Purification and Characterization of Carrageenan Extracted from Persian Gulf Laurencia snyderiae Red Algae

Carrageenans can be found in a group of red algae called Carrageenophytes (Gigartinaceae, Solieriaceae, Hypneaceae and Furcellariaceae); howe-ver, this substance has not been investigated in Laurencia species. In this study, two native species of Laurencia within the Persian Gulf were investigated to extract carrageenans. Therefore, the major aims of this study included extraction, optimization and purification of carrageenans from Laurencia snyderiae, a native red algae of Persian Gulf.

Laurencia snyderiae and Laurencia papillosa were identified based on their morphological characteristics. An experimental design was carried out using Design Expert Software to produce and optimize extraction of semi-refined carrageenans. The software programmed 18 treatments based on temperature, boiling time and KOH concentration. Products of the treatments were prepared for rheometric analyses (viscosity measurements). Optimization was carried out using the software based on the maximum viscosity. Refined carrageenan efficiency was assessed using four extraction methods. Moreover, Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy spectra were compared. Laurencia snyderiae was selected for further inves-tigation.

Based on the rheometric analyses, a semi-refined carrageenan solution was identified as a non-Newtonian pseudo-plastic fluid. The optimum treatment was investigated for Laurencia snyderiae at 65 °C for 35 min at KOH concentration of 7% w/v. Results of these two analyses showed that the refined carrageenans from Laurencia snyderiae included the lambda type. The highest efficiency was achieved using dialysis method (37%). Based on the abundance of the Laurencia snyderiae on the Persian Gulf coasts in all seasons, further studies on carrageenan with higher purities enable use of these substance in various industries. Broader rheological studies can precisely assess characteristics of the investigated carrageenans.