Buckwheat Hulls as an Emerging Industrial Feedstock: Valorisation Pathways, Technological Readiness, and Scale-Up Challenges

Buckwheat dehulling produces a concentrated side stream rich in dietary fibre and phenolic compounds. The lignocellulosic structure of the hull also makes it suitable for several forms of material and thermochemical processing. Earlier reviews have focused mainly on composition, extraction, and food applications; much less attention has been paid to whether the proposed uses are ready for industrial implementation. This critical narrative review compares direct food and fibre use, extraction of bioactive compounds, biosorption, production of biochar and engineered carbons, polymer and wood-based composites, and solid-fuel applications. Peer-reviewed studies formed the primary evidence base, while targeted patent screening was used as supplementary evidence of buckwheat-hull-specific technological concepts and was not treated as proof of pilot- or commercial-scale readiness. The available evidence was assessed with regard to unit operations, product function, processing intensity, application-relevant testing, scale-up limitations, and indicative Technology Readiness Levels. Among the assessed pathways, direct food incorporation showed the highest technological maturity, with BH-enriched bakery products produced under commercial bakery conditions, providing evidence beyond laboratory-scale validation. Pelletisation and combustion, together with selected biochar applications, showed intermediate technological readiness, whereas extraction and engineered carbon applications remain supported mainly by laboratory-scale studies. Composite processing can draw on established industrial equipment, although this does not by itself confirm the readiness of complete BH-specific processes. Selected biochar studies extend performance testing to laboratory fixed-bed metal removal or agronomic reuse after phosphorus adsorption. Across all routes, the most important barriers to industrial implementation are feedstock variability and lack of standardisation, insufficient validation at pilot or operational scale, and limited techno-economic and life-cycle evidence. Logistics and resource requirements represent additional constraints, particularly for low-value and resource-intensive pathways. Cascading use, in which valuable fractions are recovered before the remaining solids are directed to material or energy applications, is a promising option, but integrated buckwheat hull biorefineries have yet to be demonstrated beyond laboratory scale.