The Best Way to Freeze Food in Glass Pyrex Containers

Glass storage containers are an excellent choice for freezing because they’re quite durable compared to plastic. And they don’t leach nasty byproducts when reheated (also compared to plastics).

Here’s some best practices though for using Pyrex glass containers in your freezer(s). Because yessssss girl, you can stack your deep freezer (or upright freezer) with these if you are into batch cooking at home. 10/10 would reccomend.

Pyrex is the trade name (I think) you might be most used to hearing. And as I was learning about freezing glass, I discovered Pyrex used to be manufactured by Corning. You know ’em. Bet your mom had a lil white casserole dish with 3 blue flowers on & a clear glass lid.

But when Corning sold it off it became pyrex (with lower case font) in America. This type of pyrex is made with soda-lime glass. The European version PYREX (with capitol font – how confusing ahahaha) is made of borosilicate glass.

Both have a high durability factor, but it’s said the European version is stronger than the soda-lime version in America. 🤷🏽‍♀️

Anyway, this post will apply to other glass food storage container systems like those made by Anchor or OXO too. I actually have taken a liking to Anchor lately myself. Compare brands side-by-side by reading through The Spruce Eats article on the glass food prep & organizing systems; it’s pretty informative!

Benefits of Freezing Food in Glass Pyrex

The borosilicate glass dishes ability to withstand extreme temperature changes also makes them ideal for heating in a microwave oven or preheated oven. 

Just don’t introduce sudden temperature changes because that comes with a higher risk of breakage! It’s called thermal shock & should be avoided.

Just like in the case of canning, you’ll want like to like temperatures. Frozen glass containers coming to room temp first before loading them with boiling hot food. This applies to washing them too! Don’t take a frozen glass container & immediately run it under hot water. It could shatter!

Non-toxic & Transparent

Unlike some plastic containers & plastic lids, glass food storage containers like Pyrex don’t leach chemicals into your food. That’s important if you value health and safety along with flavor.

So what I love about freezing foods in glass is that after defrosting, I can warm my foods directly in their vessels! For instance, I’ve put casserole pans straight into the oven to reheat (or finish off cooking), like in the case of my homemade lasagna which I love batch cooking.

The clear glass makes it easy to see what you have stored without opening the containers. And THIS alone is worth some gold.

Eliminating that guessing game when doing your freezer inventory is incredible. I used to hate coming across unlabled ziploc bags of something freezer burned beyond recognition.

Save the time and effort & use mason jars or glass casserole dishes to store food. But still don’t forget to label it, especially because you might not be the only one pulling something out to eat!

Versatile & Beautiful

Pyrex containers can transition seamlessly from the freezer to the oven or microwave. And that gives you added flexibility in meal preparation & batch cooking.

The real convenience is that you won’t have to dirty up another vessel or tray. What you cook in, it can cool in, then it can be stored in. It’s a 3-for-1 deal! Now ain’t that somethin’ to shout about?

And if you’re not using extra dishes, you’re not leaving food behind in them which means you’re minimizing food waste too, girl! Check you out!

But who can deny the timeless beautiful of a good glassware container? 😍

They retain their value as long as they aren’t cracked or damaged. And they come in a variety of sizes (often times colors too, or at least their lids do). So there’s truly one for every occasion.

And… they aren’t prone to discoloration like plastic food storage containers are; that’s good stuff!

How Freezing Food Preserves It

So, let’s talk about why you’re freezing food in the first place. Other than that’s just the first use everybody & their momma thought of growing up. (After the invention of actual freezers that is).

Freezing food is a great way to preserve your meals and ingredients for a long time. We can’t dispute that.

When food is frozen, the lower temperature slows down the growth of bacteria, yeast & mold, generally all undesirable things. And this decrease in microbial activity is what ensures food safety.

So freezing food in glass pyrex containers also maintains the nutritional value of the food. When you freeze fresh food, you lock in that flavor & the texture usually keeping your food in good condition while extending its shelf life.

That makes this method one of the best ways to enjoy seasonal produce year round. So whether you’re freezing tomato sauce, liquid foods, or any other of your favorite healthy foods, always use a container with an airtight seal for the best results.

Best Practices for Freezing Food in Glass Pyrex

Some good questions about using pyrex glass to freeze food can be answered by following best practices.

And if you do so, you’ll enjoy the highest quality in your food & also the best care of your glass storage containers. 

I think of these as assets in a well-equipped, self-sufficient kitchen. And if you want access to wholesome, comfort food all the time – you’ll need more than a couple to make it happen.

After all, the vessels we use to serve & share meals at the family table are just as much part of the memory as the food! That’s why you instantly thought of that little white & blue flowered dish when I mentioned it earlier.

Whether moms had a bajillion she was probably gifted in the 80’s or not, it was a staple at the table.

1. Cool before freezing.

Don’t take food straight out from hot water or high oven heat & then try to put it in the freezer. No, no, no. And no.

This is just begging for thermal shock (or mechanical shock). You should always allow hot food to cool (at least to room temperature) before placing it in the freezer. That shock is usually caused by putting a hot Pyrex dish directly into the freezer which can cause the glass to crack due to extreme temperature changes.

But you know what they don’t tell you? It also overworks your freezer. It’s trying to cool that dish down, putting your other frozen foods at risk of partially defrosting before the fresh dish is frozen.

Not cooling can also introduce the risk of deformation. So, it’s crucial to let hot glassware cool to room temperature before freezing.

Simply place hot dishes on a cooling rack (for optimal airflow) and allow them to reach a cool surface temperature before storing. This is also something to keep in mind when you pull a glass dish off a direct heat source to place it on a hard surface or even metal surface like a stainless steel trivet.

No cooling rack? No problem. Use a dry cloth to prevent the same thermal shock from happening from direct contact with a potentially cool item.  

2. Leave space for expansion.

Liquids expand when they freeze & if you don’t know that, you might overfill your jar. Make sure to leave plenty of room at the top of the jar or Pyrex dish. This is known as headspace.

And the headspace rule is one reason some people suggest only freezing in wide-mouth jars (or wide-necked jar) that have no shoulders. The thought is that using a jar without a narrow opening will prevent this.

But, if you overfill, that becomes irrelevant hello. Either way, leaving a good amount of headspace will ensure your good food freezes properly. (For what it’s worth, I freeze in both styles of jars all. the. time.)

3. Use airtight seals.

Even if you don’t though, avoid using a non-watertight product since it probably won’t provide the necessary protection your frozen lasagna needs. Don’t half do the job or you’ll get half-ideal results. And no one wants meh food, amIright? I’m right.

4. Label & date.

I preach this everywhere! For the best answer to keeping track of your frozen foods, label and date any food you freeze in glass pyrex containers.

This helps you know the shelf life of each item and ensures you use it while still in good condition. You should also track this sort of data in a kitchen logbook.

I think it’s a good idea to write the date (at least) on the top of the jar or the most prominent place you see at a glance so you don’t have to go searching for it.

You can even put the types of food or instructions on how to re/heat food when ready. All this because you may not be the only one pulling food out the freezer.

If we’re creating kitchens that encourage other family members to be there & cook or bake, we gotta make it easy for them to do that. Labeling isn’t just for you. It’s for them too. So your husband can make a homemade meal one night just because. So your teen can surprise you with breakfast in bed someday.

5. Gradual temperature changes.

When ready to use the frozen food, thaw it gradually in cold water or in the refrigerator overnight. Again, trying to avoid thermal shock here.

Despite being a glass product that holds up well to high (& low) temperatures, avoid placing a cold Pyrex container directly into a hot oven, microwave oven or pre-heated toaster oven.

Keep your temperatures alike. Cold dishes in cold glassware into a cold environment to defrost. Likewise, don’t place cold Pyrex directly into a hot dishwasher either. Hot glassware to cool to room temperature or very low heat first.

This is best practice – you may skate by without any pretty consequential damages but the wear on your cookware over time may make this scenario more likely to occur. So don’t tempt fate.

Extra Tips to Freeze Food in Glass Pyrex

1. Smaller Portions: Freeze food in smaller portions for quicker freezing and thawing. This also allows you to use just the amount you need without defrosting the entire container. So if you absolutely despise leftovers, this makes that nearly irrelevant. And if you hate reheating food more than once like me, it’s great for that too.
2. Avoid Overfilling: Similar to above, resist the temptation to overfill your Pyrex containers. Leave space for the food to expand as it freezes to avoid cracking the glass. Yes. Even food may expand (because remember there’s usually a good bit of liquid in most foods. That would expand.)
3. Stacking: Pyrex containers are great for stacking, but be mindful not to overload your freezer with too much weight. That can restrict air circulation and affect the freezing process.
4. Freezer Safety: Ensure your freezer is set to the correct temperature (0°F or -18°C) to keep your food safe and properly preserved.
5. Avoid Abrasive Cleaners: Clean your Pyrex dishes with care to avoid scratches. Using abrasive cleaners can damage the smooth surface and increase the risk of cracks. Stick to gentle, non-abrasive cleaners to maintain the integrity of the soda lime glass or borosilicate glass you’re gonna love so much.

Key Take Aways