Major companies are increasingly using blockchain technology to improve food safety and product recalls, as well as to boost supply chain transparency so that consumers get a closer look at food's long and complex journey from farm to fork.

Walmart Inc., Carrefour SA, Koninklijke Ahold Delhaize NV and Nestlé SA are among those that have begun to use blockchain — the technology that powers the bitcoin cryptocurrency — to trace food back to its source within seconds instead of days or weeks. The speed enables companies to quickly investigate the origin of contaminated food, certify the organic provenance of their products, improve shelf life and reduce loss from spoilage. While companies have previously used other types of software to track their food supply chains, blockchain's advantage is that it can digitally store and send secure data from multiple parties in such a way that it cannot be tampered with.

"It provides the capacity to create trust in the system," said Brigid McDermott, vice president at IBM Food Trust, in an interview. "It's the missing piece of the puzzle" in the traceability of food supply chains.

Global food supply chains are mind-bogglingly complex. For a head of lettuce to travel from a farm to a salad bowl, it must go through a dozen or more handoffs — from farmer to processor to distributor to delivery company, which might then use a ship, plane or truck to dispatch it to a retail store, where it is purchased by the consumer. Multiply this process by 70,000 — the number of food items typically stocked by a grocery store — then add to it the cross-border nature of food distribution, and the enormity of the tracking task becomes apparent.

Blockchain is a method of recordkeeping that is open to users. When data gets entered into the chain, other computers in the network are notified. Because the change in information is open for all to see, the information is very hard to falsify. More accessibility means more accuracy, greater trust and, crucially, faster access to information. This is vital when it comes to tracking down the origin of, say, salmonella in a shipment of eggs.

Because large food companies often share producers, processors and distributors, blockchain offers another benefit: everyone can use the same system, and yet sensitive data can be kept secure. "When you have Walmart and Kroger on the same system, how do you trust that Kroger can't see Walmart's data and vice versa?" says McDermott. "With blockchain, you can do it."

In Aug. 2017, IBM Food Trust, owned by International Business Machines Corp., said it was teaming up with Unilever PLC, Nestlé, Tyson Foods Inc., Walmart, The Kroger Co. and other food giants to champion blockchain for supply chains. IBM's system stores data about harvests, food processing, packaging and shipping on a secure blockchain network. All participants, from growers, suppliers, processors and distributors to retailers, regulators and consumers, can quickly learn the origin and state of food in their transactions.

Since its launch in October 2018, more than 4,600 facilities have been connected to the network, over four million transactions have been entered onto the blockchain and nearly three million packaged food products have been traced via IBM Food Trust. One early tester was Nestlé, which used the system to track the multiple fruits, vegetables and other ingredients from different countries that end up in some of its Gerber baby food products.

"We are using blockchains in North America when we source pumpkins from farmers," said Benjamin Ware, Nestlé's global head of responsible sourcing, in an interview. "In the future, we want to pilot blockchain in trade channels such as palm oil, where there are six to seven intermediaries between a plantation and Nestlé, and six to seven more between Nestle and [a supermarket] like Tesco PLC."

Walmart also tested the technology. Using old-style tracking systems, "it took Walmart six days, 18 hours and 26 minutes to trace a package of sliced mango from its store back to a farm," said McDermott of IBM. But when the mango trace was tested on IBM's blockchain system, "we did it in two seconds."

On Sept. 28, 2018, following a large U.S. outbreak of E. coli in romaine lettuce that sparked food contamination fears, Walmart wrote to suppliers of fresh, leafy greens, requiring them to use IBM's blockchain to track their produce all the way back to the farm. "Our suppliers are expected to ... enable end-to-end traceability back to farm by September 30, 2019," the retail giant said in its letter.

French supermarket chain Carrefour says it is using IBM's blockchain on its "Quality Line Auvergne chicken," of which it sells a million each year, and is also rolling out the system for tomatoes, eggs, cheese, milk and Norwegian salmon. The company expects to extend it to all 100 Quality Line products by 2022. Separately, Carrefour Spain has a plan to certify antibiotic-free chicken with a QR code for consumers to see the data, and Spanish fish products maker Angulas Aguinaga has also joined the blockchain system, according to IBM.

Other software providers have spotted the opportunity, too. A small U.K. firm called Provenance is using blockchain to help British food retailer The Co-Op track fresh produce from origin to grocery shelf. Dairy Farmers of America Inc. — the world's largest milk processor — recently teamed up with food technology startup Ripe.io to test blockchain in its vast supply chain.

In September 2018, Albert Heijn, the biggest supermarket chain in the Netherlands and a unit of Ahold Delhaize, said it was using blockchain from privately held Supply Chain Information Management to make the production of its own-brand orange juice completely transparent to consumers. "Through a QR code on the packaging, they can track the entire route traveled by a bottle of orange juice, from the grove to the store shelf," Albert Heijn says in an explainer posted on its website.

The blockchain captures a wealth of data along the complicated, nine-step route that the orange juice takes. The journey starts at Brazilian plantations owned by LDC Juice that are certified to be deforestation-free, then moves to the plant where oranges are pressed for juice, turned into concentrate, and then transported to the port of Santos. From there it is on a two-week boat journey to Gent, Belgium, and then on to the Netherlands by truck. Water is added to the concentrate, as well as vitamin C to ensure that the color is maintained. The juice is pasteurized, packaged, labeled and eventually sent to an Albert Heijn supermarket. At every step of the way, a trove of information is added into the blockchain: when the oranges were picked; their level of sweetness; working conditions in the plantation; processing period; transport time; sensory smell, color and taste tests; and the control of the sweetness-acidity ratio.

"Transparency in the chain is becoming increasingly important," said Marit Van Egmond, commercial director at Albert Heijn, in a statement. "We know all the steps that our products go through to ensure that they are produced with respect for people, animals and the environment and we want to show these steps to our customers, in an open and transparent way."