                Evaluating Home Canning Recipes For Safety



What do you do when someone gives you "Aunt Tillie's Special" old
favorite jam recipe?  Or Uncle Willie's barbecue sauce?  Or
Cousin Millie's dill pickle recipe?  In today's heightened
awareness of food safety, how do you tell which are safe and
which are not?  There are no hard and fast rules, or secret
formulas, to help you decide. But there are some priorities you
can use to help you balance the pros and cons. They depend on the
factors that molds, yeasts and bacteria need to grow, and on the
relative hazards that molds, yeast and bacteria present in foods.


Factors Influencing Safety

In food preservation, the growth factors that are important are:

     Sugar - enough sugar will stop the growth of most organisms 
     Salt - enough salt will stop the growth of most organisms
     Acid -enough acid will stop the growth of most organisms

       ** Too little sugar, salt or acid will permit spoilage.

     Air - most organisms must have air to grow, BUT the most 
          dangerous bacteria in home food preservation,
          Clostridium botulinum, will only grow without air.

     Temperature - most dangerous microorganisms grow best at 
          room temperature or a little above. But in preserving
          food, we are interested in killing the organisms and
          their spores, not just in slowing their growth.

The death rate of microorganisms depends on:

     The microorganism - they die at different rates
     The number of cells or spores present initially in the food
          - the more there are, the longer it will take to kill
          them all
     The medium (food) that they are in - most die faster in 
          acidic food than low acid food, and in wet food than
          dry food.
     The temperature - in canning the important temperature is 
          the temperature at the coldest spot in the jar.  
     The length of time at that temperature - when we heat food,
          not all the organisms will die at the same time, they
          die gradually, and the full process time is necessary
          to be sure that all, even the most heat-resistant ones,
          have died.

     These last two factors, temperature and time, depend on how
much solid vs. liquid is in the jar, and on how tightly the food
is packed.  Heat from the steam or water in the canner penetrates
into different foods at different rates.  Liquids circulate in
the jar and carry the heat into the center of the jar.  Solids
must heat slowly from the outside in.  A process time for
randomly packed green beans, which have spaces for water to
circulate, will not be adequate for "tin soldier" green beans,
when the tightly packed, vertically aligned beans leave no room
for water to circulate.
    
The most important microorganism in home canning is Clostridium
botulinum.  The toxins it produces damage the nervous system,
producing paralysis and possible death.  The damage to nerve
cells is permanent.  Minute amounts of contaminated food can
carry enough toxin to cause death.  This bacteria produces spores
which are very resistant to heat.  It is also very sensitive to
acid, and will not grow in acid foods.  Other pathogenic bacteria
are usually killed by much less heat and in a shorter period of
time than Cl. botulinum.  Most require air, so will not grow in a
sealed jar. They are of less concern in home canning. 

Molds and yeast are of concern because if they grow they can
reduce the amount of acid present in the food.  If that occurs
Cl. botulinum may be able to grow.  Some molds, particularly
those that grow on fruits and fruit products are known to produce
toxins that cause damage to the nervous system and kidneys, or
cancer in research animals.  The likelihood is that they will
cause some damage in humans if consumed often enough. 
(Toxin-producing molds grow well on grains and peanuts, but these
products are not home-canned.)   Molds and yeasts will also spoil
the taste, texture, color and overall appearance of the food,
making it unfit for consumption. 

Jams, Jellies, Sweet Spreads

In a jam or jelly recipe made with regular pectin, not the low or
no-sugar variety:  If the jam or jelly sets properly (stiffens
into jam or jelly) it has enough sugar to inhibit the growth of
bacteria and all but a few sugar-tolerant molds and yeasts.  This
will also be true for marmalades and preserves, and for jellies
made the long-boil method without added pectin.  The fruit blend
used is not crucial. 

However, mold growing on a fruit spread is a problem.  It should
not be scooped off, rather the entire product should be
discarded.  To avoid mold problems, all jellies, jams and sweet
preserves should be packed in pre-sterilized jars and processed 5
minutes or more in a boiling water bath canner.  The exceptions
are some of the sugar-free types which explicitly state on the
package of jelling agent that they should not be processed. 
These contain preservatives to prevent mold growth, and the heat
of processing would cause soft jelly.  In addition, heat will
cause the sweetener to break down and lose its sweet taste.

Pickles and Relishes

The pickle recipe is more complicated.  The proportion of acid
(vinegar) to the amount vegetable is crucial. Enough vinegar must
be added to change the low-acid cucumber into a high-acid pickle
to be safe.  There is no formula or set proportion to decide if
the recipe provides for adequate vinegar. The best thing to do is
to find a recipe with similar procedures in the USDA Guide to
Home Canning and compare the amounts. This is especially true of
pickle relishes or vegetable relishes where several vegetables
are ground together.  

Similarities to look for include:

1.   Similar recipes will use the same presoak - soak in ice
     water, or in salt water, or no soak. 

2.   They will call for the same size cucumbers - 4", or 6", or
     8", or specify small or large. 

3.   The maturity of the cucumber influences how much acid it
     will take to pickle it.  Smaller, less mature cucumbers have
     the capacity to neutralize more acid per unit of weight than
     do larger, more mature ones. 

4.   Similar recipes will also specify similar procedures with
     the brine: Are the slices or spears packed in the jar raw
     and the brine poured over, are they merely heated in the
     brine, or are they simmered before packing?  Is the
     simmering or boiling time the same?  Each of these will
     influence how rapidly the acid penetrates the cucumber and
     how much the cucumber juice will dilute the acid.  

5.   Similar recipes will call for similar proportions of onion
     or other vegetables. 

6.   Quantities of salt are critical in fermented pickled
     products; proportion of salt to vegetable to vinegar should
     be very similar to USDA recipe to be sure that it will be
     safe.  Proportions of spices are not crucial and may be
     adjusted to suit tastes without danger.

     If too little salt is used the cucumbers will spoil, get
     slimy, float, smell foul, and the fermenting mixture may
     support the growth of hazardous microorganisms. If too much
     salt is used, there will be no fermentation, just shriveled
     cucumbers sitting in salt water. Either case is obvious: the
     recipe is not good.

     In quick pack pickles the amount of salt is not critical.
     Salt may be omitted, or a reduced sodium salt-type product
     used.  The flavor and texture may be noticeably different,
     and probably less acceptable but, the product will be safe. 



All pickle products should be processed in a boiling water bath
to reduce the likelihood of mold or yeast spoilage.  Old recipes
for whole or sliced pickles that have been used for generations
without processing and without spoilage should at least be given
a 10 minute process.  

Pickle relish products must also adhere to the USDA proportions
and process times.  Quantities of vegetable and vinegar, heating
prior to packing, and process time must be similar to a USDA
recipe.  An old, tested and trusted recipe may be used if the 10
minute process time is used.  Other recipes may be changed, or
the product refrigerated.  

For comparison of quantities, note the following equivalencies:

       1 lb 5" cucumbers = about 5 cucumbers
       1 lb mushrooms = about 6 cups chopped = 1 1/2 cups sauteed
       1 lb onions = about 3 cups chopped = about 4 medium
       1 lb green peppers = about 3 C chopped = 8-9 peppers
       1 lb sweet red peppers = about 3 cups chopped = 6-7       
            peppers
       1 lb celery = about 4 cups chopped)
       1 lb tomatoes = about 3 medium = about 1 1/2 cups chopped
       22-23 lb tomatoes = about 7 quart or 28 cups cooked juice


     Other Ingredients:

     The use of alum is unnecessary.  The slight increase in
     crispness that it provides is lost after about 2 months of
     storage.  Few pickles are consumed within 2 months of
     processing.  However, since alum is usually used in very
     small amounts, its use does not constitute a safety problem.

     The use of grape leaves might contribute slightly to flavor. 
     They have no significant effect on safety. 

     Lime does cause a significant increase in the crispness of
     pickles.  If it is used, all excess lime must be rinsed away
     before the vinegar is added since it will neutralize the
     vinegar.  After the soak in lime water, the cucumber slices
     should be soaked in fresh water then drained, re-soaked and
     drained two more times (3 rinses in fresh water).
 
     Honey may be used safely, but quantities will need to be
     adjusted for taste, and color may be darker. One cup of
     sugar is equivalent to 3/4 C + 1 T honey (or 1 C less 3 T).


Tomato Products

Tomatoes and tomato products are very hard to categorize.
Tomatoes are borderline acidic.  Lemon juice or other acid
(vinegar, citric or ascorbic acid) must be added to all tomato
products to insure adequate acidity.  Added acid is necessary
whether the product will be pressure canned or boiling water bath
processed.  Bacteria and spores die faster in an acidic
environment, and the recommended process times for pressure
canning assume that the tomatoes are acidic.  The times would not
be reliably adequate to insure safety if the tomatoes were
low-acid.

Green tomatoes are more acidic, and may be used safely in any
recipe calling for red tomatoes.  Overripe and frosted tomatoes
are less acidic and can not be safely home canned.  They can be
frozen.

Addition of salt, while optional, does give an extra margin of
safety.  For dietary information, one teaspoon of salt added to 1
quart of juice or sauce adds about 526 mg sodium per cup.

Addition of low-acid vegetables to tomatoes decreases the
acidity.  The amount by which the acidity is lowered depends on
which vegetables, how much, how finely they are chopped, if they
are boiled in the tomatoes or not, if seeds and skins remain in
or are removed, and if the chunks of vegetable and tomato remain,
if they are ground together or sieved out.  The initial acidity
of the vegetables and tomatoes depends on maturity, growing
conditions, post-harvest holding conditions, and soil/location of
growth.

It is impossible to test every recipe.  It has so far been
impossible to develop a set of proportions or an equation that
would take into account all the variables and give a reliable
assessment of the acidity or the necessary process times.  The
only safe recommendations can be made by comparing the recipe in
question with the USDA guide recipes.  If more vegetable or less
acid (vinegar or lemon juice) is added than the USDA recipe, the
recipe in question can be changed or the product should be
processed according to the process times for the vegetables.
Alternatively the product may be frozen or refrigerated.  

These proportions of vegetables have processing times in the USDA
Home Canning Guide:

  Tomato-vegetable juice   22 lb tomato : 3 C chopped vegetable
  Spaghetti sauce          30 lb tomato : 8 C vegetable : no acid
  Ketchup #1               24 lb tomato : 3 C onion : 3 C vinegar
  Ketchup #2               24 lb tomato : 1 C peppers : 2.6 C  
                              vinegar
  Ketchup #3               24 lb tomato : 9 C vegetables : 9 C
                              vinegar

Use the equivalencies above to convert the amount of vegetables
to cups before a recipe is evaluated for safety.
      
The tomato-vegetable juice recipe specifies "chopped vegetables". 
Up to but no more than 3 cups of mixed vegetables may be safely
added to tomatoes to make 7 qts of juice.  Which vegetables are
used is not important, the margin of safety is large enough to
tolerate the variations in this recipe.  BUT, after boiling, this
recipe is pressed or sieved, so the chunks are removed, and a
smooth juice is canned.  These proportions can not be used for a
chunky sauce.

The spaghetti sauce is pressure processed, so the proportions can
be different.  The tomato acid and the long boiling prior to
canning are sufficient.  These proportions and procedures can be
used with different spices to make a taco or barbecue sauce type
products.

Ketchups 1 and 2 are pressed or sieved so skins and seeds are
removed.  The proportions are similar, #2 with less added
vegetable has a little less added vinegar.  Ketchup #3 is a
blender ketchup, skins are not removed prior to canning.  The
amount of added vegetable and of added acid is much greater
relative to the amount of tomato.

If these proportions are maintained, the amounts of sugar and
spices may be varied to suit one's taste without endangering the
safety of the product, and processing times given in the USDA
Guide can be used.  If other proportions are used, if the product
is canned chunky instead of sieved smooth, or blended raw
(uncooked) or any other variation,  the processing times are not
valid: the recipe must be changed, or the product must be frozen
or held refrigerated. 


Fruits and Vegetables

These products may be safely canned only according to USDA
guidelines.  Piece size, packing density and process times must
be followed.  Grated carrots can not be safely processed
according to times for carrot chunks.  Pumpkin puree can not be
safely canned. The density varies too much, according to variety
and preparation method, to give safe recommendations.  Only
pumpkin chunks may be canned.  Addition of aspirin, salt, or
"canning powders" will not increase the safety or allow for
reduced process times.  Deviations from the specified procedures
might not be safe. The only safe recommendations that can be
given for other procedures is to freeze or refrigerate the
product.

Fruits and vegetables may be pickled.  In this case the
guidelines for pickled products should be used. 


Jar Sizes

For all products, if the USDA Home Canning guide only offers
processing times for pint jars, then the product should not be
canned in quarts.  Usually this occurs for dense or tightly
packed products such as cream style corn, or for heat-sensitive
products such as jelly, mushrooms or pickle relishes.  In all
cases, the extra processing time that would be required to insure
an adequate temperature for an adequate time in the coldest part
of the jar would be so long that the quality of the product would
be lost.  Relishes would be soft and mushy, corn would be tough,
jelly would be syrupy.

Packing food for canning in irregularly-shaped jars such as
ketchup bottles or honey bears is not acceptable.  The irregular
shape and size might not allow for normal circulation and heat
penetration, and cold spots might exist that would allow for the
survival of bacteria. 

If the product has all ready been packed and processed within the
last 24 hrs, it may be repacked and reprocessed in smaller jars,
or refrigerated.  If it has been longer than 24 hrs since the
processing, the product should be discarded to ensure safety.

Food may be packed and processed in smaller jars, half pint
instead of pint if desired, but the processing time to be used
should be that specified for pints. There is no formula to
determine how much less processing would still be adequate. 
Mayonnaise or other straight sided, regularly shaped, commercial
packer jars may be used for boiling water bath canning only. 
They should not be used for pressure canning, due to the danger
of breakage, particularly when the canner is opened.  Flying
glass is dangerous. SUMMARY

1.  SWEET FRUIT SPREADS

     If it was made with regular pectin, high sugar recipe:
     Did it jell?  If it jelled, it has enough sugar, so is safe.
     Was it processed?  If not processed, it should be
     refrigerated for added safety.
     Is there visible mold?  If so, discard the entire contents
     of the container.

     If it was made with a low sugar or no sugar pectin product:
     Were the directions on the box, particularly the processing
     or refrigeration, followed exactly? If the directions were
     not followed, but there is no visible spoilage, the product
     may be refrigerated, or possible frozen. If there is mold,
     if there are bubbles rising, or other signs of spoilage, the
     product must be discarded.

2.  PICKLED VEGETABLE OR FRUIT:

     Find a recipe that has similar ingredients and procedures,
     ie. presoak, size of pieces, maturity and size of
     vegetables, treatment in brine.

     If there is no similar recipe, you can make no judgement on
     the recipe.  If it is an old recipe that has been used
     successfully for generations without spoilage, a 10 minute
     processing should be added.

     If there is a similar recipe, compare the amount of acid to
     vegetable between the two.
     If the recipe in question has less acid, either the acid can
     be increased or vegetable decreased to fit the USDA recipe. 
     If acid is increased, sugar may be increased to adjust the
     flavor. 

     If the product is all ready made and the recipe is unsafe:
          If it was made less than 24 hrs previously, it may be
          refrigerated.
          If it was made more than 24 hrs previously, it should
          be disposed of in a safe manner. 

     If the recipe is safe but the product was not processed:
          If it was made less than 24 hrs previously, it may be
          processed, with new lids. 
          If it is cold, either empty the jars, heat product,
          repack, and put into hot water, or put cold, filled
          jars in cold water, heat together; process for full
          time. 
          It may be refrigerated, or frozen if feasible.
          If it was made more than 24 hr previously, and has not
          been refrigerated, it should be disposed of in a safe
          manner.


3. TOMATO-VEGETABLE BLEND:

     Find a similar recipe in the USDA Guide. Check ingredients,
     proportions, and procedures.

     If there is no similar recipe, no processing times can be
     estimated.  To err on the side of safety, do not using the
     recipe, or freeze the product.

     If there is a similar recipe, check proportions of tomato to
     vegetable, and be sure there is added lemon juice or
     vinegar.  Minor adjustments to quantities of ingredients may
     be made to fit the USDA recipe.

     USDA recipes for juice can not be used to judge chunky sauce
     recipes, or vice versa.

     Spices and seasonings are not crucial to the safety of a
     recipe and can be adjusted.


4.  FRUIT OR VEGETABLE:

     Only USDA procedures and processing times may be considered
     safe.
 
     Products improperly processed less than 24 hours previously
     may be reprocessed, with new lids, or refrigerated or
     frozen.

     Products improperly processed more than 24 hrs previously
     should be discarded as potentially unsafe. 


5.  Wrong JAR OR JAR SIZE:

     If a larger jar or an irregularly shaped jar was used, and
     the food was processed less than 24 hours previously, it may
     be reprocessed, with new lids, in smaller jars.

     If more than 24 hours have passed, the food should be
     discarded. 


Prepared by Mary A. Keith, Foods and Nutrition, September, 1991   
        
Revised by M. Susan Brewer, Foods and Nutrition, June, 1992      
EHE - 705

