Agro-Industrial By-Product Valorization for Sustainable Materials: A Systematic Literature Review of Methods, Trends and Research Frontiers

Rising population pressures and growing resource consumption underscore the urgent need for sustainable strategies in resource management and waste valorization. Agriculture and the agri-food industry generate substantial biomass residues that, when effectively reused, can be transformed into high-value materials aligned with circular economy and bioeconomy principles. This study presents a Systematic Literature Review (SLR) on the valorization of agro-industrial by-products, focusing on their potential to drive sustainable material innovation strategies. Using the Scopus database, 1063 publications (2015–2025) were analyzed through bibliometric, network and content analysis methods combined with a quantitative meta-analytical approach. The bibliometric analysis outlines research trends and identifies leading journals and disciplines, while network mapping reveals five thematic clusters and a transition toward integrated frameworks linking sustainability and industrial applications. The content analysis is performed through a quantitative meta-analytical approach that highlights that studies integrating multiple waste origins tend to achieve higher scientific visibility. Overall, results highlight a 27.5% annual growth in publication output and five dominant thematic areas: waste recovery, chemical recovery, systemic valorization, energy recovery and alternative fuels. Studies involving multiple waste sources display higher citation averages, highlighting the relevance of integrated valorization strategies. This review provides a solid foundation for future research on agro-industrial by-product management by contributing to the definition of sustainable supply-chain strategies.