Mono- and diglyceride production from microalgae: Challenges and prospects of high-value emulsifiers

Monoglycerides (MAG) and Diglycerides (DAG) belong to the category of naturally-occurring glycerolipids. They have wide applications in the food, pharmaceutical, and cosmetic industries, with commercial demand supplied by the consolidated industrial catalytic route of vegetable oil glycerolysis. Despite the economic competitiveness of producing these types of emulsifiers from vegetable oils, the increasing demand for products with high nutrition value makes some kinds of microalgae oil potential feedstock of high-quality fatty acids to serve this growing market. An alternative to the use of vegetable oils is the production of triacylglycerols from microalgae. Usually, microalgal oils have a high content of Polyunsaturated Fatty Acids (PUFA) and the cultivation of microalgae may present fewer environmental impacts, considering reduced use of arable land, efficient CO2 biofixation, and high productivity. Microalgae lipids are mostly studied for biodiesel production, but this work shows the potential to explore more valuable applications due to their composition, discussing the possibility of producing MAGs and DAGs from microalgae lipids. While biodiesel B99-B100 costs USD3.56/gallon according to the U.S. Energy Dept. (April 2021), a food emulsifier (soybean lecithin) is sold for USD147/kg (Alfa Aesar, August 2021). Hence, it is imperative to consider high-value bioproducts from an economic point of view. Microalgal oil can be rich in ω-3 and ω-6 fatty acids, being a promising source of MAGs and DAGs with higher nutritional value. Glycerolysis studies of this feedstock are restricted to the enzymatic route, but different alternatives are shown in this work.