How temperature affects taste
And how you can use the science to eat better
Key points
Food tastes more sweet/bitter/umami at temperatures of 15-35C (cool room temperature to just below body temperature (37C), i.e. lukewarm).
This happens because microscopic channels inside of sweet/bitter/umami taste receptor cells are heat regulated, sending a stronger electrical signal to the brain at temperatures of 15-35C.
We know less about how sour and salty taste receptors work, but it appears that sour receptors also respond to warmth, making food taste more sour when it’s warm, while salt receptors are cold-activated, so that food tastes more salty at cold temps.
It’s not just the temperature of the food that counts, but also the temperature of your tongue. Having iced/chilled drinks or hot beverages with your meal decreases the intensity of sweet/bitter/umami flavours whereas room temperature or lukewarm liquids amplifies them.
You can leverage the thermal dynamics of taste to eat more healthily, for example, by tricking your taste buds into eating more veg or reducing your consumption of sugary foods. Or simply to enjoy your food more by maxing out your sense of taste.😋👌
Introduction
This week, I did another guest slot on BBC Radio. This time, to give a definitive, evidence-based answer to the question, ‘Why does food taste better/worse at different temperatures? For example, chocolate in the fridge, and Vic (the presenter) can't stand vegetables unless they're piping hot!’
The short answer is: Because temperature affects how our taste buds† work.
In this article, I explain the thermal dynamics of taste perception. The science is spellbinding, but what’s really cool is that you can use it to cast healthy food spells on yourself and your loved ones, or simply to enjoy your food more. For example, tricking your own or the kids’ taste buds into loving veg by downplaying their bitterness. Curbing your intake of sugary foods by optimising sweetness perception. Calling all chefs and foodies: maxing out your sense of taste to enjoy food at its most flavourful. Or restoring your food mojo and lust for life by combatting age-related loss of taste (sadly, taste buds shrink in both number and size from age 40). It’s the stuff of food alchemy!
Read on for the full lowdown, or press play to listen to an excerpt from the interview.
Thinking of optimising your health with your diet?
The thermal dynamics of taste perception
As humans, we have taste receptor cells for five basic tastes: sweet, salty, sour, bitter and umami. Umami being the intensely moreish, lip-smackingly good, savoury flavour found in cooked and cured meats (think: meat juices, broths and extracts, and those flavour bombs that get stuck to the bottom of the pan when cooking meat that you deglaze into jus and gravies); aged cheeses like crystalline Parmesan and aged Gouda; fermented foods like soy sauce and fish sauce; and some vegetables such as tomatoes and mushrooms, especially shiitake. Specifically, umami is the taste of glutamate, a building block of protein.
Of those five basic tastes, three are highly heat-sensitive. The reason foods taste different at different temperatures is because our taste buds for sweet, bitter and umami work best within a specific temperature range: from 15-35C.[1] 15C being cool room temperature (average UK room temp is 18C) and 35C being lukewarm (just below body temperature, 37C).
We have different taste receptors for each of the five tastes. However, if you were to look at the taste receptor cells for sweet, bitter and umami tastes under a very powerful microscope, you’d see a common feature inside all three: microscopic conducting channels, termed TRPM5 channels.[1] When sweet/bitter/umami taste molecules land on the taste buds in your tongue, those microscopic channels open up and send an electrical signal to your brain (via nerves), resulting in that specific taste sensation. At 15C, they’re scarcely open and send a very weak sweet/bitter/umami signal to the brain. At 35C, they’re wide open (imagine a set of flood gates) and send a signal that’s 100 times stronger.[1]
Thus, sweet, bitter and umami tastes are most intense within that temperature window of 15-35C; it’s our sweet spot for sweet/bitter/umami taste perception:
Below 15C, they’re at their least noticeable
From 15C, they become progressively more intense, reaching PEAK TASTE at 35C
Above 35C and they start to tail off again.
Our salty and sour taste receptors don’t have TRPM5 channels, they use different mechanisms to transduce taste into an electrical signal, so they’re not affected by temperature in the same way. We know less about how they react to temperature, but some research suggests that sour receptors also respond to warmth, increasing sourness at warm temperatures,[2,3] while salt receptors are cold-activated, making food tasty more salty when it’s cold.[4]
Examples of taste variation by temperature
All this explains why:
Sweet:
Ice-cream gets sweeter as it gets warmer – when it’s frozen, it’s pleasantly sweet, but when it’s melted it’s cloyingly sweet
The same is true of fizzy drinks – think of a glass of Coca Cola that’s been left out on the side, and how sweet it is compared to a can straight out of the fridge – sickly sweet!
Refrigerated chocolate is less sweet; research shows it’s also less ‘chocolatey’ and less creamy.[5]
Bitter:
Piping hot veg are less bitter and strong-tasting than those served at room temperature/lukewarm.
Beer tastes more bitter as it gets warmer.
It’s also why we prefer to drink bitter drinks like tea, coffee and cocoa hot, as that decreases their bitterness – a cup of tea or coffee that’s been left to get cold is so much more bitter by comparison.
Umami:
Ham tastes saltier when cold and more savoury (umami) when warm – a ham sandwich just out of the chiller cabinet tastes salty and not of much else, but allowed to come up to room temperature and its flavours are released.
Sour:
Cheese becomes more sour at warm temperatures.[2]
Similarly, tomatoes (which are both sweet and umami) and strawberries (sweet) taste of very little straight out of the fridge, whereas at room temperature they taste wonderfully sweet and intense.👌
The temperature of your tongue also matters!
The really interesting thing is that it’s not just the temperature of your food that affects taste, but also the temperature of your mouth. Studies show that heating or cooling the tongue changes taste perception in exactly the same way as food temperature, which means that what you drink with your meal also affects food's taste.[6,7]
If you drink fluids in our PEAK TASTE range of 15-35C, you accentuate sweet/bitter/umami tastes. Whereas if you drink fluids above or below those temperatures, you downplay them. Let’s take some examples:
If you drink a glass of chilled or iced water either just before or with your meal (any beverage <15C), sweet/savoury/bitter tastes will be weaker
The same is true if you have a glass of hot water or a hot drink like tea/herbal tea (any beverage >35C)
However, if you have a room temperature or lukewarm drink (any beverage between 15-35C), sweet/savoury/bitter flavours will be amplified.
How to use the science of taste and temperature to eat more healthily & enjoyably
Now you know how temperature affects taste, you can harness the science to eat more healthily or simply to enjoy your food more!
Trick your taste buds into loving veg
Sweetness and umami are the pleasant tastes, markers for energy (calories) and protein respectively. But we’re not so keen on bitter, an evolutionary legacy that helped us avoid natural toxins, which is why some people find cruciferous veg (e.g. cabbage, cauliflower, broccoli, Brussels sprouts) hard to swallow. High levels of natural chemicals called glucosinolates (pronounced: gluco-sin-o-lates) impart crucifers’ characteristic bitterness and sulphurous pong on cooking, inconveniently, they’re also what makes them so darned good for us.
If you’re in the crucifer-averse camp and want to reap their health benefits, simply tweak the temperature of your food or taste buds to avoid the 15-35C window where bitter taste is at its strongest:
Serve veg hot (above 35C) or cold (below 15C)
Cool off your taste buds with a glass of chilled/iced water either just before or with your meal
Or dampen them with a warm cuppa (above 35C).
Children are particularly sensitive to bitter tastes as they have more taste buds than adults, so these three strategies are top tricks to encourage them to eat their veg.
Beware of chilled/frozen desserts
Because cold decreases sweetness, manufacturers have to add a LOT of sugar to make foods like ice cream, sorbet, frozen yoghurt, ice lollies, chilled and frozen desserts taste sweet. Avoid excessive sugar intake by enjoying them as a very occasional treat. And definitely don’t have them with a chilled/iced drink as that will further mask the sweetness, encouraging you to eat more.
Sonnda’s top 3 tips to max out your sense of taste
Certain factors reduce your sense of taste: ageing, illness – when you have a cold say, or as a symptom of coronavirus infection – certain medications, smoking, wearing dentures. You’re born with roughly 9000 taste buds, but they begin to shrink in both number and size from age 40,[8] with women generally reporting some loss of taste in their 50s and men in their 60s.[9]
Not being able to taste your food properly takes the fun out life, and can lead to more serious problems if you end up not eating enough because your appetite is diminished. But you needn’t consign yourself to a bland food fate! Instead, exploit that 15-35C window with these super-simple 3 steps:
Always allow refrigerated foods to come up to room temperature before serving
Instead of eating food piping hot, let it cool to lukewarm
Or have a room temperature/lukewarm glass of water/beverage either just before or with your meal.
And if you possess intact taste buds and just want to enjoy your food at its most flavourful, follow these same top tips for KABOOM! intensity.😋👌
References
Talavera K, Yasumatsu K, Voets T, et al. Heat activation of TRPM5 underlies thermal sensitivity of sweet taste. Nature. 2005;438(7070):1022-1025. Available from: doi:10.1038/nature04248.
Drake MA, Yates MD, Gerard PD. Impact of serving temperature on trained panel perception of cheddar cheese flavor attributes. Journal of Sensory Studies. 2005;20(2):147-155. Available from: https://doi.org/10.1111/j.1745-459X.2005.00013.x.
Lipscomb KA, Rieck JR, Dawson P. Effect of temperature on the intensity of basic tastes: Sweet, salty and sour. Journal of Food Research. 2016;5(4):1-10. Available from: https://doi.org/10.5539/jfr.v5n4p1.
Perez KT, Ninomiya Y, Winkel C, et al. Influence of temperature on taste perception. Cellular & Molecular Life Sciences. 2007;64(4):377-81. Available from: 10.1007/s00018-006-6384-0.
Mony P, Tokara T, Panga P, et al. Temperature of served water can modulate sensory perception and acceptance of food. Food Quality and Preference. 2013;28(2):449-455. Available from: https://doi.org/10.1016/j.foodqual.2012.12.002.
Green BG, Frankmann SP. The effect of cooling the tongue on the perceived intensity of taste. Chemical Senses. 1987;12(4): 609–619. Available from: https://doi.org/10.1093/chemse/12.4.609.
Bajec MR, Pickering GJ, DeCourville N. Influence of stimulus temperature on orosensory perception and variation with taste phenotype. Chemosensory Perception. 2012;5: 43–265. Available from: https://doi.org/10.1007/s12078-012-9129-5.
Comfort Keepers. Aging gracefully: Changes in the taste buds and sense of smell. 2014. Available from: https://www.comfortkeepers.com/info-center/category/senior-health-and-wellbeing/article/aging-gracefully-changes-in-the-taste-buds-and-sense-of-smell [Accessed 8/07/20].
Jacewicz N. Why taste buds dull as we age. NPR; 2017. Available from: https://www.npr.org/sections/thesalt/2017/05/05/526750174/why-taste-buds-dull-as-we-age [Accessed 8/07/20].