Thermal pyrolysis of two synthesized Amadori derivatives prepared by protecting the active groups

Abstract

Maillard intermediates, especially Amadori compounds, played a crucial role in the formation of flavor or adverse Maillard products, directly influencing the sensorial and organoleptic properties of foodstuff. Here, in order to modulate the degradation products of Amadori compounds, the active hydroxyl and carboxyl groups on the Amadori skeleton were protected, then two new Amadori derivatives based on leucine (Leu-AD) and glutamic acid (Glu-AD) were obtained with relatively high yield. The subsequent TG-DTG and DSC tests showed that both Leu-AD and Glu-AD were stable at room temperature and could be fully degraded at 400 °C. The TG-DTG curve of Glu-AD was more complicated than that of Leu-AD due to the asynchronous degradation of the two carboxyl groups on Glu-AD. Their pyrolytic products also exhibited great difference, specifically, the flavor products released from Leu-AD were mainly pyrroles and Strecker degradation products, while the pyrolytic products of Glu-AD mainly included methyl substituted furans derived from the pyranose ring and esters resulting from the degradation of glutamic acid moiety. Comparatively, the species and relative content of their (Leu-AD and Glu-AD) pyrolytic products were distinct to the reported flavor products generated from the corresponding Amadori compounds and glucose-leucine/glutamic acid mixtures, indicating Amadori derivatives could be an alternative flavor precursors generating Maillard-type aroma.