Accelerated Dissipation of Free and Immobilized Water Facilitating the Intramolecular Dehydration of N-Xylosamine and Conversion Improvement of the Amadori Rearrangement Product of Aspartic Acid–Xylose Reaction

Abstract

Compared to the method of aqueous Maillard reaction at atmospheric pressure tandem vacuum concentration, a coupling dehydration method combining spray drying and vacuum drying was used to increase aspartic acid−xylose conversion to the Amadori rearrangement product (ARP). The water activity and moisture states were found as effective indicators to characterize the degree of dehydration of Maillard reaction intermediates and efficient formation of ARP. During the vacuum drying process, the water activity of the product powder decreased significantly. Because the formation of ARP was accompanied by intramolecular dehydration, combining spray drying and vacuum drying increased the proportion of bound water in the vacuum-dried product. Free water was easily dissipated via dehydration, which then converted the immobilized water continuously to free water, and the decreased immobilized water further converted the bound water to immobilized water. The reduction in bound water contributed to the intramolecular dehydration of N-substituted D-xylosamine, which would further be transformed to be the ARP through an intramolecular rearrangement. The yield of ARP was increased from 1.68 to 21.53% after spray drying. The ARP yield was substantially increased up to 77.9% by subsequent vacuum drying.

Formation of Amadori compounds in LIGAO (concentrated pear juice) processing and the effects of Fru-Asp on cough relief and lung moisturization in mice

“…† The nuclear magnetic 13 C spectrum could divide the peaks into 10 groups (corresponding to 10 carbons). The presence of the chemical shifts of 174.3 and 171.7 ppm in the 13 C spectrum could prove the presence of -COOH, which was consistent with the findings of Zhang et al 12 According to Kaufmann et al, 26 there were different conformations of…”

“…Food & Function Amadori ketones in the aqueous phase such as ring-forming and ring-opening ketones in dynamic equilibrium. The chemical shift of 53.0 ppm in 13 C NMR indicated the ring closure of Fru-Asp, 12 instead of the chained keto form. As Hansen et al 10 reported, only one major anomer was observed in the spectra of Fru-Asp consistent with the preference of molecules of this sort for the β-pyranose form.…”

“…The TTC (2,3,5-triphenyl tetrazolium chloride) positive reaction fraction was collected. 12 Liquid chromatography with evaporative light scattering detection (HPLC/ELSD) was used to further separate Fru-Asp and Asp. The purified sample was collected and evaporated by vacuum freeze drying to remove excess ammonia.…”

Temperature-Dependent Catalysis of Glycylglycine on Its Amadori Compound Degradation to Deoxyosone

“…3 During the thermal treatment, nucleophilic addition of the amino group on peptides or amino acids to the carbonyl group on sugars readily occurs, followed by dehydration to form a Schiff base. 4 The subsequent Amadori or Heyns rearrangement of the Schiff base lowers the energy of the molecule and results in a relatively stable deoxyaminoketose or deoxyaminoaldose existing either in the acyclic form or as their cyclic hemiacetal isomers. 5 These Amadori or Heyns rearrangement products (ARP or HRP) are nonvolatile precursors of flavor and browning compounds, and they are regarded as important intermediates of Maillard reaction.…”

“…The Maillard reaction can take place even at room temperature but is favored by high temperature; thus, it significantly influences the quality and acceptance of the foods prepared through thermal treatment . During the thermal treatment, nucleophilic addition of the amino group on peptides or amino acids to the carbonyl group on sugars readily occurs, followed by dehydration to form a Schiff base . The subsequent Amadori or Heyns rearrangement of the Schiff base lowers the energy of the molecule and results in a relatively stable deoxyaminoketose or deoxyaminoaldose existing either in the acyclic form or as their cyclic hemiacetal isomers .…”