Are Ziploc Containers Airtight?

July 6, 2022
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Preventing Oxidation and Spoilage with an Airtight Seal

Ziploc is one of the most recognizable brands of resealable bags ranging from sandwich bags to portioned ground beef in the freezer or just a simple bag of snacks. They’re great for storing food to keep it from spoiling longer than it usually would. However, this doesn’t mean your food is safe from spoiling for long, as even properly sealed bags are not airtight.

This is a problem because the more food is exposed to air, the more it will oxidize, which increases the rate of bacteria growth in the food. The solution is to find a food storage container which is airtight.

How Does The Air Get In?

  • The plastics used to make Ziploc bags are permeable, meaning that over time moisture and vapors can pass into the interior. The bags are made of polyethylene, which is the most commonly used plastic in plastic packaging. Think about when you leave a water bottle in your car for a few days, water and moisture begin to build at the top because it is evaporating through the plastic.
  • Most Ziploc seals have small spaces within the grooves of the seal where air can slowly slip in.
  • While odors are trapped in the bag, they can still escape or enter through those same small spaces along with the seal of the bag

Ways To Make Plastic Bags Airtight

There are numerous ways to make your ordinary Ziploc bags airtight. One simple way is by partially sealing your bag and then placing the majority of the bag into a container of water before fully sealing it. This causes the water inside the container to press on the bag and push the remaining air out through the unsubmerged seal. This won't stop air from reentering the bag through the seal.

If you want to ensure that all your bags are airtight, you can invest in a vacuum sealing machine that heats the seals of the bag shut to keep air from entering. This won’t stop vapors from permeating through the plastic, depending on what type of bags you use. Vacuum sealing is certainly more effective than using a plastic container with a lid if you're looking for long term storage options.

A cheaper method is to freeze your bag. If you submerge your bag fully into the water for the first 30 minutes of the freezing process, it will ensure that there is no air sealed inside.

To counteract air from getting back into a sealed bag, you could tie off the seal like you would a bag of bread. If you want to be safe, you can wrap the entire bag in aluminum foil to prevent anything from permeating through the plastic.

Plastic Containers With Lids

Certain foods only take minutes to experience the effects of oxidation, like when the inside of an apple begins to brown when left out in the open air. Since plastic bags are not fully airtight or long-lasting, it is much better to use a quality plastic container.

Plastic containers with lids are usually much more airtight than plastic bags, thus keeping food safe from oxidation and spoiling for longer. There are several types of methods used by lids to seal a container. However, the mechanism does not matter as much as the quality of the plastic and the lip itself. The quality directly affects how strong the seal between the container and the lid will be.

You can tell if you're working with effective airtight containers by filling the container with water and then holding it upside down. If no water leaks out, that means that you have a good seal and you're in possession of an airtight container. The better the seal, the safer your food is from oxidation.

Buy Plastic Containers

Pretty much any grocery store has a section for plastic containers and kitchenware. Fortunately, they are also pretty affordable.

It is much better to invest in plastic containers than plastic bags since they last longer and are not wasteful like bags, which you will eventually have to throw away. Not to mention they are better at keeping food from spoiling for longer.

Bulk Plastic Containers

If you want a lot of bang for your buck, bulk containers are a great choice.

  • 12 oz deli cups are a great way to portion out ingredients or condiments for later use
  • IUME meal-prep containers are microwavable and are great for packing lunch
  • Variety packs like 32-piece food storage sets have many uses and are far more reusable and non-wasteful

All of these products have (nearly) airtight lids.

Ziploc Containers

Just like a Ziploc bag, a Ziploc Container isn't completely airtight - but it is close enough for short duration food storage purposes. So while not 100% airtight, they're a great option for your weekly meal prep or for keeping your leftovers fresh for a few days in the refrigerator.

Ziploc Twist 'N Loc Containers are said to be leak proof - and able to block out air and lock in the freshness of the food that you're sealing. They're even safe for the freezer - which can help prevent - or at least delay freezer burn from affecting your food.

A Ziploc Twist ‘N Loc Container - Which Also Doubles as a Piggy Bank in this Video

Many plastic containers are prone to losing their seal over time - especially when exposed to heat and cold - which can expand and contract the plastic of the container and lid - which can have a negative effect on the seal.

Ziploc Twist 'N Loc Containers are dishwasher safe - meaning that they're probably less likely to lose the effectiveness of their seal after being exposed to heat.

Ziploc Endurable Containers Can Survive Large Temperature Changes and Remain Intact

Hefty Plastic Containers

If you’re looking for something far more sturdy and durable, the Hefty brand of plastic containers is for you. It should be pointed out that most Hefty containers are unintended for food storage. Moreover, they’re perfect for storing belongings such as clothes, old electronics, etcetera. These containers are ideal for storing extra belongings or for packing up to move.

Hefty does manufacture resealable food storage bags with high-quality slider seals. However, as stated above, these plastics are permeable because on a microscopic level they are porous. This means that vapors can seep through the plastic and eventually oxidize the food. Furthermore, the grooves along the slider seal do not keep air out entirely either.

BPA Free Plastic Containers

BPA plastic containers are a horrible health hazard for many reasons, so it is ideal to look for BPA-free plastics. Recently manufacturers have tried to produce more BPA-free plastics. However, several recycled plastics containing BPA are still used today, and not all manufacturers have stopped using them.

Your safest bet is to look for products specifically labeled BPA-free, but in the absence of a product label, you can check the recycle code if there is one. Codes 1, 2, and 5 are known to be BPA-free, while 3 and 7 have a high chance of containing BPA.

Note that plastics with low levels of BPA are not considered dangerous by the FDA. However, intake of BPA can lead to severe or even life-threatening health problems, so is it worth the risk?

BPA Plastic Containers

BPA is an acronym for Bisphenol A. It is a chemical that has been used in the manufacture of plastics since the 1950s. You will find BPA in water bottles, baby bottles, and other food storage containers. Bisphenol is an ingredient of the protective epoxy resin that lines the plastic and breaks down in the presence of heat. Plastics that usually contain BPA are hard and see-through.

It has been shown that BPA can be transferred onto food when heat is applied to the plastic, especially in a microwave or dishwasher. As stated, heat breaks down the resin coating the plastic, which gets transferred to the food. Ingesting BPA can cause grave problems to your health which include:

  • Fetuses, babies, and children can have their hormone levels disrupted
  • Babies and children can also have their brains possibly affected according to research
  • There is evidence that supports the possibility of BPA ingestion linked to an increased chance of cancer
  • It can cause heart problems and lead to increases in blood pressure
  • There is research that supports a correlation to cases of type 2 diabetes

There are potentially many more risks associated with the ingestion of BPA. It is a no-brainer to avoid any plastics containing BPA because why would you ever want the risk of these side effects, in addition to the fact that BPA is another factor on why these plastics are hazardous to the environment.

Glass And Plastic Containers

There are several pros and cons to both a glass container as well as plastic food storage containers. Plastics are more favorable for convenience, while glass food storage containers are safer, reliable, and longer-lasting.

A mason jar is glass storage option that is highly effective at preserving food. If you remove all air from the glass jar, you can obtain an airtight seal which preserves the contents of the jar.

A Rubbermaid container that is glass and is said to be 100% airtight (according to Rubbermaid) - is the Rubbermaid Brilliance. These are glass containers that are not only airtight, but they're able to withstand relatively high oven temperatures (up to 450 degrees Fajrenheit).

Plastic containers are great for storing food on the go because they’re lightweight and won’t break when dropped, making them perfect for children’s lunches. Since plastic containers are hard to break you can stack and store them virtually any way you want. Glass is heavy and can crack or shatter when too much weight is applied or it is dropped.

Rubbermaid Brilliance Airtight Containers

Since plastics are porous materials, gasses and vapors that pass through the plastic can mix with and carry hazardous chemicals from the plastic onto the food. Plastics are easily warped, discolored, or melted by heat. This makes it potentially hazardous to microwave foods in plastic or to place them in a dishwasher, as these can also cause plastics to contaminate your food.

If you care about the environment, glass is the way to go, as only specific plastics are recyclable after being thrown out and the rest are left in landfills for several years because they’re non-biodegradable. All glass is entirely recyclable as long as it is disposed of properly.

Glass is a solid, non-porous material, meaning that it is far more airtight than a plastic bag because nothing can permeate through it. Glass is also far more heat-resistant so it is entirely safe to microwave, wash with hot water, and certain types can even withstand an oven.

Frank Salvatore

Hey there - I'm Frank Salvatore. I created this site as a comprehensive kitchen resource. You'll find everything you need to know about everything in your kitchen. From appliances to utensils and layout - it is covered on this site!

About Me
Frank Salvatore
I created this site as a comprehensive kitchen resource. You'll find everything you need to know about everything in your kitchen. From appliances to utensils and layout - it is covered on this site!
Learn More About Me
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