The figures may be a little past their sell-by date, but in 2010 the Grocery Manufacturers\u2019 Association put the cost of food fraud, including counterfeiting and economically motivated adulteration, at over $10 billion \u2014 a significant sum in what was then a $2.1-trillion industry.\nTo protect customers and to back up claims about the quality of their products, supermarket chains need to be able to trace the provenance of ingredients back through the supply chain all the way to the farm.\n\n[ Cut through hype to find out which blockchain pilots are showing enterprise promise and where blockchain is poised for a big-business breakout. | Get the latest on emerging technologies and digital transformation by signing up for our CIO newsletters. ]\n\nCarrefour, a French supermarket chain with 12,300 stores in over 30 countries, has been working on food traceability for years with an ad-hoc mix of information stored in its own ERP systems and those of its suppliers, as well as on paper and in the databases of auditors. Now the company is making the data more accessible by migrating it to a blockchain.\nWith information scattered across various systems, it could take as long as two days to obtain full details of a specific batch of products from a food processor or distributor, but these days consumers want assurance at the push of a button or the scan of a QR code.\n\u201cWith the blockchain, the information is available right away,\u201d says Emmanuel Delerm, director of organization and methods at Carrefour France.\nIt\u2019s not a panacea, though: If you don\u2019t already have confidence in the data you gather, then blockchain won\u2019t help you. \u201cBlockchain is not a replacement for quality and traceability; it's just a plus in terms of sharing and gathering of the information,\u201d says Delerm.\nChickens as pilot project\nCarrefour initially weighed two blockchain platforms, Hyperledger and Ethereum, when it first began looking at the technology.\n\u201cAt that time Hyperledger was on Version 0.6, which was not offering all the services we needed, while Ethereum was already very stable,\u201d says Delerm.\nAround May 2017, a team formed to install Ethereum on Carrefour\u2019s Microsoft Azure cloud. A key concern, given that data would be provided by, and accessible to, users outside the company was controlling access, \u201ceverything concerning security and user administration, certificates and so on,\u201d he says.\nThe team also paid attention to the user experience for suppliers and supermarket customers, and to the APIs through which it provided access to the blockchain. \u201cThe idea from the very first was to say, no extra work for the farmer or the industrial firm or the veterinarian. The impact should be as limited as it could be,\u201d Delerm says.\nCarrefour\u2019s first blockchain application was to modernize the traceability of free-range chickens sold under its Carrefour Quality Line brand. The goal was to track the birds from farm to supermarket shelf and package each one with a QR code that customers could scan to see where it was raised, what it was fed, and when and where it was slaughtered.\nThe company used smart contracts written in Ethereum\u2019s Solidity language to validate the data it gathered about the chickens. For example, a smart contract can check whether chickens meet the quality requirements of the French \u201cLabel Rouge\u201d certification, which requires chickens to be at least 81 days old when slaughtered. If the difference between the date of slaughter and the hatching date already recorded for that batch is less than 81 days, it will issue a warning.\n\u201cWe are putting in place some extra consistency checks on the data we are ingesting, but not refusing the data, which is quite important in terms of philosophy,\u201d says Delerm.\nThe quest for scale\nBy the time Carrefour put its chickens on the blockchain in January 2018, it had plans for Carrefour Quality Line eggs, tomatoes and pomelos to follow. But with Ethereum, that would mean building separate blockchains for each product line.\n\u201cIn January we said, well, Hyperledger is now on Version 1.0 or 1.1, it\u2019s really working, and they are offering some new features that are very interesting for us,\u201d Delerm says. In particular, its \u201cchannel\u201d capability, which enables a subnet of blockchain users (such as those involved in a particular product line) to communicate privately with one another.\n\u201cIf we can have multiple products on one blockchain but not visible one from the other, it\u2019s really a plus in terms of maintenance, of availability and so on.\u201d\nHyperledger also offered support for consensus mechanisms such as Byzantine Fault Tolerance, and proved somewhat faster at ingesting data, he says.\n\u201cThe mining even on a private blockchain with Ethereum was, let\u2019s say, 15 seconds. Now, 15 seconds is not a big deal if you are entering a few items each day, but we were talking about millions of products sold every year so, at the end, 15 seconds was not very efficient,\u201d Delerm says.\nPlus, Ethereum smart contracts were proving hard to write, as it was easier for Carrefour to find developers versed in writing smart contracts in JSON or Go than in Ethereum\u2019s Solidity, he says.\nAs Carrefour began work on its second in-house blockchain, though, it became apparent that scale would be a problem. Putting its own-brand products on its own blockchain is one thing, but to modernize all its food traceability work, Carrefour would need to get national brands such as Nestl\u00e9 on board.\nEnter IBM, which has used Hyperledger to build its own food traceability service, IBM Food Trust.\n\u201cWe saw very quickly that Nestl\u00e9 was not going to connect to one blockchain with Carrefour, another one with Walmart and a third with Tesco, for instance,\u201d Delerm says.\nLikewise, Carrefour didn\u2019t want to have a different blockchain platform for each supplier. \u201cBecause blockchains are not very easy to interoperate, the idea of installing or being part of IBM Food Trust was interesting.\u201d\nBuilding on its blockchain experience\nCarrefour announced its participation in IBM Food Trust in early October, joining early adopters Walmart and Kroger, and their suppliers Nestl\u00e9, Tyson Foods, Dole, and McCormick. The move was simplified by the early attention paid to interfaces.\n\u201cIt\u2019s not very complicated to reuse some of the APIs we developed for Ethereum,\u201d says Delerm. \u201cThese are the same codes, except that IBM is not using the same grammar in terms of data collection. It\u2019s not a big deal.\u201d\nAnother thing Carrefour has reused is its experience of putting products on the blockchain. \u201cWe have been developing methods to try to industrialize the approach,\u201d Delerm says. \u201cAll the functional analysis was completely reused.\u201d\nThis enabled Carrefour\u2019s Spanish subsidiary to put some of its chickens on IBM Food Trust in November.\nCarrefour is keeping its internal Hyperledger blockchain running too, for own-brand products. A shipment of pomelos on the way from China will carry QR codes that will display traceability information in French or Chinese depending on the default language of the smartphone used to scan them. Next year, it could work in English too.\nWhen it comes to putting all these products on the blockchain, technology is the easy part, according to Delerm: \u201cThe challenge is in the very deep understanding of your supply chain, of the way your product is made.\u201d\n\u201cFor us,\u201d he says, \u201cthe key success factor was being able to find people within Carrefour \u2026 who knew the chicken business well, and were able to explain what\u2019s important, who the key actors are, what type of data we can gather.\u201d\n\nMore on blockchain:\n\n Blockchain pilots show big-business promise \n Blockchain is poised for a big business breakout \nWhat is blockchain and how does it work?