Blockchain as the trust layer of supply chain 4.0: A theory-based systematic review of transparency and governance mechanisms in agrifood supply chains

Blockchain is increasingly positioned as a transparency infrastructure for digital supply chains, yet empirical outcomes remain heterogeneous and the theoretical mechanisms through which blockchain reshapes trust, information flows, and governance are still fragmented across disciplines. This study conducts a systematic literature review of blockchain applications in agrifood supply chains and synthesises the field through a digital business lens. Building on information economics and complementary perspectives on trust and governance, the review distinguishes how blockchain-enabled transparency operates via signalling and screening mechanisms across multiple quality dimensions (e.g., origin, process, sustainability) and across supply chain actors. The findings show that blockchain's value does not stem from the ledger alone but from its embedding in broader Industry 4.0 architectures (IoT, data analytics, AI) and from the design of data governance - particularly decisions on data standards, access rights, verification arrangements, and cost/value allocation. Based on the synthesis, the paper proposes an integrative conceptual model that links (i) the digital infrastructure stack, (ii) the configuration of transparency, and (iii) governance choices to expected business outcomes such as trust formation, reduced information asymmetry, coordination efficiency, and new data-driven business models. The study contributes by reconciling dispersed theoretical approaches and by identifying boundary conditions that explain why blockchain implementations succeed or fail in delivering transparency benefits. Practical implications are derived for managers and policymakers regarding architecture choices, incentive alignment, and governance design in digital ecosystems.