Carbs that aren't sugars...

[Tom Kretchmar]

I'm a bit confused... I was under the impression that all
carbohydrates are one form of sugar or another. But looking
on the nutritional label of most foods shows that there are
apparently carbs not considered sugars... I would have then
thought that these were the carbs constituted by fiber, though
friends of mine who study chemical engineering, bio-chem, etc
have insisted that - technically, at least - fiber isn't really
a carbohydrate. Whether that's true or not, I'm really curious
what constitutes a carb that's not a sugar... this really got
me wondering when I looked at a package of baked tofu I was
eating today that said it had 10 grams of carbohydrates per
serving, but 0 grams of sugar and only 2 grams of fiber. What's
not adding up? My only guess would be that only simple carbs
count as sugars as far as nutritional labelling is concerned,
and that complex carbs, even if technically sugars (they are
technically sugars, right?), don't count.

Explanation? If it helps with the mystery there's also 140 kcal
per serving, 18 grams of protein, and 3.5 grams of fat, so all
of the calories per gram of carbs/protein/fat add up just about
right.

In short, what the heck is a carb when its not a sugar?

Tom

[Adam Holland]

I think you are right on the ball here, Tom. Carbs get classified as
"sugars" when they are simple enough, though I don't know what the cut-off
is . (anyone?)
gumdrops or the like have all of their carbs as sugars on the label.
Adam

Tom Kretchmar <tmkr...@mail1.sas.upenn.edu> wrote in article
<7cep12$alg$1...@netnews.upenn.edu>...

>
>
> I'm a bit confused... I was under the impression that all
> carbohydrates are one form of sugar or another. But looking
> on the nutritional label of most foods shows that there are
> apparently carbs not considered sugars...

My only guess would be that only simple carbs

> count as sugars as far as nutritional labelling is concerned,
> and that complex carbs, even if technically sugars (they are
> technically sugars, right?), don't count.

> In short, what the heck is a carb when its not a sugar?
>
>
> Tom
>

[Stewart Rowe]

Tom Kretchmar wrote:
>
> I'm a bit confused... I was under the impression that all
> carbohydrates are one form of sugar or another. But looking
> on the nutritional label of most foods shows that there are

> apparently carbs not considered sugars... I would have then
> thought that these were the carbs constituted by fiber, though
> friends of mine who study chemical engineering, bio-chem, etc
> have insisted that - technically, at least - fiber isn't really
> a carbohydrate. Whether that's true or not, I'm really curious
> what constitutes a carb that's not a sugar... this really got
> me wondering when I looked at a package of baked tofu I was
> eating today that said it had 10 grams of carbohydrates per
> serving, but 0 grams of sugar and only 2 grams of fiber. What's

> not adding up? My only guess would be that only simple carbs

> count as sugars as far as nutritional labelling is concerned,
> and that complex carbs, even if technically sugars (they are
> technically sugars, right?), don't count.
>

> Explanation? If it helps with the mystery there's also 140 kcal
> per serving, 18 grams of protein, and 3.5 grams of fat, so all
> of the calories per gram of carbs/protein/fat add up just about
> right.
>

> In short, what the heck is a carb when its not a sugar?
>
> Tom

Well, starch is a carb, and it's not sugar, but it hydrolyses to
sugar in the digestive tract.

Fibers, including insoluble fiber such as cellulose, is a carbohydrate
literally, but it cannot be digested by our system. So are the polymers
which make up thye "soluble" fiber. These are mostly made up of
sugar molecules (someone will tell us about the exceptions) but they
are hooked together into long chains by conections different from
say, starch, and also cannot be digested by us. Some of these can
be digested in part by the anaerobic bacteria that live in our
intestines,
pproducing the gas for which beans etc are well known.

[Kostas Polyzonis]

If you ask me carbohydrates and sugars are the same thing. There can be
small ones (glucose or fructose have 6 carbon atoms: C6H1206). Then there
are dimers like sucrose (sugar) with 12 C atoms: C12H22O11 . At the top end
there are the big polymers: starch and fibre. You have the enzymes to digest
the former but not the latter. That doesn't mean though that fibre isn't
useful: Amongst other things it lowers your cholesterol.

Kostas Poltyzonis
Chemistry BSc
Food Science MSc

[Ejwize]

I noticed that Fiber One cereal has very few calories. Is that because all the
fiber in it is indigestible? Would consuming lots of fiber net negative
calories since it requires calories to digest it?