Non-enzymic browning

Summary Tocopherols are easily oxidized by ferric salts and other oxidizing agents present in food products, the major reaction products being toco red and toto spiro dimer and trimer. Toco red reacts either with the e-amino group of lysine bound in protein with formation of insoluble products or may form chloroform-soluble amino derivatives via Strecker degradation. These latter products of purple colour which are chloroform-soluble are easily polymerized, especially at high temperatures or during longer beating times. Brown polymers remain liposoluble at least partially. The dimer is partially decolourized by reaction with protein, probably because it is not able to attack amino acids via Strecker degradation. As the condensation reaction is relatively rapid, quinoid derivatives of tocopherols are probably almost completely transformed into brown nitrogenous condensation products under the conditions of processing and storage of food.