Curdlan is a microbial fermentation extracellular gum. It is a polymer prepared commercially from a mutant strain of Alcaligenes faecalis var. myxogenes. It is relatively expensive by weight but becoming rather less so. Curdlan gum is tasteless and produces a retortable freezable food elastic gels. It is insoluble in cold water a but aqueous suspensions plasticize and briefly dissolve before producing reversible gels (that is, curdling, hence its name) on heating to around 55 °C ã??Heating at higher temperatures produces more resilient irreversible gels, which then remain on cooling, by the aggregation of the triple-helical structures and syneresis. The 'curds' consist of mixtures of single and triple helices. Salts tend to prevent curdlan from gelling and their presence weakens the final gels