Date

2014-05-23

Author

Kilercioğlu, Mete
Özel, Barış
Mert, Behiç
Öztop, Halil Mecit

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Olive is the fruit of a tree that grows in Mediterranean climate. Olive grows in the regions of Turkey where Mediterranean climate is dominant. Olive being an important export product for Turkey, the quality of the olive and the products derived from olive has gained significant importance. In this study, Nuclear Magnetic Resonance Relaxometry and Magnetic Resonance Imaging experiments was used to characterize different oil varieties in terms of tissue structure, fat and water contents. Experiments were performed on a low resolution (13.52MHz) and on a high resolution system (123.5MHz, SIEMENS Scanner). With the low resolution system Saturation Recovery, CPMG and FID_Spin Echo sequences were used to determine T1, T2 times and water/fat contents respectively. With the high resolution system Multi Slice Multi Echo (MSME), Turbo Spin Echo (TSE) and Gradient Recalled Echo (GRE) sequences were used. T2 times were also calculated from MSME images spatially and GRE sequence which was taken at two different flip angles was used for spatial T1 determination. With the auto set parameters at TSE sequence water and fat suppressed images were taken to compare the different olive varieties. Moisture analysis experiments were conducted in a 105oC oven and oil content values were obtained through Soxhlet extraction. Four different olive varieties were used in this study: (black light, black mega, black sele and green Ayvalik). T1 values were detected between 88 and 173ms at the low resolution system. The highest T1 value was found for green Ayvalık whereas the lowest value belonged to black light olive (due to low fat content). In order to determine T2 spectra, the exponential curves obtained by CPMG experiments were analyzed by Inverse Laplace method. Water and oil are the sources of the protons in olive samples. Different proton pools are observed as different peaks in the olive spectrum. The relaxation spectra of three olive samples showed two peaks whereas green Ayvalık showed three peaks. First peak values of black light, black mega and black sele were detected between 5.1-6.2ms. Second peak values were between 35-57ms. The area of peaks were found for first and second peaks as %10.21-%21.64 and %68-%80 respectively. The T2 value of second peak of black sele olive and the peak area of black sele were observed as the lowest values. In green Ayvalık, in addition to these two peaks, a third peak was observed. NMR Relaxometry experiments has showed that olives can have characteristic T1 and T2 values. FID_Spin echo experiments were performed after decreasing the moisture content of olives below 15%. Calibration curves were obtained through emulsions prepared by olive and water. Fat and water suppressed images obtained from the high resolution system were consistent with the analytically determined fat/water contents. TSE images were also used to calculate seed/tissue ratio for each variety. In this study NMR and MRI have been used to characteristic olive varieties. The information obtained from this study could be further used as markers for certain chemical parameters of the olives.

URI

https://hdl.handle.net/11511/70872

Collections

Department of Food Engineering, Conference / Seminar