Capsicum Processing and By-Product Valorization in Food Systems: A Critical Review

The transition toward a circular food bioeconomy requires systematic valorization of agricultural biomass beyond primary edible fractions. Capsicum species are globally important crops that generate substantial processing by-products rich in high-value bioactive compounds; yet their effective utilization remains constrained by fragmented knowledge linking processing, matrix structure, compound stability, and functional performance. This review adopts a whole-plant perspective, synthesizing recent advances across the capsicum value chain. We examine how primary processing operations reshape food microstructure and govern the stability and extractability of key compounds. Conventional extraction approaches are evaluated alongside emerging green technologies, including deep eutectic solvents and enzymatic treatments, with emphasis on efficiency and preservation of bioactives. Focus is placed on whole-plant valorization strategies, highlighting the transformation of processing by-products into natural colorants and functional bioactives for food applications. Evidence indicates that end-product quality is strongly influenced by processing-induced structural modifications, emphasizing the need for integrated process optimization across the valorization pipeline. Key challenges persist, including selective purification, pigment stabilization in complex food matrices, lack of standardized analytical protocols, and limited techno-economic assessment of scalable green technologies. By framing capsicum as a model whole-plant system, this review outlines processing-structure-function relationships driving circular valorization and identifies future research and industrial priorities.