17 / AGRICULTURE / SUPPLY CHAIN TRACEABILITY

Two-tier QR traceability down to the individual banana, with an optional blockchain seal that lets a buyer verify a shipment without taking the exporter's word for it.

Client: Banana export operation, Western India

Tags: Agriculture · Supply Chain · Blockchain · QR Traceability · Polygon

// Problem

A buyer receiving a shipment had no way to verify where it came from, or whether the harvest record behind it was genuine — only the exporter's word for it. Making that verifiable meant either trusting one company's database completely, or paying a blockchain transaction fee per banana, which was never going to be economical at real volume.

// Our Solution

A two-tier QR traceability system, with an optional blockchain seal that removes the need to trust the exporter at all. Every banana and every box carries a unique QR code, assigned to a shipment before harvest and confirmed only when actually loaded — nothing invented, nothing guessed. For buyers who need independent proof, one cryptographic fingerprint covering an entire truckload is sealed on a public blockchain — one transaction per truck, not per banana.

// Technical Details

Serialized Two-Tier QR

Every banana sticker and shipping box carries a manufacturer-preprinted, unique serial QR code — assigned to a shipment record in advance and confirmed only when actually loaded onto the truck. Anything damaged or unused is simply never linked to a finalized shipment, with no separate cleanup step required.

Merkle-Sealed Blockchain Verification

Every banana serial range, box serial, and truck record in a shipment is hashed into a Merkle tree; only the resulting root hash is written on-chain, one transaction per truck rather than per banana or box. A minimal, append-only smart contract stores the truck ID, Merkle root, and timestamp per sealed shipment.

On-Scan Verification

Scanning a banana or box QR resolves the serial to its box and truck and displays the full farm-to-store history. For blockchain-sealed shipments, the app recomputes a Merkle proof for that specific serial and checks it against the on-chain root; any mismatch is flagged as tampered.

Two Sealing Options, Same Experience

A no-blockchain mode locks the shipment record in the database for buyers who trust the exporter's systems directly. A blockchain-sealed mode adds independent, tamper-evident proof for B2B buyers who need it, at a fraction of the cost of sealing every unit individually.

Stack

Polygon for low-cost, EVM-compatible on-chain anchoring; PostgreSQL as the off-chain store for the full shipment record — with the blockchain holding only the tamper-proof fingerprint, never the underlying data.