Effects of non-enzymatic browning reactions on lipid oxidation in emulsified model systems

The effect of non-enzymatic browning (NEB) reactions (Maillard reaction, caramelization) on lipid oxidation was studied in emulsified model systems in order to confirm the antioxidative activity of Maillard Reaction Products (MRPs) and to verify the eventual antioxidant properties of the caramelization products (CPs). The model system (E) was broken up into its components in order to form four other systems and to study the different chemical reactions: A) soybean oil (control); B) system A with water and xanthan; C) system B with glucose; D) system B with lysine. The complete model system (E) was made up of oil, water, glucose. Lysine and xanthan. All model systems were treated at 90°C for 120 hours and samples were taken at regular intervals. Peroxide value, paraanisidine number and volatile hydrocarbons were used as lipid oxidation indices; colour and carbon dioxide present in the head space vapour of equilibrated samples were used as indices of NEB reactions. In our experimental conditions lipid oxidation was clearly slowed down by MRPs but not by CPs. However, lysine seemed to have a prooxidant effect, if judged by pentane formation.