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Roast Levels - Correlation Between American Terms and CS Terms

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  • kwantfm
    replied
    Nice post... so much to learn!

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  • GrahamK
    replied
    Possibly something to bear in mind is that the Bean temperature is considered as just an indication of Bean temperature. (Based on a little formal training I have done). Commercial quality roasters (I believe) tend to measure at least both Bean & Exhaust Temps. The exhaust (environmental) temp is the temp of air passing from the drum to the exhaust, and that temp is probably more of an actual temp than the Bean Temp which is measured by the beans tumbling over a probe, and would also have some dependency on the % of beans vs total capacity available, probe placing, and a raft of factors etc. The exhaust Temp has a more direct correlation to changes to the %Heat applied, and its the temp that the beans are "aspiring" to, so to speak.

    I think for a while I was myself originally too focused on the Cracks as indicators, (because they are an easy milestone to hear & capture) rather than understanding they were more a consequence of a variety of factors including the roast profile you use. As a home roaster without usually all the technical aids that determine bean moisture content, hardness, and possibly even the environmental humidity etc, you may need to allow more of a sensory approach to helping determine how a roast is progressing, e.g. smelling it at the stages in the lead-up to FC, to ascertain whether its going too quick or slow, and therefore how to adjust to prevent it either running away from you or stalling, then using colour to determine the drop point rather than SC. Of course once you are used to the way a particular batch of beans reacts, then it should react similarly for a good period of time. Of course the CS monitor is also very useful.

    The sensory points I learnt were 1. The smell of grass (after about 3mins), then 2. Hay (another 2 or so mins), then 3. Baking Bread (5-7min). There is another point before FC, that can apparently indicate the final potential of the roast, but I'm still struggling to sense that one. FC is usually not that long after then. Generally from FC to Unload would depend on your requirements, but keep it slow enough to allow at least a >3min <6min for the development of flavours etc. Under 3min could end up being too acidic and over 6min could become too leathery. However that is in very general terms, as I'm sure there will be a raft of people that will tell you that certain beans require totally different timings.

    I'm not putting this forward as an expert just still in training like many of us.

    I'm also not sure how easy it is to check sensory progress on setups like Correto's, KKTOs so it may be a mute point. On the Hottop I know you could get a sense of the smell.

    GrahamK
    Last edited by GrahamK; 13 September 2013, 02:40 PM. Reason: spelling/grammar

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  • kwantfm
    replied
    Happy for a moderator to shut me down... but don't think it is a problem mentioning Sweet Maria's... it's both much easier and much cheaper to get greens from Andy. "Much easier" is likely a significant understatement!

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  • ggoosen
    replied
    Originally posted by kwantfm View Post
    If you haven't already, I think it worthwhile to visit the coffee roasting library on the Sweet Maria's website. You might find the articles on lengthening the roast particularly interesting (they discuss the taste differences resulting from changing the roast times in three phases of the roast).

    Thats the "other" site that i refer to, wasnt sure if we are allowed to name drop other sites in this forum.

    But SM's library is great. Therein lies the issue. Most of hte charts/discussion talk about Roast levels being, City, CIty +, Full City etc. Which has no correlation to CS numbers..

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  • kwantfm
    replied
    If you haven't already, I think it worthwhile to visit the coffee roasting library on the Sweet Maria's website. You might find the articles on lengthening the roast particularly interesting (they discuss the taste differences resulting from changing the roast times in three phases of the roast).

    Leave a comment:


  • ggoosen
    replied
    How good is this discussion!

    It’s exactly what I was trying to achieve I have no idea how the colours/names/temp match and i thought if i start a thread, that would allow for some "expert" advice that will allow me to fine tune the numbers in the chart

    In my limited (VERY LIMITED) experience, I have found that although coffee roasting is more of an art than a framework/process. There are some "Basic" guidelines that can be used.

    The questions i have being a new roaster, are questions like.

    When should First Crack be starting?
    What is the taste difference going to be like between FC and SC.
    Have I taken this too much into SC?
    Ok, so this is roasted, Is it CS8? Is it CS10? is it a City? Who knows...
    Have a taste.. Oh wow. that’s kind of bitter? what did i do wrong? Or oh no.. that taste sour? or is it bright? i don’t know but what can i do to change it?

    The biggest problem is that most of the experimenting is based very much on taste, but what happens if you don’t trust your taste? How i know that what i perceive as "good" is actually good.

    The aim of this chart is to try and correlate some basic ranges that should be in ball park, this is my basis for starting, and from there as with anything people will then start adapting as per thier own preferences taste etc.

    A final point i am trying to address is, there is a wealth of information on the net. And as i found 1 site/person will have FC at 195 the next has it at 200/190. There is a lot of variation.
    Also, because of all the different placements of the temp probes. The numbers can be different. but what i used was "avg bean temp at termination of roast". Im hopeful that, that will be pretty standard.

    I can then use the information you guys provide and try and re-adjust the chart to more closely resemble reality.

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  • DesigningByCoffee
    replied
    Morning all
    I've never been big on trying to match the colours and predict the taste - there is so much other stuff that impacts final flavour!
    You can turn a bean to CS11 in 3min in a popper - and it probably won't be roasted, so will probably taste bitter & sour :-)
    But an identical bean slow roasted to that colour using a longer profile will be completely different.
    I rarely take any bean beyond 2C (CS8-9 if you must :-) - but can vary the taste hugely by changing the profile that leads up to it …
    Just my 2 bob :-)

    Matt
    Last edited by DesigningByCoffee; 13 September 2013, 12:26 PM.

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  • GrahamK
    replied
    Originally posted by GrahamK View Post
    My interpretations of the CS numbers are also quite a bit different. My CS9 is generally closer to start of FC.
    Sorry that should have read: "My CS9 is generally closer to start of SC"

    GrahamK

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  • chokkidog
    replied
    Hmmmm…… been thinking ……..

    I do some pre-blends but group beans according to moisture, hardness (altitude) and desired roast level.
    I have noticed if I roast an El Salvador, (for instance) with 30% (approx) of an Indian, the 1st and 2nd
    cracks are 195° and 119°, respectively. If I then roast a pre blend of the same El Salvador with 30% of a washed
    high altitude African then 1st and 2nd cracks are more like 198° and 221°.
    Last edited by chokkidog; 12 September 2013, 08:58 PM.

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  • kwantfm
    replied
    I don't count myself as very experienced, but I think that the temps also look high and that the CS numbers look low compared to roasting position vis-a-vis cracks (e.g. I see CS10 as a few seconds after 2C for most beans).

    Lots of good info thanks. Really interesting with regard to decaf, moisture levels and lower temps required for 2C.

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  • chokkidog
    replied
    I don't put myself in that category, I like to roast and I like to share, sort of sums it up.

    Even tho', to an extent, roasting is a numbers game, everything is relative and not a lot of the hard and fast
    can be transposed from one roaster to another.

    I agree with Vinitasse and Graham and also echo 'good job' sentiment but
    if I followed a chart stuck to the wall I would hit myself out of the ballpark and out of the game.

    For the most part, my range for the very start of 1st crack is 195°-198° and start of (audible) 2nd crack 218° - 221°.
    If I didn't watch what I was doing, I would have missed the start of 2nd crack, the other day, when it started, (for a new bean), at 216°.

    My figures are slightly different to Vinitasse's, highlighting the relativity. Our figures say something about roasting in general
    but the detail says more about thermocouple probe placement, roaster design and manufacture, drum material and roasting style.
    (oh yeah and the beans we're using and the outcomes desired)

    Cheers.
    Last edited by chokkidog; 12 September 2013, 08:12 PM. Reason: others posted while I was typing!

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  • Vinitasse
    replied
    Originally posted by kwantfm View Post
    Interesting... I've roasted about 20 different types of bean thus far and haven't seen as much variation as you have. I've never seen one hit 2C below about 219.
    The lowest 2C readings are for decaf coffees, which happen to have lower moisture levels than regular beans. And... I roast on a commercial drum roaster so perhaps that makes a difference. Of the 100+ types of beans I have roasted, 90%+ would fall into the 215-218 C start of 2C range... with 1C usually starting around 190-193 C. Also, keep in mind that everyone's machine will read slightly differently, depending on the type/quality/calibration of temp probes used, the placement of said probes, the offset value of the thermo/datalogger, the airflow etc...

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  • GrahamK
    replied
    Well done attempting to try and document something that may help de-mystify some of these parameters and that others may find useful. I would suggest however you stipulate its your interpretation and no doubt intended to be a continual "Work In Progress".

    From my experience:

    The stated temps look a bit high based on my using both a Hottop & Proaster. My interpretations of the CS numbers are also quite a bit different. My CS9 is generally closer to start of FC.

    I also think the Cracks and the colour may not be quite as closely tuned together, although often used as milestones.

    I imagine temps will depend on the measurement setup etc, and are more probably relevant from a relative situation within your own setup, especially for many home roaster setups rather than absolutes.

    And yes as mentioned I find the different beans make a difference.

    The temps will also depend on the roast profile.

    Grahamk

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  • kwantfm
    replied
    Originally posted by Vinitasse View Post
    Every bean is different. Of the beans I roast on a regular basis, one will hit 2C at just 209 C, most hit 2C between 215-218 and there are a couple that hit 2C at 221-223 but I have never come across a bean that hits 2C beyond 223.
    Interesting... I've roasted about 20 different types of bean thus far and haven't seen as much variation as you have. I've never seen one hit 2C below about 219.

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  • Vinitasse
    replied
    Originally posted by kwantfm View Post
    Really helpful... I'd love to hear whether the super experienced roasters agree with your levels especially as CS numbers relate to second crack.
    Every bean is different. Of the beans I roast on a regular basis, one will hit 2C at just 209 C, most hit 2C between 215-218 and there are a couple that hit 2C at 221-223 but I have never come across a bean that hits 2C beyond 223.

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