27 Sep 2018 --- Rapidly pinpointing potential food contamination is one of the major virtues of blockchain – that’s why US retail giant Walmart is lauding the benefits of tracking lettuce and spinach through the supply chain using this burgeoning technology. The move is aimed at seriously ramping up food safety following US outbreaks of E. coli in romaine lettuce and salmonella in a number of products from eggs to breakfast cereal.