Ferulic acid extraction and purification for the wheat bran valorization

Resumen

Wheat bran is an important and underused by-product of the milling industry, and constitutes a very interesting feedstock to be treated, from which many high added-value components can be extracted sequentially. Many works in literature deal with the valorization of the cellulose and hemicellulose fractions. However, wheat bran is also a good source of phytochemicals, which are minor compounds, but with high economical value. In this regard, ferulic acid (FA) is the main phenolic compound present in wheat bran and it has many potential applications in the food, cosmetic and health industries, associated to many beneficial effects such as antioxidant, antithrombosis and anticancer activities, among others. In the wheat bran, FA is mainly found attached to the arabinoxylans, and the traditional procedure employed for its release is the alkaline hydrolysis. However, it is an aggressive and non-selective method, making it not suitable for a fractionation stage of a bio-refinery (where it is intended to take advantage of the different fractions of the biomass). This PhD thesis is focused on the valorization of wheat bran by the extraction and purification of FA using environmentally friendly techniques. For this, the use of pressurized solvents and, in particular, pressurized water, was tested as an alternative technique to the traditional alkaline hydrolysis with NaOH. Additionally, since FA is a minor and highly bonded compound, it is expected that other compounds will be co-extracted during the extraction process. Therefore, the identification and quantification of these compounds, as well as the purification of the extracted FA, are also objectives of this thesis.