Sugar sugar, ah honey honey
November 19, 2006 11:57 AM   Subscribe

Chemistry and flavour: Do all sugars taste sweet? Are there substances that are sweet tasting that are not sugars/carbohydrates?

Breaking down the second question: edible substances? and how does the degree of sweetness compare?

Just contemplating the absence of a commercial sugar substitute that tastes good (to me). Not looking for food suggestions in particular, but more of an understanding of the reasons behind this absence.
posted by winston to Science & Nature (12 answers total) 3 users marked this as a favorite
Clarification: I guess I meant "naturally-occurring substances" in the second question. But I suppose artificial ones other than what's already being marketed as a sugar substitute are interesting too.
posted by winston at 11:59 AM on November 19, 2006

Have you tried Stevia? It's also called Sugarleaf, and it's all natural. It's said to be 300 times sweeter than sugar.
posted by amarynth at 12:14 PM on November 19, 2006

For a discussion of the physiology of sweetness, Wikipedia has a good article. Basically, compounds with hydroxyl groups in the right arrangement taste sweet.

That's for common edible sweeteners - there are some oddball sweet things, like beryllium chloride, that don't follow this rule of thumb, but what we usually think of as sweet foods have hydroxyl groups arranged properly to bind the sweetness receptor.

So yes, there are some sweet-tasting things that are not sugars or carbohydrates, but we generally don't eat them (BeCl2 is toxic). Why current artificial sweeteners don't taste good to you ... I don't know. I don't like 'em either, but I can't quite figure out why.
posted by Quietgal at 12:33 PM on November 19, 2006

Ethylene glycol is an ingredient in antifreeze that happens to taste sweet. It's an alcohol, not a sugar. (It's also very bad for you.)

Your taste buds bind to certain molecules (physiology of taste), and signal your brain that said molecule has been detected. This works fine, usually, because most of the sweet things that homo sapiens would normally encounter happen to be fruit and the like, which is good to eat. If the world were filled with ethylene glycol this would have been a crappy mutation and would have been bred out of the species. (Or perhaps we would have bred in an immunity to ethylene glycol!) Attempts to find artificial sweeteners are attempts to find things that:

a) trigger the sweet taste buds
b) don't have calories (aren't broken down in the body for energy)
c) don't kill you
posted by jellicle at 12:33 PM on November 19, 2006

Oh, historical note: one of the reasons that is given for the decline of the Roman Empire is that they used a chemical called "sugar of lead" as an artificial sweetener - the first artificial sweetener. The sugar cane plant was not known to Rome, so honey was the only real sweetener available.

This chemical, lead acetate, tastes sweet and is not immediately lethal to humans. But it produces lead poisoning over the long-term, which the Romans never figured out. There are some historians who link the craziness of certain Roman emperors with their love for sweets.
posted by jellicle at 12:49 PM on November 19, 2006 [1 favorite]

The ability to sense a chemical as sweet is completely dependent on its ability to bind protein receptors, and companies spend a lot of money testing and developing new compounds that fit tightly into the binding sites of these receptors. I found this webpage that summed it up pretty well, and had a little bit of comparison between the potency of a couple sweeteners. It kindof raises more questions than it answers, though, since it doesn't really say why different people taste differently, or why the warming of the tongue might increase sweet taste.

Although it doesn't directly answer your questions, this minireview is pretty interesting, pointing out that natural sugars (sucrose, glucose, fructose) activate one type of receptor on your taste bud cells, and artificial sugars (saccharine, aspartame (which is really type of amino acid)) activate a different type of receptor. These two receptor types cause different sets of signaling to occur in the cell, but ultimately have the same result - "firing" of the cell and communication to the brain the sweet sensation. One potential problem is that the natural sugars also inhibit the "bitter" cells, while the artificial sweeteners don't seem to do that. So there are many different subtleties that are going to affect how you perceive the taste.

(sorry, that was far more science-nerdy than you wanted, but I thought it was cool)

The obligatory wikipedia page lists (toward the bottom) artificial sweeteners and their relative sweetness.
posted by twoporedomain at 12:54 PM on November 19, 2006

How about things like glycerin or inulin?
posted by bink at 1:11 PM on November 19, 2006

The "sugars" are known technically as saccharides. There are basic ones such as glucose, fructose, maltose, and lactose. But it turns out that saccharides are nearly as good at polymerization as amino acids. There are disaccharides such as sucrose (table sugar) which is a fructose bonded to a glucose. There are short-chain polysaccharides like starch, which is pleasant tasting but doesn't taste sweet.

And there's the grandaddy of all long-chain saccharides, cellulose, which is the primary structural component of wood. It doesn't taste like anything and we are not capable of digesting it.

So in answer to one of your questions: no, it is not the case that all sugars taste sweet.
posted by Steven C. Den Beste at 1:54 PM on November 19, 2006

Rats. Lactose is a disaccharide. And so is maltose. Sorry about that.
posted by Steven C. Den Beste at 1:56 PM on November 19, 2006

This chemical, lead acetate, tastes sweet and is not immediately lethal to humans. But it produces lead poisoning over the long-term, which the Romans never figured out.

posted by reklaw at 3:02 PM on November 19, 2006

You mean like fat? Fats are not sugars but are sweet, oh, so sweet... mmm, fats.
posted by Pollomacho at 5:45 PM on November 19, 2006

heh. as a biochemist working in immunology (I aint no chemical engineer) I think I understand what you are asking that hasn't been answered yet.

Sugars, as chemists know them, refer to a BROAD group of chemicals, or Carbohydrates. They take the general form CH20, or a Carbon plus a water! like say, sucrose, whose formula you probably know, is C6H12O6. if you divide by six, you get CH2O. Thus, sugars CHEMICALLY refer to these molecules that have this composition. This refers to a lot of stuff that does not follow this rule exactly, too! it's just a general guideline for what a sugar is. If it's missing an O or two, it may still be a sugar. (see deoxyribose)

Anyways, as for the sweetness, the general idea is, there's a receptor molecule that sticks to sugars when they are on your tongue. The better the particular sugar is at sticking, the more the receptor detects "sweetness". So, different sugars that even look very similar stick with vastly different power, allowing for sweetness differences. For instance, the Cellulose in trees that is sugar SHOULD taste sweet, if your body had the enzymes to break it into single sugars. As it is, in long chains, it is really bad at interacting with your sweet receptors.

You are probably used to real, natural sugar. This stuff sticks in a way the sweet receptors are used to; hard, but not too hard, just the way you are used to from real food, the kind grown from the ground. These things, like sucrose, probably taste good to you.

Other things that were manufactured, like nutrasweet, are sweets that stick to your receptors WAY too hard in some cases, and kinda funny in others. The bottom line is, they don't stick exactly like your childhood favorites, natural sugar. Thus, things like splenda make sense; splenda is a sugar ring that simply has a chlorine or two stuck on it, to prevent your body from converting it to a metabolizable shape. Since splenda looks ALMOST the same plus a few chlorines (it's just unbreakable in your body's environment) the sweet receptors behave favorably, and a lot of people think it tastes okay.

As for you, you just might be boned. You just might think that anything that doesnt taste like real sugar sucks since you grew up on the real stuff (the conditioning theory) or your receptors just hate the fake sugar and don't bind well. (biochem theory) or, even, other receptors LIKE the sugar that trigger bad tastes, like bitter or something. Who knows, I just did some fact checking, and no one knows the exact cadre of receptors that do all of these shenanigans.
posted by wuzandfuzz at 12:36 AM on November 20, 2006

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