Development of a sustainable method for the extraction of suberin-related compounds from biomass using supercritical transesterification

Suberin is a biopolyester which has a unique molecular diversity in long chain aliphatic molecules such as omega-hydroxyacids, alpha,omega-dicarboxyacids and their derivatives carrying functionnalities1. However, the use of suberin as a source of building blocks on an industrial scale for the development of new products and materials is hampered by the chemical resilience of suberin. Of all the methods that have been developed to depolymerize and extract suberin, transesterification is one of the most effective methods. However, it has the drawbacks of requiring a catalyst, of being sensitive to water and free fatty acids and of requiring a long purification thereafter.
This work is based on the development of a SCTE (supercritical transesterification) method which offers the advantages of being tolerant to the presence of water and free fatty acids while being catalyst-free2. As a result, SCTE allowed to successfully extracting suberin from potato peels, cassava peels and oak bark in less than 1 hour with a high selectivity thus limiting the need for purification. The results also show that by adjusting the duration of the treatment it is possible to obtain a total or partial depolymerization depending on the desired final product. SCTE is therefore a promising method to obtain suberin monomer mixture at a large scale.
(1) Gandini, A.; Neto, C. P.; Silvestre, A. J. D. Suberin: A Promising Renewable Resource for Novel Macromolecular Materials. Prog. Polym. Sci 2006, 31, 878–892. https://doi.org/10.1016/j.progpolymsci.2006.07.004.
(2) Karki, S.; Sanjel, N.; Poudel, J.; Choi, J. H.; Oh, S. C. Supercritical Transesterification of Waste Vegetable Oil: Characteristic Comparison of Ethanol and Methanol as Solvents. Appl. Sci. 2017, 7 (6). https://doi.org/10.3390/app7060632.