The change when coffee cools

My last post on this generated some amazing comments, for which I am very grateful.  It has also meant I’ve been talking about and thinking about the change in flavour when coffee cools quite a lot recently.

Something dawned on me – I can’t think of another beverage that goes through such a huge change. (And I’m very much open to suggestion here!)  Sure, wine breathes and changes, tea changes as it cools but you don’t get this massive shift in flavour, taste and mouthfeel that some great coffees can offer.  This is something unique and enjoyable about brewed coffee.

So why don’t we talk about this more?  This is interesting! I don’t mean amongst ourselves as an industry, but to customers.  While it does get harder to notice with the addition of condiments, it still seems like a relatively easy promise to make that you can be confident will come true.  It has been something I’ve been talking to people more about, and while they may not always agree with me about exactly how the coffee changes (also a good thing) – they do always remark at how much it changed.

Could we use this better, as an industry?  To those who drink coffee at home – is that change in flavour an enjoyable part of the coffee experience, or merely something that happens in the background while you drink your delicious coffee?

27 Comments

  1. How about iced coffee? Being in the South, I’ve served quite a bit of iced coffee this summer, and it seems to me that in the same way that coffee changes as it cools, it also changes as it . . . warms (uncools?). I know some of it has to do with the introduction of ice and dilution, but I’ve tried a few different ways and it seems to be fairly noticeable (in a not so pleasant way).

    I would propose that coffee brewed at (to) an extreme temperature (very hot or very cold), when allowed to normalize to room temperature, decreases in desirability/quality. Not in the sense that when you drink a warm Coca Cola it’s unpleasant, because while it tastes the same you prefer it cold, but that the flavor profile itself changes. Just a thought.

  2. I’d say milk probably changes flavor as much as coffee. so that’s a possible addition to the list.

  3. Well! I probably should’ve shared my experience about it before.

    In 2007 I had an opportunity to learn cupping in one coffee farm in Brazil, I was invited by a coffee agronomist who was involved in the changes of coffee culture in the country. In that time the team which worked for this farm had prepared a wide range of coffee samples to cup. They had the winners of ‘Cup of Excellence of 2007′ to robustas as well a variety of coffee those were produced for them. Before my training I watched them cupping, then I observed they tasted the coffee in three sequences, the third one was after half hour they had brewed the coffee, the coffee was completely cold. They explained to me they could fell better the taste like that, mainly the defects.

    In my training we followed the same system, and I was impressed with the results, we could cup some coffees those were great when they were hot, they were seriously good, but as long as they got cold we could notice some undesirable tastes, even with coffee which were classified speciality. One of the cuppers told me: ‘The coffee tells the truth when it gets cold’, certainly he is right. Since then I’ve been trying filtered coffee in that way, I love to take it cold, and sometimes it surprises me with smashing tastes as well sometimes it lets me down.

  4. Its definitely an under-discussed topic. We do a vac pot demo every wednesday at our cupping and its pretty fun to guide customers through the change in flavor as it cools. The flavors seem to really open up. I’ve been preferring vac pot cooled almost to room temperature. There seems to be much more of a fullness to the flavor, especially with naturals, with more sweetness and acidity coming through.
    Its definitely a concept many casual coffee drinkers aren’t acquainted with and one the deserves some more attention!

  5. As a coffee amateur, I really enjoy the changes of flavour with temperature – although this has been a relatively recent revelation. It’s interesting to note that there isn’t a preferred temperature. With a lot of other beverages, there seems to be an accepted “best” temperature. However, in contrast, I’ve found some coffees that I distinctly prefer at lower temperatures, and others that I enjoy much more at higher temperatures. The variety of possible changes with temperature really makes coffee distinctive, and adds yet another dimension to explore in each coffee.

  6. I’m currently in Taiwan and just visited a syphon bar where they serve half of your coffee in a ceramic mug and the other half in a glass so that, as one coffeegeek poster already explains: “They serve the coffee in vintage ceramic mugs and a small brandy/schnapps glass. He then stood around explaining (in Mandarin) why they serve it like this (they serve it in the ceramic mug to retain the heat and a small amount in a glass, to allow you to see the different colours of the coffee and to let it cool down quicker, to give you a taste of what it is like cold) and how to drink the coffee (like slurping).” http://bit.ly/adTnDp

    The staff told me that if I sipped the coffee over the course of 2 hours, I would see that the coffee became tart and bitter after a while but that it would then regain its sweetness. I unfortunately didn’t have 2 hours to wait.

  7. I love how a mug of (beautifull beans, fresh roast good extracted etc.) brew provides a journey of flavours. The duration of drinking of such a mug should be stretched so that the last sips are basicly cold (room temp).
    You should start drinking the mug when it’s already cooled off (75 degr).

    One of the most evident changes in flavour is the huge bump of accidity at lower temps.

    In my opinion is this what makes brew a much better beverage to drink to-go, since milky coffees and espresso’s seem to fall apart fairly quickly. This could be something valuable to consumers.

    This experience actually made me a bit of a temp nerd when it comes to wine too(Cupping coffee started me off as a newbe winegeek.). Eg. with Pinot the range of perfect drinking perfect temp is rather small, depending on the make and origin between 16 and 20 c)

    But with coffee the whole temp range (75-5) is interesting and brings unique things to the table.

  8. For me, the change in taste has always been something I look for, but I’ve never thought too far past it.

    At the rate you’re exploring, I can see folks measuring the temperature of their coffee and noting what they think has changed every 5-10 degrees.

    Am I willing to do that? Probably…

  9. i’ve been thinking about this quite a bit as well, at my work (Catalina Coffee in Houston, Texas) we just started offering a Costa Rica La Candelilla Estate Geisha lot and i was terribly disappointed in the coffee at first. While it had some wonderful floral aromatics, it seemed to just be a standard central american chocolate and balanced coffee, but after it cooled almost to cold there was the interplay between sweet juicy soft fruit and a sharp citrus that comes out as a complex spiced peach sort of profile as it washes over you. Its been a unique challenge in serving this coffee to our customers, especially since it is a higher price point than our other coffees, in finding the best way to encourage them to sit and wait 20 minutes or so in order to fully understand and appreciate the coffee for all it can be!

  10. I prefer room temperature coffee most of the time simply because my mouth does not enjoy being burned. However, there are some coffees that are not as enjoyable cold so I stick with an Ethiopian or Kenyan for the room temperature. Our Mocha Java blend is also good when room temperature. It is a combo of an Ethiopian and Java. Mocha is a varietal of an arabica bean. As with most food and beverages, we all have our own likes and dislikes.

  11. How much of our flavor perception can be attributed to the chemical change within the brew as it cools compared to our palate being able to detect more flavor as the brew cools?

    My assumption has always been that we detect little of a coffees flavor immediately after extraction, simply because the temperature shocks the palate, and as the brew cools our palate is then able to pick up more of the flavor profile within the brew. Certainly, my assumptions could be wrong? And certainly there are changes happening within the brew every minute after extraction.

    My assumption has come from drinking Belgian Trappist beers. When first poured, the beer is quite cold, and my palate seemingly senses the temperature more than the flavor. As the beer warms the flavors seem to open up. I attributed this mostly to the temperature, because I also assume that very little changes within the beer as it warms, but again, my assumptions may be wrong.

    I feel that this could be why some consumers prefer their coffee burning hot, and their beer freezing cold, especially with poor quality coffees and beers, because the temperature masks the brews true flavor.

  12. I’ve only quickly browsed these comments, Tom is leading onto what I’m thinking, perhaps someone else has mentioned this in your prior post, but…
    Anything I have learned regarding this was from the SCAA’s sensory skills test.
    In it’s most basic sense, my comment will side in favor of saying it’s not the coffee that’s changing with temperature, it’s our taste buds and physical ability to pick up varying levels of sweetness.
    My most enjoyed example was a comparison of ice cream (or frozen custard if you’re regionally privileged) flavors one perceives when the ice cream is most cold compared to “melty” compared to melted… melted ice cream always tastes the sweetest and I’m lead to believe that is because when things we’re tasting are closest to body temperature the most sweetness is perceived.
    Granted, I may be wrong, this info could have expired and been disproved some time ago…
    Is it the coffee that’s changing? Or the human’s physical perception?

    keep up the good posts James.
    sL

  13. Great post. Another challenge to this is that coffee’s flavors change daily from the time roasted, thought not the subject of the post. Coffee’s flavors are a moving target in one brewed cup and along a linear spectrum. Would the flavors changes as much on day #4 as day #16? I suspect additional flavors of aging can be picked up. Keep up the great posts.

  14. I think another factor that may be at play here is the further development of organic acids after a coffee is brewed and sits. Also, in relation to this is there a volume consideration? What I mean is that with a small (let’s say 4oz-6oz) amount of coffee, I agree with with what’s stated above as far as temperature interference and more perceived sweetness and dynamics as a coffee cools. But with 16oz or more, I personally find that the change in flavor has more to do with the presence of quinic acids where the cup is showing increased bitterness as it cools. Or, I could be wrong.

  15. Okay, I see that Nick Cho says something to this effect on the original post as far as the organic acids deal-o, but I’m still curious about peoples thoughts on the volume issue.

  16. For years we have been encouraging people to avoid ‘large espresso based drinks’ with coffee experts frowning at the sight 16oz and even 20oz drinks. Now great slow brewed coffee is making a come back I would actively encourage a larger vessel, minimum 12oz.
    For 2 reasons firstly in recent years filter coffee seems to have taken 2nd place to espresso and always been regarded as the ‘cheap’ option. By serving a nice large cup of fresh brewed coffee the price sensitivity is removed. The second reason is that it will take longer to drink so the whole cooling and flavour changing experience will be enjoyed a whole lot more.
    Keep americanos small and make them the cheaper option for a change!

  17. I’m a Barista at P&S in Calgary. After reading this, I did a ton of research on taste and temperature and led a tasting on this specific idea. We tasted the coffee at three different temperatures and delved into taste receptors, Ion channels, and many other small factors contributing to taste and temperature. Thanks for the idea!

    Chris Tellez

  18. When brewing siphon I usually recommend customers let it cool for four to five minutes, to let it get to 150 F (ish). I find the transition from thereabouts to your body temp is where the best flavors will emerge. I don’t find there to be any advantage to drink a portion of the cup when all you have is hot magma overwhelming any existent flavors. You might as well be patient. Personally I find the sweet spot around 130 F (as an average). Of course many professionals who have tasted and cupped thousands upon thousands of coffees have a much more bullet proof palate and do not seem to be dissuaded from a scalding hot liquid.

    Also, some coffees have sweetness from the first sip, no matter when it is, and others take a bit of cooling.
    I haven’t tried to think about natural or dry processed coffees vs. wet processed coffees…

    My questions would be?

    Is the majority of the flavor change due to natural cooling of the coffee?

    Is the majority of flavor change due to how the various oils layer themselves withing the cup?

    OR Is it a fairly equal combination of both?

    Assuming roast degrees are the same: Are the types of changes (bitter, sweet, bright, etc.) universal among coffees? Or is there a distinctive difference in what happens depending on the processing?

    Also: Are the flavors there all the time, and it’s just at X degrees that our palate is able to detect them?
    I am sure this is something that is known, but I haven’t seen a definitive explanation on how this function of taste/temperature works. Are the flavors revealed as it cools, or are they “created” via chemical changes?

  19. I teach a coffee-centric continuing education class at a local university and this summer we have been focusing on cold coffee. Being in the industry we have all seen (tasted) the anecdotal evidence for what happens to coffee when it cools or is brewed at different temperatures and I agree that there needs to be more hard science out there explaining what is actually happening. That being said, there are a whole slew of studies on the way we perceive flavors at different temperatures, which is definitely an important part of this equation if we want to fully understand what is going on with cold coffee. In my mind there are 3 major variables here. 1. hot brewed coffee (generally sweetens as it cools, but keeps a wider flavor profile because of the hot extraction. 2. cold brewed coffee (generally sweeter and more smooth, but less complex because it’s basically under-extracted) 3. the senses (the way we perceive flavors at different temperatures)…..there are the variables guys, lets experiment.

  20. Indeed. It is something I look forward to when I sit down to drink a cup, this unique capacity for the falling temperature of the beverage to have such an amazing effect on its flavor. It is the opposite approach to that which is taken when you are intent on enjoying a shot (or two) of espresso. This idea of lingering and paying attention to the changes that happen is unique to the cup of brewed coffee.

    The only other beverage that comes to mind that I think exhibits a somewhat comparable temperature induced flavor morph would be a glass of beer. Some ales that I have experienced have a very enjoyable cooling process.

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  22. We have to count time in the equation, when a brew is served in a cold cup to reach a certain temp. Or when it is allowed to cool to that specific temp.
    Time in relation to contact with air is also of importance. A brew can get bitter due to oxidation, not mere temperature loss.

  23. I was able to read all the comments, but I can sure agree with everyone it has to do with the acidity. I find that the flavour changes most with brewed, but I think that is probably because with brewed we start with a temperature around 90c, I think its the change from 90 to 70 which is the largest in taste. Due largely to the fact that our mouths can handle the temperature more. What do you do when its really hot (well I leave it until it cools) but lots of people sip. with sipping you don’t take enough coffee into your mouth to taste the flavor properly. You are usually alarmed by the heat of drink before any of the flavor. I would say the flavor changes as Little flavor just Hot >> Coffee more acidic >> coffee more bitter. I’m not a coffee scientist but when we refer to acidity, do we actually use that term because it relates to actual pH of the coffee. (from my A-level chem) Like vinegar (ethanoic acid) like any weak acid it doesn’t fully dissociate, meaning not all the H+ is available in the solution. Any weak acid if heated will usually dissociate more because the forward reaction is endothermic, when heated the equilibrium shifts to try and lower the increase in temperature. Complicate chemistry aside, it could very well be possible, that as the drink is cooling less of the acidic comments of the coffee are dissociated and you can’t taste the acidity as much.

  24. I found this post as I searched for an answer to my curiosity about why I like hot and iced coffee, but dislike coffee that has cooled. Yes we all have preferences, but this is one of mine I don’t quite understand. I never thought it was about flavor, that has never been part of my reaction, but it is possible that is what I am responding to. I always have a response similar to drinking sour milk…Yuk!

    If I pick up my mug and find that it has cooled, I will literally spit it out. If i drink in one sitting, I typically dump the end of the mug due to cooling. I drink several different varieties, but it is interesting to think that perhaps certain coffee may be tolerable cooled. I do not have an issue with iced coffee warming but that seems to be “Off Topic.”

    I prefer dark roast, pressed or perc., black, perhaps the oil level (from brew method) is a factor too. Maybe as coffee cools it becomes more similar to a mild or medium roast flavor.

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