Nondestructive measurement of squalene in olive oil by near infrared spectroscopy

- Near infrared spectroscopy is suitable for sorting olive oils by squalene content.
- Models can be built to roughly estimate squalene contents in olive oils.
- The contribution to the model of the 1700-1850 nm spectral range is remarkable.

This study sets the basis for developing a rapid technique for measuring olive oil squalene, which is a healthy compound. This technique, based on near infrared spectroscopy, is environmentally friendly. The most suitable wavelength ranges were defined, studying the possible contribution from the visible spectra. For this purpose, Partial Least Squares analysis was independently set up using two optical arrangements, with wavelengths 350-2500 nm and 1100-2300 nm. Models from only near infrared wavelengths gave the best outcomes. The external validation exercise for estimating olive oil squalene was satisfactory, with r2 0.83 and residual predictive deviation 2.31. The results suggest the proposed technique is useful for estimating olive oil squalene content. A sorting test of olive oil in two classes according to its squalene content was carried out, with threshold in 5.0 g.kg−1, using the model built. The success of this classification was 90%.