Show April 2019 Cooking with Fats and Oils: Can they withstand the heat?By Anita Bancroft An assortment of fats and oils are available at your local grocery store to use in all types of cooking applications. Some are better to use than others, especially when the heat is involved, so it is necessary to select the right tool for the job. Many oils are suitable for dressings or garnishes, while others are preferable for grilling or stir-frying with higher heat. It’s important to avoid the smoke point (the temperature a fat or oil begins to smoke), as this can produce toxic compounds and bitter or ‘off’ flavors. Exceeding the smoke point can also destroy valuable nutrients. When selecting your oil, it is important to note that food cooked on the stove top rarely exceeds 350°F. However, this temperature can be exceeded with other cooking techniques such as baking, grilling, and frying. Understanding Types of Fats SATURATED FATS Saturated fats typically come from animal products, but some plants are high in this type of fat as well. These fats are solid at room temperature. Saturated fats commonly used in cooking include: butter, coconut oil, palm oil, and lard. Although saturated fats can add flavor to your dish, they should be consumed in small amounts, as they can raise blood cholesterol levels, which is associated with an increased risk for heart disease. The 2015-2020 Dietary Guidelines for Americans recommend limiting saturated fat to less than 10% of daily calories (example – less than 200 calories from saturated fat for a diet of 2000 calories per day, or less than 22 grams/day). UNSATURATED FATS Plant oils, and some animal products, are high in both mono- and poly-unsaturated fats. Unsaturated fats commonly used in cooking include canola, flaxseed, avocado, peanut, and olive oil. These fats are associated with a reduced risk for many conditions, including heart disease and stroke. Unsaturated fats lower bad cholesterol, blood pressure, and inflammation while providing nutrients that are essential for building and maintaining cells in the body. The DGA recommends replacing saturated fats with healthier unsaturated fats. TRANS FATS Trans fats are created through hydrogenation, a process that takes oil that is liquid at room temperature (unsaturated) and turns it into solid fat (saturated). These are commonly found in margarine and shortenings. Like saturated fats, trans fats also have the ability to raise blood cholesterol levels and increase the risk of heart disease. The DGA recommends avoiding trans fats. Storage Storage is essential when it comes to oils. The quickest way to damage stored oil is to expose it to heat, air, and light. This causes oil to break down, which leads to a loss of nutrients. Oil should be stored in a cool, dark area and replaced if it has a bitter odor. Some oils (polyunsaturated oils such as flaxseed, grapeseed, and walnut) become rancid quicker than others and should be stored in the refrigerator to extend their shelf life. Olive Oils Olive oils are a heart-healthy choice. They are high in antioxidants and omega-9 fatty acid (Oleic acid). Virgin oils provide the most antioxidants. There is controversy regarding the use of olive oils in cooking. Compared to many other oils, they are actually more stable during heating, making them excellent for all cooking methods.
• Formation of trans fatty acids (TFA) occurs during frying/heating of fats/oil. TFAs were estimated in 6 fats/oils before/after heating/frying at 180 °C and 220 °C. Heating/frying
led to formation and increase in TFA in all fat/oil samples. Heating/frying also increased the saturated fatty acids and decreased cis-unsaturated fatty acids. Guidelines for heating/re-frying of fats/oils by Asian Indians should be devised. Heating/frying and reuse of edible fats/oils induces chemical changes such as formation of
trans fatty acids (TFAs). The aim of this study was to investigate the effect of heating/frying on formation of TFAs in fats/oils. Using gas chromatography with flame ionisation detector, TFA was estimated in six commonly used fat/oils in India (refined soybean oil, groundnut oil, olive oil, rapeseed oil, clarified butter, partially hydrogenated vegetable oil), before and after subjecting them to heating/frying at 180 °C and 220 °C. All six fats/oils subjected to
heating/frying demonstrated an increase in TFAs (p < 0.001), saturated fatty acids (p < 0.001) and decrease in cis-unsaturated fatty acids (p < 0.001). The absolute increase in TFA content of edible oils (after subjecting to heating/reheating) ranged between 2.30 ± 0.89 g/100 g and 4.5 ± 1.43 g/100 g; amongst edible fats it ranged between 2.60 ± 0.38 g/100 g and
5.96 ± 1.94 g/100 g. There were no significant differences between the two treatment groups (heating and frying; p = 0.892). Considering the undesirable health effects of TFA, appropriate guidelines for heating/re-frying of edible fats/oils by Asian Indians should be devised. Edible oils Fats Fatty acids Frying Heating Reheating Trans fatty acids Asian Indians Cited by (0)© 2016 Elsevier Ltd. All rights reserved. What is the effect of heat on fat and oil?Heating/frying led to formation and increase in TFA in all fat/oil samples. Heating/frying also increased the saturated fatty acids and decreased cis-unsaturated fatty acids.
What happens to fat when you heat it?The quickest way to damage stored oil is to expose it to heat, air, and light. This causes oil to break down, which leads to a loss of nutrients. Oil should be stored in a cool, dark area and replaced if it has a bitter odor.
What happens to cooking oil when you heat it?After just a single exposure to frying temperatures, vegetable oils begin to break down to free fatty acids and glycerol. As free fatty acids increase in the oil, its smoke point declines rapidly. The longer oil is used for frying, the lower its smoke point.
What happens to fats and oils if they are heated at too high a temperature?An oil's smoke point is the temperature at which it will start to smoke and break down. When cooking oil starts to smoke, it can lose some of its nutritional value and can give food an unpleasant taste.
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What happens when you heat fats and oils
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