Lutein and biodiesel sequential production from microalga using an environmentally friendly approach

The use of microalgae as a raw material to extract pigments and biodiesel is an economical and environmental challenge due to the costs and toxicity of the chemical used, as well as the time and energy consumed in the production chain. Thus, the objective of this work was to develop an environmentally friendly sequential process to obtain lutein and biodiesel from <i>Choricystis minor</i> var. <i>minor</i> microalga. To overcome these challenges, the wet biomass of this microalga was dried in the sun, and lutein was obtained in an optimized extraction using methanolic solution containing potassium hydroxide, followed by the extraction of fatty acids and conversion into biodiesel using methanolic solution with phosphoric acid. The optimum conditions for lutein extraction were 0.3 mL of methanolic solution with 8% potassium hydroxide, at 60 °C for 1 hour. Then, the residual biomass was used to produce biodiesel by acid catalysis, with addition of 0.8 mL of methanolic solution containing 10% phosphoric acid at 100 °C for 1 hour. This approach obtained 1 kg of lutein and 10.83 kg of biodiesel from 75.75 kg of dry biomass of microalga. From the economical point of view, biodiesel is a less valuable coproduct of the lutein production chain.