The effect of simultaneous dehydration-reaction (SDR) on Amadori rearrangement product (ARP) N-(1-deoxy-d-xylulos-1-yl)-glutathione and its key degradation products, 3-deoxyxylosone (3-DX) and 1-deoxyxylosone (1-DX), were investigated in an aqueous glutathione-xylose (GSH-Xyl) system. The yield of ARP was increased to 67.98% by SDR compared with 8.44% by atmospheric thermal reaction at 80 °C. Reaction kinetics was applied to analyze the mechanism and characteristics of ARP formation and degradation under SDR. ARP formation and degradation rate was highly dependent on temperature, and the latter was more sensitive to temperature. By regulating the reaction conditions of temperature and pH, the ratio of ARP formation rate constant to its degradation rate constant could be controlled to achieve an efficient preparation of ARP from GSH-Xyl Maillard reaction through SDR.

Amadori rearrangement product (ARP) derived from glutamic acid (Glu) and xylose (Xyl) was prepared by aqueous Maillard reaction. Subsequently, ion exchange chromatography, MS, and NMR were used for purification and identification, confirming that the molecular formula of ARP was C10H17NO8, namely N‐(1‐deoxy‐α‐D‐xylulos‐1‐yl)‐glutamic acid, with a molecular mass of 279 Da. To improve the aqueous yield of ARP, a thermal reaction coupled with vacuum dehydration was used and the yield of ARP was increased from 2.07% to 75.11%. Furthermore, flavor formation capacity of ARP by a thermal treatment simulated to a baking process was compared with Maillard reaction products, Maillard‐dehydration reaction products, and Glu‐Xyl mixture. The results indicated that a larger amount of volatile flavor compounds and a biscuit‐like, burnt aroma was generated rapidly from the mixture of ARP and unreacted Glu‐Xyl, which could be a potential flavor enhancer for baked foods. Practical Application Maillard reaction performed in aqueous medium through thermal reaction combined with vacuum dehydration is a novel and practical technology that could be widely used to produce Maillard reaction intermediates (MRIs), such as Amadori or Heyns rearrangement products, which are regarded as significant nonvolatile aroma precursors and have stable physical and chemical properties compared with Maillard reaction products (MRPs). MRI derived from glutamic acid and xylose is a potential substitute of MRPs for flavorings preparation and shows a great capacity to generate fresh flavors in a short time at high temperature, which meets the requirements of baking foods. Therefore, the new developed method could be a promising tool for MRI preparation and application in food and flavoring industries.

Maillard reaction intermediate (MGX) generated from glutathione and xylose in aqueous medium was prepared via the Maillard reaction performed under a two-stage temperature increase process. The purified MGX was identified by Fourier-transform infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance as N-(1-deoxyd-xylulos-1-yl)-glutathione (Amadori compound, C 15 H 25 O 10 N 3 S) with five main isomers. The method of Maillard reaction performed under a two-stage temperature increase process was further verified by high-performance liquid chromatography. The optimal reaction time and temperature for the preparation of MGX was determined as 60 min at 90°C. The yield of MGX was increased from 8.60% to 55.52% through thermal reaction coupled with vacuum dehydration. In addition, rapid and more Maillard-type volatile compounds were formed in MGX during thermal treatment than that in Maillard reaction products or glutathione-xylose mixture. Beside, MGX possessed more pleasing meat-like volatile profile compared with the Amadori compound of glutamic acid-xylose (AAX), cysteine-xylose (ACX), and glycinexylose (AGX). Therefore, it suggested that the MGX had the potential to achieve a better flavor formation during thermal treatment.Keywords: a 2-stage temperature increase process, Maillard reaction intermediate, Maillard-type volatile formation, N-(1-deoxy-d-xylulos-1-yl)-glutathione, thermal treatmentPractical Application: Maillard reaction intermediates, such as Amadori or Heyns rearrangement products (ARP or HRP), are important flavor precursors, which possess stable physicochemical properties, but tend to degrade into flavor compounds at high temperatures. Maillard reaction intermediate from glutathione and xylose acts as primary flavor enhancers to complete Maillard reaction to produce flavors in the subsequent thermal processing, which can significantly improve and stabilize the flavor quality of the meaty food, and deserves a very broad application prospects. The new developed method will be a significant theoretical basis on research preparation and properties of Maillard reaction intermediates in complex food systems.