I made a float, starting with a glass of cola and putting a scoop of ice cream in it. After it stopped fizzing, I stirred it so that the ice cream melted and the foam settled down and was more or less incorporated back into the liquid. When the glass had been sitting for a few minutes, I noticed that the cream portion, which was slightly curdly the way that an Italian soda will be when you add the cream after the soda, had separated out. This is fairly normal and I usually just stir it back in before drinking. This time, I noticed that the colour of the soda had disappeared as well, leaving the liquid portion more or less clear. The creamy part was slightly beige, and when I stirred it back in, it looked as it usually did when the dark cola and white ice cream mixed.
Any idea how the caramel colouring could have been removed from the liquid?
Regular Pepsi (European, so cane sugar rather than corn syrup), and Haagen-Dazs vanilla ice cream. Are these critical details? Inquiring minds want to know.
Well, trying to be helpful… is it possible the ice cream froze the soda and the dye separated from the near-ice?
I’m in the US so I can’t test with the cane sugar pepsi. I’ll try to duplicate with ice cream and whatever else I have around. Oh, the things we do for science!
I appreciate your sacrifice. I don’t know if it made a difference that I added the ice cream to the soda rather than the other way around. You might have to try it both ways… for science, you know.
Pepsi is made with real sugar (not HFCS) and is available across America. It’s called Pepsi Throwback. BTW, “Haagen-Dazs” is fake Danish for “Made in Brooklyn,” by the Pillsbury Dough Boy (originally two Polish Jews). Geez, talk about melting pot.
They had Pepsi Raw here for a while, which was made from all natural ingredients (including all natural cane sugar, heh) instead of mostly industrial chemicals. I really liked that stuff, but they didn’t market it well enough, and discontinued it when it didn’t sell as well as it might have if they’d made more of an effort to get the word out.
But at least all* the soda here is made with sugar instead of HFCS (or glucose-fructose as it’s called here.
*okay, all except the crap that they put artificial sweeteners in, which I can’t tolerate. The ONLY commonly found brand of root beer I’ve seen so far has aspartame. Bastids.
OK, here’s the scoop: the acid-proof caramel color used in colas carries a negative charge in solution. It’s made by heat treating high-fructose corn syrup in the presence of sulfite and ammonia, and is therefore also known as “sulfite ammonia caramel color.”
Unlike lower-priced ice creams, which are emulsified with carrageenan (negatively charged), methylcellulose (neutral), and the like, superpremium ice creams like Haagen-Dazs are emulsified only with egg yolk, which contains lecithin, which is positively charged.
It’s my guess that the lecithin and the caramel color are strongly drawn to each other, so that along the bubbling ice cream-cola interface, the heavy, grainy brown foam contains a large amount of a lecithin/caramel/butterfat complex, which binds the caramel color and lightens the cola.
When you stir in the foam, the complex breaks down, because you have exposed the complex to an aqueous acid environment, where the lecithin is attracted by the phosphoric acid and the butterfat is too dispersed to stabilize the complex.
Because most people use cheaper ice cream in their floats? I dunno. I like Breyer’s better because it’s got that hard graininess to it. I like the crunchy ice interface that builds up on the ice cream when it reacts with the soda. The creamier the ice cream, the less that happens. I got some really hard ice cream here a while back that worked perfectly for my purposes. Didn’t notice the colour separation with that, but I also ate off the ice cream’s surface as the crunchy bit formed instead of mixing it in until it melted, so maybe that had something to do with it.
Are these critical details? Inquiring minds want to know.
