High Oleic Oils in Contrast to Hydrogenated Oils

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High Oleic Oils in Contrast to Hydrogenated oils JoAnn Guest Aug 07, 2003

09:32 PDT

High Oleic Oils

 

High oleic varieties are oils that have been hybridized through

traditional plant breeding to contain higher levels of

monounsaturates (oleic acid).

 

The rise in oleic acid increases the oil's stability and shelf life.

High oleic oils have been bred to

reduce polyunsaturated components and increase the monounsaturated

content.

 

High oleic oils should have at least 90% of the oleic content similar

to olive oil. Olive oil is the benchmark for good

culinary oleic-based oils.

 

This means that an oil should be at least 75% oleic by total fat

content to be regarded as high oleic. High

oleic oils perform well in medium to high heat cooking applications,

such as deep frying or high heat sauteing.

 

Hydrogenated Fats and Oils

 

Hydrogenated fats are oils that have been processed through a

chemical hardening method to achieve increased plasticity

(stiffness) of the liquid oils at room temperature.

 

Partial hydrogenation (brush hydrogenation) hardens oils but does not

make them fully solid.

Full hydrogenation requires complete conversion of a liquid oil into a

solid fat at room temperature (72° F). A fully

hydrogenated oil has natural saturated fats left intact and all the

remaining mono- and polyunsaturated fatty acids become converted

from their fluid configuration to a full trans fat rigid

configuration. (See Trans Fatty Acids or Trans Fats).

 

Hydrogenation Process

 

The hydrogenation process employs 1) high heat, 2) a metal catalyst

such as nickel, zinc, copper, or other reactive metals, and 3)

hydrogen gas.

 

The metals are used to react with the hydrogen gas which is bubbled up

through the mixture. The metals catalyze the hydrogen and carbon atoms

and converts the fatty acids by flipping

one of the attached hydrogen molecules and rotating it half the

diameter of the carbon chain.

 

This effectively creates a new molecular shape resulting in a stiffer

or more rigid material, hence the change from a liquid to a semi-solid

or solid substance. This

new shape stiffens with the hydrogenation process making the oil

behave more like a saturated fat (similar to coconut fat which is 92%

saturation and solid at room temperature).

 

Trans fats are the result of this reaction. Partial hydrogenation,

or " brush hydrogenation " is a minimal conversion step which only

offers a small degree of reaction by hydrogenation. Brush

hydrogenation increases stability for volatile fatty acids like the

omega 3 (alpha-linolenic) and omega 6 (linoleic) polyunsaturated

oils.

 

Most commercial salad dressing oils, such as soybean oil, have

been brush hydrogenated.

 

Hydrogenation raises the melting point of the fat and retards

rancidity.

 

But as recent health studies have found other problems can ensue when

consuming large amounts of trans fats from hydrogenated products.

 

Hydrolysis

 

A chemical reaction involving molecular breakdown by the reaction of

an ester with water forming an acid and alcohol. It is a reaction

between a fat or oil and water in the presence of various alkali

agents, acids, metals lipase, or molds, which form new fatty acids

and glyceride compounds.

 

This reaction usually occurs under high temperatures and pressures.

Hydrolysis also occurs when high degrees of moisture are naturally

present in an oil.

 

Over time, the vegetable oil will breakdown as a consequence of the

hydrolytic

action taking place between the fatty acids and the water content in

the oil.

 

http://www.spectrumnaturals.com/fatsterminology.html

 

JoAnn Guest

mrsjo-

DietaryTi-

http://www.geocities.com/mrsjoguest/Transfats.html

 

 

 

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