PROBLEMS WITH HOME-CANNED FOODS



    Even when you follow directions, occasionally you may have
problems with home- canned foods.  Many of these problems can be
traced to use of non-standard canning jars, lids and rings or use
of other-than-recommended canning equipment or procedures. 
Checking your equipment and reviewing current canning
recommendations can go a long way towards preventing potential
problems.  If you do have a problem, you may be able to determine
the cause and prevent its reoccurence by consulting this
"trouble-shooter's guide".


1.  Jars do not seal
    a.  Off-standard jars and/or lids.
    b.  Chipped or uneven sealing edge.
    c.  Using one-piece caps instead of two-piece lids.
    d.  Screwbands are rusty or bent providing poor contact.
    e.  Bands not screwed down tightly enough before processing.
    f.  Sealing edge not clean.  Wipe edge well before placing    
        lid on rim.
    g.  Liquid siphons out of jar during processing taking food  
        particles on to the sealing edge.
    h.  Insufficient heat during processing--air not evacuated   
        from jar, so a vacuum seal never forms.
    i.  Lids were improperly prepared before placing them on     
        rims--most lid manufacturers require some pretreatment   
        (heating, boiling, etc.).
    j.  Rapid, forced cooling of a pressure canner can cause a    
        rapid pressure and temperature change inside the canner  
        causing the liquid to "boil" out of the jars, leaving    
        particles on the sealing rim and unsealing the jars.      
        Canners should not be "forced" into cooling rapidly by    
        submerging them in water or by adding ice.
    k.  Insufficient processing of raw-packed food; the air may  
        not have been completely driven out of the food leaving   
        residual air in the jar so the seal does not form.
    l.  Use of canning procedures which are not recommended such
        as open kettle canning, microwave canning, and oven       
        canning.  Use USDA recommended procedures.

2.  Food spoils
    a.  Processing at an incorrect temperature--can occur with:
    1.  Inaccurate pressure canner gauge.
    2.  Failure to exhaust canner.
    3.  Failure to make altitude adjustment.
    4.  Heat source fluctuates--inaccurate pressure or            
        fluctuating pressure.
    5.  Water not at a rolling boil when jars are put into        
        canner.
    6.  Water not covering jar caps by 1" throughout processing.
    7.  Water not at full boil throughout processing.
    8.  Insufficient processing time.
    9.  Use of canning procedures which are not                  
        recommended--recommended procedures (USDA) are based on  
        the time it takes to achieve a temperature which will    
        sterilize the food in the jar. 

    b.  Improper cooling of jars after processing.
    1.  Failure to remove jars from canner when processing time  
        is up (or when pressure gauge reads 0).
    2.  Failure to set jars at least 1" apart during cooling.
    3.  Covering jars which retains heat--vacuum does not         
        develop.
    4.  Attempting to cool either the canner or the jars very    
        rapidly.

    c.  Using damaged (freeze damaged), spoiled, under ripe or   
        over ripe food--the pH may not be correct for the type of
        processing you used (water bath versus pressure).

    d.  Very large number of microorganisms due to spoilage,     
        bruising, etc. A very large number of microorganisms     
        present on the food which are not destroyed in the        
        usually recommended amount of processing time.

3.  Food loses liquid during processing
    a.  Jars filled too full.
    b.  Fluctuating pressure in a pressure canner.
    c.  Forced cooling of a pressure canner.

4.  Food turns dark (not spoiled)
    a.  Insufficient processing time.
    b.  Processing temperature too low (water not at a full boil
        at beginning of processing or drops below full boil       
        during processing).
    c.  Water not 1" over jar lids.
    d.  Packing foods raw that should be precooked (pears).
    e.  Liquid loss during processing causing fruit at the top to
        be out of the liquid.
    f.  Lack of appropriate pretreatment for light-colored foods. 

5.  Fruit or tomatoes float or separate from the liquid
    a.  Using overripe fruit.
    b.  Packing fruit too loosely.
    c.  Syrup too heavy.
    d.  Processing too long--pectin damaged.
    e.  Processing at too high a temperature (pressure canner).
    f.  Raw packing--food contains a lot of air.
    g.  Smashing or pureeing food prior to heating it activates   
        enzymes which break down pectin in the juice so the food
        pieces are lighter and rise to the top.  Heat or crush    
        while heating any foods to be pureed or food to be packed
        in its own juice to help prevent separation.



Prepared by Susan Brewer
Foods and Nutrition Specialist
Revised,1992                                                      
 EHE-665