Characterization of degradation products of carrageenan by LC-QTOF/MS with a hypothetical database

Carrageenan (CGN) belongs to the sulfated polysaccharides family that is commonly used in the food industry. For oligosaccharide analysis, a liquid chromatography quadrupole time-of-flight/mass spectrometry strategy was developed using a hypothetical database. There are 2100 structures in the developed hypothetical kappa-CGN database. To eliminate false-positive results, three approaches were used, including size exclusion chromatography with mass spectrometry, which differentiates the loss of sulfated groups caused by the hydrolysis process or the ionization process. Profiling of acidic hydrolysis products of lc-CON was found that after 12 h of HCl cultivation, the kappa-CGN was hydrolyzed to oligosaccharides lower than the degree of polymerization 10, breaking the a-1,3-glycoside linkage and producing even-numbered oligosaccharides. Another finding was that the pH at which acidic hydrolysis is terminated affects the generation of even and odd oligosaccharides. Peeling reaction occurs at the reduction end 4-linked-3,6-anhydrous-D-galactose when adjusted to alkaline conditions, thus generating odd oligosaccharides.

Automated summary

Carrageenan is a sulfated polysaccharide commonly used in the food industry. This study developed a liquid chromatography mass spectrometry strategy using a hypothetical database for oligosaccharide analysis. The results showed that the time and pH at which acidic hydrolysis is stopped affects the length and evenness of the generated oligosaccharides.