This value chain focuses on the valorisation of grain residues, specifically oat bran pellets that originate as byproducts from other cereal-processing activities. Rather than being used solely for low-value applications, these nutrient-rich pellets are repurposed as feedstock for the production of a Fermented Probiotic Fiber Mix. Through controlled fermentation, enzymatic treatment, and downstream processing, the oat bran is transformed into a functional ingredient enriched with dietary fiber and beneficial microbial metabolites. This high-value mix serves as a health-promoting component for use in functional food supplements. This value chain covers: the sourcing of oat bran pellets from grain processing, the fermentation and bioprocessing steps, and the production of the final probiotic fiber supplement mix.