How to freeze food in glass jars (+ defrost it safely) | Treading My Own Path


I freeze meals in glass jars, and I’ve accomplished for years (we’re speaking a minimum of 15 years). As a pupil I resented shopping for issues like zip-lock luggage to freeze meals – they appeared costly and pointless. Glass jars have been one thing I all the time needed to hand – they usually are available all sizes and styles, which meant there was all the time one appropriate for what I wanted to freeze.

In order that’s what I used.

It’s a subject that will get a variety of questions. Some individuals are stunned that it’s attainable in any respect, others have tried and failed and wish to know why. And there are just a few guidelines it’s essential comply with for those who don’t need damaged glass within the freezer.

In all my time freezing in glass I’ve solely ever had a few breakages, and each occasions have been once I didn’t comply with my very own recommendation. Persist with the principles, and also you’ll be capable of freeze in glass jars with out breaking something.

Understanding the science of freezing in glass

First, a science lesson! It’s useful to know what’s occurring. Glass breaks due to stress. It’s inflexible and strong, so when strain is utilized it tends to crack. (Like, for instance, while you drop glass on a tough floor. It may possibly’t take in the affect, so it breaks.)

Though it’s inflexible, glass truly shrinks a little bit when it’s cooled and expands a little bit when heated. Nothing that you may see, however it occurs. When the skin and the within of the glass have totally different temperatures (equivalent to placing a glass jar of frozen meals right into a bowl of scorching water, or placing scorching liquid into a chilly glass) the glass is shrinking on one facet and increasing on the opposite, which creates stress.

The glass cracks to alleviate the stress.

Water expands when it freezes. Meals comprises various quantities of water and so totally different meals increase to totally different quantities when frozen. Pure water will increase essentially the most. (You may need seen while you make ice cubes that the extent of the cubes rises as they freeze.)

Inventory, soup and sauces are all liquid, and so will increase extra when frozen than meals like bread or wraps, which have a low water content material.

As liquids freeze and increase, they want a spot to go. The perimeters of a glass jar are inflexible and so the one approach to increase is up. If a jar is slim, or has sides that taper inwards, the additional strain positioned on the glass sides because the contents freeze will make it crack (which relieves the stress).

Because of this wide-necked glass jars, or these with sides that taper outwards, are higher for freezing, particularly when freezing liquids.

Filling a wide-necked jar to the brim after which screwing a lid on tightly can also trigger a jar to crack, as a result of now there is no such thing as a area on the prime for the meals to increase. Leaving a lid ajar till the contents are frozen will stop this.

Meals like chickpeas or frozen sweetcorn have areas between them, so there’s much less strain utilized to the perimeters of the glass (the air gaps may be crammed) which means narrower jars can be utilized for some of these meals.

Easy methods to freeze meals in glass jars: selecting appropriate jars

I want wide-necked jars for freezing, and ideally those who taper outwards. My absolute favorite is the Bonne Maman jam jar. Every jar matches a one-portion serve, and the tapered sides imply the frozen contents virtually slip straight out once I’m able to warmth them up.

They’re additionally free (I rescue from a neighborhood cafe, and neighbours who eat jam.)

I also can stack them in my freezer, which maximises the area.

For liquids, a large neck is essential. For beans, lentils or chopped greens, it’s much less essential, however nonetheless preferable.

I all the time select jars that may have been by way of some sort of heating course of in a manufacturing unit. Jars that beforehand contained jam, pickles or sauce could have been heat-treated, and are my desire. Jars from the reject store received’t, and are sometimes thinner glass.

Typically you’ll see jars which have a particular spherical circle on the backside, which is a separate piece of glass fused to the jar. This be a part of is one other level of stress weak point, and it’s higher to keep away from these jars for those who can. In the event you can’t, select to make use of solely with low water content material meals. (Breadcrumbs sure, frozen chickpeas sure, sauces or inventory, no.)

I discovered this out when the bottom of a jar I’d simply used to freeze one thing fell out as I used to be washing it up. I didn’t understand it was a ‘factor’ till then! Fortunately the meals was advantageous, however the means of freezing and defrosting should have weakened the seal, and the jar broke. Now I examine for this earlier than utilizing.

In the event you want, you may keep on with glass jars which are designated freezer-safe. These are typically the manufacturers additionally appropriate for canning – they’re designed to face up to extremes of temperature. Ball Mason, Fowlers Vacola, Weck, Le Parfait jars are all examples.

Easy methods to freeze in glass jars, step-by-step

When you’ve chosen an acceptable jar, fill it with no matter you wish to freeze, following these guidelines:

  • Fill to the widest level of the jar, and depart an area on the prime to permit the contents to increase;
  • Cool the meals utterly earlier than placing the jar within the freezer;
  • If attainable, chill the contents first. Advisable for liquids like inventory;
  • Place the jar within the freezer, with the lid off or ajar;
  • As soon as the contents have utterly frozen, screw the lid on tightly.

Don’t overlook to label your jars except it is extremely apparent what’s inside! Your reminiscence is not going to be nearly as good as you assume it’s. A date is beneficial in addition to labelling the contents.

The explanations most jars break within the freezer are placing scorching contents straight into the freezer, overfilling the jar, utilizing a slim jar – or the entire above.

My largest mistake was making an attempt to freeze inventory in a passata bottle. Fortunately it didn’t crack till it was virtually frozen strong, so there wasn’t a giant mess to wash up. However it needed to be discarded. Lesson realized – these items want room to maneuver!

Easy methods to defrost frozen meals in glass jars

Heating frozen glass (equivalent to plunging right into a bowl of scorching water) will make it crack. Don’t do this.

In the event you’re tremendous organised, you may take the jar out of the freezer and depart on the facet for just a few hours. Or, you may put within the fridge to defrost in a single day.

(In the event you’re defrosting meat or fish I’d put within the fridge to thaw as a result of they’re increased danger when it comes to meals poisoning.)

A big and well-packed frozen Pyrex container can take a few days to thaw within the fridge.

Jars, much less watery issues, and items with extra floor space, will defrost extra rapidly within the fridge.

In the event you’re much less organised, and wish to defrost one thing extra rapidly, take it out of the freezer and put in a bowl of chilly water. It’s essential that it’s chilly, as a result of heat water will crack your jar. Chilly water remains to be hotter than ice.

Relying what it’s, you may add chilly water to the frozen merchandise (pour chilly water into the jar) – that is how I thaw my frozen chickpeas. It separates them, which implies I can get them out of the jar.

It might work for frozen veg, like sweetcorn. You wouldn’t do it to a bit of cake. 

In the event you’re much less organised and in addition impatient, your greatest guess is to freeze meals in containers or jars that taper outward. Pyrex tapers out barely, as do Weck jars, as do my all-time favorite, Bonne Maman jam jars. What this implies is, as quickly because the meals begins to defrost, which is able to occur from the perimeters inward (the centre would be the bit that thaws final), the frozen meals will slide out of the jar.

Take out of the freezer, sit in a bowl of chilly water, wait 10 minutes or so after which empty the frozen lump right into a pan or bowl, or no matter you’re going to use to warmth up your meals. I don’t have a microwave, so I take advantage of a saucepan.

I take advantage of a low warmth and a lid on the pan, and stir to separate the thawed bits from the frozen core. Progressively it reduces down, and ultimately its piping scorching, and also you’re good to go. 

Readers have informed me that they put frozen glass jars in a microwave to defrost. I’d be extraordinarily cautious doing this, as microwaves don’t warmth evenly – if a part of the glass is touching scorching meals and one other half remains to be frozen, the glass will probably be below stress and should crack. However (apparently) it may be accomplished.

I hope this solutions your entire freezing-in-glass-jar associated questions! As all the time, any ideas, solutions or concepts that you’ve got, please share with us within the feedback. Ask away, I’d love to listen to from you!

How to freeze food in glass jars (+ defrost it safely)  from Treading My Own Path | Zero waste + plastic-free living | Less waste, less stuff, sustainable living. Reducing waste in th kitchen, how to make less trash, use less plastic, avoiding plastic in the kitchen, freeze in glass, low waste kitchen, less waste kitchen, food storage in glass, glass jars, reduce food waste, love food hate waste. More at

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