Carrageenan extraction from red seaweed (Kappaphycopsis cottonii) using the bead mill method

Abstract

Carrageenan extraction can be carried out using a novel method, the bead mill, to produce a high yield and good characteristics of carrageenan. This study aimed to evaluate the environmentally friendly carrageenan extraction method using a bead mill and the physicochemical properties of the extract. Factors such as seaweed concentration, extraction time, agitator speed, and temperature were analyzed. Furthermore, the yield, gel strength, viscosity, and sulfate content were evaluated. The results show that the carrageenan yield, gel strength, viscosity, and sulfate content were significantly affected by seaweed concentration, extraction time, and extraction temperature in a bead mill method. They were not affected by agitator speed. The optimum condition was obtained at a concentration of 1.90 % w/v, an extraction time of 50.26 min, and a temperature of 51.35 °C. The carrageenan had a yield of 67.86 %, gel strength of 68.49 g/cm2, the viscosity of 11.81 cP, sulfate content of 15.35 %, gelling point of 29.33 °C, the melting point of 44.70 °C, the water content of 5.69 %, ash content of 26.54 %, pH of 8.27, and purity of 55.67 %. FTIR analysis confirmed that the carrageenan type was kappa-carrageenan. Thus, the bead mill method can be considered an effective way to obtain high yields with a shorter time in extracting carrageenan from seaweed. Total operating cost of bead mill was lower than chemical method. Nevertheless, the physicochemical properties of carrageenan obtained by this method were lower than that obtained by the conventional KOH method, especially the gel strength.