Liquid Nitrogen Ice Cream
Two things us Advanced Scientists love are science, and liquid nitrogen. Combining the two, and you get something worthy of a demonstration at the ASSSoc demonstration this Wednesday morning at the Quad (10AM). We’re going to make some ice cream with the help of liquid nitrogen, and we’re going to make an excess, which is why we want you guys there to help us eat it all up! But before we make it, let’s have a look at the SCIENCE behind liquid nitrogen (or LN2). LN2 boils at standard atmospheric pressure at roughly -196ºC, so you’ll be right if you inferred that it is an extremely cold substance. It’s pretty useful too– we use it to cool electronics, smash tissue or plant matter in smaller bits to extract DNA, and to keep our cell cultures preserved and fresh. LN2 has a low viscosity, so when dropped onto a flat surface, it seems to form beads that travel with little relative friction across the surface, until it finally evaporates into nitrogen gas. But most importantly, it can be used to make the best ice cream. When making ice cream commercially, manufacturers rapidly cool, and stir their ice cream mixture to create the smallest ice crystals within the product. This gets them that smooth texture we all associate with ice cream. Whenever you take ice cream out of the freezer the uppermost layer melts and later recrystallises when replaced into the freezer, resulting in a gummy layer that isn’t very appetising. When we use LN2 to make ice cream, the product freezes so rapidly that the ice crystals fail to form large structures, leaving us with ice cream that’s smoother than commercial products. Barring the use of liquid helium (it’s 50 times more expensive than LN2), this will be the closest thing you get to the best ice cream you’ll ever taste! Remember, we’re making ice cream, and doing other fun things at the ASSSoc demonstrations at the centre stage in the Quad, this Wednesday at 10AM!
