If you bite into a granola bar and it has a disgusting, kind of fishy flavor, it’s probably because the oil in the nuts has oxidized. This is the kind of thing Dawn Chapman knows. A sensory and consumer scientist at the National Food Lab, she runs a team of 40 part-time testers who taste packaged foods—over and over again—to determine how long they stay tasty. “Anything in the grocery store, we’ve likely tested it,” she says.
The goal is to identify how much time can pass before a food no longer tastes good, which in turn dictates the sell-by date. Generally, foods are still safe to eat after that point, but they won’t taste as they were intended. Hiring people to eat food repeatedly until it’s certifiably icky can costs anywhere from $8,000 for a simple test to $100,000 for a more complicated, long-term evaluation. For the manufacturers of shelf-stable foods, the goal is the longest possible shelf life, while also making sure consumers don’t eat their products when they’ve passed peak quality.
At “the other NFL,” as the National Food Lab calls itself, Chapman, an applied statistician, has the job of quantifying based on the taste tests the not-always-pleasant characteristics of food samples as they age. On any given day, she works on projects ranging from mayonnaise and snack bars to frozen dinners and canned tuna.
Taste-testers are an elite bunch. In its last recruitment period three years ago, 150 people applied. The NFL accepted 15. (It’s only slightly less selective than the Massachusetts Institute of Technology.) Would-be testers were asked to describe, for instance, if a strawberry tasted fresh or jammy or artificial, or identify the scent of a cotton ball dipped in vanilla. This is harder than it sounds, Chapman says: People tend to be specific when they talk about, say, color—”If you point to something that’s blue and say it’s red, you’d be corrected”—but they are less exacting when describing flavor.
After a process that lasted about three months, Chapman’s testers were selected primarily for their skill in describing tastes and smells, but also for their willingness to eat food that may be rancid on any given day. All the testers happen to be women, some are homemakers. Some have had this gig for 20 years.
Only shelf-stable foods—those in cans, jars, and boxes—can touch the tongues of the testers. Such foods are processed to eliminate harmful microorganisms before they’re packaged, so they don’t pose a safety threat as they age. The NFL conducts roughly 25 such shelf-life studies per year, ranging from nine months to three years. A separate microbiology group judges the shelf life of fresh foods, such as refrigerated deli meats, based on the growth of microbes. There’s no tasting involved in the testing.
In two-hour-long sessions, the tasters sit at what looks like a partitioned study carrel (no cheating!) with a computer and a small hatch through which numerically labeled samples are passed from a kitchen on the other side of the wall. They’re given a score card to rate certain attributes of the food on a 15-point scale, from nonexistent to very strong. They don’t have to swallow—they also get a spit cup. Afterwards, they gather to discuss their results.
The problem in many foods, Chapman explains, is oil. As oils get rancid, they start to smell—first like cardboard, then like paint, and then fishy. This can affect any food with nuts, too, which contain oils.
In one session, a group might taste about eight different samples. Sometimes red lights are used within the testing room so the color of the sample doesn’t impact the taste feedback. But generally, the NFL uses lightbulbs that mimic northern daylight, which helps visual details stand out, says Chapman. The lab is also designed to have a higher rate of airflow to get rid of smells faster.
Tasters receive some samples that have only been stored at room temperature. Others have also been through “abusive temperature conditions” to simulate, for instance, what happens to a bottle of water accidentally left in a car trunk in a hot parking lot for a month—will the water taste like plastic (or hot trunk)? Sometimes the tasters test the same food every few months for years to determine how they change as they age.
While one of its more unique services, tasting for shelf life is only a tiny fraction of the NFL’s business. The panel also helps clients identify distinctive qualities of a product so they know how to market it or how consumers might react to an ingredient change. The lab also runs tests to help clients develop new food products or production processes, and it evaluates safety and quality (such as testing for contaminants), among other services.
“Not everything we taste is great,” says Chapman. Hopefully, those products never get past the lab.