Date of Award

Fall 2011

Degree Type


Degree Name

Master of Science (MS)


Food Science

Committee Chair

Srinivas Janaswamy

Committee Member 1

Rengaswami Chandrasekaran

Committee Member 2

Osvaldo Campanella

Committee Member 3

Fernanda San Martin-Gonzalez


Iota‐carrageenan, a sulfated galactan from marine algae, is used by food and pharmaceutical industries for its gelling and thickening properties. This hydrocolloid adopts a variety of solid‐state structures, depending on the amount and nature of co‐solutes, and displays a wide range of functional properties. Information about the relationships between atomic structure and macroscopic behavior, however, is still lacking. The overall goal of this research was to understand the effects of cations (Na+ and Ca2+) and sweeteners (sucrose and Rebiana, a non‐nutritive sweetener) on the three‐dimensional structure, solution and thermal properties of iota‐carrageenan. X‐ray diffraction analyses revealed typical half‐staggered molecular structures and trigonal packing arrangements in the presence of either Na+ or Ca2+ ions. Observation of new non‐half‐staggered helical arrangements and orthorhombic basal nets, however, suggests greater versatility of this biopolymer. Viscoelastic properties showed that increasing NaCl and/or iota‐carrageenan concentrations results in increased elastic modulus and rheological gel‐to‐solution transition temperature (Tg). Addition of sucrose in the presence of NaCl resulted in larger basal net dimensions, elevated rheological Tg and DSC enthalpy values, portraying involvement of sucrose in the iota‐carrageenan network formation. Finally, Rebiana with NaCl yielded substantially larger basal dimensions and layer line spacings but with only small increase of rheological Tg. Overall, iota‐carrageenan’s electrostatic interactions and hydrogen bonding with surrounding co‐solutes of Na+, Ca2+, sucrose, and Rebiana significantly affect its three‐dimensional structure and solutions properties. The outcome aids in the design, and development of iota‐carrageenan based functional materials.