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Roast evaluation model: help wanted
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I meant I will set something up using my business Google account. Google accounts aren't sentient...yet.
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My Google account (Lyrebird Cycles) will set something up.
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Just thinking as well, you may need different calibrations for different diameter thermocouples. Thinking more along early in the roast (when beans and thermocouple temp equilibrate), your variables in the model may not represent the different heatflow and temperature as well.
I know I've suggested a few things, but it's all to be taken with many grains of salt as I haven't seen the code. 😂
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Would you have a Google drive folder/Dropbox people can add the roast files too? When I get around to properly writing down observations I'll send them through .
I.e. could drop any relevant files in (i.e. test photo/roast logs/observation files - thinking if you could use the CS cards photo or something so everyone is using a similar measure... wouldn't account for printer variation, but allows for link between camera, eyes and objective colour)
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It seems that you can export a Kaffelogic log as a csv file (Export to Artisan, select csv, seems to be tab delimited so 'text to columns' it if needed). This file just has a couple of time variables and 'BT' (bean temp...via a thermocouple in the middle of the bean mass). You could theoretically match it the roast profile used if desired I guess.
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If that's the case, wonderful, and sounds fair! I wouldn't have thought they'd be low enough with the temperature as conventional and fan forced baking result...still, I'll trust the science more than my intuition, thanks for the reference. If the values are low enough to not create a statistically significant result, then I'd agree bean temp should be a dependent measurement. I would have thought that having environment temp would have been useful for a) what you'd expect the beans to asymptotically approach and b) help match out rates of change.
That point r.e. if it is actually small enough to ignore should show up if/when you plot your model based on the calculated values. I.e. if the turning points (thinking more time than temperature) and gradients match up (to within a given uncertainty) at certain relevant points. But again, if the model matches the data well enough, may not even be necessary. 😂
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That would be the case if different heating regimes lead to different intrabean heat fluxes.
If you read Basile's excellent paper on modelling heat transfer in different roasting regimes,
https://www.semanticscholar.org/pape...1e466a21ae74f6
He comes to the conclusion that in all cases the Biot number is sufficiently low that the adherent air film is the major factor that influences heat flux into the bean. In turn this should mean that any differences in caramelisation rates will be small.
I am hoping that they are small enough to ignore but as always I am prepared to be wrong.
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Sure, I was thinking more about interplay between bean temperature and air temperature (and how heat is transferred between air-beans and drum-beans) may result in different caramelisations for a given temperature. So, 1 minute at 200C for pure direct irradiation will not result in the same colour change or CU vs 1 minute only drum roasting vs 1 minute more air roasting. It was more I'm not sure what your benchmark is because caramelisation is a very complex mechanism (more so that PU where the measure is cell death).
Point above being, you may have temp vs time plots for the entire roast, but that may not tell enough of the story (or it may, hence the question about how well your model fits the experimental data).
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How are you defining the CU? I'd be keen to have a look. Also interested as to how you'd be taking into account the differences between heat transfer modes (as 200 deg of x cc/sec air flow would/should have a different rate of energy flow than pure conduction/etc...).
How does your simplified kinetics plot relative to the measured values?
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One advantage of 100g batches is the high number of repeats( for your purposes).
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Heat application at around the inflection point between the two caramelisation regimes would appear to be very important.
The second number in my triplet above is an indication of where this inflection is occuring. The differences between the numbers then indicate how much heat is being applied either side.
As I see it, first crack ismuch less important than is commonly supposed. I think it occurs as a byproduct of other processes that aremuch more important: CO2 evolution and the structural polysaccharides reaching their glass rubber transition temperature.
This last is a guess as there is precisely no published research on the polysaccharide transitions in coffee roasting even though these processes possibly dominate the late phase of roasting.
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