The idea of "spray DNA" sounded very sci-fi when I first read it, until further investigation showed me how behind-the-times I was.
It is already used in stopping burglars (BB Feb. 2011), and now the technology of an invisible spray-on serial number is being leveraged in the fight against food fraud, a growing problem in a price-conscious world which is costing the food industry between $10-$50 billion a year according to food chain security firm Inscatech.
Making food traceable in the supply chain is the work of DNATrek, whose odorless, colorless, tasteless product DNATrax "is 100% safe and approved as an edible product by the FDA." There's no telling if consumers will have a problem with using a food additive in the fight against protecting them from food additives, but it's a tool we could use. With "Iron dust in tea and brick powder in chilli in India" (via Barfblog) or worse, last year's viral tale of "pig bung" being passed off as squid, maybe a little spritzer of traceable bacteria might be easier to swallow.