Pecan shell phytochemicals: chemical fingerprint, agro-industrial applications and delivery systems

Global pecan production has increased, with consumption focused on the kernel, while the shells (endocarp) remain underutilized. This review presents the chemical composition of pecan shells and discusses their agro-industrial applications and delivery systems. A literature search in the Web of Science using the term "pecan shell" retrieved 236 documents, analyzed using bibliometric indicators and keyword co-occurrence mapping. Pecan shells are rich in phenolics, melanins, insoluble fibers, and minerals, with notable antioxidant, antimicrobial, and antifungal properties. Their main bioactive potential lies in antioxidant action, especially in lipid product preservation, as well as pathogen inhibition, partial replacement in bakery products, and development of active packaging. Technologies like zein-based microencapsulation via spray-drying, and electrospun melanins have been investigated to enhance compound stability and delivery. Although progress has been made, over 90 % of the biomass remains as solid waste, which can be converted into by-products such as biochar, contributing to circular bioeconomy strategies.