A mechanism for the synergistic gelation properties of gelatin B and xanthan gum aqueous mixtures.

Gelatin B and xanthan gum aqueous mixtures (GB/XG, (0.2-2%)/0.2% w/v) exhibit enhanced gelling properties compared to their pure component solutions at similar compositions. The mixed gels comprise co-localized networks of GB and XG-rich domains. Our results show that these domains are composed of intermolecular complexes and their aggregates stabilized by the neutralization effect of GB, and linked together by formation of GB triple helices. GB/XG mixtures display composition-dependent microstructural transitions: from discontinuous aggregates (GB/XG ratio≤1) to a continuous GB/XG network (ratio=2-6), followed by network fragmentation (ratio=8-10). Increasing the GB Bloom index accelerates network formation and results in higher elastic modulus (G'), while increasing the XG molecular weight causes the opposite effect due to diffusion limitations. This work provides a set of fundamental guidelines to design novel thickeners and/or gelling agents based on proteins and polysaccharides, for food or pharmaceutical applications.