Chemical process behind hardening ice cream
We made a simple ice cream by mixing whipping cream, sugar, and Nutella.
After 5-6 hours (surely enough time for the ice cream to cool to the temperature of the freezer), it was soft (mechanically soft, while getting it out with a spoon). After 20-30 hours it became hard. Is there some chemical process involved? What is it?
Best Answer
I don't think there's a chemical process here. It just takes a really long time for it to freeze solid. After 5-6 hours it was probably firmer around the outside than in the middle, and after a day it was probably fully frozen. (I've made a lot of ice cream, and have reliably seen this.)
It takes so long because the heat transfer is so inefficient. It's already bad since there's no convection, just slow conduction from the outside in. And the conduction is slow because your ice cream is basically insulating itself: it's full of air.
If there is something on top of that, it's probably that your emulsion is breaking as it freezes, so water gets forced out and freezes into harder ice. This would be pretty noticeable - you'd get a grainy, icy texture. (If you really are mixing whipped cream and nutella I can certainly see that happening.)
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What is the chemistry behind ice cream freezing?
Liquid nitrogen, which boils at \u2013196 \xb0C, will freeze ice cream almost instantly. Because the ice cream freezes so quickly, the size of the crystals is small, resulting in a creamy texture. And because it boils when it hits the mixture, the ice cream is aerated during the process.What causes ice cream to harden?
Ice cream crystallisation occurs when the moisture in the air meets the frozen food. This moisture can then refreeze on the ice cream's surface, forming these telltale freezer burn crystals we've come to dread.What type of chemical reaction is involved in making ice cream?
An exothermic reaction is a chemical reaction that releases light or heat, otherwise known as energy . In this case, heat is released from molecules moving around, freezing cream into ice cream!How does icecream solidify?
\u2013 Ice crystalsCreated when the water-content in the base starts to freeze; they put the \u201cice\u201d in \u201cice cream\u201d, giving solidity and body. The size of the ice crystals largely determines how fine, or grainy, the ice cream eventually turns out.Science Xplained: Ice Cream Chemistry
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