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The frying performance of pure refined olive-pomace oil (ROPO) and blended with refined coconut oil (RCO) (80:20) was compared during a frying operation of French fries at 180 °C. Blending polyunsaturated oils with highly saturated or monounsaturated oils has been studied extensively, however in literature there is no study has been reported so far on blending ROPO (rich in monounsaturated fatty acids) with RCO (rich in saturated fatty acids) to formulate new frying oils. At the end of the frying process, the blend of ROPO/RCO exhibited a higher chemical stability than the pure ROPO based on total polar compounds (TPC), and polymers. The rate of TPC formation was achieved 23.3% and 30.6% for the blend and the pure oil, respectively. Trans and free fatty acids content, as well as anisidine value were also observed to be the highest in the pure ROPO. This study evaluated the frying performance in the search for appropriate frying oils to deliver healthy fried products with optimized nutritional qualities.

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The aim of this work was to compare the frying stability of refined olive pomace oil alone and blended with refined coconut oil during 60 successive sessions. Frying experiments were carried out at 180 °C and samples were evaluated by high-performance size-exclusion chromatography (HPSEC), measuring the polymers and polar compounds formed. The tocopherol content was also analyzed. At the end of the frying process, the lowest content of polymeric compounds (PC) and total polar compounds (TPC) were detected for the blend of refined olive pomace oil-refined coconut oil (ROPO/RCO) with 13.20% and 25%, respectively, compared to refined olive pomace oil (ROPO) pure with 16.9% and 34.5%, respectively. Hence, the present study based on PC and TPC as best quality indicators of frying oil degradation indicated that the frying behavior of ROPO pure significantly improved by the blending application with RCO and showed a higher chemical stability.

Since olive leaf is a potential source of phenolic fraction that is assumed to have good antioxidative effects, we purposed to add its extract to the refined olive-pomace oil during heating to increase its oxidative stability. RP-UHPLC-DAD-QTOF-MS was employed to characterize the phenolic fraction.The oil samples were evaluated by measuring the polymers and the polar compounds and thus detecting specific oxidized compounds. Using this approach, the results showed that incorporating olive leaf extract in refined oil significantly reduced the formation of polymers from 14.39% to 10.45% and the oxidation state by the variation of extinction ΔK from 3.02 to 2.29 during 20 h of heating compared to unenriched oil. This study has proven that the use of natural substances is an opportunity to extend the life of refined oils.