Assembly process of locust bean gum and xanthan gum for synergistic gelling revealed by atomic force microscopy

Synergistic interaction gels (SIGs) have become attractive in food industry due to their ability to modify rheology features, realize safe swallowing and apply as fat simulants. Locust bean gum (LBG) and xanthan give rise to SIG, however, their assembly process remain elusive. This work demonstrated that, in xanthan-rich system, xanthan chains transformed into helical structure and aggregated into thick bundles upon cooling. Subsequently they bound with LBG clusters, constructing a xanthan-like 3D gel network. However, in LBG-rich system, LBG chains gradually dissociated from clusters and associated into helical structure during cooling ("dissociation-association" process), forming an LBG-like "sea-island" structure. With further cooling, LBG continued to undergo "dissociation-association" process, along with specifically binding by xanthan chains (helical structure or thick bundles), generating thick grid contour lines and larger sparse gel network. The enthalpy change values indicated that with the decrease of xanthan content, synergistic binding extent was increased and then decreased, reaching the maximum at LBG: xanthan ratio of 7:3. This was responsible for the increment of G′, gel hardness, and capacity to accumulate energy for the weak shear-induced structure for LBG/xanthan SIGs. This study serves to facilitate the design and production of SIGs with the requisite performance characteristics.