Health & Gastronomy 09/02/2015

The extra virgin olive oil is safer than sunflower in frying

Monounsaturated groups degraded at faster rate than polyunsaturated groups. 4-Hydroxy-2-alkenals were not found and 2,4-alkadienals were formed in small amount in extra virgin olive oil


Generally, thinking the frying we take care the flavor and the "lightness".

Not reason instead on the fact that, during the heating of the oil at high temperatures, it may come to create potentially toxic compounds for our health.

But all oils behave so? What happens when we heat an oil, especially if the process takes place in an industrial deep fryer?

The University Basque researchers have investigated, heating oil exra virgin olive oil at 190 ° C in a discontinuous industrial fryer for 40 hours. Same treatment has undergone an sunflower oil.

The process was followed by repeated analysis with nuclear magnetic resonance, particularly with regard to the relationships of the acyl group and the iodine number, indices of the degree of unsaturation in the fatty acids.

The formation of primary oxidation compounds was not observed with this technique, which contrasts with the early detection of different types of aldehydes, such as alkanals, (E)-2-alkenals, (E,E)-2,4-alkadienals, and 4-oxoalkanals, whose concentrations follow a curved path in most cases.

In addition, the formation of (E) and (Z)-9,10-epoxystearyl groups was also observed and the evolution of their concentrations throughout the heating time determined.

Equations that relate the above mentioned composition parameters to the heating time were obtained, all of them with high correlation coefficients and predictive value. Major differences were found between the behaviour of this extra virgin olive oil and sunflower oil submitted to identical conditions.

The safety level, in terms of aldehydes contained, is higher in the extra virgin olive oil than in the sunflower; in fact, cytotoxic and genotoxic 4-hydroxy-(E)-2-alkenals were not detected in extra virgin olive oil, unlike in sunflower oil.

Significant differences have also been noted in relation to the percentage of polar compounds in favor of extra virgin olive oil, which entails large differences in the level of safety in use in frying between the two oils.

di R. T.