Food potential of Scenedesmus obliquus biomasses obtained from photosynthetic cultivations associated with carbon dioxide mitigation

Abstract

Microalgae are photosynthetic microorganisms that stand out from conventional food sources and ingredients due to their high growth rate and adaptability. In addition to being highly sustainable, significant concentrations of proteins, lipids, and pigments accumulate in their cell structures from photosynthesis. Hence, this study sought to evaluate the food potential of Scenedesmus obliquus biomasses obtained from photosynthetic cultures enriched with 3, 5, 10, 15, 20, and 25% carbon dioxide (CO₂) (v/v). Cultivations with 3, 5, and 10% CO₂ showed greater amino acids and proteins synthesis; the protein content reached values above 56% of the dry biomass and high protein quality, due to the presence of most essential amino acids at recommended levels for the human diet. The highest concentrations of chlorophylls were found in cultures with 15, 20, and 25% CO₂ (24.2, 23.1 and 30.8 mg g^-1, respectively), although the profiles showed higher percentages of degradation compounds. Carotenoid concentrations were three times higher in cultures with 3, 5, and 10% CO₂ (25.3, 22.7 and 18.1 mg g^-1, respectively) and all-trans-β-carotene was the major compound. Lipid synthesis was intensified at higher CO₂ enrichment; the percentages obtained were 14.8% of lipids in the culture with 15% CO₂, 15.0% with 20% CO₂, and 13.7% with 25% CO₂. In addition, greater polyunsaturated fatty acids accumulation and a significant reduction in the n6/n3 ratio were also observed at the highest CO₂ concentrations. Our findings showed that CO₂ treatments significantly altered all compounds concentrations in S. obliquus biomasses, which presented satisfactory composition for application in foods and as ingredients.

Keywords: Amino acids; Carotenoids; Chlorophylls; Fatty acids; Free polar compounds; Lipids; Proteins.