Simplified Kinetics and Colour Formation in Sucrose Solutions Based on A-Dicarbonyl Compounds

Abstract

Colour formation in technical and model sucrose solutions was investigated resulting in a novel kinetic approach of MAILLARD reaction during thermal processing of sugar solutions. Presented results describe new aspects of the non-enzymatic browning reaction (MAILLARD reaction). Two temperature depending pathways of colour formation were found. Both reaction mechanisms are based on the formation of a-dicarbonyl compounds, the key intermediates of colour formation.Discussing temperature dependence of colour formation, a change on MAILLARD reaction mechanism takes place at 100.4 °C. Above this temperature the colour formation is strongly accelerated. Activation energy of the non-enzymatic browning energy for temperatures from 65 ° to 100.4 °C amounts 77 kJ/mol. In this temperature range, D-glucosone is the most important a-dicarbonyl compound for studied reaction systems. Above 100.4 °C, activation energy is equal to 112 kJ/mol and 3-deoxyosone is the dominant colour formation intermediate. Achieved results bridge the gap between the termination step of a MAILLARD reaction –i.e. of colour formation (represented by its activation energy) and intermediates formation (reaction kinetics). In particular, a change of colour formation mechanism with reaction temperature was confirmed by specific formation of two a-dicarbonyl compounds, responsible for MAILLARD reaction in technical sugar solutions.