Pedialyte + metamucil = instant gel

[Omega_Glory]

I started pouring pedialyte into a cup containing one teaspoon of metamucil and they immediately formed a thick gel. Metamucil will gel with water if left to sit for awhile. Metamucil + salt (NaCl) water reacts the same as regular water does. What ingredients are causing the instant thickening?

pedialyte igredients are:
Water , Dextrose , Potassium Citrate Less Than 2% , Sodium Chloride Less Than 2% , Sodium Citrate Less Than 2% , Citric Acid Less Than 2%

For metamucil:
Ingredients
Sucrose, Psyllium Husk, Citric Acid, Natural and Artificial Orange Flavor, FD&C Yellow No. 6

Active Ingredient (in each TABLESPOON)
Psyllium Husk, Approximately 3.4 g

Inactive Ingredients
Citric Acid, FD&C Yellow No. 6, Natural and Artificial Orange Flavor, Sucrose

[HMS_Irruncible]

From what I know, the main factor determining mucilage behavior is hydrogen bonding which depends on very specific pH ranges depending on the type of mucilage. Under some conditions the branches of these long mucilage chains will bond like zippers zipping together, binding up all the water and creating large structures that appear like gel on the macro level. Under other conditions they don’t bond at all and are totally dissolved. And under still other conditions they can be made to precipitate out completely and separate from the solvent. It varies based on the type of mucilage.

I’m a little rusty on the wet chemistry but I think the citrate salts plus the citric acid will result in a solution buffered at a particular pH. So maybe that particular pH is exactly what the psyllium mucilage chains need in order to hydrogen-bond. I tried a mini-experiment with metamucil, table salt, and vinegar. None of the ingredients created an instant gel, either together or apart. So I think the buffering at that particular pH is key.

[Squink]

@Cosmic Relief

I’m a little rusty on the wet chemistry but I think the citrate salts plus the citric acid will result in a solution buffered at a particular pH.

Yup. I can’t find the pH of pedialyte online, but it’s probably different than the water you usually dissolve metamucil in. That said, the gellation rate psyllium decreases with decreasing pH :

It is possible in one way to control the rate of gellation by using acids to reduce the pH of the drink mix solution. However, typical acids can impart too strong a flavor (e.g., a sour or bitter flavor, especially at higher levels which may be desired to maximize the reduction in gellation rate) to the solution, and this must be

consistent with the flavor system being used. Obviously, such an acidic medium is not suitable for flavor systems which require neutral or basic conditions.

The link also hints at a possible explanation for what Omega Glory is seeing:

The present invention relates to psyilium husk-containing drink mix compositions comprising the divalent cation salt of strong inorganic acids selected from the group consisting of magnesium sulfate, calcium sulfate, calcium chloride, zinc sulfate, zinc chloride and mixtures thereof. These salts provide the benefit of reducing the gellation rate of the psyilium husk when dispersed in an aqueous solution.

It may be that if strong divalent salts slow down gellation, weak monovalent salts will speed it up. Or the effect might be caused by potassium ions in the pedialyte.
Potassium ions are quite good at driving soaps and such out of solution.
Try mixing some metamucil with gatorade. It should gel quickly.

[Omega_Glory]

Thanks guys. Squink, pedialyte is similar to gatorade, so I think you’ve figured it out.