I spent a number of years at a past employment situation working on a product that most people think is a pretty good idea - a time-temperature indicator for perishable food. Simply put, it was a small label that would change color to indicate that the food had reached the end of its shelf life and should be disposed of. It was sensitive to both time and temperature, as both of these (and the interplay between the two) affect the quality of food - even properly refrigerated milk will eventually spoil [*]. Such a product is far better than the printed date codes that never change when a product is thermally abused.
While I do think that the product was a good idea, it's one of those products that will never see the light of day unless it is mandated by the government. Why? Well, follow the money.
Here in the US, groceries are a very low margin business, typically just a few percent. So even if a label costs just a few pennies, that will wipe out the profit margin of the grocer unless they raises their prices, and there is no way that one grocery store will do that if their rivals won't, especially on low end foods like milk and ground beef. Beyond that, food distribution in this country consists of the producer, a distributor, the grocer and the consumer. For a label such as this to be useful, everyone in the chain has to agree to participate in the game, otherwise no one can. While the largest grocer in the US (Walmart, yes, Walmart) may want the label, rest assured they will not pay for it and will be loathe to be stuck with the "shrinkage" that occurs if the label goes off in their stores. They will make sure to blame the expired label on the distributor or the producer or whoever else, and fights will quickly ensue.
The product that I helped develop underwent a gradual color change, which we thought was a good attribute. (Contrast the gradual color change with one that occurred suddenly: for any one in the food chain buying the product, it would just like playing Russian roulette). However, with the gradual color change, we knew that consumers would look through the products for better less-changed labels, much like they currently pick through product for better shelf-life dates.
Despite have very simple, robust technology that was inexpensive, (far better than any competitive products out there at the time or developed in the last 10 years since then), management could see that they product would never make it and so they killed the project.
I was reminded of all this when I saw this report late last week about an novel oxygen sensor that will tell when food, in this case, whole cuts of meat, should be tossed. While the physics and chemistry are different, the economics in the food industry are the same. Nobody will decide who will pay for the label and nobody will decide who will pay for the spoiled product. Sadly, I can state that this product is DOA.
[*] You are actually integrating k ti exp(Ea/ R Ti), where k is Arrhenius equation prefactor, ti is the ith temperature interval with corresponding temperature Ti, Ea is the activation energy and R is the gas constant. By the way, we did this integration using adhesive tape and sandpaper (Eat your heart out, MacGyver!)