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Describe the physical and chemical effects of heating on fats and oils

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Heating oil changes its characteristics. Oils that are healthy at room temperature can become unhealthy when heated above certain temperatures. When choosing cooking oil, it is important to match the oil's heat tolerance with the cooking method.
Polyunsaturated oils like soya, canola, sunflower, and corn oil degrade easily to toxic compounds when heated. Prolonged consumption of burnt oils led to atherosclerosis, inflammatory joint disease, and development of birth defects. The scientists also questioned global health authorities' recommendation that large amounts of polyunsaturated fats be incorporated into the human diet without accompanying measures to ensure the protection of these fatty acids against heat- and oxidative-degradation.
Saturated fats withstand high heat of deep frying and are resistant to oxidation compared to highly unsaturated vegetable oils.
Oils that are suitable for high-temperature frying (above 230 °C/446 °F) because of their high smoke point.
The important thing about cooking with any oil is not to heat the oil over its smoke point (also referred to as smoking point). The substance smokes or burns, and gives food an unpleasant taste
Smoke point for a vegetable oil will vary according to the variety and growing conditions, and how the oil was produced. Various manufacturers and sources cite different numbers.
A high smoke point is desirable for a cooking oil. When frying, best results occur when the oil is very hot. The food is placed into the hot oil and the natural sugars caramelize and proteins denature into a thin shell which protects the food from soaking up the oil.
An oil at its smoke point is closer to its flash point - the point where it will burst into flame.
Oil which has oxidized because of exposure to air, heat and light will have a lower smoke point. Using oil repeatedly will also make it smoke sooner.

Titany answered the question on April 25, 2022 at 13:21

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