Wheat bran-based biorefinery 2: Valorization of products

Wheat bran is multi-layered and consists of different cell types with different chemical compositions. The relatively high content of protein as well as the small amount of lignin is the key differentiator to other lignocellulose containing biomasses. Following the classical route of a biorefinery, bran may be disintegrated to a high extent and separated into fractions of high purity in order to build up new chemicals which serve as precursors for higher polymerized compounds. Secondly, bran contains substances that are per se valuables, but need to be further separated and purified. There are basically two directions of valorization, aiming at carbohydrate and non-carbohydrate based products. Both groups are of great heterogeneity, thus candidates are usually grouped according to their functionality. Due to this theoretical approach the production of glucose and fermentation to lactic acid, succinic acid or ethanol, the extraction of proteins and production of essential amino acids including γ-aminobutyric acid (GABA), the extraction of ferulic acid (FA) and its conversion to vanillin, as well as the extraction of arabinoxylans (AX) seem to be feasible and of economic relevance, which will be highlighted within this review.