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We got in the office some kind of coffee-machine, I think it's Moccamaster CD Thermo, and it has 2 thermoses, to keep a coffee warm/fresh for certain period of time.

Thermoses are good and easy to use. I think they do great job in terms of electricity economy... But does it really good for a coffee quality? According to the specs, they say, it's keeping temperatures between 80°-85° and meeting the requirements of the ECBC/SCAE/SCAA, what does it really mean? It may be there are facts, which I haven't found, rather than too broad explanations, or opinion based thing.

I understand, that caffeine is not burning at temperature coffee is left at, and it does not evaporate. But for how long it's acceptable to keep coffee in thermoses, without loosing the taste/smell and quality of coffee?

Farside
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2 Answers2

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ECBC , SCAE and SCAA are organizations that are specialized in Coffee. They organize many events like contests. Sometimes these contests are held for people sometimes for equipment. They also produce many reports on Coffee; from taste of a cup to cultivation politics. So, these organizations also have a certification procedure for coffee brewing machines.

From the question, I understand that you want to keep the brewed filtered coffee in the carafe for a while and you are asking for the maximum allowed time for that.

The answer is; the machine will try to keep the coffee intact as long as it can; however, at that temperature the water will eventually vaporize and the rest of your coffee will turn into a bitter, dark, burnt coffee.

Simply, your coffee will eventually die as living beings and your high-quality gadget may just slow this, but cannot stop.

Solution: Just taste it. Fresh filtered coffee always tastes better. According to my experience, first half hour is the tasty period.

(1) European Coffee Brewing Center (kaffe.no)

(2) Specialty Coffee Association of Europe (scae.com)

(3) Specialty Coffee Association of America (scaa.org)

MTSan
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  • Thank you! But it's not really what I asked. I haven't asked about coffee machine specifics, as well as we don't have carafe :). I was asking about thermoses (e.g. in our case it is Moccamaster CD Thermo) and keeping coffee in them, while temperature is stale for some period of time (no heating). I know what these abbreviations for associations mean, but the question was ... meeting the requirements of the ECBC/SCAE/SCAA, what does it really mean?. It may be there are facts, rather than too broad explanation, or opinion based thing. – Farside Apr 12 '16 at 00:25
  • I meant the carafe of the brewing machine itself. :) I never heard that they have certified any thermos, sorry. Couldn't you find anything on the websites or in the manual? Some parts of the websites require membership, though... – MTSan Apr 12 '16 at 00:31
  • neither me found... That's why asking :) But thank you for the try (I will up-vote for the effort)! My personal feeling is that it is another marketing thing, but wanted to find out some facts and references, rather that to rely on thoughts and a subjective opinion – Farside Apr 12 '16 at 07:42
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Well, I barely found any details and facts regarding keeping coffee in thermoses after brewing, and what does "meeting the requirements of the ECBC/SCAE/SCAA" actually mean.

But while investigating and analyzing data, discovered interesting facts, to my mind, which are against of approach of keeping coffee in thermoses:

  1. Caffeine is getting out quicker, than I was thinking. A cup of brewed coffee left at room temperature for 24 hours had about 60% of its caffeine remaining. Coffee left at 4 degrees Celsius for 2 weeks had less than 5% of its original caffeine content.
  2. It's hard to wash these kind of thermoses from inside, normally you just rinse them intensively. So initial bacteria concentrations are higher than in dish-washed containers and cups. (this topic on cleaning of stainless coffee carafe could be considered)
  3. The coffee which gets into thermos containers isn't that boiling hot (80°-85° according to specs) to make the container "sterile". It would likely be safe for many bacteria that found coffee a nice growth medium. As the counter argument, for a sterile container, not related to thermoses storage: coffee can be stored for and consumed within 8 weeks (the general bacterial count was <1 CFU/mL).
  4. The thermos doesn't have heating source, and loses it's temperature pretty quick 1.5-3 hours, is my guess. It reaches ideal temperature (approximately 34-37 degrees) and boosts the processes being perfect medium, which encourages the growth of bacteria/fungi (see #2 and #3 above).
  5. Coffee degradation over time and the loss of aromatics affects the flavor profile.

It may be there are other thoughts, links, references, facts to add here, welcome!

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Farside
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    As far as I remember, there are some agents to clean coffee remains from thermos like media, which is hard to reach its interior. Yes, I found it. It's discussed here. – MTSan Apr 13 '16 at 13:44
  • Thank you, @MTSan, I will add the reference to the answer – Farside Apr 13 '16 at 14:24
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    Another relevant answer is the second answer to http://cooking.stackexchange.com/questions/34150/bottling-and-storing-cold-brewed-coffee - it references a Korean scientific paper that analyzed cold-brewed coffee weekly for eight weeks. The full paper is blurred unless you pay for it, but squinting at Table 3 on page 4 I think the initial caffeine content of their brew was ~1200-1400 (not sure what units they were using) and after eight weeks this had declined to ~1000-1200, only a 15% loss. They did use a sterile container, though. – Lyrl Apr 13 '16 at 17:56