This is what Walmart has done so many people, he said, and he said that he would like to do it all.
Walmart says it has a better system for pinpointing which batches of leafy green vegetables might be contaminated. After a two-year pilot project, the type of database technology behind Bitcoin, to keep track of every bag of spinach and head of lettuce.
More than 100 farms that supply Walmart with leafy green vegetables will be required to input information about their food into a blockchain database developed by I.B.M. for Walmart and several other retailers.
The burgeoning blockchain industry has generated a great deal of buzz, investment and experimentation. Central banks are exploring whether it would be good for tracking money flows. Eastman Kodak has explored a platform that could help photographers manage their collections and record ownership of their work, while a group of reporters and investors are using the technology to start a series of news publications.
But only real-world uses as cryptocurrencies like Bitcoins, which use their own blockchains to store transactions. Walmart is now trying to bring blockchain into the lexicon of everyday consumers.
Said Brigid McDermott, vice president of I.B.M. Blockchain.
For Walmart, the initiative fits squarely into two key strategies: bolstering its digital savvy and emphasizing the quality of its fresh food to customers. The blockchain could also save Walmart money. When another food-borne illness hits – like the E. coli outbreak affecting romaine – the retailer would only have to discard the food that was actually at risk.
I.B.M. is trying to position itself as a leader in the emerging technology of blockchains. Microsoft and upstarts like Ethereum, which have been developing projects in the United States.
The Walmart will take time to roll out. In the meantime, it is possible to face questions from the critics of the technology, who are the skeptical of the blockchains being developed by corporations.
Said David Gerard, the author of "Attack of the 50 Foot Blockchain."
"I think it's mostly at P.R. move, I know these companies can sell themselves as blockchain leaders, "he said.
Walmart's embrace of the blockchain highlights how difficult it is to be grocers, including the nation's largest, to keep track of their food.
Last year, Walmart conducted an experiment trying to trace the source of sliced mangos.
It took seven days for Walmart employees to locate the farm in Mexico that grew the fruit. With the blockchain software developed by IBM, the mangos could be tracked in a matter of seconds, according to Walmart.
"The food chain is not always linear," said Frank Yiannas, vice president for food safety at Walmart.
The original blockchain was the online database on which all Bitcoin addresses and transactions were stored. The database is maintained and stored by a network of volunteer computers, so that no single institution. Because many computers have the records, it is much harder to change or fudge the data after the fact.
Many large global corporations have been studying how they could use a database.
[Confusedaboutblockchains?[Confusedaboutblockchains?Here's what you need to know.]
The blockchains being tested by companies, including the version adopted by Walmart, generally have nothing to do with Bitcoin or any cryptocurrency – they are all new databases with no coins involved. And unlike the Bitcoin blockchain, which can be viewed by anyone.
The system that Walmart is using, IBM Food Trust, has been developed for consumer companies, including Dole, Wegmans and Unilever, to track products moving through the supply chain.
People in the world, people who work for Walmart will make an entry on the blockchain, signing off when they receive it and then when they move into the chain. IBM and Walmart say they are already tracking other products like yogurt and poultry on the system.
Without any central authority in charge. But now, all of the records for the Walmart are being stored on IBM's cloud computers, for Walmart's use. That has led to questions about why a database like a blockchain is even necessary.
"The idea is right but the execution seems off," said Simon Taylor, the co-founder of 11: FS, a consulting firm that advises on blockchain adoption. "IBM took new technology that does not need to middleman and made themselves the middleman."
Ms. McDermott said that the data would be encrypted in a way that will make it impossible for IBM to access or change it.
More to challenge. A blockchain can capture the digital record of a box of spinach. But it can not tell if someone opened the box and changed the spinach inside, replacing it with arugula or illegal drugs.
"Blockchains will not protect you from fraud," Mr. Gerard said. "You need human inspectors who know the scams."
Walmart says its blockchain will allow it to track food from the field. It was possible to pinpoint which part of the field was harvested.
Mr. Yiannas said Walmart was focusing on the leafy green vegetables because, along with beef, they tend to have the highest incidences of contagion.
"We can bring trust to the system," he said.