Frying with unsaturated oils

[Guest guest]

Here are some bad news about frying with unsaturated oils (corn oil,

soybean).

Tony

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http://www.coafes.umn.edu/2may20054.html

Toxic compound in vegetable oil heated to frying temperature

5/2/2005 3:45 PM

What: Toxic compound in vegetable oil heated to frying temperature

When: To be presented at American Oil Chemists Society meeting

Wednesday, May 4

Where: Salt Lake City Convention Center

Who: A. Saari Csallany, (612) 624-3683. In Salt Lake City May

1-4: (801) 531-0800 (Marriott Hotel)

Contacts: Deane on, University News Service, (612) 624-2346

Food Fried In Vegetable Oil May Contain Toxic Compound

MINNEAPOLIS / ST. PAUL ( 5/2/2005 ) --University of Minnesota

researchers A. Saari Csallany, a professor of food chemistry and

nutritional biochemistry, and graduate student Seppanen have

shown that when highly unsaturated vegetable oils are heated at frying

temperature (365 F) for extended periods—or even for half an hour—a

highly toxic compound, HNE (4-hydroxy-trans-2-nonenal), forms in the

oil. Previously, vegetable oils such as soybean, sunflower and corn

were regarded as heart-healthy because of their high levels of

linoleic acid, a polyunsaturated fatty acid. HNE is incorporated into

fried food in the same concentration as it forms in the heated oil.

Also, Csallany and her colleagues have found three toxic HNE-related

compounds (known as HHE, HOE and HDE) in heated soybean oil. They will

present their work at a poster session from 9 a.m. to 2 p.m.

Wednesday, May 4, at the 96th annual meeting of the American Oil

Chemists Society in the Salt Lake City Convention Center.

" HNE is a well known, highly toxic compound that is easily absorbed

from the diet, " said Csallany. " The toxicity arises because the

compound is highly reactive with proteins, nucleic acids--DNA and

RNA--and other biomolecules. HNE is formed from the oxidation of

linoleic acid, and reports have related it to several diseases,

including atherosclerosis, stroke, Parkinson's, Alzheimer's,

Huntington's and liver diseases. "

Csallany's work underscores the risk of repeated heating, or reusing,

highly unsaturated oils for frying because HNE accumulates with each

heating cycle. In future studies, Csallany and her colleagues plan to

determine how long polyunsaturated oil must be heated at lower

temperatures in order to form HNE and its related compounds. The study

was funded by the University of Minnesota.