Can I cool jam and store it in the fridge before canning?
July 21, 2021 3:36 PM   Subscribe

I googled for an answer to this, but couldn't sort out relevant answers*: can I make a batch of jam, store it overnight in the fridge, and then can it?

I feel like it shouldn't be a problem since processing is what kills all the bad stuff. Any reason this wouldn't work? I'm thinking I'd re-warm the jam to make it easy to pour into jars, and then process a bit longer than usual. The issue is that I have fruit that is ready to go but have not bought jars. I've frozen fruit before making jam in the past, but didn't love the texture.

*got a ton of refrigerator or freezer jam advice, which is not what I want to do.
posted by oneirodynia to Food & Drink (9 answers total) 1 user marked this as a favorite
Yes? In general, I have seen this addressed for jam that doesn't set-- you can wait a couple days post-water-bath to see if it's going to set, then cook it again with more sugar and added pectin to get it to set, then re-process with a new lid.

I think if you get it to a full boil before you put it in the jar, you should be OK since the processing times are calculated for hot product in a hot jar going in a boiling water bath. I don't see this as different from re-cooking a poor set. But since botulism is not just a "no" but a "hell no" experience, I would want to ask my local extension office on this one.

Note that you often can't re-boil or boil too long if you're using commercial pectin for texture and set reasons. I would also look at your freezing method if this happens a lot-- maybe get a vacuum sealer and freeze in a colder freezer to preserve texture, if this is a common problem for you.
posted by blnkfrnk at 3:51 PM on July 21 [2 favorites]

In my family we pick berries every summer, process them, freeze them, and then make jam in the fall when it is cooler.

Processing doesn't include adding pectin or sugar. For strawberries it involves cleaning, slicing, and mashing. For raspberries we leave them whole, and just clean them up a bit. For beach plums, they are boiled, mashed and strained and the juice frozen. In all cases, we freeze the berry product in measured amounts that we can use in our jelly and jam recipes. This works fine. We've done it for years and every seems to love the result. I wouldn't suggest fully preparing the jam recipe, i.e. adding pectin, sugar, etc. The sugar might possibly work, but it's not necessary and the pectin could cause real problems. But maybe someone who has actually done it can chime in.
posted by alms at 4:24 PM on July 21 [2 favorites]

Best answer: Processing doesn’t actually kill ALL of the bad stuff. What it does is make an environment inhospitable to the bad stuff growing.

I would mix the fruit and sugar, store in the fridge overnight and then cook and can. Mostly because it is so frigging hot and the thought of heating and steaming up the kitchen twice is….no.
posted by bilabial at 5:13 PM on July 21 [2 favorites]

Filling the jars with chillled mix - or chilling then portioning without reheating, would be bad because you wouldn’t meet the temperature profile across the interior of the jar while in the canner using the recommended times. So that would be bad.

Re-cooking seems like a pain but doesn’t seem unsafe. Nor that it saves much? Except to blanch fruit that’s on the hairy edge of rotten?
posted by janell at 6:10 PM on July 21 [2 favorites]

Best answer: You can do this; the main problems you might run into are 1) de-activating the pectin (if your recipe calls for it) on a re-boil or 2) breaking the jars in the hot water bath if the jars are too cool. I'd recommend mixing your prepared fruit with the sugar and non-pectin ingredients, storing it overnight in the fridge, then cooking and canning as normal once you get the jars. You could also try cooking the fruit to about 50-75% done and finishing it the next day, if you want to save time on the actual canning day. You shouldn't need to process the jars longer than recommended if you're using a tested recipe.
posted by radiogreentea at 6:15 PM on July 21 [3 favorites]

It may be difficult to get the cold 4°C /40°F jam back to canning temp 104°C 220°F without burning on the bottom of the pan. That's because the jam is sugar-laden and, like, sticky. Me, I'd bring the fruit to the boil now, to put a stop on the fermentation, and fridge that. Add sugar when you've got jars.
And what's with the water bath? I boil the lids in our electric kettle and then let them dry inside-surface down on the counter-top . . . while I dry-roast the jars in a slow oven [150°C / 300°F).
Pectin schmectin, apple cores cost nothing.
You'll never take me alive, Dr Botulinum.
posted by BobTheScientist at 8:00 AM on July 22 [1 favorite]

Best answer: You would need to bring the jam back up to a boil before canning it to ensure that it didn't pick up any cross-contamination, not only to get a proper vacuum seal, but also because cool jam in a hot canner is a recipe for broken jars from thermal shock. Broken glass in your canner is the WORST.

But bringing the jam back up to a boil after it has set is not the best path to tasty jam -- it'll either degrade the pectin or overcook your jam into glue.

The far easier way is to prep your fruit, add the sugar and lemon juice and spices if you're using them (but NOT the pectin), and store it in the fridge until you're ready to jam. I do this ALL the time. Every experienced canner I know does this all the time.
posted by desuetude at 9:49 AM on July 22 [1 favorite]

Response by poster: Thanks for all the responses! It sounds like the best thing to do safety and texture/flavor -wise is to prep the fruit for cooking and store that in the fridge, then later cook and process normally.
posted by oneirodynia at 11:07 AM on July 22

Depends on the fruit (this works with strawberries) but: if you pack your fruit in sugar and let it sit, you get more identifiable bits of fruit in the resulting jam - because the fruit is dehydrated by the sugar and stands up better to being cooked.

Conversely, you don't want that you might squish the fruit a bit before mixing the sugar in.
posted by How much is that froggie in the window at 5:30 PM on July 22 [1 favorite]

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