Canning 101: Extending the Life of Open Jars

February 7, 2013(updated on October 3, 2018)

a fruit butter bar

One of the dangers of doing as much preserving as I do is the number of open jars that are constantly in the fridge (jars from brunches, from tasting events and those jars holding the overflow from recent projects). No matter how much I use, there’s always a fresh flow of jam, fruit butter, chutney and pickled things rushing in to fill the void. Because I can only eat so much on a daily basis, part of my refrigerator management is making sure that I’m taking steps to extend the lifespan of my preserves.

Now, for those of you who live in bustling households where a jar of jam empties in a day, you might not be particularly concerned about this issue, but for those of us with small households (and partners who aren’t interested in anything having to do with fruit), preventing spoilage is a real concern. Here are a few things that you can do to keep mold and other funks at bay.

  • Use clean utensils. This might sound obvious, but often, the temptation to dip into the jam jar with a buttery knife is there. Using clean knives and spoons every time you go for a dollop will keep foreign bodies out of your preserves and keep them fresher longer. 
  • Keep jars tightly closed. This is particularly true if you’re keeping fermented foods in your fridge. If things aren’t sealed well, you run the risk of having the fermentation bacteria leap from sourdough starter to jam. Not good.
  • Label the jars with the date that you open them. This keeps you aware of just how long the jar has been opened and will remind you that the jar of peach jam from last summer should be finished before the more recently opened jar of cranberry jelly.
  • Wash off dried, gloopy jam from the lid. I don’t have any scientific evidence here, but I have found that when I wash the lid of the jar, the preserve lasts longer. Less medium for the mold to grow, I think.
  • Eat the fruit butters first. Sugar is a preservative. Because fruit butters typically have less of it, they just don’t last as long once opened. The same goes for preserves sweetened with honey. Eat them first.
  • Consider canning in smaller jars. If you’re finding that you’re losing much of your preserves to mold, consider using smaller jars. This will mean that you’ll have less open in the fridge at any one time and so will be able to move through it at a more timely clip.

Do you have any other tips for extending the lifespan of your open jars?

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24 thoughts on "Canning 101: Extending the Life of Open Jars"

  • Ball was making some BPA-free plastic screw-on lids for their jars, but they’re becoming harder and harder to find, so I suspect they’ve stopped making them. I find them easier to deal with than the lids and rings used for the canning process itself, and don’t know why they were apparently unpopular.

    1. I love those one piece tops! I couldn’t find them anywhere locally either, so I searched amazon. They have both regular and wide-mouth versions that are cheap and ship for free. Good luck!

  • I love those Ball lids (still have them available here). I like to use a grease pencil on these to mark the contents and date–funny how if you know what something IS, you’re more likely to use it, ha! (IE, is that ketchup or jam??). Definitely agree with your smaller jar tip too, we can almost entirely in half pints and pints as for two people quarts of most things (salsa, tomato sauce) don’t get used fast enough.

  • I agree about the small jars! When I started canning, I bought myself a set of quart jars and another of pints, but now I’ve seen the light and focus on half-pints and 4 oz jars. There’s less potential for waste, and I feel like my stock of jars is larger.

  • I like to keep those precious opened jars in the back of the ‘fridge. It’s much colder there. The handy door shelves invite swirls of warm air every time we open ‘er up.

  • My preserves stay much fresher, if I decant a large jar of whatever into a clean small jar once the large jar is half empty. The “funk” seems to start in the air exposed dregs clinging to the side (or on the lid) . It’s well worth the effort!

  • I find the exact same thing about cleaning the lids and rims of the jars. It’s something about small amounts of jam or whatever hanging around the rim that ends up moldy or at least icky-looking.

  • I agree with the plastic lids, those are super-handy and seal better than a 2-piece lid once you’ve opened the jar. Use stuff like applesauce quickly or put some of it in a smaller container and freeze.

  • I keep my jars on a lazy susan in the fridge–gets them off the warmer door area, but still able to be accessible with a spin, so none get “buried in the back–lost forever,” so to speak….

    1. What a great idea! In our house, it’s not unusual to have a great variety of canned things “open” at a time. We’ve been using smaller containers, too, which does help. Also, since I have local access to a HUGE variety of 1-piece lids from Fillmore Container, if I didn’t can it with a 1-piece lid in the first place, it usually gets replaced with one of my “spent” 1-piece lids pretty quickly!

  • Also make sure you have the “go with” on hand – the strawberry sauce that my kids adore does not get eaten if we don’t have any vanilla ice cream.

  • I definitely can in smaller jars – I go with 1-cup and half-cup jars as often as possible (unless I’m doing cucumber garlic-dill pickles – we go through those really fast).

    I appreciate the variety that I can get with tiny jars – go through a half-cup of rhubarb-strawberry jam and be on to the choke-cherry jelly in a couple of weeks, rather than going “Well… this is the jam we’re using for the next three months. Let’s hope it’s a good one!”
    Plus it means that a single jar of chutney or relish can be thrown into a slow-cooker meal as a glaze and I can be done with it.

    I find them really convenient and, yeah, a good way to avoid getting mold in your preserves.

  • I’ve found that fridge real-estate is not all equal-things stored in the door, where they are exposed to warmer temps more often, do not last as long. This is a shame, since the door seems to be made for things like jellies and condiments, and its easier to see them, but I’ve found that unless something is vinegar based or low spoilage like salted butter, you’re better off keeping it in the fridge proper, rather than the door.

  • Any tips for un-crystallizing jam? It’s not spoiled, just undergone a molecular structure change. I have some awesome fig “candy” that I would love to be able to spread again… thanks to all you jammers for any ideas!

  • I too have a partner that does not eat any fruit/veg fresh frozen or canned. So I often have the same problem.

    What I do is empty the jar into a CLEAN pot, and bring to a boil, then gently simmer for 5 minutes.
    Pour the HOT ‘jam’ back into the same jar that I have washed well. I then screw on one of those whit plastic caps, also washed well.

    Let come to room temperature, then store in refrigerator. They sometimes Pop when opened, and you have restored product for a longer life.

    Hope this was of interest to all.

  • Is it possible to re-can foods into smaller jars? I would like to be able to take a can of spaghetti sauce for example and re-can it into smaller portions for use when I don’t have the time to make my own.

    1. You can do it with homemade things, where you knew about the acid content, but it’s not safe to recan store bought food.

  • what do you with a husband who doesn’t look and opens yet another jar? I end up with two half jars of everything!! And a fridge that is way too full.

  • Anything liquid and acidic I always store upside down each time it goes back in the refrigerator, pasta sauce, pickles, olives, relish. keeping the material on the lid well bathed in the acid kills more infiltrates and keeps mold from forming around the lid and rim.

  • I have Costco peaches in glass jars and realized they expired two years ago May 16, 2017. Would they still be good?

  • Are home made chicken soup Jared it boiled it sealed and putting back of fridge about :3 months ago opened today and a vinegar taste is there is that okay?

    1. That is not how you should preserve chicken soup. It would be incredibly dangerous to eat it at this point. Please throw it away.