Abstract:In this study we compared the ratios of mannuronic acid to guluronic acid (M/G) in different brown algae species of Costaria costata, Scytosiphon lomentarius, Sargassum pallidum, Undaria pinnatifida, Saccharina japonica, and monitored the change of M/G during the growth of S. japonica. The M/G ratio was determined with a high performance liquid chromatography (HPLC) with pre-column derivatization technique. The results showed that C. costata had the highest M/G ratio (2.22), which was followed by S. japonica (2.10), and S. lomentarius had the lowest value (0.60). These demonstrated that algin of C. costata and S. japonica had small intensity but excellent water-holding capacity, and that algin of S. lomentarius had the opposite properties. The M content showed the order as C. costata (18.84%) > S. japonica (14.83%) > S. lomentarius (8.77%). The algin of S. lomentarius had the lowest level of M (14.58%) and the highest G content. The characteristics including fast growth rate, high yield, and commercial cultivation would make S. japonica as suitable material in food industry that requires excellent elasticity and water-holding capacity, such as food coating and thickener. They could also be largely applied in medicine that demands high M content. The algin of S. lomentarius, owning to its high G content and combination with Ca2+ and other metal cations to form compact structures, can be applied to the removal of toxic metal ions as well as calcium in foods. Algin with high G content could also be used as gelatinizers, additives in the food industry, textile and rubber industries. M/G ratios of different species of S. japonica were similar, and they declined over time and reached the minimum at maturity, which was caused by the transformation from M to G during the growth. Our study provided more information for both industrial production and scientific research.
