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    Bioactive lipids, antiradical activity and stability of rosehip seed oil under thermal and photo-induced oxidation
    (Consejo Superior Investigaciones Cientificas-Csic, 2018) Turan, Semra; Solak, Rukiye; Kıralan, Mustafa; Ramadan, M. F.
    In the present report, the fatty acids, tocopherols, and sterol profiles as well as the total phenolics and carotenoids of rosehip (Rosa canina) seed oil were determined. The major fatty acids in the oil were linoleic and linolenic acids, comprising 54.80% and 23.47% of the total fatty acids, respectively. Other bioactive lipids in the oil included total tocopherols (786.3 mg/kg), total phenolics (37.97 mg/kg) and total carotenoids (218.8 mg/kg). Rosehip oil was rich in gamma-tocopherol (472.0 mg/kg) and beta-sitosterol (78.0% of total sterols). The DPPH center dot (2,2'-diphenyl-1-picrylhydrazyl) radical scavenging activity of the oil showed 1.08 mg alpha-tocopherol/g oil and 4.18 mu mol TEAL (Trolox equivalent antioxidant capacity)/g oil, respectively. The ABTS(+) (2,2'-Azino-bis-3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activity of the oil showed 1.00 mg alpha-tocopherol/g oil and 3.02 mu mol TEAC/g oil, respectively. The induction period (IP) of the oil was 3.46 h for the Rancimat test (110 degrees C), while the IP of oil in differential scanning calorimetry (DSC) test (100-150 degrees C) ranged between 0.26 and 58.06 min. The oxidative stability of the oil was determined under thermal and photo oxidation conditions. The progression of oxidation at 30 degrees C (under UV light) and at 60 degrees C (in the dark) was followed by recording the ultraviolet absorption (K-232 and K-270) and degradation of total tocopherols, gamma-tocopherol and total carotenoids. Rapid deterioration occurred in the oil stored under UV light conditions. The information provided in the present work is of importance for using rosehip seed oil in different food and non-food applications.
  • Küçük Resim
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    Stability and volatile oxidation compounds of grape seed, flax seed and black cumin seed cold-pressed oils as affected by thermal oxidation
    (Consejo Superior Investigaciones Cientificas-Csic, 2019) Kıralan, Mustafa; Çalık, Gürkan; Kıralan, Sündüz; Özaydın, Ayşegül; Özkan, Gülcan; Ramadan, M. F.
    The old-pressed oils (CPO) from gape seeds (GSO), flax seeds (FSO) and black cumin seeds (BSO) were analyzed for their fatty acid profiles, tocopherols, total phenolics, bioactives and phenolic compositions. The stability of CPO under thermal oxidation conditions was evaluated. The main fatty acid in FSO was linolenic acid (56.5% of total fatty acids); while GSO and BSO were rich in linoleic acid, which accounted for 66.8 and 56.8%, respectively. GSO was rich in alpha-tocopherol (123.0 mg/kg), while gamma-tocopherol was a prevalent isomer in FSO and BSO (137.9 and 128.9 mg/kg, respectively). The total phenolic contents in the oils ranged from 554 mg GAE/kg oil (FSO) to 1140 mg GAE/kg oil (BSO). Luteolin, dihydroquercetin and benzoic acids were the dominant bioactives and phenolics in FSO, GSO and BSO, respectively. Based on the oxidative stability index (OSI) value, BSO showed the highest value (6.14 h) among the other oils. The oxidative stability of FSO and BSO were higher than GSO according to peroxide value (PV) and conjugated diene (CD) values of the oils during storage at 60 degrees C. Hexanal, 2,4-heptadienal and (E,E)-2,4-heptadienal were the major volatile oxidation compounds (VOC) in FSO. Hexanal and (E)-2-heptanal were the main identified VOC in the GSO and BSO under the same oxidation conditions.