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Canning 101: Fruit Float

April 9, 2011

Recently one of our readers asked us, “When canning strawberries or peaches in syrup, or even tomatoes packed in water, why do they float in your jars?”   We thought this was a great question that required an explanation.

Many of us have experienced fruit float when canning whole fruits and some vegetables.  It’s not attractive and if given a choice we’d probably all prefer if our fruit co-operated and did as it’s told…that is sink to the bottom, submerged in liquid.  But, sometimes this just doesn’t happen and we are left wondering “Why?  Is it safe to eat?  And, what could we have done to prevent it?’ 

Firstly, the good news, it is perfectly safe to eat.  Fruit float will not affect the taste or the shelf life of the preserve (as long as proper canning practices were followed).  But, don’t you still wonder why it happens and if there is anything that can be done to prevent it? 

Here are a few suggestions that may help to prevent future buoyancy problems.

  1. Select fruit that is fresh, firm, unblemished, and ripe.  A few years back, we purchased multiple boxes of peaches that were seconds.  At half the price we thought it was a steal but they caused us 10 times more grief and ended up floating like crazy. They were all at different stages of ripeness with bruised areas which made it challenging to slip off the skins.  Plus, over ripe fruit does not absorb enough sugar causing them to float in the jars. 
  2. Use the hot pack method.  While both the hot pack and cold pack methods are used to can whole fruits and vegetables, the hot pack method may help to prevent fruit float.  The hot pack method requires the fruit to be heated through before packing into hot sterilized jars.  This method helps to expel the air that all fruits contain, making them more dense and less likely to float to the surface.  Heating them through also shrinks the fruit (slightly) allowing jars to be packed tightly; again, helping to prevent the fruit from floating.  The cold pack or raw pack method of preservation allows fruits and vegetables to be packed without heating but it requires a longer processing time.  During processing, the air in the fruit or vegetables will be cooked out causing them to shrink in size and create more room in the jars which allows them to float to the surface.
  3. Packing jars.  Be sure to pack the fruit tightly in each jar without crushing the pieces.    Remove all air bubbles and top up with additional fruit and/or liquid.  Some shrinkage will occur during processing so fruit that is well packed in each jar is less likely to have the space and/or room to float.
  4. Sugar content.  Some fruits like apricots, rhubarb, and berries naturally have more air in their cells which makes them more buoyant.  Coating these fruits in sugar and setting aside allows the fruit to absorb the sugar and expel some of the water to make the fruit more dense.   Heavier, more sugary syrups may cause fruit to float.  Why?  Light syrup, juice syrups, or water packed fruits/vegetables are in an environment where the fruit/vegetables are equally as dense as the liquid, diminishing buoyancy.  Fruit in a heavier syrup  is lighter than the liquid and therefore may float.  Note: We pack 90% of our fruits in a very light syrup and will still occasionally experience fruit float. 
  5. Follow processing times carefully.  Over processing fruits and vegetables will destroy cell structure, making fruit lighter and more likely to float.

Although, it may be impossible to prevent fruit float every time, the above suggestions should help.  And, sometimes understanding why something is happening is enough.

The peaches on the left are fine but both the strawberries (center) and the plums (left) have fruit float.  But, we guarantee they all taste yummy!

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14 Comments leave one →
  1. April 9, 2011 9:41 pm

    Floating or non-floating…it all looks good to me.

  2. April 10, 2011 10:46 am

    Not to mention they all look so beautiful! I can’t wait to get some canning done this summer. Strawberry jam…dilly beans…peaches…and then I’ll add something new to my repertoire. Not sure yet what that will be…

    • April 10, 2011 1:16 pm

      Thanks. We want to hear all about what you are canning this summer…so let us know!

  3. Jeff....Tornado Brigade.....Kansas permalink
    April 10, 2011 2:51 pm

    I always add a pinch of cayenne pepper to all my canned fruit…..Try it then eat it on a cold winter’s day and you’ll understand why…

  4. April 10, 2011 5:18 pm

    I’ve found macerating the fruit overnight in a little sugar greatly reduces fruit float. I think it has to do with sugar being hygroscopic and drawing out the water in the cells, allowing them to collapse a little with less air in them. Add the juice drawn from the fruit to the water you’re using to prepare a light syrup.

  5. April 10, 2011 7:18 pm

    Thank you for an excellent explanation and solutions. My daughter and I canned 2o# of peaches that turned out to be under ripe (a bargain at a central Washington fruit stand) and had the fruit float experience. We cold packed but will try hot packing this summer.
    P.S. found your site on Food In Jars blogroll. Thanks again!

    • April 15, 2011 4:31 am

      We still raw pack or cold pack our peaches ~ some have a little bit of fruit float while others are fine. I think the blanching and light syrup helps to reduce the floating…plus, using ripe fruit. We had a similar experience one year with under ripe peaches. Good luck! If you do hot pack them let us know which you prefer?

  6. Meghan permalink
    April 15, 2011 3:17 pm

    Is it bad that I thought all fruit floated when canned? My mother and grandmother canned peaches, pears, apples, tomatoes and cherries and everything floated. None of it ever tasted bad.

    • April 15, 2011 7:39 pm

      It’s not bad and the taste is not spoiled by the floating. We have some fruits that have more float than others but it looks really nice when they rest on the bottom. And, the texture of the top bits is better when they remain submerged in syrup, water, or juice.

  7. Fiona Bradbury permalink
    September 20, 2011 10:56 am

    My first time canning peaches…and yes they floated. I don’t think I packed tightly enough…seems to be a fine line and some of the peaches were too ripe. I had difficulty with peeling them. I blanched them for 60-75 seconds, submerged them in ice water and attempted to peel away the skin by hand. Was I doing something wrong? Or was it the ripeness of the peaches. I would have thought that if they were overripe, the skin would be easier to remove. ????

    • September 20, 2011 4:43 pm

      Although it is really nice when they don’t float…lots of our canned fruit does. It doesn’t affect the taste or preservation of the product so we don’t worry about it. Some fruit cells have more air than others…you can always try hot packing to eliminate the fruit float but it may still happen. Last year we had great success blanching and slipping the peach skins (the year before we had to peel the whole lot by hand) and this year they are being a bit stubborn…we don’t think they are quite ripe enough. With the peaches we don’t put them on ice instead we lay them out on cookie sheets and start removing the skins as soon as they are cool enough to handle. This method usually works great. The skins should slip off nicely when they are ripe…we’re wondering if putting them on ice makes it more difficult. Hope this helps. Let us know how you make out if you try it again.

  8. Judy permalink
    August 23, 2013 1:21 pm

    Funny thing- I assumed there was something wrong when they didn’t float!

  9. abi permalink
    October 6, 2013 12:26 pm

    I did some pickled spiced pears last night- they are now floating like crazy and have shrunk loads since I hot packed them. I didn’t stick anything in there to get rid of air bubbles, so that might explain the floating (although I can’t see any bubbles) but they have shrunk to half their size- I’ve got two pears in each 1lb jar and they only look half full now! Do you know what I’ve done wrong?

    • October 15, 2013 10:02 am

      Hi Abi,
      You’ve done nothing wrong…fruit float is very common can be the result of numerous things. For example if you remove the jars too quickly from the hot water bath, liquid will leak out. Most of our fruit floats. As long as you’ve followed the guidelines for preserving and your jars are sealed you will be able to enjoy them during the winter months.

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