Different people use different vegetable oils and animal derived fats during cooking.
Commonly used vegetable oils are Coconut oil, Mustard oil, Sunflower oil, Rice bran oil, Groundnut oil etc.
Milk fats (butter and Ghee) and different animal fats are also used in the same or related purposes.
What chemical changes of the components happen during boiling these oils and fats at different level of high temperatures?
What are the impacts of those on our health?
Saturated fats (like butter and lard), they say, are bad for us, and polyunsaturated fats (like sunflower oil and corn oil) are good for us. But this is just looking at fats at room temperature. When they get hot, they can change completely, breaking down into harmful chemicals. And then the situation is much more complicated.
When considering a cooking fat or oil, you should first consider smoking points. Every fat and oil has its own smoking point, which is the absolute highest temperature the fat or oil should be heated. Smoke points are the temperature in which the fat begins to break down into glycerol and free fatty acids. Heating an oil or fat beyonds the smoke point changes the chemical composition, in turn, producing toxic fumes, releasing harmful free radicals, and creating harmful carcinogens. Each fat and oil has their own unique smoke point
Heating causes the oil to undergo a series of chemical reactions like oxidation, hydrolysis and polymerization [2]. During this process, many oxidative products such as hydroperoxide and aldehydes are produced, which can be absorbed into the fried food..
these products unhealthy ..
Changes occurring in vegetable oils composition due to microwave heating
http://grasasyaceites.revistas.csic.es/index.php/grasasyaceites/article/viewFile/219/219
Sir/Madam,
Please add a complete list of production of chemicals (as aldehydes etc.) from oils/fats in relation with temperature.
It may act as a good source of knowledge of many RG followers like me.
Thanks.
Saturated fats (like butter and lard), they say, are bad for us, and polyunsaturated fats (like sunflower oil and corn oil) are good for us. But this is just looking at fats at room temperature. When they get hot, they can change completely, breaking down into harmful chemicals. And then the situation is much more complicated.
Hello Shibabrata Pattanayak,
Answer to your 1st point: Yes, Answer to 2nd Point: As per the USDA report (recent); globally, palm oil is extensively used for frying purposes, followed by soybean oil, rapeseed, sunflower oil, etc. Answer to 3rd Point: Yes milk Fat (Ghee) is the best choice,
Answer to 4th and 5th points: Most important changes that take place during atmospheric deep-fat frying are as a consequence of the high temperatures employed and presence of oxygen.
Exposure to elevated temperatures promotes formation of desired textures and flavors in the fried food. However, exposure to high temperatures is also responsible for degradation of nutritional compounds and formation of toxic compounds either in the foodstuff (e.g., acrylamide, glycidamide, hydroxymethylfurfural, heterocyclic amines) or in the frying oil itself (e.g., secondary lipid peroxidation products, such as 4-hydroxy-2-trans-nonenal and related compounds). Also, the presence of oxygen promotes oxidation of beneficial compounds present in the raw material as well as oxidation of polyunsaturated fatty acids of healthy oils.
The most important criteria used to select frying oils include long frying stability, fluidity, bland flavor, low tendency to foam or smoke formation, low tendency to gum (polymerize), oxidative stability of the oil in the fried food during storage, and price. Oils with a high content of saturated fatty acids have great stability in traditional frying applications; however, these oils are undesirable from a nutritional standpoint. On the other hand, oils high in polyunsaturated fatty acids show lower thermo-oxidative stability than rich monoenoic unsaturated fatty acids or saturated fatty acids oils.
I know butter get rancid quickly when temperature rises , that is why we put them in buttermilk to increase shelf life or make ghee .
Ghee has longer shelf life and need not be refrigerated .
Other than that , I know by practice , olive oil should not heated too much unlike vegetable oil.
So I do not use it for deep frying stuff ...
Heating of oils and fats lead to various deteriorative chemical processes e.g., hydrolysis, oxidation, and polymerization take place, and oils decompose to form volatile products and nonvolatile monomeric and polymeric compounds. With continued heating and frying, these compounds decompose further until breakdown products accumulate to levels that produce off-flavors and potentially toxic effects, rendering the oil unsuitable for frying. In addition, these chemical reactions are interrelated producing a complex mixture of products such as generation of free fatty acids, small molecular alcohol, aldehyde, ketone, acid, lactone and hydrocarbon, diglyceride and monoglyceride, cyclic and epoxy compounds, trans isomers, triacylglycerol monomer, dimmer, oligomer etc. The intermittent heating and cooling of oils causes higher deterioration of oils than continuous heating due to the oxygen solubility increase in the oil when the oil cools down from the frying temperature. Due to high concentrations of dimeric and polymerized molecules can lower significantly the digestibility, while oxidized fatty acid monomers are readily absorbed and raise concern about their effect on lipid metabolism. Diminished feed efficiency, increased liver, kidney and heart sizes, reduced activity of liver enzymes such as thiokinase and succinyldehydrogenase and evidence of carcinogenicity are some of the adverse health impacts.
Excellent contribution, Dr. Tripathi!
Deep fried foods prepared in Palm oil by repeated boiling at different days is very common in all over India.
What we are consuming?
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