Determination of the oxidative stability of hazelnut oils by PDSC and Rancimat methods

Abstract

The present study was conducted to determine the oxidative stability of hazelnut oil and compare it with more common and previously tested olive oil and rapeseed oil. The oxidative stability was determined by means of two independent methods, pressure differential scanning calorimetry (PDSC), and oxidative stability index (OSI) using TA Instruments DSC and Metrohm Rancimat equipment, respectively. Both the PDSC and Rancimat devices were set at five different isothermal temperatures in the range of 100-140°C. The times to reach peak maximum (s max ) obtained from PDSC exotherms were statistically related with the Rancimat induction times (s on ) to obtain correlation coefficient [0.99 within linear relation. Based on the Arrhenius equation and activated complex theory, activation energies (E a ), pre-exponential factors (Z), and specific rate constants (k) for studied oils oxidations were calculated. To the best of our knowledge, this is the first study dealing with oxidative stability of hazelnut oil using PDSC technique. According to the results obtained, PDSC seems to be useful and quick method for kinetic analysis of lipid oxidation in hazelnut oil.

Assessment of the Hazelnuts Roasting Process by Pressure Differential Scanning Calorimetry and MID-FT-IR Spectroscopy

“…The oxidative stability of the tested oils were determined using differential scanning calorimeter (DSC Q20, TA Instruments) coupled with a high-pressure cell (Q20P) as reported previously by Ciemniewska-Żytkiewicz et al (2014b). The isothermal temperature for each sample was programmed at temperature 140°C.…”

“…As reported previously (Ciemniewska-Żytkiewicz et al 2014b), statistically significant linear correlations between PDSC maximum induction time (τ max ) and the Rancimat values imply that PDSC can be recommended as an appropriate unbiased method for assessing the oxidative stability of hazelnut oils. According to Ciemniewska-Żytkiewicz et al 2014b, the Pearson correlation (R >0.99) (Eq. 1) enabled the authors to express, herein, the obtained results of oxidative stability through Rancimat induction time, as well ( Table 2.).…”

“…The autooxidation rates of oleic, linoleic, and linolenic fatty acids relate to degree of unsaturation and are 1:40:100, respectively (Frankel 1985;Arranz et al 2008;Ciemniewska-Żytkiewicz et al 2014b). Because of that, the C18:2 ω6 and C18:3 ω3 fatty acids should be more susceptible to the roasting process, especially in higher temperatures.…”

“…DSC technique coupled with a pressure cell (PDSC-pressure differential scanning calorimetry) have the potential to be used as an accelerated thermal method to determine oil quality. It has previously been successfully used for hazelnut oil quality assessment (Ciemniewska-Żytkiewicz et al 2014b).…”

Impact of Selected Chemical Characteristics of Cold-Pressed Oils on their Oxidative Stability Determined Using the Rancimat and Pressure Differential Scanning Calorimetry Method

“…The difference in generated heat is recorded over time as a graph from which can be the determined onset time (τ on ) and the maximum of oxidation time (τ max ). Both parameters are used to characterise oil oxidation process, but they correspond with different stages of oxidation (Ciemniewska-Żytkiewicz et al 2014;Kowalski et al 2004).…”