Quantitative detection of melanoidins formed from d-fructose and l-alanine based on three-dimensional...

There is no clear conclusion for the quantitative detection of melanoidins. The present study aimed to characterize the melanoidins formed from d-fructose and l-alanine at different treatments (hydrothermal and dry-heating treatment) using the three-dimensional excitation-emission matrix (3-DEEM) and high-performance liquid chromatography (HPLC).

The Maillard reaction products gradually increased and the content of melanoidins (A420 nm) gradually increased with the prolongation of reaction time. The 3-DEEM spectrum and fluorescence area integration revealed the change of fluorescence products, with the melanoidins mainly concentrating in the region V (humic acid-like organics). In addition, the HPLC system equipped with a fluorescence detector also effectively separated melanoidins from Maillard reaction products. Fourier transform infrared spectroscopy results showed that the polymerization of melanoidins is related to aldol condensation accompanied by a decrease of CO and OH, as well as an increase of CO. The aromatic ring and conjugated double bond in the melanoidins structure enhanced the fluorescence intensity. The linearity of melanoidins was confirmed over the range 0.01-10 mg mL^-1, and fluorescence quenching occured when the concentration was greater than 10 mg mL^-1.

The 3-DEEM combined with HPLC effectively characterized melanoidins, and the melanoidin concentrations showed a linear relationship in the range 0.01-10 mg mL^-1. This study provides a new idea for the determination of melanoidins content in a complex food matrix. © 2025 Society of Chemical Industry.