Plastic Food Storage Containers

Published May 2010

How we tested

Packing up leftovers ought to be easy, but food storage containers are one of life’s persistent little annoyances. Once you dig through a slippery stack of containers to match tops and bottoms that aren’t too stained or warped, you have to fuss over them for a tight seal. Then comes another series of quandaries: Does it fit in the fridge or freezer? Will it leak if it tips over? Can you microwave in it? Do you have to remember to wash it only on the top rack of the dishwasher? Should you worry about possible health risks with plastics containing bisphenol-A (BPA)? Frankly, we don’t think food storage containers should take this much thought or effort.

In search of a caveat-free bottom line, we bought eight 8-cup rectangular and square containers made from purportedly safer BPA-free plastic (most manufacturers, with the notable exception of Tupperware, have produced new lines without this controversial material, which research has linked to health issues including hormonal disorders and cancer). We submerged, froze, refrigerated, and microwaved them. We dropped them and ran them through dozens of dishwasher cycles. Then we did all the tests again. In a separate series of tests, we tried out three containers made from glass, a worry-free yet heavy and breakable alternative to plastic and its reported health risks.

No Drips

A few decades ago, Tupperware set the food storage standard with seals that close by pressing all around the rim. Today’s trendsetter is Snapware: You put the lid in place and snap down flaps that project like wings from the lid. Five of the eight plastic containers we tested use this newer snap seal; manufacturers hoping to woo converts to this style pledge simpler, tighter, leakproof technology. To test their claims, we filled each container with chicken soup and shook them. Five of the eight containers (including one traditional and two snap seals) kept us dry, but three dribbled. Next, we filled containers with pie weights and sugar and sank them under water; two kept the sugar bone-dry, only one of which also passed our soup test. Not that you’ll be scuba diving with your leftover lasagna, but tighter seals—and so far snap seals were performing at least as well as traditional seals—keep food fresher.

That said, not all snap-type seals are alike. All lids contain a soft silicone gasket embedded in a groove around the perimeter of the lid, but their construction and the flap design determine how tightly and—more important—how evenly the gasket can seal. It mostly comes down to a ridge on the underside of the lid: On better models, this ridge completely encircles the underside, distributing the pressure evenly when the snaps click into place, while leak-prone containers have only sparse sections of ridge, if any.

Easy Does It

Speaking of clicking into place, some containers were easier to close than others. Some took force to snap—threatening pinched fingers—and a lot of wiggling to align the lid. One particularly fussy unit wouldn’t close unless its lid was fitted in a particular (yet poorly indicated) direction. All you want here: a container whose flaps slip into place neatly and firmly.

Besides a snug lid, there are a few other practical concerns. First, odor absorption. Nobody wants a container that smells like yesterday’s tuna salad, so we refrigerated oil-packed tuna for three days, ran containers through the dishwasher, and sniffed. One of the “disposable” supermarket containers retained a whiff of fish. Most of the glass and polypropylene containers were fine.

Second, a truly convenient storage container should cope with the freezer or microwave without warping, melting, or staining. We froze chili, then microwaved the containers until hot. We detected no plastic scents or flavor, but one “disposable” container softened and then rehardened as it cooled (would we really like to eat that chili?); another’s snap flaps warped—and then wouldn’t lock. Chili stained them all, but a few dishwasher cycles removed most traces.

Third, a storage container is serviceable only if it fits in the prescribed storage space. After weeks of cramming containers into freezers and refrigerators, we preferred low, flat rectangles that slide onto any shelf, leaving room for other items, and simple, stackable flat—not bulbous—lids. But there’s also a food-quality reason to opt for flat: more efficient chilling and heating. After 24 hours in the freezer, water in tall containers was still liquid at the center but frozen solid in lower, flatter models. In the microwave, the chili in deep containers overheated at the edges before heating through in the middle.

Time Will Tell

All these features should be basic to a new container, but a really good one should retain them over time. We put our lineup through 50 home-dishwasher cycles to simulate about a year of use, noting which came with top-rack-only instructions. Then we repeated our tests—and found disparate results: All our heating, chilling, and washing had damaged a few models, warping their lids and loosening their seals. The only container to pass both leak tests the first time did so again, but only after painstaking efforts to lock the seal, indicating a lack of durability. Meanwhile, some brands—including our three top-rated containers—actually sealed better. Polypropylene is extruded and molded to make these containers, and heating can correct small irregularities.

One container worked nicely out of the box, survived all our tests, and met all our long-term goals. Our winner sealed tightly and easily; resisted warping, stains, and smells; and fit easily among the contents of our refrigerator. It performed well before taking more than 50 baths—and perfectly afterward. This might be the last container we’ll have to buy for quite a while.


We tested eight BPA-free plastic (according to manufacturers) food storage containers, choosing square or rectangular sizes as close as possible to 8-cup capacity. All were purchased online or in Boston-area retail stores.


We filled the containers with chicken noodle soup and shook them vigorously for 15 seconds, then filled them with sugar and pie weights and submerged them in water for two minutes. Containers that didn’t leak in the soup test and that kept their contents dry when submerged received high marks.


We refrigerated oil-packed tuna in each container for three days, then ran containers through a home dishwasher and checked for odors.


We filled containers with chili, froze them, and reheated them in the microwave, checking for warping, staining, and plastic flavors or odors.


After testing, including 50 cycles in a home dishwasher, we observed stains, warping, and wear and tear; then we froze water in the containers and dropped them from chest height.


We considered features that made the containers easier to use, including simple, intuitive seals or efficient shapes.

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The Results


Design Trifecta 360 Knife Block

Admittedly expensive, this handsome block certainly seemed to live up to its billing as “the last knife block you ever have to buy.” The heaviest model in our testing, this block was ultrastable, and its durable bamboo exterior was a breeze to clean. Well-placed medium-strength magnets made it easy to attach all our knives, and a rotating base gave us quick access to them. One tiny quibble: The blade of our 12-inch slicing knife stuck out a little.


Schmidt Brothers Downtown Block

This roomy block completely sheathed our entire winning knife set using just one of its two sides—and quite securely, thanks to long, medium-strength magnet bars. Heavy, with a grippy base, this block was very stable. An acrylic guard made this model extra-safe but also made it a little trickier to insert knives and to clean; the wood block itself showed some minor cosmetic scratching during use.


Schmidt Brothers Midtown Block

This smaller version of the Downtown Block secured all our knives nicely, though the blade of the slicing knife stuck out a bit. With a base lined with grippy material, this block was very stable. An acrylic guard afforded extra protection against contact with blades but made it a little harder to insert knives and to clean; the wood itself got a little scratched during use.

Recommended with Reservations

Swissmar Bamboo Magnetic Knife Block

This small, scratch-resistant model had a stable, rubber-lined base and could hold all our knives, though the blade of the 12-inch slicing knife stuck out a bit. But inch-long gaps between its small magnets made coverage uneven and forced us to find the magnetic hot spots in order to secure the knives. Its acrylic guard made it safer to use but harder to insert knives and to clean.

Not Recommended

Messermeister Walnut Magnet Block

This handsome block was done in by its shape—a tippy, top-heavy quarter-circle that wasn’t tall or broad enough to keep the blades of three knives from poking out. It lacked a nonslip base, and its extra-strong magnets made it unnerving to attach or remove our heavy cleaver. Finally, it got a bit scratched after extensive use.


Epicurean Standing Knife Rack 12"

This magnetic block sheathed all our knives completely, though with a bit of crowding. But it was hard to insert each knife without hitting the block’s decorative slats on way down, and because the block was light and narrow, it wobbled when bumped. Worse, we couldn’t take it apart, so splatters that hit the interior were there to stay. Additionally, the outside stained easily, and when we wiped it down, the unit smelled like wet dog.


Kapoosh Rondelle Knife Block

This model stabilized knives with a mass of stiff, spaghetti-like bristles that shed and nicked easily after extensive use, covering our knives with plastic debris. While all our knives fit securely, several of the blades stuck out, making this unit feel less safe overall. Finally, though the bristles could be removed and cleaned in the dishwasher, their nooks and crannies made this block hard to wash by hand.


Kuhn Rikon Vision Knife Block, Clear

This plastic block required us to aim each knife into the folds of an accordion-pleated insert that was removable for easy cleaning but got nicked easily with repeated use. Because we could only insert the knives vertically, longer knife blades stuck out; a cleaver was too wide to fit. The lightest model in our lineup, this block was dangerously top-heavy when loaded with knives.