The Food Lab: Better Home Cooking Through Science

at relatively low temperature. Bound water, on the other
hand, requires significantly more energy and a higher
temperature before it escapes. Heat a potato slice up to
275°F, and despite the fact that the temperature is well
above the boiling point of water, some of the bound water
will remain inside until you get it even hotter. So, the hotter
you fry a food, the more water will escape, and the more
room is left for oil to be absorbed.
This was all pretty shocking news to me, so I did what
any good skeptic would do: I tested it. I filled my wok with
two quarts of oil and weighed it on a precise scale. Next, I
heated the oil to 275°F and maintained that temp while I
fried chicken for a fixed period of time. After removing the
chicken, I weighed the oil remaining in the wok. I then
repeated the test, this time maintaining the oil at 325°F while
cooking the chicken. After repeating the test a few times, the
results confirmed what I had read: the hotter the temperature
the more oil the chicken absorbed.
There’s an explanation commonly given for why foods
cooked at a higher temperature supposedly absorb less fat:
the outward pressure of water vapor rapidly escaping from
the food prevents the influx of oil. This may be true while
the food is actually in the hot oil, but as soon as it’s
removed, its temperature drops rapidly. What once was
positive pressure being exerted from inside the food
reverses itself and results in a partial vacuum within a matter
of milliseconds. Rather than pushing water vapor out, the
food rapidly sucks the oil clinging to its surface into its
interior. Even the fastest fry cook in the world can’t drain
his onion rings fast enough to stop this influx of oil. Up to