Hello friends,
I come to you with another roast analysis.
The bean we will discuss is a Kenya Mumwe Mahiga from Royal Coffee.
What made this bean special was it shined in the mouthfeel and body categories. It had a buttery, caramel-like mouthfeel and was a tasting experience I'd never had in a coffee before. The brew had some texture to it — it was strange.
I ran this bean through a couple of types of roasts:
Going high heat, then a gradual decrease to extend the roast
Same as above, but applying a soak
Going high heat, pushing to FC, then coasting with minimal development time
Each roast was then brewed through a V60 recipe:
18g coffee at medium grind
Bloom with 50g of 97-99C water
Pour 100g of water, then swirl the brewer to push fines up against its walls.
Pour 100g of water without swirling
Note I brew at a lower coffee-to-water ratio than most. I find 300g to be too much liquid, and like my brews at higher concentrations.
Analysis:
Roast #1 and Roast #2 were similar in taste and body. I couldn’t deduce any large differences in taste between the two, so the below analysis will be done between Roast #1 and Roast #3.
Roast #1 and Roast #2 both exhibited a buttery, mouthfeel texture.
Roast #3 was different.
I've encountered a case where a roast (Roast #3) was too acidic and resulted in a very harsh cup. It was also interesting that the roast lost its excellent body qualities.
I performed a similar back analysis as I did with the Ethiopian Guji to try and deduce why this happened.
The immediate difference I noticed was in total roast time. Roast #3 was 3 minutes and 13 seconds shorter than Roast #1.
Then further breaking it down, we see that it spent 35 seconds less in Maillard, 99 seconds less in Caramelization, and 28 seconds less in Post-Caramelization.
From reading around, the body of a coffee is largely attributed to melanoidin production.
Melanoidins are brown polymers formed during non-enzymatic browning reactions (Maillard reaction and Caramelization). So the longer the roast sits within both parts, the more melanoidin production occurs.
More prolonged roasting leads to more melanoidins, with longer roasts producing melanoidins of higher molecular weight than shorter roasts. The relationship between viscosity and molecular weight is that the higher the molecular weight, the more viscous the material, which in this case, the more viscous the resulting brew.
So, in conclusion, the mouthfeel texture was due to prolonged duration in Maillard and Caramelization phases — this seems like a pretty "duh" statement. Still, it's nice to understand better the chemistry level and why a longer roast results in a better body.
Further Thoughts:
What does it mean, on a chemistry level, when a roast is baked?
Is it just that there are no flavorful compounds left to taste?
Why does the RoR have to be declining? Is it to ensure roasters have adequate time in Maillard and Caramelization? A decreasing RoR would point to having high heat acceleration at the beginning and a deceleration in the heat towards the end, and a side-effect of this reduction would be time extension in both phases.
If the RoR is increasing, that’d mean shorter chemical reaction stages, which isn’t necessarily bad, it’d just mean a different set of flavors to extract?
I wonder if "sweetness" would be different if we shortened Caramelization and tried to decrease the number of sugars browned.
When the sugars brown from Caramelization, what results is the production of 3 groups of polymers (Caramelans, Caramels, and Caramelens), which all contribute to the taste of caramel (sweet, nutty, bitterness). I'd assume the brew would taste less "nutty" and "bitter"?
Something interesting I learned, the reason why all sugars are sweet is because they contain OH groups with a particular orientation that can interact with the taste receptor for sweetness in our tongues.
And that's it. I hope you enjoyed this post.
If you bought a Kenya Mumwe Mahiga from me, I hope you were able to brew similar qualities that I experienced. :)