BACKGROUND: Recently, methods have been developed for the better quality control, fraud detection and analytical investigation of olive oil. Magnetic graphene oxide (GO) material is known for its reusability, high adsorption capability and stability in food sample preparation. Monopalmitine or 2-glycerol monopalmitate (2-GMP) is one of the main parameters in the quality assay and classification of olive oil, which can be classified as extra virgin ≤ 0.9% and olive pomace ≤ 1.2. Hence, newly synthesized magnetic GO (MGO) and commercial silica-gel were used as a dispersive solid-phase clean-up (d-SPE) sorbent to determine 2-GMP value in olive oil samples prior to gas chromatography (GC) analysis. The d-SPE method is validated with olive oil certified reference material (CRM) with respect to silica-gel and a MGO nanocomposite. RESULTS:The developed d-SPE method was applied for various virgin, refined and pomace olive oil samples to determine the value of 2-GMP%. The presence of 2-GMP in the samples was confirmed by GC-mass spectrometry analysis based on silylation derivatives of the analyte. Finally, the d-SPE-MGO method was determined 2-GMP% as 1.9% for pomace olive oil, 0.6% for refined olive oil, 0.4% for virgin olive oil and 3.1% for CRM. The MGO provided satisfactory clean-up recovery (124%) in the acceptable data range for CRM2018, and silica-gel also provided satisfactory recovery (83%) for CRM2018. The proposed method performed with higher sensitivity and efficiency for screening 2-GMP% in olive oil. CONCLUSION:The MGO based d-SPE method was applied for clean-up purposes to determine 2-GMP%. It proved superior via its advantageous features of super quickness, easy isolation with an external magnet and the highly efficient exclusion of all the coexisting interfering peaks conventionally generated with a standard silica-gel material. These methods based on MGO and silica-gel are reflected in the dispersive mode of extraction and can be used as alternatives to conventional methods. Considering the benefits of the consumption of significantly fewer sorbents and less time required regarding the dispersive methods, the methods can be utilized as alternatives in contrast to conventional techniques.

In this study, physicochemical and quality properties, fatty acid composition, and triglyceride composition of Iranian Kurdish butter oil (IKBO) obtained from yogurt drink (doogh) butter were investigated. Local doogh butter, prepared from cow's (CIKBO) and ewe's milk (EIKBO), was utilized as the raw material for this purpose. The free fatty acids (FFA) and peroxide values of IKBOs of the cow (CIKBO) and ewe (EIKBO) were obtained at 0.41 ± 0.01 and 0.39 ± 0.01 (g Oleic acid 100/g oil), and 1.32 ± 0.00 and 1.35 ± 0.00 (meq O 2 kg/oil), respectively. The amounts of saturated fatty acids (SFAs): 70.27 ± 0.62 and 72.13 ± 0.84 (g/100 g), monounsaturated fatty acids (MUFAs): 19.37 ± 0.74 and 20.56 ± 0.97 (g/100 g), and polyunsaturated fatty acids (PUFAs): 1.22 ± 0.12 and 2.75 ± 0.38 (g/100 g) were obtained in CIKBO and EIKBO, respectively. The significant majority of the fatty acids (FAs) in the examined CIKBO and EIKBO were myristic (CIKBO: 13.76 ± 0.02 (g/100 g) and EIKBO: 14.83 ± 0.07 (g/100 g)), palmitic (CIKBO: 33.14 ± 0.28 (g 100/g) and EIKBO: 31.86 ± 0.02 (g/100 g)), stearic (CIKBO: 8.27 ± 0.06 (g/100 g) and EIKBO: 7.95 ± 0.06 (g/100 g)), capric (CIKBO: 4.83 ± 0.03 (g/100 g) and EIKBO: 6.75 ± 0.01 (g/100 g)), and oleic acids (CIKBO: 15.37 ± 0.12 (g/100 g) and EIKBO: 17.83 ± 0.02 (g/100 g)). The average of conjugated linoleic acid (CLA) content in EIKBO (2.20 ± 0.22 (g/100 g)) was higher than that in CIKBO (0.92 ± 0.25 (g/100 g)) ( p < .05). Therefore, EKIBO is considered the superior natural supply of CLA.