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I used the approved recipe for canning apple pie filling, including leaving a 1 inch headspace. However, after taking out the jars I noticed that filling had bubbled up out of the jars during processing. The lids seem sealed, but how can I be sure they are safe? Should I have left a larger headspace than 1 inch???

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A

When canning foods using a raw pack, air remains in the food tissues.  This is especially true for tomatoes and fruits.  Fruits in sugar brine sometimes float because of the density differences of high sugar brine versus low sugar fruit.  So, to start, the food often floats on top of the brine.  Then, during the boiling water canning process, the air is being driven out of the jar by heat.  The floating food may cause a channel for liquid to be driven out of the jar along with the air.  This causes food particles in the canning water and sometimes food particles on the jar rims.  Lastly, it will cause the brine level to drop.  I have seen the amount be up to 2 inches.

 So, is the food safe?  Yes, providing the seal is firm.  If food particles lodged on the sealing compound in a manner to compromise the seal, then it is not safe.  Otherwise, it will be safe.  How can you tell if the seal is compromised?  Remove the rings after processing.  Lift the jar by grasping the lid edge.  If the lid remains on, there is enough vacuum created to form a seal.  If the lid pops off, a poor seal was formed and the food should be reprocessed immediately. 

 Is canned food uncovered by brine any good?  If food remains above the brine level, then that portion of food may lose quality quicker during storage than submerged foods.  Try and use these jars first.

 Can I reprocess?  Yes, providing you do it immediately or store the food in the refrigerator until you reprocess.  Open all jars and clean the rims.  Add fresh brine or sacrifice one jar to top off the others.  Use new lids.  Reprocess for the full amount of time.  Since the first processing drove out the air in the food, you should not have the same problems the second time around.

 How can I avoid this in the future?  Hot pack or heat the food to help drive off air before canning. For fruit in sugar syrups, sometimes leaving them in the refrigerator in the sugar brine overnight will help equalize the sugar levels and minimize floating.

 

Posted on 3 Oct 2007

Brian Nummer
Food Safety Specialist

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