Olive oil has an extraordinary value in cooking, but through the survey, it is found that there is a saying that many people believe that olive oil is not suitable for high-temperature cooking, and is more suitable for cold salad or Western food. But is that really the case? Is it true that olive oil can't be heated?
Everyone knows that olive oil has a very important place in the Eastern Mediterranean diet. Olive oil, also known as "liquid gold", is a natural fruit juice oil that is very suitable for human nutrition among the oils found so far.
The United States FDA labeled more than a decade ago that eating two scoops (23 grams) of olive oil a day is beneficial in reducing the risk of coronary heart disease; A hospital in the United Kingdom found that olive oil had a relieving effect on rheumatoid arthritis after conducting studies and trials on olive oil.
(United States Food and Drug Administration)
The "Eastern Mediterranean diet" refers to a healthy, simple, light and nutritious diet, which is a dietary pattern recommended by modern nutrition, derived from the traditional dietary patterns of the Eastern Mediterranean region and countries (Greece, southern Italy and Spain) in the 1940s and 1950s. UNESCO inscribed the Eastern Mediterranean diet on the Representative List of the Intangible Cultural Heritage of Humanity in 2013.
(Olive oil is consumed daily in the Eastern Mediterranean diet)
So can olive oil stand up to the heat?
Today, let's explore how extra virgin olive oil behaves at high temperatures.
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1. What are the problems of high-temperature cooking oil?
When we are happily cooking in the kitchen, if you see a continuous puff of green smoke from the oil in the pan, which means that the oil has been heated to more than the "smoke point", please turn off the heat immediately and reduce the temperature.
The main ingredient of edible oil is triglycerides, which are three fatty acids tied together. As the cooking temperature rises, some fatty acids will break up with the other two companions and become a "free fatty acid". Free fatty acids, as well as other complex oxides, are emitted into the air and become a wisp of green smoke that we see with the naked eye.
When the oil reaches the smoke point, the fatty acids and glycerin in it will be separated, oxidized and deteriorated, and volatilized into the air, there is a chemical called "acrolein" in the oil smoke, which can cause the formation of lung cancer, the higher the temperature of the oil, the higher the rate of acrolein production.
Studies have found that peanut oil, soybean oil, or lard emit carcinogenic chemical fumes as long as the temperature exceeds the smoke point.
In 1996, a study related to Lung Cancer, an international academic journal, pointed out that people who were exposed to cooking fumes for a long time had a 3.79 times higher risk of lung cancer than the general population;
Chinese women put more energy into cooking at home, and after a long time, they will naturally have some habits, such as:
I'm afraid that cooking won't be fragrant, and I like to burn the oil until it smokes before putting the condiments.
I am afraid of undercooking, and I like to stir-fry at high temperatures for a long time.
Figure is cheap, like to use vegetable oil with low stability to fry at high temperatures.
These habits can lead to long-term coughing at least and greatly increase the risk of lung cancer, and common vegetable oils, when cooked at high temperatures, are more likely to oxidize and produce carcinogens.
So, the first principle: high-temperature frying should use fats with a high smoke point.
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2. Let's look at the oxidation stability of oil
Smoke point is important, yes, but it's not the only basis for judgment.
In the past, the traditional belief was that refined vegetable oils with high smoke points, such as salad oil, corn oil, rapeseed oil, and sunflower oil, were suitable for high-temperature frying.
In fact, this is a wrong view. Why? Because the oxidation stability of refined oils is often poor.
As we mentioned earlier, fatty acids can be divided into saturated, monounsaturated, and polyunsaturated, as long as there are double bonds in the fatty acid, it is considered "unsaturated fat".
The fewer → polyunsaturated fatty acids, the more stable they are at high temperatures
These double bonds are the weakness of unsaturated fatty acids, so "polyunsaturated fatty acids" with more than two double bonds are easily oxidized and deteriorated (Lipid peroxidation) in a high temperature environment.
Fatty acid spoilage is no fun, and studies have found that consuming reheated vegetable oil (i.e., spoiled polyunsaturated fatty acids) can increase blood pressure and block blood vessels.
Some scholars even believe that the association between high-fat diet and cardiovascular disease is actually because oxidized fatty acids can cause cardiovascular disease.
The following is a list of fatty acid compositions of some common oils, and the higher the polyunsaturated fat content, the less stable it is at high temperatures. Such as soybean oil, corn oil, peanut oil, etc.
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3. What will happen to the high temperature of extra virgin olive oil?
There are studies that expose olive oil to prolonged high temperatures to test its quality and nutritional changes.
It was found that the olive oil performed well even under these extreme conditions.
In an experiment, some scholars took extra virgin olive oil (monounsaturated fatty acids) and sunflower oil (polyunsaturated fatty acids) to fry for more than 24 hours, and it is clear from the figure below that extra virgin olive oil has the highest antioxidant content and the best effect.
The second principle: "Use less" oils rich in polyunsaturated fatty acids for high-temperature frying, and choose oils and fats high in monounsaturated fatty acids.
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4. Low cholesterol you didn't know
Many people may have known the above two edible oil concepts for a long time, but the following concepts are relatively little known.
In the 2015 United States Healthy Eating Guidelines, the recommended upper limit of dietary cholesterol was removed, and the (wrong) common sense of "only one egg a day" was officially abandoned by the academic community.
However, if you want to fry at high temperature, it is best not to have cholesterol in the oil, so animal fats such as cream, lard, and butter are not qualified.
It is true that cholesterol is not the killer of cardiovascular diseases, but cholesterol is not resistant to high temperatures, and it is easy to oxidize under frying, frying, and frying, and the oxidized cholesterol is very different from ordinary cholesterol.
The Lancet (The United Kingdom Medical Journal) published an interesting report: India immigrants living in London at the time had a 1.5-2 times higher risk of cardiovascular disease than back home, but there was no obvious reason to explain. They smoke, have high blood pressure, and have no higher blood fat than their relatives in India, but the proportion of heart disease is particularly high.
Scholars have investigated their diets and found that these former Asian immigrants were particularly fond of using ghee (also known as clarified cream). 12.3% of the cholesterol in the locally bought ghee has been oxidized, and eating too much oxidized cholesterol is not a good thing for the cardiovascular system.
(Ghee)
Animal products such as milk, meat, eggs, and oil almost all contain a certain amount of cholesterol, which will be oxidized and damaged during heating. Past studies have found that purified cholesterol will begin to oxidize as soon as the temperature exceeds 120 degrees Celsius, and the higher the temperature and the longer the time, the more severe the oxidation.
Oxidized cholesterol is the "evil twin" of cholesterol, which can promote inflammation, increase the oxidation of LDL (bad cholesterol) in the human body, accelerate the blockage of blood vessels in mice, promote the proliferation of precancerous cells, and even be associated with diseases of civilized society such as dementia and inflammatory bowel diseases.
Due to ethical considerations, no human trials have been conducted on oxidized cholesterol, but there have been many basic and animal studies that show the health hazards of oxidized cholesterol.
Some readers may want to ask: since lard and cream should not be overheated, then is the same for pork and beef?
That's right! Milk, eggs, fish, and meat should not be heated too high, and the time should not be too long, otherwise the cholesterol in it will also produce oxidation reactions.
Based on the above conclusions, we know the principles of oil for high-temperature cooking, and simply remember the following points:
- Low in polyunsaturated fatty acids
- Low cholesterol
- High smoke point
- Rich in antioxidants
Therefore, oils with a high smoke point, high in monounsaturated fatty acids, cholesterol-free and containing antioxidants such as polyphenols, extra virgin olive oil performs very well.
Therefore, extra virgin olive oil can be fried and fried hot, and it is more stable after repeated heating, which is more suitable for Chinese cooking.
In Eastern Mediterranean food culture, extra virgin olive oil is almost versatile in cooking, and is used in stews, salads, and deep-frying, such as Spain fried fish, fried eggs, fried steaks, and so on.
It is believed that in the future, extra virgin olive oil will become the preferred choice for Chinese families to maintain their health. Eating olive oil can not only enjoy three meals a day with Eastern Mediterranean style, but also the many beneficial ingredients contained in olive oil will also play an effective role in protecting the health of your family.
Source: Xiangyu Olive Oil
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