How to Freeze Food in Glass Jars

The following post is from Katie of Kitchen Stewardship:

source: Katie Kimball

UPDATE: Here are some glass-breaking tips and the honest-to-goodness-true best way to freeze food in glass jars.

It seems that every day a new report comes out on the dangers of something or other toxin in various materials, doesn’t it? Bisphenol-A in plastics is one of the more recent villains that’s really stuck around, even in mainstream media and conversation.

Although plastic number 5 (PP, or polypropylene) does not contain BPA, some folks have become nervous about using plastics for food storage, period. What will be the next new evil to come knocking?

For the sake of space, I do often freeze foods in plastic zipper bags (no. 4 plastic, no BPA), but I try to put as much as I can in glass jars. It can be a bit of an art form, so I’ll share the vastness of my frozen jar knowledge here today.

Where to Find Jars

In my opinion, free is the best price going. I tend to save nearly every glass jar that comes into my home, especially these helpful sizes:

  • spaghetti sauce (3 cups)
  • mayonnaise (nearly 4 cups)
  • peanut butter (1.5 cups)
  • salsa and pizza sauce (often 1.5-2 cups)
  • ½ gallons from honey
  • purchased quart-sized canning jars are also handy, especially because of the wide mouth
  • pickles

NOTE: It usually works to remove the pickle smell by filling the jar with hot broth; the broth’s flavor doesn’t suffer, and the jar is “cured” of its pickle-ness after that. Attempt at your own risk!

Our 5-year-old neighbor gazed at my pantry shelves the other day in awe, saying, “Your pantry is way different than ours. We don’t have that many glass jars…”

What to Freeze in Glass Jars

The world is yours, of course – anything you can freeze can go in a glass jar – but my most common choices, made for nutrition, frugality, and convenience, include:

  • leftover soups and side dishes
  • summer fruits like strawberries and peaches, sliced and sweetened

Most of these items help the environment, too, because I’m not having to ship, purchase and recycle so many cans of food.

How to Choose the Right Jar

Since your frozen goodies have to be thawed before adding to recipes, it’s nice to know how much you need to pull from the freezer the night before (and even nicer if you don’t have to measure before adding to a recipe).

I always try to freeze appropriate and varied sizes from the beginning.

  • For “one can” of beans or broth, freeze in approximately two cups, like salsa or peanut butter jars. Sometimes I like the tall salsa jars because they fill the space on the bottom shelf of my fridge-top freezer just right.

A confession: I often freeze beans in plastic cottage cheese and sour cream containers, just because it’s so easy to slide them out still frozen. (Those containers are generally number 5, and I don’t put anything in when it’s hot.)

  • Many soup recipes call for 4-6 cups broth, so I like to freeze broth in 3 c. spaghetti sauce jars, 4 c. quart jars, and even ½ gallon jars. The great thing about broth and soup is that you can eye things up and estimate. :)
  • Pizza sauce is perfect in old pizza sauce jars or salsa jars (about 2 cups)
  • Leftover soups are great in any size jar. I’ve found for a family of four, you’ll usually need two 3 or 4-cup jars for leftovers night if the soup is the main course.
  • Pureed veggies should be in one-cup portions, so think small jars like olives and relish.

The Importance of Headroom

When freezing in glass jars, the most important step is to make sure you leave enough headroom to prevent broken jars.

For a quart jar of liquid, leave at least an inch empty at the top. I like to leave a little extra; better safe than sorry! I freeze cooked beans without the liquid so I don’t have to drain them later, so they can go right to the top. Treat pizza sauce and refried beans like a liquid, with plenty of headroom.

How to Thaw Food in Glass Jars

Putting the jars in the refrigerator for two days is the easiest but takes pre-planning. Most of the time if I’m in a hurry or only have overnight, I’ll leave the jar on the counter for at least a few hours to get things started.

If you need something right away, the microwave will do fine on medium to low power (without the metal lid, of course!), but if you choose not to use a microwave, you can set a jar or two in a pot of water and bring it to a gentle boil, then a simmer, to thaw the contents of the jar. I recommend a washcloth on the bottom of the pot to prevent rattling.

Regardless of the thawing method, if you’re using a wide-mouthed jar and get the outside inch thawed, you can usually slide the contents out into the pot and heat five extra minutes to thaw out the soup/beans/sauce.

Labels and a List

You save yourself very little if you can’t remember what’s in your freezer and end up wasting it because it sits there for two years. It’s a vital and simple step stay organized by:

1. Labeling everything you freeze

2. Maintaining a list of what’s in your freezer

On glass jars, you’ll find that permanent marker on the jar comes off too quickly to be of any help. I recommend writing the date and contents on the lid of the jar and simply crossing off the old and writing in the new when you reuse the jar.

There are many ways to keep your freezer contents list organized. Personally, I’ve found that I like categories which help me figure out what I need to use in my meal planning.

Mine include:

  • meats
  • leftovers/meals for later
  • beans
  • broth
  • cheese
  • breads/dough
  • veggies/fruits
  • baked goods/desserts

And Sometimes…The Jars Still Break

It’s a big bummer. I know the secret of headroom, but every so often the freezer fairy decides to throw me a challenge with a cracked jar. (I’ve only broken one jar of not-yet-frozen food…turkey broth ran all down inside my chest freezer! Tip: let it freeze, then chip ice off with a plastic scraper or spoon.)

Make sure that you follow whatever the FDA recommends about broken glass and food products if this tragedy ever happens to you. Don’t ever, ever do what I do. I’m a trained professional (talker) and not always wise! It is certainly not safe to consume food from broken glass jars.

That said, I will tell you my personal experience with broken jars.

Refried beans and thick soups are common culprits, and I’ve accidentally left homemade yogurt in the freezer longer than the two hours I planned and broken some jars. If I can pull the jar into large pieces once the lid is off, I’ll do so. Left with a cylinder of frozen food, I admit I have been known to rinse it well, carefully inspect and feel the outside for glass, thaw in a bowl and serve to my family. Clearly, you should never follow my lead. Clearly.

In spite of the physical hazards, I choose glass jars because they are non-reactive and often free.

Other resources:

  • Little glass jars are awesome for homemade dressings, easy-to-grab nut snacks, and single serve yogurts or applesauce

What’s your favorite way to save food for later? What tips do you have for freezing in glass?

Katie Kimball has been “green” since 5th grade when she read 50 Things Kids Can Do to Save the Earth. She remains slightly disappointed that she didn’t actually save the whole thing back then, but now that she has 3 kiddos counting on her, she keeps plugging away hopefully. Katie blogs at Kitchen Stewardship about real food and natural living and is the author of Healthy Snacks to Go and other eBooks, available for Kindle.
  • Barbara Davis

    Good article. You’ve confirmed my thoughts exactly about freezing in glass. I plan on freezing (instead of canning) 20# of Colorado Western Slope Palisade peaches when they arrive in late August. At first I was going to use the various plastic containers I’ve “hoarded” but thought again. Why am I doing this when I’m SO against against plastics of any sort? (Time to just get rid of them to the recycling plant.) But I’ve always been hesitant to freeze in glass. Good to know you’ve had success with it and I’m going to go ahead a do it. Oh yes…I’d be the one to go ahead and use the frozen cylinder of food too after inspecting it carefully, of course.

  • Anca

    Great tips! I found them inspiring, I’ll use them to start freezing in jars and get rid of the plastic containers I used so far.

  • Melinda

    How well do re using baby food jars work? I want to purée some different things for my son. TIA