What is the maximum temperature that a beverage can be without burning the tongue?

I suspect there's a maximum temperature that the surface tissue of a tongue can withstand without being damaged (causing the burning feeling that lasts even after the heat goes away). So let's say I want to setup a device to keep my coffee to the right temperature to drink without damaging my mouth - I'm interested to know the highest possible temperature that will not damage the surface tissue of the tongue in a way that will result in lingering pain after the heat is gone.

  • I think its about 45-50°C, but why don't you try yourself? ;-) By fever/hyperthermia: "Almost certainly death will occur; however, patients have been known to survive up to 46.5 °C" so I think it is over 46°C, it's over nein-nein-nein. – inf3rno Nov 13 '14 at 22:02
up vote 8 down vote accepted

Afaik the tongue is not more heat tolerant than other parts of the body, so the minimum temperature to cause burn is about drinking a beverage having 45°C temperature for a long time (more than 5 minutes). The pain threshold of tongue is around 47°C, so you will feel when it really burns.

According to studies the hedonic value of coffee has a maximum by 60°C, and it is significantly lower by safe levels (45°C). Frequent burns of mouth increases the risk of oral cancer. So I think this will be a hard choice... ;-)

A burn is an injury which is caused by application of heat or chemical substances to the external or internal surfaces of the body, which causes destruction of tissues. The minimum temperature for producing a burn is about 44°C for an exposure of about 5-6 hours or about 65°C for two seconds are sufficient to produce burns.

I. With the object of producing standard low-temperature burns in animals, and of studying the area of tissue only partly damaged in a burn, a burning iron has been made capable of applying temperatures from 45°-80°C. to the skin; with this the amount of heat and temperature causing skin damage has been studied, and the macroscopic and microscopic damage due to graded temperatures have been delineated.

  1. Graded temperatures of 45°-80°C. have been applied to the skin of shaved, anæsthetised guinea-pigs, and in some cases rats, for times varying from 10 sec. to 6 and 10 min. Observations have been made of the development of erythema, flare, blanching, blueing, heat fixation, incipient blister formation, œdema, and edge wheal, as also upon the later scab formation and rate of epithelium regeneration.
  2. Applications of 47°C. up to 6 minutes produce no visible change.

  3. At 50°-55°C. applied for 1 minute and over, there is a critical temperature for the development of permanent and irreversible damage; in animals good scab formation occurs after burning at this temperature.

  4. After temperatures of 60°-65°C. the epidermis can be peeled off from the exposed area, leaving a punched-out exposed surface area somewhat like the exposed human blister.

In all experiments, the chosen mean preferred temperature for drinking was around 60 °C (140 °F). Black coffee drinkers chose a slightly higher mean temperature than drinkers with added creamer, and they also chose a slightly lower mean temperature when the flavor was stronger. In all cases, consumers tended to choose, on average, temperatures for drinking coffee that were above the oral pain threshold and the burn damage threshold.

Overall, the available results strongly suggest that high-temperature beverage drinking increases the risk of EC. Future studies will require standardized strategies that allow for combining data, and results should be reported by histological subtypes of EC.

  • AFAIK TRPV channels open at ~45-50⁰C. This is not really a heat that can cause burn. I have bathed many times in water @ ~>=60⁰ and it just felt relaxing (my epidermis was alright :P). It takes higher temperatures to actually cause a burn. – WYSIWYG Nov 14 '14 at 6:28
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    @WYSIWYG "I have bathed many times in water @ ~>=60⁰ and it just felt relaxing" - I seriously doubt that. Our boiler is set to 60°C and the maximum I am capable to tolerate is half cold + half warm, so about 40°C. – inf3rno Nov 14 '14 at 7:37
  • @WYSIWYG youtube.com/watch?v=0WniZ1ly5Ik watch this. – inf3rno Nov 14 '14 at 7:40
  • @WYSIWYG Just to mention, long exposure to more than 37°C can cause hyperthermia. Afaik. humans cannot bear more than 50°C air (non-scientific source), because they would sweat more than they can drink. So putting aside the burn injuries you would still die because of hyperthermia if you would bath in 60°C water (which has about 4000 folds greater volumetric heat capacity than air). – inf3rno Nov 15 '14 at 5:41
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    Just saw this answer, +1 for good answer as well as appropriate username. – March Ho Aug 21 '15 at 12:08

This depends on a lot of factors, including how you take your first sip. If you sip with air, you are altering the temperature of the liquid as you sip, as well as decreasing the volume of hot liquid in your mouth, so that the increased surface area of your exposed tongue can quickly alter the temperature of a borderline scalding liquid into a non-scalding one.

So, there is part of the answer: it depends on volume, and time in contact with the tongue.

Most coffee pots keep coffee at about 170°F - hot enough to scald your mouth.

This article, while not scientific, does discuss why people like foods at temperatures that cause scalding, and what better temperatures are. But the public wants what it wants.

Safety experts recommend that water heaters be set at 120°F because you will not sustain a first-degree burn on contact, which is important if one has mobility problems. At 120°F, it takes 8 minutes of contact to acquire a second degree burn. At 155°F, it takes one second.

So, to guarantee no scald on contact with a small volume of coffee, I would think 145°F would be about right. (At 140°F, liquid will scald in 3 seconds. If you don't chug your coffee, this seems safe enough. If you chug, it will scald.)

  • 1
    I took the liberty of clarifying your temperature units, since I assume that you aren't talking about superheated coffee ;) – fileunderwater Aug 20 '15 at 10:38

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