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Now, I know this is a very bizarre question, and I tried to find a correct exchange for this, but it might relate to biology/science as it being our taste buds and everything.

I am so sorry if there is a better exchange for this, but (I hate using this excuse) I'm new to StackExchange, so please be gentle and point me in the right direction.

Now, to meat and bones (Unintended pun; meat...bones...biology hehe), over the last few days I have noticed that after my drink returning to room temperature, it is so much sweeter than it originally tasted.

Drinks

  1. Hot Tea - I normally only add 1-2 teaspoons of sugar into my tea and it tastes just right, though after taking a sip when it had returned to room temperature, it tastes about 3 or 4 times sweeter than when it was hot/warm. (Milk)

  2. Iced Tea (Bubble Tea) - Just today I had a bubble tea with the smallest amount of sugar possible, it was still too sweet but I stuck with it, and again when it reached room temperature, it was almost unbearably sweet. (No milk)

  3. Slurpee - Again, after returning to room temperature, it is extremely sweet, with it being much lighter with respect to sweetness.

  4. Hot Coffee - Come to think of it, I have also had the same experience with sugared coffee.

  5. Coke - Also, when coke (or any other soft drink) is flat and room temperature, it also produces the same super sweet taste.

So, I tried to think of possible reasons why this happens but, I cannot think of any possible explaination other than magic.

If anyone knows why this might happen, it would be greatly appreciated since I am tripping out trying to figure out why this happens!

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  • $\begingroup$ This doesn't address all your issues, but with 1,2, and 4 - I would bet that the sugar is simply sinking (e.g. coming out of solution) to the bottom of the cup. If you drink your beverage as it comes to room temperature, a substantial portion of the sweetener has descended to the bottom of the cup where you are now drinking from. Regarding 3 - ice is less dense than water, so as your drink turns to liquid, there is more sugar per cubic centimeter than before. In neither case is the temperature making the beverage taste sweeter, it is just a coincidence with the sugar concentrations. $\endgroup$ – WannabeCoder Apr 15 '16 at 20:03
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Generally, cold suppresses sweetness. As an example, consider soft drinks that are usually served cold: they taste sweeter when warm (like you said with your examples of drinks).

Our taste receptors send a stronger signal to the brain when activated by warmer substances and so the perception of sweetness, in this case, is lessened when we consume cold food or drinks.

There are taste receptors on the surface of our tongue which refer to the proteins TAS1R2 and TAS1R3 which, which bind to the “sweet-tasting” molecules. When the molecules bind to the receptors, they trigger a series of actions which increase the number of positively charged potassium ions (K+) in the cell to which the receptor is attached. In order for the signal to continue along to the brain, the cumulative positive charge of the potassium ions must be high enough to activate a TRPM5 channel into the cell, so that calcium ions (Ca2+) can pass through. The Ca2+ ions are required for the release of neurotransmitters which send the signal. This channel requires a much lower positive charge for activation when it is warm than when it is cold.

Now if you were to put, e.g., a cold coke into your mouth, it decreases the temperature of the entire tongue and consequently the TAS1R2 and TAS1R3 proteins, and the TRPM5 channel. This will result in it requiring a greater positive charge in order for the signals to travel to the brain. This means overall also less signals are even received by the brain, thus resulting in us perceiving less sweetness.

Sources:

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    $\begingroup$ What about hot drinks? $\endgroup$ – moonman239 May 20 '16 at 17:21
  • $\begingroup$ @moonman239 Upvoted your comment, because the answer really does not answer that. Yet, my guess only could be that is due to the damage caused by hot. Even if you drink something sweet and not hot (only room temperature) right after drinking hot drink, it still will not be as sweet as usual. $\endgroup$ – rus9384 Nov 2 '18 at 8:38
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I found an article (1) which may help you understand what happened on your tongue: Light cooling from 37 to 21°C of beverages increases your sweet taste adaption, but not actual sweetness of your drink!

Another article (2) states, that a certain receptor for sweet taste perception is heat-activated.

So I guess there is no universal rule for any drink, you must look into further detail what the sweeteners are and which receptors would detect the taste.

(1) http://www.ncbi.nlm.nih.gov/pubmed/25963040

(2) http://www.ncbi.nlm.nih.gov/pubmed/17180301

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Sugar and other sweet things stimulate receptors in taste buds by binding to them with very weak chemical bonds known as hydrogen bonds. These bonds are weaker at higher temperatures so sugar binds less strongly and weaker signals get to the brain and the drink tastes less sweet.

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    $\begingroup$ Hi, welcome to Bio.SE! Thanks for providing an answer to this question. However, at this stack exchange site, we expect support (and preferably reputable citations) to back up info given as answers. (This way we remain more useful and accurate than places like yahoo answers -_- ). So please, think about providing support/citations for your answers, and you'll likely start seeing some upvotes. Failure to do so will typically result in downvotes. You can check out our help page for a guide to writing good answers. Thanks! $\endgroup$ – theforestecologist Mar 4 '18 at 21:02

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