Extra Virgin Olive Oil For Frying?
Researchers at the UPV/EHU University of the Basque Country have studied the changes that take position in fish fats and in the oil during drying.
The frying techniques, the nature of the cooking oil used and the type of fish had been shown to exert an impact on the changes that occur during the frying process. UPV/EHU researchers have proven that the option of cooking oil is massively fundamental because it has an impact on the lipid profile within the fish and on the possible release of toxins within the oil in the course of frying, which will impact meals safety and human wellness.
The journal Food Research International has released an article ’The influence of frying technique, cooking oil and fish species on the changes occurring in fish lipids and oil during shallow-frying, studied by H-1 NMR. This deals with the work applied by BÃ¡rbara Nieva-EchevarrÃa, EncarnaciÃ³n Goicoechea, MarÃa JosÃ© Manzanos and MarÃa Dolores GuillÃ©n.
To perform this research, fillets of European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) have been shallow-fried in a frying plan and in a microwave oven making use of extra virgin olive oil and refined sunflower oil. The alterations that took place within the lipid composition of the fish and of the frying oil were studied using Proton Nuclear Magnetic Resonance Imaging (H-1 NMR).
Change in Fat Components Between Fish and Frying Oil
During the shallow-frying of the fish in the house, not only do the fish lipids migrate to the frying oil, the components of the oil are also transferred to the fillet of fish. As a result, the composition of the oil used for frying is modified: first of all, it is enriched by using the acyl groups (‘fatty acids’) which are higher within the fish fats than in the common oil, and secondly, and simultaneously, it’s depleted in the acyl groups gift in a better attention within the customary oil than in the fish fats.
So after having been used for frying, the extra virgin olive oil is now richer in omega-3, omega-1 acyl groups, linoleic and saturated fats from the fish and poorer in oleic, which is the predominant acyl group in olive oil. Likewise, after having been used for frying, the sunflower oil is now richer in all of the acyl groups coming from the fish except linoleic, which comprises the majority acyl group in sunflower oil. Additionally, after frying, each varieties of oil were enriched by small amounts of cholesterol from the fish.
With regards to the fat in the fish fillets, its composition also changed throughout the frying approach, and grew to be enriched by the acyl groups which are present in a bigger concentration in the frying oil than in the fillet and in plant sterols. At the same time, during the frying procedure the fats within the fish fillets had been depleted with the acyl groups and minority components which are present in a higher concentration within the uncooked fillet than in the original oils, such as, omega-3 docosahexaenoic (DHA) and eicosapentaenoic (EPA) polyunsaturated groups.
Heat Oxidation Reactions
Apart from the migration of lipids during frying, due to the fact that these oils are subjected to higher temperatures (170 ºC) in the presence of oxygen, lesser amount of thermal oxidation may take place in them. In the extra virgin olive oil used for frying fish, this thermal oxidation response did not occur as it is more degradation-resistant than the sunflower oil. Yet in the sunflower oil being used for frying fish in the frying pan, secondary oxidation compounds such as aldehydes were formed, a few of them are regarded as potentially toxic relying on their concentration. It must be brought up that these compounds didn’t form within the sunflower oil used to fry the fish in the microwave oven. Hence, in view of the results received and bearing in mind the new release of those compounds which can be potentially harmful for health, the healthiest option for frying is to use extra virgin olive oil and fry in the microwave.
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Reference: Science Daily
Written By: Dr. Marie Gabrielle Laguna Bedia