Trans fats
Do you know what happens when your favorite cooking oil set to boil at
higher temperature? The answer
is simple; it converts in to trans fats (trans
fatty acids).
Now, what are these
Trans-fats?
How do they
form?
Why all of
us are so concerned about trans-fats?
When
the oil is set to boil at higher temperatures, a kind of chemical
reaction occurs resulting in change in the configuration
of the oil
from its natural cis-form to trans-form.
Then...what?
Traditionally,
cooking oils are either poly unsaturated (eg. Sunflower oil) or
mono-unsaturated (eg. Olive) oils. When oils deep boiled and
converted to trans-fats, they behave like saturated fats in the body;
that is, they elevate "bad
cholesterol" or LDL levels and decrease the "good cholesterol" or
HDL levels in the blood.
Trans fats do not present in the plants and only occur in small
amounts in meat and dairy products as vaccenic acid.
Actually, most trans-fats consumed today are created industrially
through partial hydrogenation of vegetable oils. Hydrogenation
(addition of
hydrogen atoms to cis-unsaturated fats) makes them more
saturated. So formed saturated fats have higher melting points and
have longer shelf-life which makes them attractive for frying and
baking. However, deep
boiling also catalyses a side reaction that isomerizes some of the
cis-unsaturated fats into trans-unsaturated fats instead of
hydrogenating them completely. Trans fats formed from
partially
hydrogenated oils are, in fact more dangerous to health than naturally
occurring oils.
In addition, deep frying of food items (carbohydrate-rich) results in
the production of toxic chemical "acrylamide";
a deep brown color, soot like substance on the outer surface of fried
items. Excess of acrylamide might cause liver cell and colon
cancers.
How
much Trans fat is acceptable in the diet?
Nil....
In fact, there is no safe levels for trans-fats in the diet and unlike
other dietary fats, trans-fats are not at all essential for our body.
New
England Journal of Medicine (NEJM-2006 edition) scientific
review
that states that "from a nutritional standpoint, the consumption of
trans fatty acids results in considerable potential harm but no
apparent benefit".
Health
risks of Trans fats
Steps to avoid or at least to reduce Trans fat consumption in the diet.
- Avoid hydrogenated fats like "dalda" in foods.
- Use only small quantity of oil. See that the
oil is not too high in temperature before food is put in.
- Do not re-use cooked oil.
- Use more stable oils at room temperature such
as olive oil as add on to foods eg. To salad dressing.
- Sautéing, use of tomato and onions as a base
can substantially reduce
the oil requirements.
- Shallow or stir frying.
- While frying, start with small amount of oil at
low heat and add small amounts of fresh oil to replace oil used up in
frying.
Also read...> list
of recommended fats and oils.
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