Enhanced yield of Scenedesmus obliquus biomacromolecules through medium optimization and development of microalgae based functional chocolate

Abstract

The freshwater green microalga Scenedesmus obliquus was cultivated to enhance the contents of proteins, carbohydrates and lipids by using Box-Behnken experimental design. S. obliquus was cultured under phototrophic conditions by using Bold’s Basal Medium with different cultivation parameters including pH (7, 8 and 9), salinity (10, 30 and 50 mM), and nitrogen source (0.125, 0.5 and 1 g/L). The highest biomass yield (64.9 ± 0.94 mg/L/day) was obtained by using optimized medium at a salinity concentration of 30 mM (w/v), and nitrogen sources of 0.125 g/L. The maximum content of protein, lipid and carbohydrates from S. obliquus optimized medium were 342.19 ± 0.28 mg/g, 241.41 ± 4.32 mg/g and 288.05 ± 1.12 mg/g of dry wt. respectively. The amino acid and fatty acid analysis of S. obliquus biomass indicated the presence of significant amount of essential amino acids and essential fatty acids. Furthermore, chocolate crispy bar was developed by fortification with encapsulated freeze-dried S. obliquus and evaluated for its oxidative stability and sensory analysis. The chocolate fortified with microalgae can be a potential source of essential fatty acids and amino acids in addition to other bioactive compounds.