Determination of the oxidative stability of vegetable oils by Differential Scanning Calorimetry and Rancimat measurements

Abstract

Samples of vegetable oils were oxidized at isothermal conditions in the cell of a Pressure Differential Scanning Calorimeter (PDSC) and in the Methrom Rancimat apparatus. The PDSC and Rancimat experiments were carried out at a temperature in the range of 90-160 7C. From resulting PDSC exotherms their times to reach the peak maximum (t PDSC ) were determined and used for the assessment of the oxidative stability of the samples. Similarly the measured Rancimat induction times (t Rancimat ) were used. As PDSC and Rancimat results were obtained at different temperatures the equations for temperature extrapolations of the t PDSC and t Rancimat values have been proposed. Using the Arrhenius type correlation between induction times and temperature and activated complex theory the reaction rate constants, activation energies, activation enthalpies and activation entropies for oils oxidation have been calculated.

Application of the calorimetric and spectroscopic methods in analytical evaluation of the human milk fat substitutes

“…DSC measurements DSC is one of the fastest and the most convenient methods for the assessment of the oxidative stability of oils and fats. There are reports saying that the DSC data for vegetable oil oxidation correlate well with Rancimat and electron spin resonance (ESR) spectroscopy results [27,[41][42][43][44]. The results of PDSC measurements expressed as the oxidation induction times are shown in Fig.…”

“…For each sample, measurement was triplicate, and the output was automatically recalculated and presented as amount of energy per gram. DSC conditions were determined on the basis of previous research [27].…”

Oxidative stability of camelina (Camelina sativa L.) oil using pressure differential scanning calorimetry and Rancimat method

“…However, along with the increase in measurement temperature, both s max and s on obtained using both methods were getting lower. Kowalski et al [17] presented convergent relationship in studies on refined oils: rapeseed, soy and sunflower; Zaanoun et al [32] studied argan oil as well. As far as authors know, no oxidation stability analysis was presented for camelina oils at various temperatures.…”

“…Metrohm Rancimat (Europe) test and OSI-oxidative stability index (USA)-are commonly applied for analysis of edible oils [16,17], however, they cannot always be successfully used to analyze cold-pressed oils, despite being useful in assessing refined oils. Studies on oil oxidation using the DSC technique, under both isothermal (constant operating temperature) and dynamic conditions (linear temperature growth), have been carried out so far [17][18][19][20]. Nevertheless, studies were mostly conducted on refined oils [17,20,21].…”

“…Studies on oil oxidation using the DSC technique, under both isothermal (constant operating temperature) and dynamic conditions (linear temperature growth), have been carried out so far [17][18][19][20]. Nevertheless, studies were mostly conducted on refined oils [17,20,21]. Parameters of coldpressed oils-relatively high non-glycerol content, very high influence of the raw material on final product quality and pressing parameters on the oil content-make the selection of the appropriate method and conditions of the analysis arduous and difficult.…”