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

The thermal degradation of ß-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 k90 °C = (2.0 ± 0.3) × 10-3 to k130 °C = (11.0 ± 0.7) × 10-3 min-1, the experimental activation energy having been calculated as (52 ± 1) kJ mol-1. This Ea value is close to the DFT energies corresponding to a C15-15' or a C13-14 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 C15-15'- cis rupture as the predominant reaction pathway and retinal as the major degradation product.

Resveratrol treatment controls microbial flora, prolongs shelf life, and preserves nutritional quality of fruit.

Resveratrol is known as a grapevine secondary metabolite with fungicide activity. Its exogenous application on harvested grapes resulted in the reduction of microbial flora growth, and consequently, prolonged shelf life, without affecting the nutritional quality of the fruit. Resveratrol treatment also resulted in being effective on fruit that normally does not accumulate such metabolites as, for example, tomatoes, apples, avocado pears, and peppers. As a result, all treated fruits maintained their post-harvest quality and health longer than the untreated ones. This study demonstrates the potential use of resveratrol as a natural pesticide to reduce post-harvest fungi development on a broad spectrum of fruit types.