Omega-3 fatty acids, also known as omega-3 and omega-3 fatty acids, are polyunsaturated fatty acids. A study published by American Medical Association 200 1 shows that eating fish rich in omega-3 fatty acids has obvious health benefits, including promoting antidepressant and anti-inflammatory effects, improving children's psychological skills and reducing the probability of thrombosis.
Marine oily fish is the richest source of omega-3 fatty acids, including mackerel, salmon and tuna. Omega-3-3 fatty acids also exist in various other seafood. There are three kinds of ω-3-3 fatty acids in the food we eat: α linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA α linolenic acid exists in walnut, rapeseed, soybean, cabbage, spinach and flaxseed. However, EPA and DHA exist in oily fish, and part of ALA is converted into EPA and DHA in human body.
There are many studies on how fried, baked and canned fish affect the content of omega-3, which explain the possible changes in the nutritional composition of fish during heating.
Loss of Omega-3 content in fried fish and canned fish
Omega-3 fatty acids are exposed to high temperature for a long time when frying fish. As the temperature is too high, omega-3 fatty acids begin to decompose gradually, which means that your intake of omega-3 will be greatly reduced.
According to a study in India, after frying tuna, researchers were shocked to find that 70%-85% of EPA and DHA omega-3 were destroyed during frying. The researchers also tried several other cooking methods of tuna, and as a result, canned food destroyed almost all omega-3 in tuna.
Omega -3 after food processing is the easiest to deteriorate, because it has to go through a set of high-temperature processing procedures for refining. Deodorization is an indispensable link in oily food processing. This process will make the oil pass through N kinds of heaters, and the temperature will rise to about 200 degrees Celsius to realize efficient steam distillation. At such a high temperature, the basic structure of oil will change and become harmful to human body. This process of fatty acid structure change is chemically called isomerization.
A series of trans fatty acids will be formed when oils and fats are processed at high temperature. The oil becomes colorless and tasteless after being steamed and filtered. By this processing method, oil can be stored for a longer time without worrying about deterioration. However, this oil no longer has the original health benefits because most omega-3-3 fatty acids have been destroyed. Eating this "plastic fat" is not good for the human body. In addition to oily fish oil, various vegetable oils are also suitable.
Difference of EPA and DHA contents between grilled fish and fried fish
According to another latest study in Greece, different methods of cooking fish are compared. This experiment is to bake anchovies and sardines rich in EPA and DHA in an oven.
The researchers found that when sardines were baked at 200 degrees Celsius for less than 20 minutes, fish could remain rich in EPA and DHA fat. But when frying fish, the researchers noticed that the distribution of fatty acids changed completely, and there was no original fatty acid structure!
So cooking fish rich in omega-3- 3 fatty acids needs special attention. According to the suggestion of Fisheries Research Institute, low-fat cooking techniques, such as roasting, steaming, boiling and frying, are recommended for frozen oily fish to avoid overcooking. It should be cooked thoroughly, so as to minimize the loss of omega-3 fatty acids. Frying is the most undesirable cooking method, because high temperature will destroy omega-3- fatty acids and increase excess fat in food. It was found that fried fish destroyed nearly 80% omega-3 fatty acids.
The healthiest way to cook fish.
According to Food Chemistry 164C, the changes of fatty acid content of various fish under various cooking methods were detected, including species, seasons, fish size, origin and so on. The results show that compared with other cooking methods, steaming or boiling is the best way to cook fish.
The above research proves that grilled fish or boiled fish can better preserve omega-3, and it is wise to eat as little fried fish as possible.