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Thermal and oxidative stability assessment of synergistic blends of sunflower and sesame oils tailored for nutritionally stable composition of omega fatty acids

journal contribution
posted on 2019-02-28, 00:00 authored by M Ghosh, R Upadhyay, Dipendra Mahato, H N Mishra
The thermal stability of ω-6 fatty acid-rich oils is a bewildering problem. The synergistic blends of sunflower (SO) (50–80%) and sesame oil (SEO) (20–50%) were optimized for improved thermal stability, better retention of antioxidants, and balanced ratio of ω-fatty acids (ω-6 and 9). The oil blends were thermally oxidized by Rancimat (temperature 100, 110, 120, and 130 °C; airflow rate 20 L h −1 ) for estimating the induction period (IP) and kinetic rate constant (k) of lipid oxidation. The oils were exhaustively characterized for thermal stability by thermogravimetry and differential scanning calorimetry. The temperature-dependent kinetics of lipid oxidation was described using Arrhenius equation (lnk vs. 1/T) and activated complex theory (lnk/T vs. 1/T). The calculated kinetic parameters, viz. activation energies, activation enthalpies, and entropies varied from 90.80 to 99.17, 87.58 to 95.94, − 33.28 to − 4.78 J mol −1  K −1 , respectively (R 2 > 0.90, p < 0.05). The optimized blend (OB) consisted of 50.8 and 49.2% of SO and SEO, respectively, and showed the highest synergism (115%) and IP (100 °C) than SO (13.2 vs. 6.1 h). This could be attributed to lignans (6304 vs. 5289 mg kg −1 )-induced thermal stability and effective retention of tocopherols (270 vs. 197 mg kg −1 ). OB possesses balanced composition of ω-fatty acids (ω-9, 34.5 vs. 28.7%; ω-6, 49 vs. 52%) and superior thermal stability (onset temperature, 387 vs. 212 °C; oil induction time, 21.6 vs. 15.7 min) than SO. It could be recommended over SO for culinary applications while ensuing thermal stability and nutritional benefits.

History

Journal

Journal of Thermal Analysis and Calorimetry

Volume

135

Issue

4

Pagination

2389 - 2398

ISSN

1388-6150

eISSN

1588-2926

Publication classification

C1 Refereed article in a scholarly journal