Scanning electron microscopy analysis of guar gum in the dissolution, gelation and gel-breaking process

To better understand the guar gum (GG) working process, we divided it into three steps: dissolution, gelation, and gel breaking. Freeze-drying and scanning electron microscopy were used to examine the microstructures of GG in different states. The dissolution step could be divided into two processes: swelling and dissolving. The microstructures during these two processes were lined structures and random ribbon-like structures, respectively. Further, during the gelation step, the random ribbon-like structures transformed to crosslinked ordered structures. Finally, the ribbon-like structures were broken in the gel breaking step, but the orderliness was not broken. These findings are beneficial to the potential modification or design of GG and the improvement of its hydrogel performance.