Comparative Effects of Culture Sites on Agar Yield and Quality Parameters of Gracilaria edulis in La Union, Philippines
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Abstract
The agar potential of Gracilaria edulis cultured at two coastal sites in La Union, Philippines, was evaluated to determine site-dependent differences in yield and quality. Significant variations (p < 0.05) were observed between Balaoan and Rosario. While Rosario produced greater biomass, Balaoan yielded significantly higher agar. Proximate composition also differed, with Balaoan exhibiting higher protein and carbohydrate contents. Concentrations of inorganic arsenic (i-As), cadmium (Cd), and lead (Pb) were within the permissible limits set by the Department of Environment and Natural Resources for SB-class waters, indicating environmental safety at both sites. Agar quality parameters showed contrasting trends. Rosario samples demonstrated significantly higher viscosity, gel strength, and 3,6-anhydrogalactose content, suggesting superior gel-forming properties. In contrast, Balaoan agar exhibited higher melting and gelling temperatures, as well as higher sulfate levels. These results confirm that culture site significantly influences agar yield and physicochemical properties of G. edulis. The findings provide important insights for optimizing site selection to enhance both productivity and functional quality in commercial agar production.
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