Kinetic and Molecular Modeling of Selected Bio-hazardous By-products from High Temperature Cooking of Goat Meat

Abstract

The environmental fate of thermally released organic toxins including radical formation from high temperature cooking has received mounting global concern due to the potential health impacts associated with them. Therefore, this contribution investigates the thermal degradation kinetics of pyrolysis products of red meat under conditions representative of high temperature cooking. Evolution of selected molecular toxins was monitored using an in-line Gas Chromatography hyphenated to a mass spectrometer (GC-MS) in the temperature range 500–525°C. The primary focus is to propose a kinetic model for the thermal destruction of bio-hazardous byproducts; 2-(ethylthio)phenol, indole and 2, 3-dimethylhydroquinone within a temperature region 723 and 798 K using pseudo-first order rate law. A reaction time of 2.0 s was employed in line with the average residence time in combustion systems. Nonetheless, for the formation kinetics of 2-(ethylthio)phenol), various cooking times were chosen. Kinetic results showed that the destruction rate constants for indole, 2, 3-dimethylhydroquinone, and 2-(ethylthio)phenol at 798 K were 1.19, 1.42, and 1.35 s−1 respectively. GC-MS results revealed the amount of 2-(ethylthio)phenol evolved decreased with increase in the cooking time. The scission of the phenyl-sulphur linkage in 2-(ethylthio)phenol was determined using the density functional theory (DFT) and found to proceed with an energy barrier of 319.31 kJmol−1. The band-gap energy for 2-(ethylthio)phenol was calculated using Chemissian and found to be 5.298 eV. The kinetic behavior of combustion by-products from red meat is important in understanding the formation of environmentally toxic free radicals from high temperature cooking considered harmful to human health and natural ecosystems.