Directed preparation of N-(1-deoxy-d-ribulos-1-yl)-glutathione during short-term high temperature dehydration: Suppressing the side reactions of glutathione

Abstract

The Amadori rearrangement product (GR-ARP) derived from glutathione/ribose mixture (GSH/Rib) was prepared through spray drying characterized by short-term high temperature dehydration. The water activity of spray-dried samples containing GR-ARP decreased continuously with an intensified degree of dehydration. Lower water activity (from 0.23 to 0.13) and higher GR-ARP yield (from 46.56% to 64.02%) in the spray-dried products were found with the increase of inlet temperature, the slowdown of feed speed, and the alkalization of stock solution. Moreover, during the spray drying and formation of powders, the intensified dissipation of bound water to free water promoted intermolecular condensation that compensated bound water, favoring the directed conversion of GSH/Rib into GR-ARP. Compared to rotary evaporation at 80 °C, spray drying enabled a stronger restraint of amide cleavage and sulfhydryl oxidation in GSH, which reduced the yield of GSH-derived byproducts by 16.39%. Thus, GR-ARP was achieved a peak yield of 64.02% at an initial pH of 7.00 based on more efficient intermolecular condensation and controlled side reactions of GSH when the inlet temperature was set at 170 °C. The spray-dried sample containing richer GR-ARP and other flavor precursors showed a more similar flavor profile to the heated GSH/Rib mixture (complete Maillard reaction products) than other GR-ARP-related thermal processing samples, such as vacuum-dehydrated, GR-ARP, GR-ARP + GSH, and GR-ARP + Rib samples, revealing a great potential of the ARP mixture prepared by spray drying for flavor enhancement.