Optimization of chlorophyll extraction solvent of bulung sangu (Gracilaria sp.) seaweed

Algae are a photosynthetic organism, affordable and naturally rich in nutrients and a valuable source of bioactive substances such as natural pigments. Bulung sangu (Gracilaria sp.) is red macroalgae that wildly grows and distributes in Bali. The aim of this work was to optimize the solvent to extract the chlorophyll content of Bulung sangu. The pigment extraction was carried out using different solvents (100% methanol, 100% ethanol, and 90% acetone). The chlorophyll contents including chlorophyll a,b,c,d and total chlorophyll were measured using spectrophotometry UV-VIS and expressed in µg/g of algae. The results showed that chlorophyll c could not be extracted using all used solvent, while chlorophyll b can only be extracted using acetone. Acetone produced the highest concentration of chlorophyll a (717.52 ± 9.71 µg/g), chlorophyll b (7.23 ± 0.24 µg/g), chlorophyll d (21.93 ± 1.07 µg/g), and chlorophyll total (746.67 ± 8.99 µg/g) compared to other solvent, that were significantly different (p<0.05). The second solvent to produce the highest concentration of chlorophyll a, d, and total chlorophyll was methanol which produced 578.77 ± 9.74 µg/g, 5.50 ± 0.12 µg/g and 584.27 ± 9.62 µg/g of chlorophyll content, respectively, followed by ethanol which produced 520.98 ± 2.52 µg/g of chlorophyll a, 3.56 ± 0.25 µg/g for chlorophyll d, and 524.54 ± 2.30 µg/g for total chlorophyll. Acetone is considered the most effective solvent to extract the chlorophyll content of Bulung sangu.