Things That Go in Your Mouth

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nosimpleway
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Re: Things That Go in Your Mouth

Postby nosimpleway » Fri May 19, 2017 10:48 am

I mean, we're talking about chemicals with a particular molecular shape that we've evolved receptors for because they're important. Of those, the only receptor that takes exactly one shape of molecule is the salt receptor, which picks uo sodium chloride (and chemicals that happen to be shaped close enough to that, like potassium chloride, used as a substitute for people watching their sodium intake).

You say the "sweet" receptors pick up sugar, which is true! But there are receptors for monosaccharides and disaccarides, two or three each, that can also pick up sugar alcohols and ketones and aldehydes that aren't sugars -- and those often taste sweeter than the disaccharides the receptors were built to signal for. Beans are rich in trisaccharides, but aren't sweet because we don't have receptors for those. (And can't digest them, but your gut flora can, producing a lot of gas. That's why beans make you flatulent.)

Sour and bitter receptors are even more diverse, since they're looking for a whole group of compounds that indicate "this isn't ripe yet" and "this is probably poisonous". Since no one receptor is firing, they're harder to pin down in "pure" flavor.

Savory receptors pick up a spectrum of glutamate proteins. Astringency may not have its own receptor idk but is triggered by phenols. Ut wouldn't surprise me if phenols trigger receptors that aren't intended for flavors in the first place, like how capsaicin fires pain receptors and menthol fires the receptor that normally indicates cold temperatures.

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Mongrel
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Re: Things That Go in Your Mouth

Postby Mongrel » Fri May 19, 2017 12:15 pm

Today I learned
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beatbandito
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Re: Things That Go in Your Mouth

Postby beatbandito » Fri May 19, 2017 3:19 pm

karma plus

Fr srs tho, that is the most new information I've actually been interested in in one post I've read in a long time.
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MarsDragon
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Re: Things That Go in Your Mouth

Postby MarsDragon » Fri May 19, 2017 11:00 pm

That's why, if you're in a survival situation, just spitting out everything that tastes bitter is a decent starting point for figuring out what's edible. (note: please do not take this as your only advice in an actual survival situation. Call Para-medic instead.)

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nosimpleway
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Re: Things That Go in Your Mouth

Postby nosimpleway » Fri May 19, 2017 11:24 pm

Gimme another couple of years, I only just finished intro Biology.

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nosimpleway
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Re: Things That Go in Your Mouth

Postby nosimpleway » Sat May 20, 2017 11:02 am

Although it may bear pointing out that you don't do most of your tasting with your tongue. You taste with your nose.

Your tongue has receptors for five, maybe six chemical types. There's "this is calorie-rich, keep eating this" (sweet/savory), "this contains a vital nutrient, keep eating this" (salt), "this isn't ripe yet, stop eating this" (sour) and "this is poisonous, spit this out" (bitter and maybe also phenols, research is ongoing). But that's it!

Your olfactory complex is full of receptors that can pick up thousands of aromatics, many of which drift up the back of your throat into your nasal cavity while you eat and provide you with the subtler flavors of what you're eating. So while an apple and tomato are both sweet/sour on your tongue, the apple has a different aroma than the tomato. The apple carries a payload of esters, the tomato has mostly ionones*. Since they fire different olfactory receptors, the end result is a different aroma when you eat it**.

Introducing yeasts to grape juice induces the production of a lot of those volatile flavor compounds. So does curing tea leaves. Perhaps the most noticeable flavor that you pick up entirely with your nose is smoke. There isn't any receptor on the tongue for the compounds left behind in a piece of food that's been thoroughly smoked, but once you bite in and release those compounds into your olfactory complex, there's no mistaking that they're there. Smoked gouda is one of my favorite foods, but was a lousy comfort food when I had a cold. With my nasal passages all blocked up, it was just a vaguely sweet, creamy texture on my tongue.

The olfactory complex in a human is about the size of a postage stamp. The olfactory complex in a bloodhound is about the size of a pocket handkerchief. So I legit wonder if dogs taste things more intensely, or perhaps with more complexity, than humans do. I kind of hope not given that this is a creature that uses its tongue for toilet paper but it's not like I can ask.

* - [citation needed], yeah. Let me get back to you once I finish O-Chem.
** - Texture plays a big part in how you perceive the differences in the foods you eat, too, but that has nothing to do with either aroma or flavor.

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TA
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Re: Things That Go in Your Mouth

Postby TA » Sat May 20, 2017 8:41 pm

nosimpleway wrote:Although it may bear pointing out that you don't do most of your tasting with your tongue. You taste with your nose.

Your tongue has receptors for five, maybe six chemical types. There's "this is calorie-rich, keep eating this" (sweet/savory), "this contains a vital nutrient, keep eating this" (salt), "this isn't ripe yet, stop eating this" (sour) and "this is poisonous, spit this out" (bitter and maybe also phenols, research is ongoing). But that's it!


That's pretty much the thing, I'm curious specifically about those tongue receptors, not flavor profiles which are obviously a billion times more complicated. And, specifically, triggering them without involving the olfactory complex, so flavor doesn't confuse it - like, yeah, biting into a lemon is extremely sour, but it's also so many other things that it's not really what I was wondering about.

This is all very informative.
のほも is such a good word?? the concept is kind of hard to fully get across in translation, but basically it means a feeling of pure, deep, platonic affection, and i think thats beautiful

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nosimpleway
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Re: Things That Go in Your Mouth

Postby nosimpleway » Sun May 21, 2017 12:25 am

Well hell man, now you have me doing research. First thing I dug up out of the university library is a journal called "How Flavor Works", by Nak-Eon Choi. So if anything in this post is [citation needed] then... uh, it's probably that.

So, first thing! I was totally wrong about sweetness receptors. There's only the one, and it picks up a molecular shape where hydrogen and oxygen are at the end of a molecule a certain distance apart. (All sugars are made of carbon, oxygen, and hydrogen; that's part of the definition of what makes a carbohydrate a carbohydrate.*)
Dietary sugars are either monosaccharides (glucose, fructose, or galactose) or disaccharides (glucose + glucose = maltose; glucose + fructose = sucrose, table sugar; glucose + galactose = lactose**). All of the monosaccharides are C6H12O6, and have one end with the oxygen and hydrogen hanging off the molecule in exactly the right shape to fire the one taste receptor humans have for "sweet".
As it turns out, a lot of other molecules also have that sort of shape, so they also taste sweet, even if they don't carry the calorie payload that the sweet receptor is designed to signal for. Asparthame, for instance, is specifically modeled to fit the sweetness receptor but to be completely unusable by human metabolism, so it tastes sweet without contributing any calories.

There are two receptors for the savory flavor. Proteins are chains of amino acids, and can be hundreds of amino acids long. That's way too big to fit into a signal receptor on your tongue. Individual amino acids are small enough to fit into a receptor, so we have receptors for glutamic acid and aspartic acid. Glutamic acid tastes more savory than aspartic acid, which is convenient because it's the most common amino acid in things we eat.
When you cook a piece of meat or an egg, or cure milk into cheese, you're denaturing the proteins that make up that piece of food. Some of those proteins drift apart entirely, freeing the glutamic acid to bind to the receptors on your tongue when you chew. Aging and fermenting food intensifies how much of the glutamic acid is freed from the polypeptide chains, which is why aged cheese and soy sauce taste so different from fresh stuff. Parmesan cheese, carefully aged and cured, has one of the highest concentrations of glutamic acid of any food.
The artificial source of savory flavor that goes into preprocessed foods? MSG, monosodium glutamate. It's a salt where a sodium ion has bonded to a glutamine amino acid rather than the chloride anion you'd get in regular table salt. The reason controlled lab tests can't pick up any evidence of illness from eating the stuff is because the MSG molecule is just a glutamine amino acid stuck to a sodium ion -- two things your body consumes in abundance no matter what you're eating. MSG sickness is like being allergic to water.

There's only one receptor for salt, I was right about that. It looks for sodium chloride, namely free sodium ions. The chemical bond holding a sodium ion to a chloride anion is weak enough that the two drift apart when exposed to water (such as your saliva), allowing the receptor to pick up the sodium ion and send a signal that your brain interprets as the flavor of salt.
Which raises the question of how the potassium chloride I mentioned before functions as a salt substitute. Maybe that'll be the next topic I look up.
The neat thing about the salt receptor is how your brain processes salt in relation to other flavors. It makes sweet flavors sweeter, and bitter flavors less bitter. Salting watermelon is a generally-accepted idea, but I've gotten weird looks for putting a pinch of salt in a cup of bad coffee to make it more palatable. I'm not actually sure how that works, I guess that'll be the next next topic I look up.

All of your food is acidic***. Your food digests because your gastric juices are even more acidic than the food is, but the only alkaline food you're likely to see at the supermarket is baking soda. And nobody keeps a shaker of that on their table in case their food isn't astringent enough, right?
Foods that are particularly acidic taste sour. Acetic acid makes vinegar, Citric acid is the tang in an orange or grapefruit, and so on.
The chemical definition of an acid is a volatile compound that is eager, in the chemical sense, to shed its hydrogen ions****. So your tongue has receptors that fire in the presence of hydrogen ions, and the brain interprets that as a sour taste. Any fondness for acidic flavors is learned (rather than the innate drive for sweet, salt, and savory), and unripe fruit and vegetables are more acidic than their riper counterparts, so it's generally believed that the receptor for acid is meant to be a warning.
Interestingly, the receptor for sour is the only one that's found somewhere in the body other than the mouth. There are some of those on your spinal cord. Probably to monitor your body's pH level.

There are 25 receptors for various alkaloids that the brain interprets as bitter. Alkaloids are poison, so the bitter flavor is the sign that says "Stop eating that". That having been said: good chocolate, good beer, and good coffee all roll around on an unapologetic layer of bitterness, so the presence of some of those alkaloid compounds can be tolerated. Kids tend to perceive bitter flavors more intensely than adults, probably because children need less of a given poison to get sick. Pregnant women are also known to get ultrasensitive toward bitter flavors. Most animals don't tolerate bitter at all; green bell peppers are one of the few things a goat won't enthusiastically devour.

Like I mentioned before, there's ongoing research into whether phenols have a receptor that's interpreted as the astringent mouth-puckering flavor in wine tannins and strong tea.

There's no receptor for fats and oils. You pick up the aroma of the compounds that are dissolved in them, and you feel the richness on your tongue, but you can't taste them in the strictest sense. The difference in taste between corn oil, olive oil, and lard comes from the stuff dissolved in the lipids, not the lipids themselves.
I'm pretty sure sulfur is entirely aromatic, too. Broccoli and eggs taste the way they do because of sulfur, but that's a thing we pick up in our noses rather than on our tongues.

So! tl;dr: The things your tongue receptors are looking for are a spectrum of alkaloid compounds, free hydrogen ions, free sodium ions, free glutamine amino acids, and molecules in a shape resembling glucose. Those are your pure flavors, the stuff that will fire one flavor receptor without any interference from other receptors on your tongue or in your nose.

Now you just have to find a big pile of hydrogen ions to try it yourself.

* - It's right there in the name. Carbon. Hydrogen. Carbo-hydr-ate.
** - The body has to break sugars down into monosaccharides to metabolize them. If you lack the digestive enzyme that breaks lactose down into glucose and galactose, it passed through your stomach and intestine unchanged and your gut flora, who can break it down, have a feast. And any time your gut flora have a party, they produce a lot of gas -- enough for cramps and bloating, in this case. That's lactose intolerance.
*** - Your body tries damned hard to keep your blood pH at 7.3 to 7.4, regardless of what you eat, and changing that up or down by as little as .1 can damn near kill you. I have a friend with a genetic predisposition for a blood pH of 7.2 and her health problems are myriad. Next time someone promotes an alkaline diet at you, I want you to punch them as hard as you can. For me. Please.
**** - Bases, for contrast, are compounds that are eager to suck up hydrogen ions from something else.

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Silversong
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Re: Things That Go in Your Mouth

Postby Silversong » Mon May 22, 2017 9:52 am

I had heard that before, about salt in coffee, but had forgotten about it. I should try it some time. The office coffee is Starbucks though, so I don't think even salt can save it from its burnedness.

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Büge
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Re: Things That Go in Your Mouth

Postby Büge » Mon May 22, 2017 10:03 am

Really? I've heard that putting salt into coffee is bad. That's what makes it such a good prank to pull on someone.

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nosimpleway
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Re: Things That Go in Your Mouth

Postby nosimpleway » Mon May 22, 2017 10:33 am

We're talking a tiny pinch to cut out the bitterness compared to a couple of tablespoons for a prank.

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Mongrel
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Re: Things That Go in Your Mouth

Postby Mongrel » Mon May 22, 2017 12:56 pm

Alternately, use sugar to summon a lvl 100 cop.
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