quite a slow rate, in fact over a few days the bag barely inflates.
Yesterday by way of a change decided to roast 750 grams of Yirg 10 seconds past SC, all went to plan, yep the beans were decidedly darker than usual, so, into a one way valve bag, expelled as much air a possible before sealing it, 2 hours later the bag had inflated considerably and by this morning had almost reached balloon proportions.
Wonder if others have experienced this?
This short article was all I could come up with after a brief search on Google.
Xiuju Wang, Loong-Tak Lim
Department of Food Science, University of Guelph, Guelph, On, N1G 2W1, Canada
Food Research International 01/2014;
ABSTRACT CO2 is one of the major gases formed during coffee roasting, which has important implications on coffee’s quality and packaging requirements. In this study, the residual CO2 content and CO2 degassing behavior of an Arabica coffee processed using a fluidized bed roaster, as affected by the roasting temperature-time conditions, were investigated. The results showed that positive correlations existed between the degree of roast (expressed as lightness value) and residual CO2, implying that lightness could be used as an indicator of initial CO2 content in roasted coffee. At the same degree of roast, coffee roasted with high-temperature-short-time process had significantly higher CO2 degassing rate than those with low-temperature-long-time process. Moreover, the CO2 releasing rate increased with the degree of roast. The degassing rate of CO2 in ground coffee was highly dependent on the grind size and roasting temperature, but less dependent on the degree of roast. The different degassing behaviors observed between roasted coffee samples were explained on the basis of chemical composition and microstructural differences.
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