The Food Lab: Better Home Cooking Through Science

(Nandana) #1

rendered bacon fat). Avoid using bacon fat for more delicate
things like vegetables or fish.


Q: I’ve heard that if you fry fish in oil, it can make the oil
smell fishy. Any truth in that?
At one point or another, you’ve probably walked into a
restaurant or perhaps a neighbor’s home and immediately
caught a whiff of rancid, fishy-smelling oil. You may even
have said to your host (or if you are more restrained than I
have been in the past, to yourself), “Oof, somebody frying
fish in here?”
Well, here’s the thing: I’ve got both a fried fish shop and
a fried chicken shop right on my block in Harlem. Oddly
enough, it’s the fried chicken joint that smells like rancid,
fishy oil, while the fried fish shop smells only of fresh
seafood. What gives? Turns out that the “fishy oil” smell
you get from fried foods has nothing to do with the fish
itself; it’s caused by the inexorable breakdown of fat
molecules.


Q: Hang on a minute. Breakdown of fat molecules?
Sounds to me like you’re talking about oxidation and
hydrolysis. Can you explain yourself?
No problem. Remember high school biology, where we
learned that a fat molecule is made up of three fatty acids
attached to a glycerol backbone, all arranged in a large
upper-case-E shape? Well, the problem is that these fat
molecules are not exactly stable. Given exposure to oxygen
and enough time, they break down. And this gradual
breakdown is sped up by exposure to heat, light, and air.

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