As any longtime fry cook will tell you, you should always
save a bit of the old fry oil to add to the new batch if you
want to make sure your foods come out at optimum
crispness right from the first batch of fresh oil. For home
cooks, this amount can be as little as a tablespoon of old oil
per quart of new oil.
Q: What should I do with the oil in between batches of
frying?
Just as with fresh oil, used oil should be stored in a cool,
dark, relatively airtight environment. If you are planning to
do a bunch of frying over the course of a few days, this can
be as easy as straining it through a fine-mesh strainer lined
with cheesecloth or a paper towel into a pot with a metal lid
(not glass—glass lets in light) and keeping it in a cool corner
of the kitchen. For longer-term storage, strain the used oil
through a fine-mesh strainer, then funnel it back into its
original packaging. Seal tightly and store it in a cool, dark
cabinet.
Q: And what should I do once the oil finally does reach
the point where it can’t be reused any more? How do I
get rid of it?
Discarding used oil can be a real pain in the butt. Small
amounts, say, less than a half cup or so, can be poured
down the drain with plenty of soap and warm water (the
soap helps the oil emulsify with the water, preventing it
from sticking to and coating the insides of your pipes), but
larger amounts require a bit more care.
The absolute best way to get rid of used oil is to donate it