Food Storage Bags

From Cook's Illustrated | July/August 2014

Crummy plastic food storage bags leak, rip, and are tricky to seal. We wanted a strong, leakproof bag that would close securely without a fuss and keep food fresher longer.

Overview:

Why is it so hard to find a good plastic food storage bag? Too often the plastic is flimsy, the closure doesn’t work without a fight, and when you finally get it closed, it leaks. Then there’s the dizzying array of options. Do you need both “storage” and “freezer” bags? Do you want zipper locks or plastic sliders? Expandable bags for bulky foods or double-layer bags for extra protection? One thing, though, is clear: American consumers use a lot of these bags, spending $1.6 billion on them last year alone, according to Chicago market-research firm IRi. A few years ago we picked a favorite bag by Glad: a thick, protective freezer bag with an airtight double-grooved seal. Recently we received conflicting reports from the manufacturer about whether this product was being discontinued. Ultimately we decided that it could no longer hold our top spot, and we went back to the drawing board.

As in our previous testing, we focused on gallon-size bags, in which we store everything from herbs and cookie dough to meat and tomato sauce. We… read more

Why is it so hard to find a good plastic food storage bag? Too often the plastic is flimsy, the closure doesn’t work without a fight, and when you finally get it closed, it leaks. Then there’s the dizzying array of options. Do you need both “storage” and “freezer” bags? Do you want zipper locks or plastic sliders? Expandable bags for bulky foods or double-layer bags for extra protection? One thing, though, is clear: American consumers use a lot of these bags, spending $1.6 billion on them last year alone, according to Chicago market-research firm IRi. A few years ago we picked a favorite bag by Glad: a thick, protective freezer bag with an airtight double-grooved seal. Recently we received conflicting reports from the manufacturer about whether this product was being discontinued. Ultimately we decided that it could no longer hold our top spot, and we went back to the drawing board.

As in our previous testing, we focused on gallon-size bags, in which we store everything from herbs and cookie dough to meat and tomato sauce. We also opted exclusively for freezer bags this time, since past tests have taught us that freezer bags are generally made with thicker plastic, which can keep food fresh longer than the thinner plastic of storage bags. Our wish list: a bag that was easy to seal, leakproof, and durable and that excelled at protecting food. We bought eight products—four sold in supermarkets, two food-service bags sold in bulk via mail order, and two eco-friendly options. Five closed with zipper-lock tracks; three used sliders. Prices ranged from 10 cents all the way up to a staggering 49 cents per bag.

Holding the Bag

Our first criterion: simplicity. You shouldn’t need extra hands to prop up a bag for filling or have to guess if it’s really closed. Bags should swallow up plenty of food and still be easy to seal. To push the limits, we packed each bag with 4 pounds of large carrots. We were able to zip all the carrots into all the bags, and none poked holes in the plastic. But one bag had a petite zipper channel that was hard to match up, while another was tough to keep open because of its dual layers of flimsy plastic; plus, when we flipped over the edges of this bag’s opening (a handy trick to help prop open any bag), its side seams ripped. At least some bags came with useful features—one had a foldout bottom panel that helped it stand up and made it easier to fill. Two bags were particularly sturdy around the opening (one was made of sturdier plastic overall and the other had a wide band of thicker plastic around the top), which made them easy to prop open, and both had deep zipper channels that were effortless to seal.

Next we filled the bags with a gallon of water each and laid them on the counter, noting whether any leaked. To our chagrin, four bags bombed, leaking a few drops—or entire puddles—all over the counter. We didn’t imagine any of them would turn around and prove their worth (and indeed none did, all four falling to the bottom of our rankings by the end of our testing), but we forged ahead with them anyway.

Freezing Out

Our next benchmark: an airtight bag that protects the food. The development of freezer burn, indicated by the appearance of brownish-white discoloration on the food and snowy ice crystals, is a visible sign of likely failure in this department. It happens when frozen food dehydrates and oxidizes when it is exposed to air. We froze bags filled with bone-in pork chops, hamburger patties, cookie-dough balls, and sandwich bread. Within two weeks, several bags revealed icy crystals forming on the food, some of which got progressively worse. But in the top-performing bags, scarcely any snowy residue appeared, even after two months.

We sent the bags to a lab to measure their thickness as well as how fast moisture travels through their plastic, called the water vapor transmission rate. A lower, or slower, rate would indicate better protection. But when the results came back, they didn’t reveal a clear trend. Our front-runner, which exhibited only a little residue after two months, had the fastest transmission rate of all the bags, while bags with slower rates, which should translate to better protection, had food that iced up. What was going on? Well, if a bag has a leaky seal, it doesn’t matter how impermeable the plastic is.

So we devised a follow-up test that would also factor in the seal. We weighed desiccant packs (the moisture-absorbing packets found in product packaging), enclosed them in each bag, submerged the bags in water for a week, and then reweighed the packs. One product failed outright—we found the pack floating inside a water-filled bag. The packs in three other bags weighed about 1/2 gram more, indicating that some moisture had gotten in. But four sets—including in our front-runner—stayed remarkably dry, gaining only tenths or hundredths of a gram.

A Blowout Finish

Our last standard: bags that can hold up to abuse. We poured 3⁄4 gallon of tomato sauce into each bag, sealed the bags, and pushed them off the counter. While we don’t expect home cooks to throw around bags of sauce, bags can get knocked around in the fridge or freezer, and accidents do happen. Although four bags exploded, four—our front-runner among them— bounced to the floor without spilling a drop. And finally, we shook each bag briskly three times, both upright and upside down. Our top two bags didn’t leak even a dribble. Interestingly, in both abuse tests, all the failures but one happened at the site of the seal.

Our conclusion: While thick plastic helps, strong seals are more important. The seal on our runner-up, a commercial bag, never blew out; plus its plastic was the thickest in the lineup. It lost a few points in the desiccant test and burst a side seam during the extreme tomato sauce test, but it’s a reliable option if you want to buy in bulk. Our winner features a fail-safe dual zipper and a thick plastic collar that makes it easy to prop open and serves as an improved barrier to air. Leakproof and sturdy, it was also the cheapest bag we tested. And finally, we were pleased to find an environmentally friendly bag we can recommend, too.

Methodology:

We tested eight gallon-size freezer bags, evaluating freezer protection and whether they were leakproof, tough, and easy to handle. Scores were averaged and bags appear in order of preference.

FREEZER PROTECTION

We froze four bone-in pork chops, 2 pounds of ground beef patties, one dozen balls of frozen chocolate-chip cookie dough, and a half-loaf of white sandwich bread for two months, checking them after two weeks, one month, and two months for freezer burn and ice crystals. Bags that kept food in the best condition the longest received high marks.

DURABILITY

We pushed bags filled with 3/4 gallon of tomato sauce from kitchen counters and shook bags filled with 1 gallon of water (upright and upside down) to test strength. We checked for damage during routine handling.

LEAKPROOF

To assess bag permeability and the quality of the seal, we weighed packets of moisture absorbing desiccant, sealed them in bags, and kept the bags submerged in water for one week. Then we reweighed the desiccant packs. Drier packets rated highest. Bags also lost points for leaking when filled with 1 gallon of water and laid flat on counter.

EASE OF USE

We preferred bags that were sturdily constructed, making them easier to prop open to fill, and that were easy to securely seal even when very full.

THICKNESS

The thickness of a single wall of the plastic bags, measured by an independent laboratory, in mils (1∕1000 of an inch).

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  • Product Tested

    Results Key:

    Good ★ ★ ★ Fair ★ ★ Poor
  • Prices are subject to change.
  • Highly Recommended - Winner

    Ziploc Brand Double Zipper Gallon Freezer Bags with the Smart Zip Seal

    Frozen food stayed fresh in this bag even after two months. Its band of thicker plastic extending 2 inches below the zipper provided structure that made for easier filling and offered an extra barrier of protection. Its double zipper helped it remain leakproof and stand up to abuse.

    • Leakproof ★★★
    • Durability ★★★
    • Ease of Use ★★★
    • Freezer Protection ★★★

    $3.99 for 30 bags ($0.13 per bag)

    BUY NOW Amazon
  • Highly Recommended

    Elkay Plastics Ziplock Heavy Weight Freezer Bag

    With the thickest plastic in the lineup and a tight seal, this bag provided excellent protection. Frozen cookie dough and pork chops had virtually no ice crystals and were fresh-looking after two months. A side seam split when we dropped this bag (full of tomato sauce), and the bag let in a little moisture when we submerged it.

    • Leakproof ★★½
    • Durability ★★
    • Ease of Use ★★★
    • Freezer Protection ★★★

    $9.69 for 100 bags ($0.10 per bag), plus shipping

    BUY NOW Amazon
  • Recommended

    Green’N’Pack Food Storage Freezer Gallon Bags

    This eco-friendly bag, designed to biodegrade, performed well, though it didn’t quite match our top bags. Frozen food stayed in excellent shape for a month but began to show a few signs of ice crystals after two months. Its seal could be a little bigger and stronger.

    • Leakproof ★★½
    • Durability ★★
    • Ease of Use ★★½
    • Freezer Protection ★★½

    $11.90 for 30 bags ($0.40 per bag)

    BUY NOW Amazon
  • Recommended

    Diversey, Inc. Ziploc Commercial Resealable Gallon Freezer Bags

    This food-service version of our winner just wasn’t as good. Frozen foods stayed in very good condition for the first two weeks but then began showing moderate amounts of ice crystals. While it has dual zippers like our winner, it lacks that bag’s collar of thicker plastic, which meant it was not as easy to handle and delivered less freezer protection.

    • Leakproof ★★★
    • Durability ★★
    • Ease of Use ★★½
    • Freezer Protection ★★

    $34.99 for 250 bags ($0.14 per bag), plus shipping

    BUY NOW Amazon
  • Recommended

    Hefty Slider Bag, Gallon Freezer

    Frozen food quickly acquired a moderate amount of “snow” around the edges. This bag claims to have “a stronger seal than Ziploc bags when shaken, dropped, or stacked,” and it tied our top-ranked Ziploc when dropped and shaken, but its zipper leaked. It was also a bit too floppy.

    • Leakproof ★★½
    • Durability ★★★
    • Ease of Use ★★
    • Freezer Protection ★★

    $3.29 for 13 bags ($0.25 per bag)

    BUY NOW Amazon
  • Recommended with Reservations

    Ziploc Brand Gallon Freezer Slider Bags

    We really liked this bag’s gusseted, expandable bottom, and foods stayed in good condition in the freezer. We only wish its sliding seal were stronger: It failed during abuse testing, dripped when full, and let in some moisture when submerged.

    • Leakproof ★★
    • Durability
    • Ease of Use ★★★
    • Freezer Protection ★★★

    $2.49 for 10 bags ($0.25 per bag)

  • Not Recommended

    Natural Value Slider Gallon Freezer Bags

    Frozen food became icy after two weeks; meat showed gray freezer burn spots after a month. The bags themselves are not particularly “green,” as their manufacturer admits, but the box is made from recycled materials. While the bags survived abuse testing intact, the seal leaked when full of water.

    • Leakproof ★★½
    • Durability ★★★
    • Ease of Use ★★
    • Freezer Protection

    $2.35 for 10 bags ($0.24 per bag)

  • Not Recommended

    Ziploc Brand Double Guard Double Layer Gallon Freezer Bags

    This pricey double-layer bag claims to provide a better barrier against freezer burn; we found it only middling. Floppy and flimsy, this bag was also hard to fill and its weak seal burst during abuse tests. The side seams above the zipper ripped as we filled bags and leaked steadily when filled with liquids. We found our desiccant packs floating inside the bags.

    • Leakproof
    • Durability
    • Ease of Use
    • Freezer Protection ★★

    $6.37 for 13 bags ($0.49 per bag)

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