The water-binding capacities of gelatin, potato starch, and carrageenan gels were measured by the use of a filter paper suction pressure method. It was found that the gelatin and potato starch behaved similarly over a wide range of concentration but had poor water binding compared with carrageenan. The de Boer-Zwikker-Bradley equation did not describe the behavior of water in the gels, whereas the Flory-Huggins model was more suitable. Gelatin and potato starch behave like solutions up to a breakpoint in the shape of the suction pressure isotherm, which suggests extensive internal binding or clustering. Above this point the water-binding capacity is not gel-concentration dependent. Carrageenan, on the other hand, behaves more like a solution, with water a good solvent. The technique of using suction pressure allows for comparison of the water-binding strengths of the gels.
Bibliographical noteFunding Information:
This is paper number 9876 from the University of Minnesota Agricultural Experiment Station. This study was supported in part by the University of Minnesota Agricultural Experiment Station Project No. 18-72 and Contract NAS 9-12560, Lyndon Johnson Space Center, Houston, Texas.