Guide to Commercial Roasting Technology and Controls - Page 2

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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another_jim (original poster)
Team HB

#11: Post by another_jim (original poster) »

Thanks for the link. I'll need to read it more closely.

Warning: Some of the graphs are badly mis-drawn. The first one on the glass phase has an axis that runs 50 to 300, and it should be 0 to 250 or 50 to 250 in order to agree with the text. The ones showing LTLT and HTST roasts both have a line for bean center temperature lines which is not mentioned in the text. The LTLT one is physically impossible, since the center gets hotter than the environment and does so in 30 seconds. In any case, the article's editor must have been sniffing something other than coffee, so be on the lookout for further errors.
Jim Schulman

DavidMLewis

#12: Post by DavidMLewis »

another_jim wrote:Some of the graphs are badly mis-drawn. The first one on the glass phase has an axis that runs 50 to 300, and it should be 0 to 250 or 50 to 250 in order to agree with the text. The ones showing LTLT and HTST roasts both have a line for bean center temperature lines which is not mentioned in the text. The LTLT one is physically impossible, since the center gets hotter than the environment and does so in 30 seconds. In any case, the article's editor must have been sniffing something other than coffee, so be on the lookout for further errors.
I'm missing something. The text says that the LTLT roast had an environment temperature of 228 °C, and the bean center temperature line appears to have the logarithmic shape I'd expect, which basically asymptotes to around that temperature somewhere around 300 seconds. Are we looking at the same graph?

Best,
David

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another_jim (original poster)
Team HB

#13: Post by another_jim (original poster) »

Page 454. The graph shows that the bean center hits 225C in 100 seconds with the air blowing in at 228C. Then the bean center stays constant for another 600 seconds. 225C is 437F, roughly the second crack. So according to the graph, the roast hits the second crack at 1 minute 40 seconds, and then stays there for another 10 minutes. Either there's a mistake here (for instance, the solid line is the supply air temperature, not the bean temperature) or I really don't want to try this coffee.
Jim Schulman

DavidMLewis

#14: Post by DavidMLewis »

I suspect it's the latter. If you put 100 g of coffee into a fluidized bed roaster and supply a high volume of air at 225 °C from the beginning of the roast, I imagine that's what you would get, more or less. The original Schenker study in 2000 had the same methodology, and I'm guessing that they chose to replicate what was already in the literature so that they could add to an existing body of research, rather than try to optimize it for actual taste.

Best,
David