Preparation of thermally stable emulsion gels based on Glucono-δ-lactone induced gelation of gellan gum.

In this study, we investigated the gellan gelation mechanism induced by Glucono-δ-lactone (GDL) addition, and subsequently we further fabricated a series of thermally irreversible emulsion gels with the GDL-induced gel matrix as the continuous phase and the methyl cellulose (MC) stabilized emulsion as the dispersed phase. The results showed that GDL- induced gellan gelation was both a time- and temperature-dependent process, which was similar to the gelation process of NaCl-induced gellan gels, but with a higher temperature-dependence. Moreover, GDL-induced gel had a significantly higher rupture strength and the resulting gel did not melt on heating, meaning that the GDL-induced gellan gel can be deemed thermally irreversible. This is because decreasing pH is commonly more effective in promoting gellan gelation. Besides, by mixing the MC-stabilized emulsion with a hot gellan sol, followed by adding GDL, we fabricated the emulsion gels with a wide range of oil phase fraction (0-30%). The emulsion gels exhibited good thermal stability, without melting and oil droplet coalescence observed when heating the gels in a boiling water bath for 30 min. Conclusively, our results may deepen the understanding on gellan gelation induced by GDL and also broaden the utilization of gellan in building gel-related food structures.