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Gelling agents according to Wikipedia:

Some thickening agents are gelling agents (gellants), forming a gel, dissolving in the liquid phase as a colloid mixture...

But colloid according to Wikipedia:

A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance.

Gelling agents dissolving as a colloid seem contradictory to me. Because colloid is insoluable. Am I missing something?

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Wikipedia is wrong when stating that "gelling agents, dissolving in the liquid phase as a colloid mixture". A colloid mixture is not a solution. If something is dissolved in water, it forms a solution, it does not form a colloid mixture.

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    $\begingroup$ I see. Then, are gelling agents solvents or colloids? $\endgroup$
    – new
    Commented Jun 23 at 0:46
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    $\begingroup$ Gelling agents can be both solvent or colloids. They are solvent for substances that can be dissolved like $\ce{NaCl}$. They produce colloids with substances that are not dissolved but suspended. The optical effect is different. A solution is transparent. A colloidal suspension is not transparent. The light is diffused in all directions when crossing a colloidal suspension. $\endgroup$
    – Maurice
    Commented Jun 23 at 9:03
  • $\begingroup$ I think I phrased my questions badly. I meant: are gels(made from water and gelling agents) solution or colloids? $\endgroup$
    – new
    Commented Jun 24 at 10:24
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    $\begingroup$ @new, They are colloids. $\endgroup$
    – ACR
    Commented Jun 25 at 3:06
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Gelling agents dissolving as a colloid seem contradictory to me. Because colloid is insoluble. Am I missing something?

Do not take Wikipedia too literally. This is why we still have libraries. The correct term, instead of dissolving should be dispersed. Colloids are dispersions. A gel is a dispersion of a solid in a liquid.

Now there is a thin line between being dispersed and dissolved. It is just the matter of size.

OP further asks: Then, is it incorrect to describe gelling agents like pectin and inulin as 'soluble' dietary fibers?

Soluble dietary fiber (SDF) SDF is hydrophilic, non-crystalline, and easily wetted by the aqueous gastrointestinal fluid, forming viscous colloidal dispersions or gels when hydrated.

https://www.sciencedirect.com/topics/food-science/soluble-dietary-fiber

Yes, the the usage of soluble is perhaps a misnomer here. As I stated above, there is a thin line between soluble and being dispersed. Look up the properties of colloids from a good physical chemistry textbook.

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    $\begingroup$ Thank you for answer. Then, is it incorrect to describe gelling agents like pectin and inulin as 'soluble' dietary fibers? $\endgroup$
    – new
    Commented Jun 23 at 7:01

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