Optimization of carrageenan production from Persian Gulf algae Laurencia obtusa: Purification and rheological characterization

Abstract

In this study, Laurencia obtusa (Yamada, 1931) species was investigated for carrageenan extraction. L. obtusa species was identified using the molecular barcoding method with two COI and rbcL genes. Rheological analysis was performed to determine the rheological properties of semi-refined carrageenans. Experimental design was carried out with Design Expert software to produce and optimize SRC extraction. The software presented 18 treatments based on temperature, cooking time and concentration of KOH. Treatments were prepared for rheometric analysis (i.e., viscosity measurements). Optimization was performed by the software with maximum viscosity. Also, two refined carrageenan extraction methods were performed, and the FTIR and NMR spectra were compared. Barcoding showed similarity values of 96 and 94% using the COI sequence and therbcL sequence, respectively. The optimal treatment included temperature of 77°C, 99 minutes, and 7% concentration of w/v KOH. The highest efficiency was associated with the dialysis method, which was 19%. Based on the rheometric analysis, the SRC solution was introduced as a pseudo plastic Non-Newtonian fluid. According to these two analyses, the refined carrageenans of L. obtusa were of the iota type.