Influence mechanism of oxygen on browning of sorbitol-glycine system by regulating reducing sugar generation and deoxyglucosone degradation

Abstract

To elucidate the impact of oxygen concentration on the browning reactions containing sugar alcohols and amino acids, the sorbitol-glycine model system was investigated. The color changes under varying oxygen levels were observed. The melanoidin formation and evolution of browning precursors including reducing sugar, Amadori rearrangement product (ARP), and α-dicarbonyl compounds were traced during the accelerated incubation process at 60 °C. Compared with the system under 2% O₂, the browning index decreased by about 2.5 times after 28-day storage at 30% O₂, with the accumulation rate of fluorescent compounds decreasing by 3.9 times. Furthermore, the content of pyrazine compounds decreased by 20.7 times after six months of storage at 30% O₂. This was related to the competition between oxidation reactions and dehydration reactions. Although a higher oxygen concentration promoted the conversion of sorbitol to glucose and the formation of ARP and 3-deoxyglucosone, it also accelerated the oxidative cleavage of α-dicarbonyl to organic acids and inhibited the retroaldolization of deoxyglucosones into shorter dicarbonyl compounds. Moreover, the inhibitory effect of oxygen on the generation of dicarbonyl compounds was more pronounced, ultimately leading to the suppression of browning. This study proposes a new strategy for maintaining the quality of low-sugar beverages containing sorbitol through modified atmosphere packaging.