What else is going on during coffee resting?

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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farmroast

Postby farmroast » Dec 02, 2010, 10:27 pm

We speak of degassing of co2 then being replaced with o2 during the rest and fresh time frame. I'm guessing there are other volatile chemicals that are unpleasant and are degassing during the rest period. A premature cup seems to have chemical/solvent tastes/aromas. Our hope being that they degas quick enough to uncover the desired volatiles that also have a limited life. Such as the floral and fruity ones.
This has had me wondering if immediately putting the beans in a tight container is the best idea. Might it be better to allow a little airing of unpleasant volatiles that could settle solids onto/into the beans in a tight environment? I can't see an early airing as really getting into the bean to start early damage as the % of co2 would still be high. Something between a few and 24hrs? Any thoughts?
LMWDP #167 "with coffee we create with wine we celebrate"

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another_jim
Team HB

Postby another_jim » Dec 02, 2010, 10:59 pm

Straight out of the roaster, coffee has little aroma and tastes flat and unaromatic, even when cupped. The maximal variety in aroma (both good and bad) is between 8 and 24 hours. After that, the aromatics gradually decline. My guess is that the CO2, being a small molecule and having less mass than the aromatics, outgasses first. After eight hours, it is mostly gone, and the coffee starts losing its aromatics.

As to aging/staling and taste: Is it that coffee that is a day or two old is unpleasant, or just too "in your face." My feeling is that it's mostly the latter. If a coffee is all fruit and flowers, it'll taste good right off the bat; but if it has more aggressive aromatics, then it needs age for these to get into a good proportion.

But coffee chemistry is staggeringly complicated, so blanket statements like this probably have a huge number of exceptions.
Jim Schulman

Ken Fox

Postby Ken Fox » Dec 03, 2010, 12:26 am

farmroast wrote:We speak of degassing of co2 then being replaced with o2 during the rest and fresh time frame. I'm guessing there are other volatile chemicals that are unpleasant and are degassing during the rest period. A premature cup seems to have chemical/solvent tastes/aromas. Our hope being that they degas quick enough to uncover the desired volatiles that also have a limited life. Such as the floral and fruity ones.
This has had me wondering if immediately putting the beans in a tight container is the best idea. Might it be better to allow a little airing of unpleasant volatiles that could settle solids onto/into the beans in a tight environment? I can't see an early airing as really getting into the bean to start early damage as the % of co2 would still be high. Something between a few and 24hrs? Any thoughts?


There are a couple of elements to your question.

With the caveat that I only roast single origins, roasted on the light side, and with those, only ones that I think can work for espresso, I have found few of these coffees to be "objectionable" even at the 1 day point after roasting. I have yet to find a single origin that I liked for espresso at day 1, however I have found some fruity Ethiopian DP coffees that were not bad at day 2. The coffees I liked at day 2 have tended not to last very long at peak; generally by day 7 I would only use them in a cappa, unless I had nothing else left to drink. The few coffees I have found objectionable at day 1 or 2 were either simply objectionable, period, or were like Yemens that needed to air off their raunchy components before the more desireable "underside" became evident. But again, I don't find very many coffees that I like will have objectionable flavors when drunk "too young," rather they simply taste somewhat generic and their charms are hidden only to show up a day or two later.

As to whether storage early in a sealed container might impart bad and lasting flavors and aromas to freshly roasted coffee, I have not noticed this. None of my storage methods is truly "air tight," and the great majority of coffees that I "store" as opposed to consume rapidly, are in the freezer where degassing is greatly slowed down. If a coffee is degassed somewhat first, before freezing, it is my observation that it simply does not last as long after being brought up to room temperature than it would had it been frozen immediately, and the taste is otherwise unaffected. This is understandable since the degassed and then frozen coffee is physically "older" than it would be had it been frozen immediately.

ken
What, me worry?

Alfred E. Neuman, 1955

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iginfect

Postby iginfect » Dec 03, 2010, 8:01 am

As far as Ethiopian varieties go for vac pot, for me at least, they are best the day after roasting and lose their blueberry and fruit rapidly.

Marvin