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Effects of processing on oxidative stability of sesame oil extracted from intact and dehulled seeds
Author(s) -
AbouGharbia H. A.,
Shahidi F.,
Adel A.,
Shehata Y.,
Youssef M. M.
Publication year - 1997
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-997-0126-9
Subject(s) - roasting , iodine value , chemistry , peroxide value , steaming , acid value , thiobarbituric acid , food science , fatty acid , saponification value , composition (language) , peroxide , nuclear chemistry , antioxidant , organic chemistry , biochemistry , lipid peroxidation , linguistics , philosophy
Oxidative stability of oils extracted from intact and dehulled sesame seeds was determined by monitoring changes in fatty acid composition, iodine value (IV), peroxide value (PV), conjugated diene (CD), para ‐anisidine value ( p ‐AV), and 2‐thiobarbituric acid (TBA) value and by nuclear magnetic resonance spectroscopy after storage under Schaal oven conditions at 65°C for up to 35 d. The oils from coated seeds were more stable, as reflected in PV, CD, p ‐AV and TBA values, than those extracted from dehulled seeds after roasting at 200°C, steaming at 100°C, roasting at 200°C plus steaming, or microwaving at 2450 MHz, except for TBA values of oil from microwaved seeds. After 35 d of storage at 65°C, the CD, p ‐AV, and TBA values of extracted oil from dehulled microwaved seeds were 17.72, 10.20, and 1.22, respectively, while those of their coated counterparts were significantly ( P <0.05) different at 14.20, 16.47, and 1.26, respectively. Few significant changes were evident in the fatty acid composition of oil obtained from either coated and dehulled seeds subjected to different treatments. Nuclear magnetic resonance analyses found that R ao (aliphatic to olefinic protons) and R ad (aliphatic to diallylmethylene protons) ratios increased steadily over the entire storage period, which indicated progressive oxidation of unsaturated fatty acids.