FTIR Spectroscopy and DFT Calculations to Probe the Kinetics of β-Carotene Thermal Degradation

Abstract

The thermal degradation of β-carotene in air was investigated. The sample was heated at different temperatures (90, 100, 115, and 130 °C) for periods of up to 8 h to perform a complete kinetic study, the product analysis having been carried out via infrared spectroscopy in attenuated total reflectance mode coupled to density functional theory (DFT) calculations. The kinetics of this thermal degradation process was found to follow a first-order scheme, with rate coefficients varying from k 90 °C = (2.0 ± 0.3) × 10 −3 to k 130 °C = (11.0 ± 0.7) × 10 −3 min −1 , the experimental activation energy having been calculated as (52 ± 1) kJ mol −1 . This E a value is close to the DFT energies corresponding to a C 15−15′ or a C 13−14 cis−trans isomerization, followed by the formation of a carotene−oxygen diradical, which was characterized for the first time. Comparison between the experimental and calculated infrared data confirmed the C 15−15′ -cis rupture as the predominant reaction pathway and retinal as the major degradation product.

Shedding light into the health‐beneficial properties of Corema album—A vibrational spectroscopy study

“…Under these conditions, the wavenumber accuracy was better than 1 cm -1 . The spectra were corrected for the frequency dependence of the penetration depth of the electric field in ATR (considering a mean reflection index of 1.0, as previously used for other phytochemical using the Opus 7.2 spectroscopy software) …”

A light‐mediated study of carotenoids in carrots (Daucus carota) using resonance Raman spectroscopy

“…Carrot root consists of very complex carotenogenesis; various carotenes and xanthophylls are synthesized and deposited there. [ 1 ] Carotenoid is one of the most useful and widespread biomarkers in all the species, which are resistant to breakdown, [ 2 ] with no inorganic source yet known. [ 3 ] Recently various methods have been applied and studied for the separation of carotenoids and their isomers by liquid mass spectrometry to trace the pathway of carotenoids.…”

Novel Insights into Corema album Berries: Vibrational Profile and Biological Activity

“…A Ge on KBr substrate beamsplitter with a liquid nitrogen-cooled wide band mercury cadmium telluride detector was used. The spectra were corrected for the frequency dependence of the penetration depth of the electric field in ATR (considering a mean reflection index of 1.0, as previously used for other phytochemicals using the Opus 7.2 spectroscopy software) [13,53,83] and the three-term Blackman-Harris apodization function was applied. Each spectrum presented corresponded to the average of two measurements of 128 scans each, at a resolution of 2 cm −1 .…”