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I'd accept survey data (blind taste tests) but real science would be better. If coffee tastes better when served in heated cups, why? Is it chemistry? Or is this all opinion based on nothing?

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  • 9
    I would assume this is similar to the concept of preheating plates for food to ensure that the food stays at the preferred temperature longer.
    – quarague
    Jun 9, 2023 at 7:06
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    I wonder how a "blind test" would look like?: Take some coffee out from the cup with a spoon (so that you don't notice the temperature of the cup) and then taste. Wouldn't that test reduce everything to the temperature of the coffee?
    – U. Windl
    Jun 9, 2023 at 7:23
  • @quarague: That’s for food which cools down way too quickly so you want to serve it as hot as possible and reduce heat loss to the plates by heating them up first. Especially if it’s food which you can’t just make hotter to compensate for heat loss to the plates.
    – Michael
    Jun 9, 2023 at 7:44
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    @U.Windl I don't think that would work super fairly - the cup being hot is part of the experience, drinking coffee with a spoon probably sucks in both cases. Jun 9, 2023 at 10:13
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    @Michael if you like your drink to stay reasonably hot while you drink it slowly, and you have something with a lot of milk in it, you need the heat reserve of the warm cup. Apparently the milk for something like a cappuccino is only heated to about 65°C. With my preferred americano (black for me, or with a little warmed milk if you prefer) the drink is going in to the cup far hotter (90°C).
    – Chris H
    Jun 9, 2023 at 13:15

3 Answers 3

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I doubt that heating the cup influences the the actual flavor of the coffee from a chemistry perspective, however, it turns out that there is a specific preferred temperature range in which consumers prefer their coffee. The warm cup probably helps ensure one is getting their coffee in that window for a longer period of time, thus it is perceived as tasting better.

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    In support of no impact on flavour - also from the same paper "Complementary analyses indicate that beverage temperature over this range had little impact on assessments of the adequacy of flavor intensity, acidity, and mouthfeel, but did correlate slightly with overall liking and purchase intent"
    – bob1
    Jun 8, 2023 at 21:16
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    Hotter coffee means quicker service or hotter water. One is likely not possible, the other is actively damaging to the production of good coffee.
    – Nij
    Jun 9, 2023 at 10:20
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    @Michael there is an optimal brewing temperature.
    – moscafj
    Jun 9, 2023 at 11:03
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    My comment to @Michael under the question hints at this, but to go a step further, hotter coffee can work, but not for all coffees. Milk that's been heated further will taste very different. With espresso, there's so little volume of coffee compared to the thermal mass of the cup, that you'd have to be above the boiling point of water (which is impossible as well as ruining the flavour) to make up for a cold cup.
    – Chris H
    Jun 9, 2023 at 13:18
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    BTW @Michael your 10°C estimate is pretty good. I've just run the numbers on 250ml of drink in a 250g cup (I happen to know that some of mine at home weigh that much). The difference in drink temperature between using a cup at 20°C and one at 60°C (hot to the touch) is indeed about 10°C.
    – Chris H
    Jun 9, 2023 at 13:24
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I would say it is mostly about maintaining an optimal serving temperature for as long as possible. If you asked a number of people, most would probably agree that cold coffee doesn’t ”taste” good. While chemically there is hardly a difference, perception of flavor depends on temperature. (Which is why white wine is served chilled while red wine is served at room temperature.) So you want to make sure it stays close to brewing temperature. That is particularly challenging when you have some 50 ml of espresso in a tiny cup – heat is lost not only to the cup, but also to the environment due to the small volume.

Cranking up the brewing temperature to compensate for loss of temperature comes with other side effects, as this will alter the chemical composition of the coffee – you get aromatics which would not get extracted at all (or to a much lesser amount) at optimal brewing temperature, whereas others may evaporate more quickly at higher temperatures, all of which have an impact on flavor.

So the solution is to get the cup close to the optimal brewing/serving temperature so as little heat as possible is lost to the cup. Also, traditional espresso cups have fairly thick walls in order to increase their thermal capacity. That helps the cup, and the coffee inside it, stay warm for longer.

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  • Depends on the wall thickness of the mug. 1/8" thick, no. +1/4", yes. I rarely use the thick one, unless I want it still too hot 5m later. 5m later on an 1/8" cup, it's expired.
    – Mazura
    Jun 10, 2023 at 19:00
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    One interesting thing is that chilled coffee tastes good again.
    – Chris H
    Jun 11, 2023 at 7:23
  • I use double-walled stainless espresso cups for moka, and the first cup is ready to drink almost immediately after pouring into a room-temperature cup despite the much lower thermal mass in contact with the drink than in ceramic.I must measure the temperature some time
    – Chris H
    Jun 13, 2023 at 13:51
  • Double-walled cups (i.e. thermal insulation) are essentially another way to minimize heat loss. Guess we’ll need some figures: optimal brewing temperature, optimal serving temperature, heat tolerance of the human lips/tongue, heat loss of brewed coffee up to the point it hits the cup.
    – user149408
    Jun 13, 2023 at 17:53
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I expect this is a simple case of using "taste" when meaning "flavour", that is, not just taste but the whole experience of ingesting something. I expect most people would agree that ~50°C milk/vodka/tea/coffee/orange juice has a very different flavour than ~20°C or ~5°C, even though the chemicals are the same.

Tongues sense chemicals differently depending on the temperature (a quick search finds Link Between Taste And Temperature Focus Of "Thermal Taste," A New Discovery By Yale Scientists, Heat as a Factor in the Perception of Taste, Smell, and Oral Sensation, Temperature Affects Human Sweet Taste via At Least Two Mechanisms, Stimulus-Dependent Effects of Temperature on Bitter Taste in Humans). Notice for example how lukewarm water seems to enhance any impurities, while really cold water seems to taste basically nothing.

(A successful barista should probably optimise for flavour rather than just taste.)

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  • "tongues sense chemicals differently depending on the temperature" if you don't have a source for this it's purely opinion and not much use
    – jcollum
    Jun 12, 2023 at 19:35
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    It was trivial to find references. I literally just posted the sentence "tongues sense chemicals differently depending on the temperature" in a search engine.
    – l0b0
    Jun 12, 2023 at 20:32
  • @jcollum I’m surprised you find that difficult to believe. It's fairly well established that, e.g., the sensation of sweetness is attenuated at low temperature.
    – Sneftel
    Jun 12, 2023 at 22:27
  • I never said it was difficult to believe. Lots of people think that things are "fairly well established" when they are nothing more than hearsay.
    – jcollum
    Jun 12, 2023 at 22:31
  • I don't understand the downvotes on this. Using "taste" to include mouthfeel is pretty common in practice, though we might not like this sloppy wording in theory. Perception of flavours varying with temperature is again well-known. I don't think it's the whole (or even main) answer, but it's certainly valid and useful (especially since it's gained some links)
    – Chris H
    Jun 13, 2023 at 13:49

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