FRANK Yiannas has spent years looking in vain for a better way to track lettuce, steaks and snack cakes from farm and factory to the shelves of Wal-Mart, where he is the vice-president for food safety.
When the company dealt with salmonella outbreaks, it often took weeks to trace where the bad ingredients came from.
Last year, IBM executives flew to Wal-Mart's headquarters in Arkansas to propose a solution: blockchain.
Mr Yiannas said of their pitch: "I became increasingly convinced that maybe we were onto the holy grail."
The blockchain - the buzzy, bewildering technology behind cryptocurrencies like bitcoin - is starting to be applied to real-world problems like tracking pork chops, shipping...