Mason jars can be extremely useful in the kitchen. You can either save empty containers from shop-bought goods or buy them in whichever sizes you want. Saving old ones makes a lot of sense as it helps to reduce waste and doesn’t cost you anything extra.
If you’re wondering… Can you freeze in mason jars without breaking them? Then the answer is yes, absolutely.
Whether you like to batch cook, make your own stock or keep leftovers in the freezer, mason jars are handy for any of those reasons. It’s convenient and toxin-free.
Freezing in plastic might leach chemicals into your food, which can be carcinogenic and harmful to your family. BPA, a common component of plastic products is suspected of leaching into food and affecting the brain and prostate gland of fetuses, infants and children. You do get an increasing number of BPA free products, but there are still other chemicals that lurk around plastic containers, which is why many are proactively choosing not to use plastic wherever possible, especially for staring food.
So back to freezing in mason jars.
What Type of Foods can you Freeze in Mason Jars?
Foods that freeze well generally can go into mason jars if you don’t overfill them. Items such as berries and fruits freeze well. If you’d like to make sure everything does not stick together you can freeze them by spreading them out on a baking sheet and then placing them into jars once frozen.
Leftovers and sauces such as soups, stews, fruit purees and baby food work well. It’s a good idea to only part cook bulky items such as lasagne, pizza and pies so that you don’t overcook them while reheating. You can even freeze uniced cakes and sponge type deserts. Vegetables should be blanched (boiled briefly and cooled quickly) before freezing.
Bread, biscuits and pastry dough, butter and pre-shelled nuts all freeze well.
Juice, cheese and milk can also be frozen quite easily. Grated cheese is a bit better as a solid block will need more time to evenly defrost in the fridge once you’re ready to use it.
Portioning foods before you freeze them is a good idea as it’s usually difficult to separate or portion food that is frozen at home as individual bits have a tendency to stick to each other as you may know. And unfortunately, re-freezing items such as meat once defrosted isn’t recommended so planning ahead can be super helpful.
Foods that don’t freeze well include leafy vegetables, tomato, salads, jellies, cooked eggs, mayonnaise, low-fat dairy etc.
Quick Tips for Freezing in Glass Mason Jars
It’s quite easy to end up with broken mason jars if you’re not mindful or aware of what might be breaking your precious jars filled with beautiful goodness. Breaking jars can be avoided with a few easy steps:
1. Make sure you cool the contents of the jar before freezing, it is a good idea to cool the food before adding them into the jar as well to avoid burning yourself if you spill the contents. Warm foods freeze more quickly and can aid breaking of the jars, which we don’t want!
2. Don’t fill the jar to the top, about 3/4 of the way will be adequate. If you’re using a jar with “shoulders” don’t fill above them. Most newly bought jars will give you an indication of how much to fill them for freezing. Liquids will expand when they freeze generally so give foods a bit of space to do so
3. If you’re worried about by how much you’ve filled the jar, put it in the freezer without a lid and then close it once frozen. You can also put the lid on loosely at first so that some air can escape and firmly close once frozen. Be sure to place the jar on a saucer just in case if you’re leaving it open
4. Use wide-mouthed mason jars for freezing like these from Ball, who have been making canning jars since the late 1800’s (it’s probably the one your grandma may have used for canning).
5. Make sure you’re using jars that can be frozen like these from Ball as mentioned, or if you’re saving shop-bought jars the ones the twist-off cap jars used for honey, jam, fruit, pickles, sauces or other vegetables will work well. Tempered glass containers will also work well for freezing.
6. Don’t cram it into the freezer. Leave a bit of space between the jars and other items or the freezer sides so that it doesn’t touch other frozen items as the varying temperatures can cause problems for your jars
7. Add a label, with a date so you remember what’s inside and how long it’s been in there as frozen foods can look similar at times and it’s so easy to forget what is what! These labels are quite handy for labelling food.
Defrosting your Frozen Mason Jar Treasures
If you are planning on defrosting, placing your frozen items in the fridge and leaving it overnight is a great option. Alternatively, leave the sealed container in lukewarm (not boiled) water to defrost or pop it in the microwave. I’d avoid refreezing most things especially raw meat and fish unless you’ve cooked it once it’s been defrosted.
How Long Can you Leave Frozen Items in the Freezer
This depends on how brave you are, I’ve personally forgotten about foods in the freezer for ages and still cooked it and it was fine. Meat that has picked up freezer burn is not nice once cooked so I’d take it out before that happens. Dairy products and fish is recommended for a month or so. Have a look at this article for a guide on recommended freezing times.
Cooking Foods from Frozen
To get the foods out of your jars, leave them in the fridge or in a bit of warm water so that the sides can loosen. Most items, other than joints of meat or poultry, can be cooked from frozen. Once you’ve removed the foods from the jar either gently reheat the contents on the hob or in the oven with a lid on, then turn the temperature up as desired to cook fully. You can boil frozen pasta directly or heat up in the microwave. If you’re placing your jars in the microwave, start with a lower heat or the defrost function to warm the glass gently, then turn the heat up.
What to do about Rusty Lids
On occasion, you might get rusty lids, especially when using low-quality jars. Re-purposing shop-bought jars will definitely reduce the risk of rusty lids, or that is my experience anyway, you can get rustproof lids like this or a plastic option like this. As the food shouldn’t be touching the lid, the chances of chemicals leaching from a lid are reduced so, in theory, should cause any issues with toxicity.
Feel free to add your tips or questions in the comments below.