Synthesis, Characterization And Properties Of Maillard Reaction Products And Their Metal Complexes

Maillard reaction products composition was extremely complex, which had a large effecton sensory evaluation or food safety. Maillard reaction had a prominent position in foodprocessing technologies and food preservation. The research on Maillard reaction productswith metal ions coordination characteristics was of great significance for the extendingapplication of Maillard products derivatives.In this paper, Maillard reaction intermediate products, including fructose-glycine andmatol, end product melanoidin and their metal ions coordination characteristics were studied.The main contents and results were as follows:As a key intermediate in the early stages of the model for the glucose/glycine Maillardreaction, fructose-glycine, named N-（1-deoxy-D-fructos-1-yl）-glycine（DFG） was synthesizedand further purified. Thin layer chromatography, ion chromatography, mass spectrometry and13C nuclear magnetic resonance were used to analyze and verify the target product. Theresults indicated that C8H15NO7was DFG’s molecular formula with relative molecular massof237. DFG’s protonation constants and metal-complex stability constants with Cu²⁺, Ni2+ions were determined by pH potentiometric titration. The DFG coordination stabilityconstants with Cu²⁺were lgK1=7.24±0.09, lg K2=6.57±0.05，lg K3=3.31±0.02, respectivelywhich were higher than that of Ni2+（lg K1=5.73±0.03，lg K2=4.69±0.02，lg K3=3.59±0.05，lg K4=3.21±0.02） correspondingly.In order to inspect the influence of Maillard reaction product melanoidinon iron-bindingability, ferric ion concentration, pH value, incubation time and PEF treatment wereinvestigated with the single factor variable method. The research result showed thatiron-binding ability decreased with the increase of the concentration of ferric ion; pH valueand PEF treatment had a remarkable effect on the iron-binding ability of melanoidins;iron-binding ability increased with the incubation time extension.Maltolato-zinc （II）, copper （II）, nickel （II） and iron （III） complexes were synthesizedusing the hydrothermal method. Their crystalline colors varied in a large degree. Theinfluence of process parameter pH value on the reaction system of maltol and zinc （II） ionwas discussed. Meanwhile, the produc with a high quality was obtained by optimizing the synthetic conditions.UV-Vis scanning spectra, IRspectra, X-ray single crystal diffraction and X-ray powderdiffraction were used to identify the structures of four maltol complexes. It was confirmedthat ligand and metal ions formed new metal complexes during the process. A further analysison single crystal diffraction showed that maltolato-zinc crystal belonged to orthorhombicsystem, specifically in space group Pbcn with unit cell parametersa=16.127（3）,b=13.1154（3）, c=13.3847（3）, α=90.00°, β=90.00°,=90.00°, and the number ofmolecules was in the unit cell4. The conjectural chemical formula was C24H30O17Zn2.Meanwhile, the five-and six-ligand zinc complexes were also found in the cell structure,connected with the hydrogen bond.The antibacterial activity of maltolato-iron （III） complex against E. coli, B. subtilis, S.aureus and M. luteus in vitro was investigated by the agar diffusion method and the opticaldensity method. The antibiotic capability of complex was M. luteus＞E. coli＞B. subtilis＞S.aureus.