And how it goes bad.
Avoiding unseen food hazards is the reason people often check the dates on food packaging. And printed with the month and year is often one of a dizzying array of phrases: “best by,” “use by,” “best if used before,” “best if used by,” “guaranteed fresh until,” “freeze by” and even a “born on” label applied to some beer.
People think of them as expiration dates, or the date at which a food should go in the trash. But the dates have little to do with when food expires, or becomes less safe to eat. I am a microbiologist and public health researcher, and I have used molecular epidemiology to study the spread of bacteria in food.
A more science-based product dating system could make it easier for people to differentiate foods they can safely eat from those that could be hazardous.
The FDA considers some products “potentially hazardous foods” if they have characteristics that allow microbes to flourish, like moisture and an abundance of nutrients that feed microbes.
These foods include chicken, milk and sliced tomatoes, all of which have been linked to serious foodborne outbreaks. But there is currently no difference between the date labeling used on these foods and that used on more stable food items.
The piece notes that infant formula is currently the only food product whose “use by” date is actually scientifically determined and therefore, y’know, actually useful. The determination there is concerned mainly with the breakdown of nutrients, protein in particular. Other food items? Eh, not so much.
Determining the shelf life of food with scientific data on both its nutrition and its safety could drastically decrease waste and save money as food gets more expensive.
But in the absence of a uniform food dating system, consumers could rely on their eyes and noses, deciding to discard the fuzzy bread, green cheese or off-smelling bag of salad.
That’s always been my go-to method. My guiding principle when it comes to answering the “should I eat this, or no?” question is pretty simple: with most foods, if it’s bad, you’re definitely gonna know it. In fact, when it comes to things like spoiled meat, rancid milk, or moldy cheese, it’s pretty hard to miss. Lettuce or other salad greens that are mostly brown, wilted, and funky-looking? Yeah, no. Raw eggs that have sat neglected in the fridge a while? The tried and true “float” test has never failed me yet. Such tests might not be molecular epidemiology, but it’s good enough for most of us.