Reusing cooking oil - what are the "rules"
Restaurant
workers regularly filter and reuse the oil in the deep fryer, and home cooks
can recycle cooking oil, too.
The
greatest health hazard when reusing cooking oil is allowing the fat to become
rancid (spoiled) and deteriorated to the point it produces undesirable flavours
and odours. Besides having a negative impact on the taste of the foods rancid
oils also contain free radicals that are potentially carcinogenic.
To
understand how to best re-use oil, it is important to know about oil smoke
points. Smoke point is the temperature at which oil begins to decompose. If you
heat oil to a temperature that is too high, it produces smoke fumes and
Acreolin, a substance that makes your eyes burn,
The
optimal temperature to fry foods at is 190°C. At higher temperatures, the food
will burn on the outside, and at lower temperatures, the food absorbs too much
oil and tastes greasy. Different oils have different smoke points. Oils with
higher smoke points are better for frying. The following is a list of smoke
points:
|
Type of Oil
avocado
oil
almond
oil
olive
oil (extra virgin)
olive
oil (extra light)
|
Smoke Point Temperature
271°C
216°C
207°C
242°C
|
|
safflower
oil
|
265°C
|
|
sunflower
oil
|
246°C
|
|
soybean
oil
|
241°C
|
|
canola
oil
|
238°C
|
|
corn
oil
|
236°C
|
|
peanut
oil
|
231°C
|
|
sesame
oil
|
215°C
|
|
olive
oil
|
190°C
|
|
lard
|
183
- 201°C*
|
|
(*varies
depending on the diet fed to hogs and the part of animal fat that is derived)
Once
cooking oil has been used it starts to break down and the used cooking oil’s
smoke point is lowered. As different cooking oils have different smoke
points, this is another characteristic one must consider when reusing oil.
The amount of times oil can be reused also depends on the type of foodstuffs
that were prepared with it previously. Protein rich foods such as meat will
cause the used cooking oil’s quality to deteriorate faster than if vegetables
were cooked with it. Every time used cooking oil is reused it picks up
impurities from the food cooked or fried with it. Cooking oil used to fry
fish for example should also not then be used to fry vegetables, as the oil
will now carry a fish flavour.
|
The
deterioration of cooking oil with re use is due to:
foreign
matter in the oil (such as batter)
salt
the
temperature to which the oil was heated
exposure
to oxygen and light
length
of time the oil remained heated
the
number of times the oil was reused
When
oil becomes deteriorated, it appears dark and thick (viscous). It may have an
unpleasant smell, and smoke appears before it reaches 190°C. If the oil smells
funy and old, better to toss it away and replace it with fresh oil.
To
re-use oil safely, use these tips:
Strain
it through a few layers of cheesecloth to catch any food particles.
Shake
off excess batter from food before frying it.
Use
a good thermometer to fry foods at 190°C.
Turn
off the heat after you are done cooking. Exposing oil to prolonged heat
accelerates rancidity.
Don't
mix different types of oil.
Store
oil in a cool, dark place.
Avoid
iron or copper pots or pans for frying oil that is to be reused. These metals
also accelerate rancidity.
Article
written by Maya Lazarova- The SkinnyFood Chef
on behalf of
Lynne van Zyl Dieticians - the
network of dieticians
