## 3 The Critical Importance of Product Identity in Agricultural Supply Chains
### Blockchain as a Solution for Traceability and Product Identity
\begin{table}
\begin{tabular}{p{142.3 pt} p{142.3 pt}} \hline \hline
**Theme** & **Details** \\ \hline Transparency and Trust & Blockchain ensures tamper-proof, transparent ledgers. It authenticates product origin, aiding industries like luxury goods and food safety [41; 42; 43; 44; 45; 46]. \\ \hline Efficiency and Cost Reduction & Automation via blockchain reduces delays and manual work, increasing supply chain agility and lowering operational costs [44]. \\ \hline Fraud Prevention \& Security & Enhances data integrity, minimizing fraud risks in sectors with high-value goods (e.g., electronics, automotive) [44; 47; 48]. \\ \hline Consumer Trust & Provides traceable and reliable product information, influencing buyer decisions and reducing reliance on e-WOM [46; 49]. \\ \hline Sustainability \& Compliance & Tracks environmental/social impacts and automates compliance checks, aiding legal and sustainability adherence [50; 52]. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary: Blockchain for Traceability and Product Identity. Key stakeholders interacting with the architecture include the following: (1) producers (farmers, cooperatives); (2) processors (factories, packaging); (3) distributors and logistics providers; (4) retailers; (5) regulatory authorities; (6) consumers. Each stakeholder plays a role in enriching and verifying product identity data as the product moves through the supply chain. Data flow walkthrough: From farm to consumer. A Protected Designation of Origin (PDO) olive oil will be used as a case example. Figure 1: Cyber–physical blockchain architecture for transparent supply chain traceability. Data Flow and Stakeholder Interaction in the Proposed Layered Architecture. Step 1: Data capture at the physical layer--The producer records primary product attributes (e.g., olive variety, harvest date, GPS coordinates of the farm). IoT devices (e.g., soil sensors, temperature loggers) capture environmental conditions. These data points are transmitted to the digital layer, linked to a unique DID representing this olive oil batch. Step 2: Digital layer--creation of the digital twin. A digital twin of the product batch is instantiated, encapsulating static attributes (e.g., origin, certifications) and dynamic attributes (e.g., storage temperature, transport conditions). The DID serves as the persistent identifier, ensuring each data update corresponds unambiguously to the physical batch. Step 3: Blockchain layer--smart contracts and immutable records. The data from the digital twin are anchored on the blockchain via smart contracts. Provenance proof (farm location, harvest certification). Transformation events (e.g., pressing, bottling at processor level). Transfer of custody (from producer to distributor). Each transaction represents a verifiable event in the product's lifecycle, creating a tamper-proof audit trail. Step 4: Application layer--access by stakeholders. Regulators verify compliance data (e.g., organic certification, PDO validity) through dedicated dashboards. Retailers access product identity data to ensure authenticity and communicate to consumers. Consumers scan a QR code on the product packaging, retrieving the product's digital twin information (origin, journey, certifications) in a user-friendly interface. Logistics providers can also access real-time data (e.g., storage temperature anomalies) for quality assurance. Data integrity and feedback loops. Each stakeholder can append verified data but cannot modify historical records, preserving data integrity. Feedback mechanisms allow for (1) quality alerts (e.g., deviations in storage conditions) and (2) consumer feedback loops, where end-users can validate product experience, adding trust signals to the product's digital twin. The architecture supports interoperability with external systems, such as (1) government certification databases (PDO/PGI registries) and (2) logistics tracking systems via API integrations. This ensures data consistency across platforms, reinforcing product identity authenticity.