The Healthiest Option When Frying Fish is Extra Virgin Olive Oil

Researchers at UPV/EHU University in the Basque Country examined changes in fish lipids and fat during frying processes.

Frying techniques, the nature of the oil used, and the type of fish have been shown to have a large impact on the changes that occur during the process.

UPV/EHU researchers have shown that the choice of cooking oil is extremely important due to its impact on the lipid profile in fish and the formation of possible toxic compounds in the oil during frying that may affect food safety and human health.

Food Research International magazine discussed the study conducted: 'The effect of frying technique, edible oil and fish species on the changes in fish lipids and oil during shallow frying were examined by H-1 NMR' published his article. Bárbara Nieva-Echevarría, Encarnación Goicoechea, María José Manzanos and María Dolores Guillén. To carry out this research, sea bass (_11100000-0000-0000-0000 -000000000111_Dicentrarchus labrax_11100000 file Frying using tolar, extra virgin olive oil and refined sunflower oil plan and shallow-fried in the microwave.

Changes in the lipid composition of fish and frying oil were examined using Proton Nuclear Magnetic Resonance Imaging (H-1 NMR).

Transition of lipid components between fish and frying oil

During shallow frying of fish under domestic conditions, not only fish lipids are transferred to the frying oil, but the components of the oil are also transferred to the fish fillet.

As a result, the composition of the oil used for frying is changed: firstly, it is enriched by acyl groups ("fatty acids"), which are present in a higher concentration in fish oil than in the original oil, and secondly, and simultaneously in a higher concentration in the original oil than in the fish oil. It is depleted in the noble groups present.

So, after being used for frying, extra virgin olive oil was richer in omega-3, omega-1 acyl groups, linoleic and saturated fats (derived from fish) and poorer in oleic, the main acyl group in olive oil.

Similarly, after being used for frying, sunflower oil was richer in all types of acyl groups (from fish) except linoleic, which is the predominant acyl group in sunflower oil.

In addition, after frying, both types of oil are enriched with small amounts of cholesterol (derived from fish).

As for the oil in fish fillets, its composition also changed during the frying process and was enriched by acyl groups (in other words, oleic, if extra virgin olive oil was present), which are found in higher concentration in the frying oil than in the fillet. or if sunflower oil is used, it contains linoleic) and plant sterols.

Simultaneously, during the frying process, lipids in fish fillets were depleted in noble groups and minority components, which were found in higher concentrations in the raw fillet than in the original oils; such as omega-3 docosahexaenoic (DHA) and eicosapentaenoic (EPA) polyunsaturated groups.

Thermal oxidation reaction

In addition to the migration of lipids during frying, some small-scale thermal oxidation may occur in these oils as they are exposed to high temperatures (170 ºC) in the presence of oxygen.

This thermal oxidation reaction did not occur in extra virgin olive oil used for frying fish, as it is more resistant to spoilage than sunflower oil.

However, secondary oxidation compounds (aldehydes) have formed in the sunflower oil used for pan-frying fish; some of them are considered potentially toxic depending on their concentration.

It should be noted that these compounds do not occur in the sunflower oil used to fry fish in the microwave oven.

Therefore, considering the results obtained and the formation of these compounds that may be harmful to health, the healthiest option for frying is to use extra virgin olives and fry them in the microwave.

Fat content of fried fish

The type of fish used was also found to be a factor that significantly affects the oil absorption-desorption process during frying.

The fat content of gilded sea bream decreased after frying, while the fat content of European sea bass remained the same or increased from the initial level.

This study shows that the frying technique, the type of oil used and the type of fish have a great impact on the changes that occur during the frying process. Proper selection of oil, its effect on the final composition of the oil in the cooked fillet and the frying process It is of great importance because it affects the possibility of the formation of potentially toxic compounds in oil that will greatly affect food safety and human health.