Gellan helical structure

The detailed structural analysis of gellan has been performed using X-ray diffraction technique by Chandrasekaran and Radha. The X-ray diffraction study on Li gellan revealed that it possesses an extended double helical molecular structure formed by intertwining of threefold left-handed helical chains of pitch 56.4 A in a parallel fashion [8]. This helical structure is stabilized by means of interchain hydrogen bond between the hydroxymethyl groups of 4-linked glucosyl units in one chain and carboxylate... 

Forms a heat-resistant and clear gel with low concentration (0.2%) under the existence of ions. The gel has a hard and brittle feeling when eaten. There is a tendency to lose water although it has good flavor upon release. The K-type gellan gum is found by x-ray diffraction to have a double helix structure. It is thought the association of the helices forms a 3D network structure. 

Recently, atomic force microscopy (AFM) and dynamic viscoelasticity measurements have been employed for investigating the detailed chemical structure of Na -gellan. The study revealed that gellan is composed of a continuous network of structures that is mainly developed through the inter-helical associations of end-to-end type rather than the associations of side-by-side type. The presence of cations (K ions) is found to be a necessary component for the development of these types of continuous network structures. The study further confirmed the fibrous model of gellan gelation instead of the conventional model which presumed that joining of the adjacent jimction zones leads to formation of disordered flexible polymer chains [10,11]. 

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