Dear EarthTalk: Many foods like tuna and pet foods that formerly were sold only in cans are now available in “pouches” as well. Is this kind of packaging less harmful to the environment or just cheaper to make for the seller?

Food pouches, which are made from a combination of food-grade aluminum foil, plastic and adhesives, do appear to have some front-end environmental advantages over the cans they are increasingly replacing on supermarket shelves. However, they are not as easily recycled.

Food pouches take up far less space and weight (in both warehouses and on supermarket shelves) and are simpler to manufacture than tin-coated steel cans. Minneapolis-based flexible packaging manufacturer Kapak Corporation reports that one truckload of the pouches it makes has the same holding capacity as 25 truckloads of traditional rigid containers (cans), and saves as much as 96 percent in warehouse storage space. The company also says its pouches use 75 percent less energy than cans to manufacture, and that they reduce the amount of source materials needed to make cans by a factor of 25 to one.

According to Anthony Andrady, author of the 2003 book, Plastics and the Environment, the pouches used to store Whiskas cat food require 30 percent less retorting time (retorting is the process of pressurizing the interior of the vessel to ensure it is sterilized) than the 10 ounce steel cans they replaced because the pouch can be heated more evenly and quickly. “That translates directly into reduced energy use for the retorting process and probably into a decrease in the amount of cooling water required as well,” he says.

On the down side, most of these pouches, despite their upfront advantages, are destined for the landfill once they are empty because their multi-material construction makes them difficult to recycle. Some manufacturers, like California-based Flex Products Inc., are working on variations of the pouch that are less complex and inherently more recyclable than what’s on supermarket shelves right now, but such products may be years away from widespread adoption. Nevertheless, technological improvements could make recycling of pouches more feasible in the future.

In contrast, the tin-coated steel cans that tuna and pet foods usually come in are both easy to recycle and are likely to have been manufactured with a large percentage of recycled steel to begin with. In fact, most steel used in the U.S. today contains a large percentage of recycled material (and creating new steel cans from recycled materials uses only about a quarter of the energy needed to produce them from raw materials). And steel cans are not just recycled to make new cans; they provide raw material for a variety of steel products, including bicycles, car parts, washing machines, refrigerators and tools.

Still not sure what to do (it is a tough call)? Perhaps Cook’s Country magazine’s cans-versus-pouches tuna taste test will break the tie: The magazine tested eight brands of solid white albacore packed in water (the most popular tuna variety), and canned tuna took four of the five top spots. The main reason given by samplers was bigger and meatier chunks of fish in the cans, compared to the “mushier, less appealing texture” of the tuna in the pouches.