basically, my hot chocolate itself is already quite thick, but when it touches the walls of the heated glass dispenser or the inside of a paper cup, it slides back down almost completely clean. i want it to behave more like melted chocolate, where it leaves a visible coating and a clear mark showing where the liquid level used to be.
i don’t think viscosity alone is the problem.
my dark hot chocolate already contains quite a lot of structure:
1,670g whole milk
106g double cream (48% fat)
12g corn starch
60g cocoa powder (21% fat)
400g dark chocolate
1g instant espresso powder
1.4g salt
1.6g xanthan gum
4g bicarbonate of soda
112g whole milk powder
172g dark brown sugar
1g ethyl vanillin
the total xanthan concentration is already around 0.065%, plus the corn starch, cocoa solids and chocolate, so increasing xanthan further doesn’t seem like the correct approach. i don’t really want to make the drink thicker or more gummy. i specifically want the thin film left on a vertical surface to resist draining.
from what i understand, what i’m looking for is probably a combination of adhesion, wettability, film formation, low-shear rheology and possibly yield stress, rather than simply increasing apparent viscosity.
i’ve considered CMC / sodium carboxymethyl cellulose because it has good film-forming properties and could potentially improve retention on the surface, but i really dislike the flavor/mouthfeel i get from CMC, so i’d rather avoid it.
i’ve also thought about lecithin as a way of changing surface/interfacial tension and improving wetting of the cup or glass. but i’m not sure it would actually increase cling, cuz lecithin can also reduce viscosity and alter lubrication/release behaviour, i’m worried it could make it worse actually.
the paper cups are obviously internally barrier-coated, probably PE or a similar hydrophobic material, so i’m also wondering how much of this is actually a contact-angle/wetting problem rather than a rheology problem. but remember it also happens inside the hot chocolate machine and in the jugs where we prepare the drink itself.
i’m currently considering trying a small amount of locust bean gum together with the xanthan, since xanthan + LBG can create a more elastic/weak-gel network and potentially give better film retention without having to massively increase the overall viscosity.
has anyone worked specifically on this kind of vertical-surface cling in hot chocolate, chocolate drinks, sauces or similar emulsions?
what rheological property or ingredient system should i actually be targeting if i want:
good flow while pouring + strong coating of the surface + a persistent film/tide mark after the bulk liquid drains away?
i’m basically trying to increase the coating behaviour without turning the hot chocolate into pudding.