Would Olive Oil be Suitable for Frying in the Catering/Industry? 
E. P. Kalogianni1*, C. Karastogiannidou2, S. Exarhopoulos1,  
1Department of Food Technology, Alexander Technological Educational Institute (ATEI) of Thessaloniki, Thessaloniki, Greece
2 Department of Nutrition and Dietetics, ATEI of Thessaloniki, Thessaloniki, Greece
*e-mail: elekalo@food.teithe.gr

The selection of frying oil or fat in the food industry and catering sector is based mainly on chemical stability, economical and cultural criteria. Around the Mediterranean olive oil is used in all culinary operations at home including frying. Also, some small restaurants follow the same practice. However, olive oil is expensive, it has a relatively low smoke point and it is not considered as a good alternative for frying in larger operations such as the catering sector or the food industry. On the contrary, saturated fats such as palm oil are often used such operations. Nevertheless, the health benefits of olive oil might make the food industry or catering sector to reexamine the use of olive oil for frying in order to prepare fried foods for a limited but more profitable market.
This work examines the performance of virgin olive oil in frying compared with palm oil and sunflower oil used for repeated frying of different foods. An overall oil heating/frying time of 52 hours was applied including 45 frying batches for each frying oil and food. The foods selected where potatoes, zucchini and meat balls. Control experiments (thermal oxidation) were performed by applying the same time-temperature profile in the oil in the absence of food. The effect of oil type vs food type on the products of main chemical reactions occurring during frying were determined including oxidation, polymerization and hydrolysis products. For oxidation, gas chromatography and UV absorbance was performed. The di- and oligopolymers of triacylglycerols were determined using High Pressure Size-Exclusion Chromatography. Finally, free fatty acids were determined in order to describe hydrolysis in the samples. The performance