It will eventually either mold or ferment. However, it will last in the freezer much longer so I would go for that, and thaw as needed. I do that with a lot of fruits. Not sure how long it will last. Based on my experience, 1 week and then after that, all bets are off. You might get 2 out of it if you are not picky. Better option for max taste and freshness is to freeze or can. Canning is really very easy. I make up small batches of applesauce and can them and use them in a similar fashion to what you describe. That saves me freezer space, which is at a premium in my house right now until I get my big freezer up and running.

I keep boxes of fruit compote, plum, gooseberry and apple, for months in the freezer. They aren't as good as fresh but they're as good as canned. And I don't expend energy pureeing or peeling. Just slice and cook. No equipment needed other than a pan and some old ice cream tubs.

I would think if you don't cook it, you'll need to add some fruit fresh or ascorbic acid to prevent it from turning to brown goo in a day or two. Not sure if that's necessary if you pop it in the freezer, but I probably would, just to make sure it stays yellow.

oops. I missed the 'no cooking' bit.

Uncooked purée would definitely go brown without some acid. I'm wondering why it needs to be puréed at all if not cooked. How about just eating the fruit as it is, or just chopping into your yoghurt? Why does it need to be mush? Is it for a baby or person who can't chew?

The tree is loaded with fruit. We cannot eat it all.

There are so many plums, and I do not have time to cook all that puree.

I could puree it and put it straight in the freezer wtih ascorbic acid without cooking it. I have some large mason jars that I could use. Not sure if mason jars would be happy in the freezer.

Mac

Mason jars are fine in the freezer, but you need to plan ahead by taking them out before you need the contents so it will thaw. Don't want to risk breaking the glass by putting it in the micro when cold/frozen.

People who use their freezer a lot for food preservation will tell you that jars are not efficient use of space, that freezer bags lay flat and stack, but if you have lots of room in your freezer, jars are fine.

That's why I can, saves me freezer space. If I'm going to wash, pit and cut up a fruit, might as well do all that into a pan on the stove and bring it to a boil. Then pack in clean jars and bring to a boil again to seal. So when I make applesauce for dinner, I usually make a real big batch and can or freeze the excess in small containers. I put in small containers because my SO and I don't eat that much at one time and big jars of stuff tend to go bad in our fridge. So I either freeze or can the excess. I like to use the re-usable square plastic containers or pint glass jars for the freezer. I haven't had trouble with anything shattering in the microwave during thawing, but you can also thaw out rather quickly by placing in a bowl of warm water. Use wide mouth jars so you can get it out of the jar easy when partially thawed, then you can put it in any type of container to heat/thaw the rest of the way. When I had my big upright freezer going, I used to freeze a lot of seasonal fruit from my garden or the U-pick farm. But plum sauce, along with applesauce, is just about one of the easiest things to can.

Fruit freezing instructions from Montana State Cooperative Extension

You can boiling water bath plums without added acid since they are in the acidic range of fruits, along with apples. But I add lemon and a pinch of sugar to my applesauce because I like the taste with a slight hint of tartness. Not sure about the color issues, since I use my plums for plum jam with cointreau, which I just love.

Preserving plums

I agree with pink mountain that cooking the fruit up is no more effort than pureeing it raw. I just rinse and cook. The cooking does the mushing up, no need to blend. You get a compote rather than a purée. For plums I don't even bother to pit them - the eater does that. And you get to play tinker tailor too... But then I put it in the freezer. I don't can it.

Ok.

It looks like I have to change my plans.

Can I just boil the plums in a pot and put the compote in mason jars and put them in the freezer (and eat them within three months)?

Mac

I don't even think you have to boil if you are freezing. But no harm in boiling either. And yes, that would be fine. The issue some of us have with mason jars is that they take up a lot of space, but if you'v got it, they are great for freezing. And I think the stuff might even keep six months or more before any loss of quality. That is a plus about freezing in glass, very airtight and safe.

I don't boil the fruit. Compote is better somewhere between a poach and a simmer. And I put it in rectangular plastic containers left over from take away meals or ice cream. No need to use jars, and as was stated above, cylindrical containers waste space. The containers don't need to be airtight. I've got year old stuff in my freezer. It's fine thawed and with a blob of yoghurt on it.

Thanks.

So I guess I will simmer these for 15 minutes or so.

Do I have to use something else, like ascorbic acid, to help them last longer?

I may add a little sugar.

I plan to eat them within - about - three months after freezing.

I do not use plastic for food. I will use the mason jars.

Mac