Research centre: Food and Nutrition Science and Technology Institute – CSIC.
Project summary. Frying is one of the most common culinary techniques and is a widely used practice, both domestically and industrially. It is a very complex process that involves numerous reactions, due to the oxygen in the air, the high temperature and the water coming from the food. The suitability of a frying oil is related, above all, to its resistance to thermal oxidation, and the main variables associated with the oil that influence it are its degree of unsaturation and the nature and content of its minor compounds having protective effects. In addition, there are important differences depending on the type of frying; that is, whether the process is continuous (industrial frying) or discontinuous (domestic frying, in restaurants, fast food establishments, cafeterias, etc.). The behaviour of olive pomace oil in relation to conventional and high oleic sunflower oils has not been evaluated in rigorous and systematic scientific studies. Considering its composition and physiochemical characteristics, this project expects clearly better results for olive pomace oil, due to its high concentrations of oleic acid, than for conventional sunflower oil, even if the latter is rich in antioxidants (tocopherols). With regards to high-oleic sunflower oils whose fatty acid content is similar to that of olive pomace oil, the primary advantage of the latter are its protective frying compounds, such as squalene and phytosterols.
This study aims to provide the necessary scientific basis to demonstrate that olive pomace oil is more suitable for frying than sunflower oils, both conventional and modified “high-oleic sunflower”, in both domestic and industrial frying.
Profile of the principal investigator
Gloria Márquez Ruiz is a Scientific Researcher at the Food and Nutrition Science and Technology Institute (ICTAN-CSIC), where he has been working since 1986, and her main research focus is the study of frying oils: quality and stability, development of analysis methods, antioxidant activity, etc. Her research in this field has contributed to the development of new analytical methods for the evaluation of alteration compounds formed in frying and quality control, including the validation of rapid methods for their determination in the hospitality sector, small establishments and cafeterias. She has also extensively studied the influence of numerous variables (temperature, surface area / volume of oil, degree of unsaturation of oil, etc.) on the alteration of different oils, and the effectiveness of different antioxidants (synthetic and natural). The major differences found with regards to the type of frying (continuous and discontinuous) and the interactions between food and oil are also topics addressed by Dr. Márquez in the frying area. She has also carried out research on the digestibility of frying oils and new compounds formed in animal specimens, and on the changes these compounds undergo under gastric and intestinal conditions. Dr. Márquez has published 126 scientific articles and 34 book chapters, directed 6 doctoral theses; and participated in 33 competitive national and international projects, and on 16 contracts with industries and private companies. She has presented the results of her research at 87 scientific congresses and has been awarded the Prize for the Best Oral Communication by the American Oil Chemists’ Society (Indianapolis, 1996), the Prize issued by the Brazilian Society of Fats and Oils for her “Contribution to Analytical Knowledge in the Area of Oils and Fats” (Campinas, 2008), the selection of Lipid Technology (Research Highlights) as one of the best scientific publications in 2003 and 2008, and the Edwin Frankel Award, from the American Oil Chemists’ Society (Salt Lake City, 2016), for the best publication in “Lipid Oxidation and Quality”.