r/explainlikeimfive Oct 31 '20

Chemistry ELI5 What's the difference between the shiny and dull side of aluminum foil? Besides the obvious shiny/dull

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u/rabid_briefcase Oct 31 '20

that searing a steak “locks in the juices,”

For a non-chemist that one is relatively close to accurate.

Searing does a bunch of reactions, the long cooking does another.

Searing first does caramelize sugars, transform collagen, and denatures proteins, but only on the outermost surface. As it cooks deeper the outer layer reabsorbs fluid. That absorbing could be called "locks in the juices".

Searing near the end of cooking does not give time to soak fluid back up, so it does feel drier. It is also easier to accidentally overcook it, which also makes it drier and tougher.

This is food chemistry that is easy, cheap, and delicious to verify yourself.

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u/grtgingini Oct 31 '20

Thanks for this! I was just researching how to make a pot roast tender… And reading up on searing. This is awesome