Roaster School Episode #3 First Crack

[.]

.

[hankua]

I just started watching the segment; and its fantastic along with the previous one. Of course one big takeaway is "development" starts after the drying phase is finished, and continues until drop.

Another is if all the moisture is not removed from the seed, some of the chemical reactions cannot occur. The result of this I think is underdevelopment, although extending the post first crack time can alleviate this.

I believe Joe stated adjusting the Malliard reaction or ramp to 1C cannot affect the perceived sweetness.

[.]

.

[hankua]

Yeah, pretty good for free; and no ads either

350f or 180c is a point where I make a final pre first crack adjustment; usually a gas decrease, same gas and more air, or none until the end of 1C. But we have members who increase the gas temporarily just before the onset of 1C to push the roast evenly without a drop-off for espresso profile.

Endothermic or gaining heat is supposed to carry thru until the onset of second crack. But the so called "flick" after the end of first crack where the BT can rise faster indicates some type of change. Is there some type of exothermic reaction or is the process still endothermic?

Extending the drying stage EOD is a profile choice that should be considered when roasting light coffee. All that is necessary is to charge at a lower temperate which automatically extends that phase.

One aspect I don't think was discussed, how the bean can have different levels of roast from the outside to the inside. Expensive roast color meters used for example by coffee review; state the whole bean color vs ground roast color.

[.]

.

[hankua]

I'll have to view the video again. There is confusion on the subject regarding when endothermic reactions end and exothermic begins. (Google search)

http://www.home-barista.com/home-roasting/post-first-crack-ror-drop-t34911-30.html

[.]

.

[hankua]

I'll have to view the video again. There is confusion on the subject regarding when endothermic reactions end and exothermic begins. (Google search)

http://www.home-barista.com/home-roasting/post-first-crack-ror-drop-t34911-30.html

Can't their occurrences overlap?

That's a really good question! What's the answer?

[hankua]

Thanks for the HB link, it was a good read. For now I think I'll follow Joe's advice and see how it works for me. Now to figure out how all this information should be applied to my approach to roasting.

I think this is more of a lecture on "the science of roasting". The Maillard reaction and Carmaliation are two separate events. Another is that sweetness is more perceived than real (if I understood correctly).

One point that can be used in a practical sense is to experiment with extending the Maillard reaction. Another is to try extending Carmaliation (as you mentioned) by slowing down the ramp.

https://www.acs.org/content/dam/acsorg/pressroom/reactions/infographics/why-does-your-coffee-taste-and-smell-delicious.pdf

There may be some overlap between these two events?

If one uses a Rao style profile where the gas is gradually turned down after EOD, the ET and BT graph lines will slowly come together. This type of maneuver can slow down the roast, extending the pre-first crack leg. This is an area where the roast can decend to a creep; which is OK for a light roast. But if one is looking for more post 1C development juicing the gas pre-1C has advocates here at Hukydom.