Subject: Re-using cooking oil?

From: [email-masked] (S.J. Berch)
Date: Wed, 11 Dec 1996 07:03:14 GMT

Is there any reason not to re-use cooking oil?  

Someone told me that there was some change in the oil after heating it
to fry foods that made the oil unhealthy to re-use.  Any truth to
this?  I can't find any references to this in a search of Medline.

Thanks.

-sb

---

From: "Peter J. Barnes" <[email-masked]>
Date: Thu, 12 Dec 1996 12:57:53 +0000

In article <[email-masked]>, "S.J. Berch"
<[email-masked]> writes
>this?  I can't find any references to this in a search of Medline.
There is no reason why you should not re-use cooking oil if it has not
been badly treated in its first use or grossly contaminated with food
material. If you only use a very small amount of oil, then there is
probably no reason to re-use it -- but let's assume that you are talking
about deep-fring.

The question is really "How many times can I re-use it?" and there are
two main aspects (other than economic!) to deciding whether to re-use.
One is quality, the other is safety.

Safety: After much re-use in frying, an oil accumulates oxidised and
polymerised products -- the waxy material on the side of a much-used
frying pan is polymerised oil. Eating a lot of these breakdown products
is probably not good for you. But the quality of the oil deteriorates
and gives you a signal that the time has come to change.

Quality: With re-use, or prolonged frying, the oil will become darker in
colour, begin to have a rancid taste, and become frothy. This tells you
to change the oil.

Watch out with polyunsaturated oils like sunflower -- these oxidise and
"go off" faster. The old traditional oils used for frying were groundnut
(peanut) and lard or beef fat. These are more saturated and therefore
more stable. But varieties of sunflower which are more saturated (so-
called high-oleic sunflower) are coming into use. They tend to be
expensive and not widely available, but will penetrate the market
eventually.

Probably the most important point is: don't be mean about using fresh
oil! I would worry about the quality of the food going down before any
safety problems arise. If you want to make good-tasting food, then use
good oil!

Peter Barnes

-- 
Peter J. Barnes
PJ Barnes & Associates, PO Box 200
Bridgwater TA7 0YZ, England.
Tel: +44-1823-698973
Fax: +44-1823-698971
E-mail: editor(a)pbarnes.demon.co.uk