Document Type : Research Article


Department of food science and technology, Faculty of agriculture, Ferdowsi university of Mashhad, Iran.


Introduction: Frying is one of the oldest and popular preparation techniques broadly used at home and food industry. High temperatures plus the presence of air as well as the water from the food being fried cause many destructive reactions. Therefore, thermal stability and performance of oil during frying is considered as one of the important criteria in the selection of frying oil. In this regard, balanced chemical composition, presents it as a valuable option for frying purposes. Studies show lipid autoxidation considered as the most important deteriorative reaction in the olive oil. This reaction leads to the formation of a series of primary and secondary oxidation products. Hydroperoxides are the primary oxidation products of lipid oxidation. Carbonyl value (CV) does measure secondary decomposition products are more stable than peroxides and the CV seems to be a good index of oxidative changes in lipids. Therefore, the determination of carbonyl compounds in frying oils is very important for evaluating the quality of frying fats and oils. Several studies have been carried out on the oxidative stability of edible oil during frying. Rancimat test has also been considered among the accelerated methods of lipid oxidation measurement due to ease of use and reproducibility. However, although estimate of oxidative stability of edible oil according to accelerated methods, is used widely but there is always worries about accordance the results of such tests with the results found under real frying conditions and Presence of food. Therefore, necessity of simultaneous study oxidative stability is essential in order to justify and extension of result together during heating and frying.
Materials and methods: Six refined olive oil samples of different brands in 1 lit glass bottles were purchased from local shops and were stored at 4 ºC for further analysis. Fatty acid methyl ester (FAME) standards, and all chemicals and solvents used in this study were of analytical reagent grade and supplied by Merck and Sigma Chemical Companies. The ratio between monounsaturated and polyunsaturated fatty acids (M/P) was determined by gas–liquid chromatography. The spectrophotometric method was used to determine the PV. The AV was determined according to the AOCS. The TT content was determined according to the colorimetric method. The TP content was determined spectrophotometrically using Folin–Ciocalteau’s reagent. The CV of the oils was measured using 2-propanol and 2,4-decadienal as solvent and standard, respectively. A Metrohm Rancimat model 743 (Herisau, Switzerland) was used to measure the OSI and IPCV of olive oil samples. Frying process was performed in bench- top deep- fryer at 180ºC. ANOVA and regression analyses were performed according to the MATLAB and Excel software. Significant differences between means were determined by Duncan’s multiple range tests.
Results and discussion: There was good correlation between the OSI and induction period (IPcv) at the temperature range studied with a high determination coefficient (R2>0.99) in the Rancimat test. Generally, the results of the present study showed that the Rancimat method at 110 ºC correlated well with stability under frying condition and this correlation decreased as temperature increased in the Rancimat test. These observations can be explained by the fact that steps or pathway of chemical reactions that take place at low and high temperatures are different. Thus, choosing the right levels of operational parameters in the Rancimat method can produce the least possible difference between frying and the OSI test.


AOCS. 1993. Official Methods and Recommended Practices of the American Oil chemists᾿Society, Champaign: AOCS Press.
Berasategi, I., Barriuso, B., Ansorena, D., & Astiasaran, I. 2012. Stability of avocado oil during heating: Comparative study to olive oil. Food Chemistry, 132, 439-446.
Blumenthal, M.M. 1991. A new look at the chemistry and physics of deep-fat frying. Food Technology, 45, 68-71.
Boskou, D., Blekas, G., & Tsimidou, M. 2005. Phenolic compounds in olive oil and olives. Current Topics in Nutraceutical Research, 3, 125-136.
Chang, S. S., Peterson, R.J., & Ho, C. 1978. Chemical reaction involved in the deep- fat frying of foods. Journal of the American Oil Chemists’ Society, 55, 718-725.
Chow, C. K. 2007. Fatty acids in foods and their health implications. 3rd ed
Capannesi, C., Palchetti, I., Mascini, M., & Parenti, A. 2000. Electrochemical sensor and biosensor for polyphenols detection in olive oils. Food Chemistry, 71, 553-562.
Endo, Y., Li, C. M., Tagiri- Endo, M., & Fugimoto, K. 2001. A modified method for the estimation of total carbonyl compounds in heated and frying oils using 2- propanol as asolvent. Journal of the American Oil Chemists᾿Society, 10, 1021-1024.
Farhoosh, R., & Moosavi, S. M. R. 2006. Rancimat test for the assessment of used frying oils quality. Journal of Food Lipids, 14, 263- 271.
Farhoosh, R. 2007. The effect of operational parameters of the rancimat method on the determination of the oxidative stability measures and shelf-life prediction of soybean oil. Journal of the American Oil Chemists' Society, 84, 205–209.
Farhoosh, R., Niazmand, R., Rezaei, M., & Sarabi, M. 2008. Kinetic parameter determination of vegetable oil oxidation under Rancimat test conditions. European Journal of Lipid Science and technology, 110, 587–592.
Farhoosh, R., & Moosavi, S. M. R. 2008. Carbonyl value in monitoring of the quality of used frying oils. Analytical Chimica Acta, 617, 18-21.
Farhoosh, R., Haddad Khodaparast, M. H., Sharif, A., and Alavi Rafiee, S. 2012a. Olive oil oxidation: Rejection points in terms of polar, conjugated diene, and carbonyl values. Food Chemistry, 131, 1385-1390.
Farhoosh, R., Haddad Khodaparast, M. H., Sharif, A., Zamani-Ghalehshahi, and Hoseini-Yazdi, S. Z. 2012b. Oxidative stability of virgin olive oil as affected by the Bene unsaponifiable matters and Tertiary-Butylhydroquinone. Journal of food Science, 77, 697-702.
Farhoosh, R., & Hoseini-Yazdi, S. Z. 2013a. Shelf- life prediction of olive oils using empirical models developed at low and high temperatures. Food Chemistry, 141, 557-565.
Farhoosh, R., & Hoseini-Yazdi, S. Z. 2013b. Evolution of Oxidative Values during Kinetic Studies on Olive Oil Oxidation in the Rancimat Test. Journal of the American Oil Chemists’ Society.
Firestone, D. 1993. Worldwide Regulation of frying fats and oils. Inform, 4, 1366-1371.
Frankel, E. N. 1998. Lipid oxidation. Dundee: The Oily Press Ltd..
Guillen, M. D., & Cabo, N. (2002). Fourier transform infrared spectra data versus peroxide and anisidine values to determine oxidative stability of edible oils. . Food Chemistry, 77, 503-510.
Kmiecik, D., Korczak, J., Rudzinska, M., Gramza-Michalowska, A., & Hes, M. 2009. Stabilization of phytosterols in rapeseed oil by natural antioxidants during heating. European Journal of Lipid Science and Technology, 111, 1124–1132.
Lacoste, F., & Lagardere, L. 2003. Quality parameters evolution during biodiesel oxidation using Rancimat test. European Journal of Lipid Science and Technology, 105, 149–155.
Machado, E. R., Marmesat, R., Abrantes, S., & Dobarganes, C. 2007. Uncontrolled variables in frying studies: differences in repeatability between thermoxidation and frying experiments. Grasas Y Aceites, 58, 283-288.
Melton, S.L., Jafar, S., Sykes, D., and Trigiano, M.K. 1994. Review of stability measurements for frying oils and fried food flavor. Journal of the American Oil Chemists’ Society, 71, 1301–1308.
Reynhout, G. 1991. The effect of temperature on the induction time of a stabilized oil. Journal of the American Oil Chemists᾿Society, 68, 983-984.
Sa´nchez-Muniz, F. J., Cuesta, C., & Garrido-Polonio, C. 1993. Sunflower Oil Used for Frying: Combination of Column, Gas and High-Performance Size-Exclusion Chromatography for Its Evaluation. Journal of the American Oil Chemists᾿Society, 70, 235-240.
Shantha, N. C., & Decker, E. A. 1994. Rapid, sensitive, iron-based spectrophotometric methods for determination of peroxide values of food lipids. Journal of the AOAC International, 77, 421–424.
Soupas, L., Juntunen, L., Saynajoki, S., Lampi, A., & Piironen, V. 2004. GC–MS method for characterization and quantification of sitostanol oxidation products. Journal of the American Oil Chemists’ Society, 81, 135–141.
Tyagi, V. K., & Vasishtha, A. K. 1996. Changes in the characteristics and composition of oils during deep- fat frying. Journal of the American Oil chemists᾿Society, 73, 499-506.
Tan, C. P., Che Man, Y.B., Selamat, J. b., & Yusoff, M. S. A. 2002. Comparative studies of oxidative stability of edible oils by differential scanning calorimetry and oxidative stability index methods. Food Chemistry, 76, 385–389.
Wong, M. L., Timms, R. E., & Goh, E. M. 1988. Colorimetric determinationof total tocopherols in palm oil, olein and stearin. Journal of the American Oil chemists᾿Society, 65, 258-261.