But the bad reputation goes beyond just the food that comes inside those cans. It's also because of things like the growth of farmers' markets in the last 20 years; influencers like California's Alice Waters and Michael Pollan, who've encouraged eating locally-raised fresh foods over processed foods; BPA linings; and scary accounts of things like botulism told by well-meaning grandparents.
So the million dollar question: Is that bad reputation deserved?
History of Canning
First let's back up and talk about canning foods as a whole. Canning was born out of a search for convenience and efficiency. A French candy maker and chef, Nicolas Appert, developed the process at the end of the 18th century. His original process isn't very different from the canning methods used today.
Appert put food in bottles and jars, covered them with cork and wax, and processed the jars in boiling water. The French government paid Appert to make his process public, and that led to the first cookbook on canning. Appert's process spread quickly. Not 20 years later, the British Navy fed sailors the first meat, soups and vegetables that were canned in tin instead of jars.
During World War II, governments in a number of countries, including the U.S. and the U.K., promoted home canning. The U.S. printed and distributed circulars and opened thousands of canning centers to help home cooks preserve food grown in home gardens. Canning became patriotic, supplementing bland rations and keeping people fed.
In the 1950s, commercially canned and other packaged foods were introduced as nutritious, time-saving modern conveniences. A popular cookbook, The Can-Opener Cookbook by food editor Poppy Cannon, promised readers they could open some cans and cook a gourmet meal without really knowing how to cook. (The recipes included roast canned chicken flambé with black cherries — made with a whole canned chicken — and another meal made of canned hamburgers covered with fried onions and red wine, baked in a casserole dish for 20 minutes.)
Canned food was promoted and seen as better than fresh, especially as industrial agriculture began to incorporate more fertilizers and chemicals. The author of The Can-Opener Cookbook wrote that the flavor of fresh tomatoes was bad, and that for real tomato flavor, you should open a can.
Fifty-ish years later, canned tomatoes are still an off-season go-to for tomato lovers and cooks. And there's no beating the convenience of a can of beans, already cooked and ready to go into a salad, soup, dip or another dish.
The Process of Canning Today
From a nutrition standpoint, the canning process today is designed to preserve as many nutrients as possible. Canning happens within hours after fruits and vegetables are picked.
"Fresh fruits and vegetables are harvested at the peak of ripeness and canned within only four hours, sealing in their nutrition and flavor," Sherrie Rosenblatt, vice president of marketing and communications at the Can Manufacturers Institute, says in an email. "The proximity of field to packaging facility, and the efficiency of modern canning facilities locks in nutrients at the peak of ripeness just hours after harvest."
The heat from canning does decrease some of the water soluble vitamins, like Vitamins B and C. What can make canned food bad nutritionally is salt and sugar added during the process. (Experts suggest rinsing canned food to reduce some of the added sugar and salt, or buying low-salt and low-sugar products.) And, of course, the cooking that happens during canning changes the texture of vegetables — regrettably so in the case of those canned asparagus.
But that heat is a plus when it comes to food safety. Remember we mentioned our grandparents' stories of botulism (and aversions to dented and swollen cans)? Well those are based in real fear of death. Botulism is caused by a bacterial toxin so deadly, just a millionth of a gram is enough to kill. And the United States and other countries even explored botulism as a biological weapon during World War II.
C. Botulinum spores are everywhere, but people associate botulism with canned foods because the bacteria reproduce in low oxygen environments — like a poorly processed can. Today, commercial canned foods go through what's called a botulinum cook, a high-heat cook that dramatically lowers the chance that any C. Botulinum spores — or other organisms that can cause foodborne illnesses — survive.
Canned Foods and BPA
The most recent concern about canned foods, however, isn't the food; it's the cans and what they're lined with, including Bisphenol A (BPA). Over the past two decades, public attention has focused on BPA, the chemical used to make polycarbonate plastics and epoxy resins. In 2008, the U.S. government's National Toxicology Program concluded there was concern about its effect on our brains, behavior, and prostate glands of fetuses, infants and children. Other studies have linked BPA to cardiovascular disease, obesity, asthma and diabetes.