BENTONVILLE, ARK. — Walmart Inc. expects suppliers of leafy greens to implement blockchain technology to ensure traceability and food safety. Suppliers to the retailer are expected to have programs in place by September 2019.

Blockchain technology uses digitized data shared in a network that is secure and trusted by all parties in the supply chain. Walmart said use of the technology will allow it to more accurately and rapidly identify food safety issues.

“Our customers deserve a more transparent supply chain,” said Frank Yiannas, vice-president of food safety. “We felt the one-step-up and one-step-back model of food traceability was outdated for the 21st century. This is a smart, technology-supported move that will greatly benefit our customers and transform the food system, benefitting all stakeholders.”

Walmart said it has been testing the technology and has successfully developed a blockchain-enabled traceability network. In the letter to leafy-greens suppliers, the retailer said it expects producers to be able to trace their products back to farms by production lot in seconds rather than days.

Salmonella outbreaks infographicIn explaining its rationale for implementing the program, Walmart referenced the recent multistate outbreak of E. coli O157:H7 associated with Romaine lettuce that caused over 200 illnesses and 5 deaths.

“We have to go further than offering that great food at an everyday low price,” said Charles Redfield, executive vice-president of food for Walmart. “Our customers need to know they can trust us to help ensure that food is safe. These new requirements will help us do just that.”

Walmart is not the only food company testing the blockchain concept in its supply chain. Cargill, Minneapolis, has been testing the program. This past January, during a presentation at the International Dairy Foods Association’s annual Dairy Forum, Mike Robach, then vice-president of food safety, quality and regulatory affairs for Cargill, called the technology “fantastic,” but added that it is a challenge to get all of the players in the supply chain engaged.

“You’ve got to incentivize the whole of your supply chain to get involved,” he said. “For us that means we have to figure out how to incentivize a cocoa farmer in Ghana to participate.”

Cargill has implemented blockchain in its turkey business unit. Mr. Robach said the company chose that business because it was an easy process the company controlled. He predicted using blockchain to trace such commodities as corn, wheat and soy will be much more difficult.