ANALYSIS OF EXTRACTION YIELD AND CARRAGEENAN CONTENT FROM THE RED SEAWEED BETAPHYCUS GELATINUS OVER MONTHLY CYCLES THROUGHOUT THE YEAR

This study investigated the monthly variation in carrageenan yield and chemical composition from the red seaweed Betaphycus gelatinus collected in the coastal waters of Ninh Thuan, Vietnam, over a 12-month period (March 2022 - February 2023). Carrageenan was extracted using a two-step hot water method, and key chemical parameters-including galactose, 3,6-anhydrogalactose, uronic acid, and sulfate content-were quantified using standard colorimetric and turbidimetric techniques. Results showed significant monthly fluctuations in extraction yield, ranging from 25.34% (July) to 55.49% (August). August was also marked by the highest galactose content (64.75%), while the lowest galactose level (13.78%) was observed in June. The 3,6-anhydrogalactose content peaked in April (30.70%), whereas uronic acid showed less seasonal variability. Interestingly, sulfate content tended to increase in months with high extraction efficiency. Correlation analysis indicated a strong positive relationship between galactose and 3,6-anhydrogalactose (r = 0.72), and a significant negative correlation between uronic acid and total extraction yield (r = -0.71). These findings highlighted the influence of seasonal and environmental factors on carrageenan biosynthesis in B. gelatinus and suggested that harvesting during August might optimize both yield and carrageenan quality for industrial application.