Free fatty acid (FFA) is one of the most critical parameters for evaluating the quality of olive oil. In this paper, we present a simple and rapid Raman spectroscopy method for analyzing free fatty acid in olive oil. First, FFA degradation of carotenoids in olive oil is confirmed by analyzing the relative intensity of characteristic vibrational modes and introducing an intensity decrease factor. Second, it is demonstrated that the relative intensity ratio of the two characteristic vibrational modes at 1525 cm-1 and 1655 cm-1 presents a good and rapid analysis of FFA content in olive oil; the relative intensity ratio decreases linearly with FFA content. In addition, resonance Raman scattering of carotenoid is discussed, showing that a green laser should be utilized to study FFA in olive oil.
Bibliographical noteFunding Information:
This research was funded by the National Natural Science Foundation of China (Grant No. 11574241) and the National Research Foundation of Korea (NRF) grant funded by the Korean Ministry of Science and ICT (No. 2017R1A2B2009309).
© 2019 by the authors.
- Free fatty acid
- Olive oil
- Raman spectroscopy
- Relative intensity analysis
- Resonance Raman