Microbial and algal alginate gelation characterized by magnetic resonance

► Magnetic resonance techniques are used to quantify differences in the physical gelation of alginate from microbes and algae. ► Differences in water diffusion, T1, and T2 magnetic relaxation times are monitored as the gel forms and ages. ► O-Deacetylated alginate from Pseudomonas aeruginosa FRD1153 forms the most rigid and heterogeneous gel. ► Bacterial alginates form a more rigid and heterogeneous gel than algal alginate. ► Bacterial alginates contract and expel water more than algal alginate indicating larger molecular stress during gelation.