How to Freeze Food in Glass Jars

Frost on a glass jar

Norman Posselt / Getty Images 

It's plastic-free, zero-waste, and most jars can be scrounged for free. What more could you want?

Whenever I'm in need of some zero waste inspiration, I poke around the Zero Waste Chef website. Run by Anne-Marie Bonneau, it's packed full of brilliant ideas for eliminating disposables from your life and using cheap, accessible reusables as an alternative – in other words, not spending a fortune on fancy 'zero waste' containers!

Case in point: Bonneau's dedication to freezing food without plastic. Check out the amazing pictures of her freezer, filled with frosty-looking jars of all shapes and sizes. She makes a point of collecting all the jars she can get her hands on and putting them to good use.

Freezing Without Plastic

Freezing food without plastic is a topic that confounds many people who are new to zero waste living. We've become so accustomed to wrapping everything in plastic, assuming that we have to use a Ziploc bag to ensure that nothing breaks, leaks, or gets freezer burn. But Bonneau's freezer is chilly proof that it doesn't have to be that way. Ordinary jars – no special glass required – do a fabulous job, as long as you treat them right.

She offers a few basic precautions. First, do not overfill and always leave headspace (room for expansion as contents freeze). Wide-mouth jars are a safer choice. Second, don't stack your jars willy-nilly in the freezer, as this increases the likelihood of one falling out when you open the door. I would add, too, to make sure that whatever you're freezing is fully cooled before putting it in the freezer.

Using Jars

Bonneau freezes everything in jars, including cooked beans (with or without liquid), roasted tomatoes, lemon zest, sourdough crackers, seasonal fruit (that she has picked and pre-frozen on a cookie sheet before putting in a jar), vegetable scraps and chicken bones for stock, leftover whey from making ricotta (which she adds to soups and warms for making pizza dough), tomato sauce, and more.

The biggest drawback I find with jars is needing to plan ahead. You can't just pop a frozen jar in a bowl of hot water to thaw it out for quick use, the way you can with a Ziploc, because the thermal shock could break it. Also, a greater percentage of the contents needs to be fully thawed before it will fit out the mouth of the jar, unlike, say, a yogurt container that you can squeeze to get the contents out. But these are minor inconveniences and, really, most people concerned with reducing waste (food and non) in the kitchen are already thinking about their cooking processes well in advance.

All this is to say, don't be afraid to give jars a try in the freezer. Start with small solid items if you're nervous, and slowly work your way up to jars of stock and soup. When in doubt, look to the Zero Waste Chef!