Chemiluminescence of cereal products. I. Kinetics, activation energy and effects of solvents.
Addition of water to cereal grains and food products such as flour, bread and crackers stimulates ultraweak chemiluminescence, the intensity of which depends upon cereal species, its origin and history, grinding, time after grinding, initial moisture content, solvent, temperature and additives. Pure carbohydrates (e.g. dextran) display much weaker and shorter chemiluminescence. A low activation energy (25 kJ/mol) in the temperature range of 20-40 degrees C, Van't Hoff coefficient of 1.4 and the diminution of chemiluminescence output in ethanol and acetone vs. water suggest that weak molecular interactions, e.g. hydrogen bond scission or formation, determine the rate-limiting steps of chemi-excitation. The emission decay kinetics fit a hyperbolic function rather than an exponential one, thus suggesting a contribution of the recombination-luminescence of ions and free radicals to the mechanism. The results appear to demonstrate a significant role of weak interactions of the water-carbohydrates systems in processes leading to electronic excitation and chemiluminescence.
Sławinska
D
D
Department of Physics, Agricultural University Poznań, Poland.
Sławinski
J
J
D001939:Bread; D002151:Calorimetry; D002523:Edible Grain / Q000737:chemistry*; D005433:Flour; D005502:Food; D005504:Food Analysis; D007700:Kinetics; D008163:Luminescent Measurements; D012997:Solvents; D013816:Thermodynamics; D014867:Water
D012997:Solvents; D014867:Water