Synthesis and Thermal Degradation Products of Two Amadori Derivatives

Two Amadori derivatives,PDFD(di-O-isopropylidene-2,3:4,5-β-D-fructopyranosyl phenylalanine ester)and TDFD(di-O-isopropylidene-2,3:4,5-β-D-fructopyranosyl tyrosine ester),were synthesized based on D-fructose,L-phenylalanine and L-tyrosine,whose structures were characterized by ¹H NMR,¹³C NMR and HRMS. TG-DTG,DSC and Py-GC/MS were conducted to investigate the thermal decomposition properties and the degradation products for PDFD and TDFD. The results showed that T_p of PDFD and TDFD with the largest mass loss rate were 273.3 and 340.5℃,respectively. Both derivatives could release aromatic compounds such as 2-butanone,benzaldehyde,2-acetylfuran and furfural. The degradation of TDFD needed higher temperature to provide phenolic compounds. The discussion of thermal degradation mechanisms for PDFD and TDFD showed that the protection of hydroxyl groups on the sugar ring could inhibit the degradation of glucopyranose moieties while the degradation of amino acids was not affected. This research provides a new kind of potential flavor precursors and offers a new strategy to control the degradation processes of Amadori compounds.