Yes apple sauce will store well in a vacuum sealed jar that has a rubber air seal to keep the vacuum in place , such as a screw top Kilner/ Mason preserving jar or a Weck preserving jar , it tends to go a darker colour in the jar even in the fridge after nine months .
It may be I needed to add lemon juice to & even more sugar to keep the lighter colour , the apples I used were 3 kg of Bramley's & made up as an apple sauce for pork they were pressure canned in my Weck preserving jars .
You say no room in the freezer . not even for small twists of cling film in three or four thicknesses filled with three dessert spoons of apple sauce and stuffed into every nook & cranny that exists in the freezer ?
I'll have a peek at " hot water bath preserving " for your screw top jar idea, if it is a goer make sure you use new lids with the heat setting seals in them .
Yep , hot water bath preserving is OK ....according to the Dummies guide to Canning & preserving , but is is for preserving apple slices in Syrup not as an apple sauce , so I suspect it is not viable or perhaps it's even dangerous wrt toxins developing to do as apple sauce in a hot water bath canner .
Anyway just in case you want to try the " Hot water bath preserving method " I've typed up what we do & have given you some figure to think of & work with .
Here is a quick rundown of the method for apple slices in Syrup , I'm sure you could convert a preserved jar of slices in heavy syrup to apple sauce for a week or so of fridge use as & when needed .
I've perhaps gone over board in typing it up for someone who knows exactly what they are doing but fel it may also help bring someone on the fringes of pressure canning & hot water bath preserving a little further into the fold .
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Sugar 1/4 cup ( super light syrup ) to 4 & 1/2 cups ( heavy syrup )
Don't use wind fall fruit , it's liable to be too ripe and not high enough quality for long term storage .
Peel & core the apples , slice & to stop discolouration treat with an antioxidant ....they are all forms of vitamin C .....such as ascorbic acid tablets or citric acid or see if you can get powdered vitamin C for preserving at a health food shop . You'll need to look up how much to use per quart /litre of syrup etc .
Remove any air bubbles in the jars with a non metallic stirrer .
Leave 1/2 " ( 13 mm ) head space of air in the jars , this allows a decent vacuum to form and seal the jar as it cools Too much or too little air space sees the lid sealing fail quite often and you don't want the resultant botulism poisoning do you ?
So make your syrup to your own preference .
Sort your apples & make the slices 1/4 " ( 6 .5 mm ) thick .
Pack the apples firmly into hot jars & pour on the boiling syrup once the jar is full ...leaving that vital 1/2 inch head space of air .
ONLY LIGHTLY TWIST THE JAR LIDS ON to get a light seal ...TOO TIGHT AND THE AIR WHEN HEATED WILL NOT BE ABLE TO ESCAPE PAST THE RED OR WHITE RUBBER SEALANT ( THE SEALANT ON ALREADY USED LIDS IS NOT MUCH GOOD TO GET A DECENT SEAL. NOT TIGHT ENOUGH AIR CAN RE-ENTER AS THE JARS COOL & CAUSE FOOD POISONING .
The idea is to get the seal to act like a one way valve .
Mum used to take the jars out of the boiling water in the hot water canning bath using the old wooden long pronged washing tongues and stand the very hot jars on the wooden table then hold each jar in a tea towel and use an oven glove to nip the lid tight .
Don't put them on a cold surface use some flat wood or a plastic chopping board as the sudden cold will also shatter the jars sendnig scalding sugar & fruit all over you & the dog etc .
You'll need a trivet or wire rack in the bottom of a large deep pan to make a stand off from the bottom of the pan to stop the jars conducting too much heat from the heat source through the aluminium pans metal. you're after the temperature of the boiling water only no more & no less .. this stops the jars shattering or cracking .
No jars are allowed to touch each other , nor touch the sides of the pan . Again this is to do with the heat transfer and too much expansion that results in a bust jar .
Only use jars of the same volume & height ( vitally important ) so they all get cooked & sealed to the same levels .
Put the hot filled & now lidded jars in an open hot water bath of boiling water with an inch or slightly more of boiling water above the tops & time the sterilization for 20 minutes exactly , have a kettle of boiling water handy to adjust the height of the water to that vital one inch above the tops of the lids on the jars .
When the timed period is up....
Take care lifting the jars out the hot water bath , I often leave them in & allow the water to cool enough for me to pick the jars out by hand .
Whilst the jars are still fairly hand hot give the lid a micro tweek to tighten it fully then stand the jars on a tripple folded towel and let them cool naturally ...don't be tempted to use cold water to cool them down as again you'll cause the jars to crack for the contents at the center of the jar it can still be nearly at boiling point .
Finally when the jars are cool enough to handle them with your bare hands , make the labels up and put them on the now hand hot warm jars . Store you jars in a cool dark place .