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Gellan gum is produced by Sphingomonas elodea and Sphingomonas paucimobilis ATCC 31461 under submerged fermentation using glucose as carbon source with a 40–50% yield [31]. Gellan gum is an anionic HePS, which is composed of d‐glucose, d‐glucoronic acid, and l‐rhamnose in a molar ratio of 2:1:1, along with side chains of O‐linked acyl, acetyl, and glyceryl groups [20]. The presence of acyl groups in gellan gum affects the rheology of the gel formed, resulting in soft, elastic, and thermos‐reversible gels. Chemical deacylation of gellan gum results in a more hard, brittle, and optically clear gels; this process generally used to produce industrial gellan gums (Gelrite or Kelcogel) [31]. Gellan gum generally has a molecular weight of 500 kDa and has the ability to form 3D network in the presence of monovalent or divalent cations such as Ca²⁺ or Na¹⁺. Gellan gum is used for its gelling properties in food products like dairy, jellies, and confectionery products as a hydrocolloid and can be used to prepare edible films [2]. It has even been approved as a safe food additive by US and EU authorities for their use in food products as a gelling, suspending, and stabilizing agent, either alone or in combination with other food hydrocolloids [31]. Gellan has good compatibility with other gums or biopolymers such as xanthan or locust bean gum. Gellan, when combined with starch, improves the gas and moisture retention in a food product, which results in the reduction of starch used and enhancement in the flavor. Gellan gum is used to form gels in a concentration of 0.04–0.05% (w/v), which is very low compared to other gums [20].

Figure 3.2 Structures of different sphingans.

Source: Based on [3].