The Maillard reaction under a stepwise increase of temperature using l-cysteine as the indicator was performed to determine the formation conditions for the preparation of 2-threityl-thiazolidine-4-carboxylic acid (TTCA) which was the main Maillard reaction intermediate (MRI) derived from the xylose (Xyl)-cysteine (Cys) model system in aqueous medium. To clarify the indicating mechanism of Cys for the TTCA formation, the thermal model systems of TTCA-Cys and TTCA solutions were investigated. The browning of the final Maillard reaction products (MRPs) and concentration of downstream degradation products of MRIs indicated that the added Cys could react with TTCA to inhibit the formation of visible color via preventing the generation of dicarbonyl compounds derived from MRIs. Through HPLC analysis, it was demonstrated that added Cys affected the normal reaction pathway from TTCA to ARP and other downstream products by restoring TTCA to sugar and amino acid under heat treatment.
Keywords: HPLC; Maillard reaction intermediate; TTCA; cysteine; indicator.