The emergence of blockchain provides a solution of decentralized integration of resources and elimination of information asymmetry for food supply chain, but most of the current solutions are facing performance and storage bottlenecks. In response to this problem, this paper proposes a dual-chain storage optimized model for food supply chain data based on blockchain. The model builds a double-chain structure of the main chain and the digest chain. Nodes can choose the appropriate storage mode according to their needs, which alleviates the problem of block storage expansion. By adopting the improved Delegated Proof of Stake and Byzantine fault tolerance consensus mechanism with the credit system to elect accounting nodes, to prevent witch attacks at the same time to reduce transaction confirmation and verification time of blocks. Finally, through simulation experiments, it is verified that the solution can adapt well to the food supply chain, greatly optimize the storage resources, increase the speed of block generation, and improve the performance and throughput of the blockchain system.