Water holding capacity and microstructure of gellan gels

This project studied the water holding capacity of gellan gels as affected by gel composition and microstructure. When not subjected to external forces such as centrifugal force, gellan gel properties including water holding capacity and texture properties were stable at room temperatures. The water losses from gellan gels after four months storage at 4°C were only 1¯2%, independent of calcium concentrations. The freeze¯thaw stability of gellan gels was poor. Water holding capacity of gellan gels, when subjected to centrifugal forces, was dependent on calcium concentrations, and was related to the texture properties. Two discrete pore-size distributions in gel matrix on the order of 0.1 and 1 mu were observed with scanning electronic microscopy. Large pores were formed with thick strings while the small ones were formed by a thin web structure. Defects in the large pore structure were observed at high calcium concentrations. The small pores may be responsible for the water holding capacity during storage, while large pore structures provide the strength of gels.