General rule to allowing coffees to rest? - Page 4

Discuss flavors, brew temperatures, blending, and cupping notes.
chang00

#31: Post by chang00 »

The interesting observation is, when I compare home roasted HotTop vs Mini500 beans, the flavors "mature" at different times. For example, I just had some Ethiopian Sidamo roasted 12/13, with the Hario V60, and the typical berry flavor is still present. However, when I tried the coffee on day 3, it tasted gassy and grassy.

The Paradise Espresso Classico behaves similarly. The HotTop roast has good flavor at day 3-4, but the Mini500 roast does not taste good until day 10.

Generally, darker roast stales a bit faster. Although coffee flavor loss is mainly due to loss of various thiol compounds, and not staling of coffee oils per se, with darker roast, due to the lipids closer to bean surface from the dragging outward migratory effect of carbon dioxide, the oxidation of lipid is faster, and therefore faster rancidity with darker roasts.

I am puzzled why electric vs gas roasted coffee will have different resting period. :?:

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malachi

#32: Post by malachi »

sounds more like a roast defect issue to me.
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chang00

#33: Post by chang00 »

Probably. I still have much to learn about roasting and cupping. Maybe I'll sign up for Willem Boot's class someday. I just wish he has a consumer class instead of courses geared toward professionals.

What intrigues me also was that Coffee Klatch espresso blends taste more balanced 2-3 weeks post roast.

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gyro

#34: Post by gyro »

I've been experimenting with different roast profiles. From my limited experience at this, it would appear that a slower roast needs less time to degas, with a faster roast needing more time. This also ties in with the coffee aroma immediately post-roast. The slower roast, at the far end of the scale at 20 min, smells coffee-like straight from the cooling tray whereas the faster circa 13 min roast smells more grasslike, which was not dissimilar to coffee straight from my old iRoar.

So, could it be that the electric vs gas difference mentioned is possibly roast profile rather than heat source related?

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farmroast

#35: Post by farmroast »

Heat type application will effect the degas process as will the profile and degree of roast. Going into 2nd crack will cause more bean fracturing and co2 release.
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chang00

#36: Post by chang00 »

So, after thinking about this thread for a while, I searched Journal of Agriculture and Food Chemistry. This 2008 article was one of the more informative research on temperature and time relationship, with different roasting methods. In the article, a Probat drum was compared with a laboratory fluid bed roaster. There was also a reference to a German article published in 1989 which discussed different roasting methods/energy source and rate of staling.

The article is here:
http://pubs.acs.org/doi/abs/10.1021/jf8 ... istoryKey=

There is a difference in the amount of formation of aldehydes and various sulfur compounds when the roasting methods are different, even though the beans were roasted to the same degree by near infrared examination. This basically translates to different "degas" or peak flavor time. One of the ideas regarding determining the degree of roast was by measurement of sulfur compound, instead of using near infrared to measure color, such as Agtron.

The experiment also examined various chemical profiles if a fluid bed and drum roaster followed a similar time-temperature profile, and found them to be similar. From what I can infer, it means the roasting profile and degree of change of temperature will affect the rate of staling/degas.

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Worldman

#37: Post by Worldman »

I've used beans just after roasting (<1 day) and they are always less than fully enjoyable...the taste is "gassy" (somewhat harsh and strident) and the crema is thin, bubbly, and collapses quickly.

Still, an imperfect shot is still a shot and can be enjoyable (on some level). I find my own blends need to degas for at least 2 days and are at their best after 3 days.

Also, for some unexplained reason, the heat sealed bags with 1 way air valve provide a better taste even if the beans are bagged for a mere 3 days.

Len
Len's Espresso Blend
www.lensespressoblends.com