Better Living Through Can Science

Manufacturers add “best by” dates to many canned-food labels, but if a tin of salmon is “best by Dec. 30,” does that mean it’s still OK to eat or donate it Jan. 31?

In a word, absolutely.

Experts have affirmed canned foods’ nutritional value, even compared to fresh. In fact, frequent canned-food use was found to be “positively associated with nutrient-dense food group consumption and higher nutrient intakes” in the U.S., according to a 2015 study. And they’re “more economical to boot,” says Michigan State University Professor Steven R. Miller.

Still worried about that “best by” date? Read on for all the reasons to put those fears to rest.

Age Is Only A Number

Thanks to modern packaging techniques, which prevent pathogens and other microscopic nasties from proliferating, canned food lasts essentially forever at normal storage temperatures. “They have found canned food that was over 75 years old, and it was still safe to eat,” says Steve Smith, a lecturer who ran the Food Science Pilot Laboratory within Purdue University’s Department of Food Science. Case in point: a vintage 1934 can of corn, unearthed in California decades later, that scientists determined was just like recently canned corn in taste and smell (the only difference they noted was slightly lower levels of some vitamins).

The End Game

You’ll find a variety of lid types on today’s cans beyond the standard can end: full-panel pull-outs, easy-open beverage tabs and peel-away membrane seals. All of these are equal in terms of their superior ability to protect food, says Smith. “The seals are hermetic and won’t allow microorganisms or even oxygen into the container.”

Crown’s PeelSeem™ technology, for example, uses heat to securely affix a thin, flexible panel to a rigid steel or aluminum ring. Its Peelfit™ design also uses heat, but it adheres aluminum foil to a collapsed bead within the can body rather than to a steel ring. To further ensure quality, Crown offers onsite training programs that give food brands step-by-step guidelines for safe and efficient sealing.

It’s What’s On The Inside That Counts

And what about rust and dents? They’re usually superficial, says Smith. Because today’s cans have strong seams and practically impenetrable linings, only under rare circumstances are these anything but cosmetic concerns. At Ball Corp., for example, can manufacturing is a complex and finely calibrated process that includes adding “beads” to cans to make them more resistant to collapse and using lights to check the cans for possible pinholes or other damage. A cured protective inner coating and final camera inspection further ensure product quality and safety.

Click image to see a larger version.

The Silver Lining

Smith notes that certain markers of quality such as texture and flavor can change with time, but the extent of that varies by product and acidity. For example, he says meats and vegetables have especially long shelf lives. The more acidic fruits and juices stay tasty for longer these days thanks to advances in can linings that keep the contents from reacting with the metal.

Air Unapparent

One of the best ways to maintain quality is by limiting oxygen. “Oxygen can change flavor, color and vitamin content,” says Smith. “So, we want to limit oxygen. We do this by creating a vacuum in the can.”