Computational Modelling of FTIR
Spectra
The Gaussian 16 software (Frisch et al. , 2016) was used for all
computational modelling and calculations. Oleic acid, palmitic acid, and
lauric acids were used as the fatty acids present in TOs required to
simulate the photooxidation of TOs (Cheng et al., 2018). The initial
geometries of the fatty acids were optimised, and the vibrational
frequencies were obtained. The geometry optimisation and vibrational
frequency calculations were performed with the density functional theory
(DFT) in the gas phase (Pereira et al. , 2017). The basis set used
was Becke’s three parameters, and the Lee-Yang-Parr nonlocal correlation
functional (B3LYP) at the 6-311++G (d, p) basis set. The final
geometries of the fatty acids after the vibrational frequencies were
visualised with GaussView (version 6.0.16) (Dennington, Keith and
Millam, 2016). A scaling procedure (Palafox, 2019) was implemented to
improve the wavenumbers and transmittance of the simulated spectra to
match those of the experimental data.
Statistical
Analysis
All data were obtained from at least three measurements, and each
replicate was reported as the mean standard\(\pm\) deviation. OriginPro
(version 2020, Northampton, MA, USA) and SPSS (IBM Corp., 2020, version
27, Armonk, N.Y., USA) were used for the one-way analysis of variance
(ANOVA). The significant difference was evaluated by the P-values
(P < 0.05).