Growth, pigments, and biochemical composition of marine red alga Gracilaria crassa

The marine red alga Gracilaria crassa was investigated for its proximate composition, minerals, fatty acids, amino acids, and agar content to decipher its nutritional implications. The growth performance and pigments were studied under different combinations of temperature and salinity. On a dry weight basis the total lipid content was 1.30 ± 0.05 %, protein was 5.18 ± 0.64 %, carbohydrate was 42.0 ± 1.2 %, ash was 43.18 ± 1.15 %, and agar content was 21.52 ± 0.73 %. Appreciable amounts of macro-, micro-nutrients (K > Na, Ca, Mg, and Fe), and essential amino acids (Ileu, His, Thr, Leu, and Lys) were found. Palmitic, stearic acid, and arachidonic acid were major fatty acids detected. The alga showed maximum daily growth rate (DGR %) 5.8 ± 0.09 % at 25 °C, 35 ‰ salinity. The highest content of pigment R-phycoerythrin (444.7 ± 1.9 μg g⁻¹ fresh weight (FW) basis) was obtained at 25 ‰ salinity at 35 °C while that of R-phycocyanin (476.3 ± 2.3 μg g⁻¹ DW) at 30 ‰ salinity at 30 °C. This study revealed that this alga can be utilized as a potential source for food and feed. The data generated on best growth conditions will be very useful for farming of G. crassa in open sea. This alga could be used for production of natural colorants at defined control condition.