One should be careful when cooking. Not everybody possesses the necessary know-how, and tends to rely on deep-rooted habits, without questioning their choices. It is necessary instead to be more prudent and inform oneself beforehand.
In their book Friggere bene (Frying well), published by Tecniche Nuove, oil specialist Luigi Caricato and chef Giuseppe Capano consulted various nutritionists, oil chemists and biochemists and other specialists operating in this field, and asked them a very specific, unambiguous question: which fats should be avoided when frying?
This is a question that most of us have probably asked ourselves countless times but never found out the correct answer. So the word now passes to the experts. Their opinions are important and should always be kept in mind. We quote their answers for the benefit of our readers.
What fats should be avoided?
Samantha Biale, nutritionist, Bruno Berra, biochemist: oils derived from seeds, such as sunflower oil, soybean oil, corn oil and so forth.
Massimo Cocchi, biochemist: Doubtlessly all oils derived from seeds.
Natale Giuseppe Frega, professor of Food Technology: All oils rich in polyunsaturated fatty acids: they have a very low smoke point and their use is therefore inadvisable.
Giovanni Lercker, professor of Food Technology: In general, all hydrogenated fats should always be avoided because they contain trans isomers. As regards frying, the more the fat employed is unsaturated, the lower the quality of the food, in terms of its oxidation. Virgin, or better, extra virgin olive oils ensure a lower oxidation degree of the oil residues present in the food. Personal tastes and habits however can condition the choice.
Francesco Visioli, chief scientist at Imdea, the Instituto Madrileño de Estudios Avanzados: If we can afford to, we should avoid or limit the use of sunflower and corn oil as much as possible. Most importantly however we should never re-heat it or employ it more than once.