Microalgal triacylglycerols: a potential source of lipids for infant formulation

Aim: Infant formula is manufactured using plant-based oil to mimic the fatty acid profile of human milk and achieve similar nutritional outcomes in infants. Fat provides most of human milk’s energy content and comprises a complex mixture of lipid types of which approximately 98% are triacylglycerols (TAGs). Microalgae are a valuable renewable source of TAGs with potential for nutritional applications such as in infant formula.

Method: In this study, we evaluated the TAG content of different microalgal species grown under normal, nutrient limiting, and altered growth conditions (buffer, medium composition and light exposure). Accelerated solvent extraction was used to extract intracellular lipids form Chlorella vulgaris, Chlamydomomas reinhardtii, Scenedesmus obliqus, Nannochloropsis ocenica and Nannochloropsis occulata and the TAG content in the extracted lipids was determined by high-performance liquid chromatography with evaporative light scattering detection.

Results: Nitrogen starvation significantly elevated the TAG content in all microalgae (two-way ANOVA p< 0.05): S. obliqus exhibited the highest amount of triacylglycerol accumulation (295.5 ± 0.9 mg/g dry biomass) followed by C. vulgaris (252 ± 9 mg/g), N. ocenica (212 ± 19 mg/g) and C. reinhardtii; (173 ± 19 mg/g). Phosphate starvation was also associated with TAG accumulation in N. ocenica (210 ± 42 mg/g), N. occulata (96 ± 23), and S. obliqus (94 ± 4 mg/g). Although altering growth conditions (buffer and medium composition) enhanced the total lipid content, this did not increase TAG content compared to nutrient limiting growth conditions. The fatty acid profile of the extracted TAGs from the microalgae under standard conditions was rich in palmitic (C16:0), stearic (C18:0), oleic (C18:1,9), cis-12-octadecenoic (C18:1 cis12), linoleic (C18:2n6), and α-linolenic (C18:3n3) acids. Under nutrient limiting conditions the fatty acid profile of the microalgae was maintained as observed in standard growth condition, consequently the quantity of palmitic acid increased up to three-fold for most of the microalgae species tested.

Conclusion: Thus, the fatty acid profile along with the increase in TAG content of S. obliquus, C. vulgaris, N. ocenica, and C. reinhardtii cultivated under nutrient limitation could be promising candidates for infant formula production.