Do not use overripe fruit. Canning doesn't improve the quality of
food, so if you start out with low quality, it will only get worse in
storage. Plus
Do not add more low-acid ingredients (onions, celery, peppers,
garlic) than specified in the recipe. This may result in an unsafe product.
Don't add substantially more seasonings or spices, these items
are often high in bacteria and excess spices can make a canned item unsafe.
I doubt whether increasing a spice from 1 teaspoon to 2 in a batch of 7
quarts will have any adverse effect, but use some common sense and don't go
overboard.
Do not add butter or fat to home-canned products unless stated in
a tested recipe. Butters and fats do not store well and may increase the
rate of spoilage. Adding
butter or fat may also slow the rate of heat transfer, and result in an
unsafe product.
Thickeners - With the exception of "Clear-Jel" which has been
tested in USDA and university food labs, do not thicken with starches,
flour, or add rice, barley or pasta to canned products - this applies to
both savory products (such soups and stews), sauces and pickled items. Items
that thicken products will absorb liquid during processing and slow the way
in which the food heats. Under-processing and unsafe food could result.
ClearJelⓇ starch has been tested in pie filling recipes - here's where to
get it:
DO add acid (lemon juice, vinegar or citric acid) to tomato
products when directed in the recipe. In 1994, food scientists proved the
risk of botulism poisoning from canned tomato products, and acid is now
added to canned tomatoes, even to those canned commercially. Lemon juice is
widely available, but will add a sharp note to canned tomatoes; citric acid
will change the flavor less noticeably, and vinegar is part of many recipes
anyway. If necessary, you can balance the tart taste by adding sugar.
Heat process (water bath canning or pressure canning, as called for
in the recipe) all canned items that will be stored on the shelf. Some
recipes, especially those
for jams and jellies, instruct you to simply seal hot-filled jars, or to
invert the jars as the final step. I know of no reputable source (university
food science departments, the USDA, FDA, National Home Canning Center, etc.)
that recommend either "open-kettle canning" or inverting jars as the final
step, as unsafe final products may result.
Never process the jars in any oven (electric, gas or microwave).
Steam canning is also, pretty broadly NOT recommended. There ARE a
couple of manufacturers selling steam canners, but you will find virtually no
credible authorities recommending them, for a variety of reasons, starting
with basic heat transfers properties of steam vs. water.
Increase water-bath processing times at altitudes of 1,000 feet or more
to compensate for the lower temperature of boiling water at high altitude.
I've tried to be sure to include the conversion charts in all recipes for
this.
To prevent darkening: Some peeled or cut fruits (such as peaches, apples, nectarines) will
darken when exposed to the air. Any of these simple treatments will help
prevent darkening:
Use a commercial ascorbic acid mixture like "Fruit-Fresh", which is
available at the grocery and drug stores. Sprinkle it over the cut fruit
and mix well. OR
Put the cut fruit in a solution of 1 teaspoon ascorbic acid (vitamin
C, available in a powdered form from the drug store) and 1 gallon water.
Drain before canning.
Put the cut fruit into a lemon juice solution (3/4 cup lemon juice
to 1 gallon water). Drain fruit before canning.
Canning jars. Use standard mason / Ball / Kerr (etc.) jars for
home canning. Commercial food jars that are not heat-tempered, such as
mayonnaise jars, often break easily (although, I've had great luck with "Classico"
brand quart spaghetti jars. Note that the Classico's manufacturer does not recommend reuse of their jars: here is
what they say on this
page). Sealing also can be a problem if sealing
surfaces do not exactly fit canning lids. Be sure all jars and closures are
perfect. Discard any with cracks, chips, dents or rust. Defects prevent
airtight seals.
Do not use jars larger than specified in the recipe, as an unsafe
product may result. It's almost always ok to go smaller. Generally
speaking, quart jars are the largest size you should use.
To remove scale or hard water films on jars, soak several hours in a
solution of 1 cup vinegar (5 percent) per gallon water. Keep the jars warm
until ready to fill (to reduce breakage from thermal shock).
Prepare the two-piece metal canning lids by washing them in water
and following the manufacturer's instructions for heating the lids (some
need to be covered with hot water for a minute or more - in steaming,
but not boiling water)
The flat lids can be used only once, but the screw bands can be reused as long as
they are in good condition. Read Do not reuse lids from commercially canned
foods.
Check jars for seals within 24 hours of canning. Treat jars that fail to
seal properly as if they are fresh (refrigerate and eat soon).
More tips for boiling water bath canning:
Fill the canner at least halfway with water. A little practice
will help you to know how much water you will need to start out with to
ensure the jars will be covered by at least 1 inch of water.
Preheat water that is added to the jars (when called for) to very warm but not boiling (around 140 degrees F) for raw-packed foods (the lower
temperature helps to reduce jar breakage) and to boiling for hot-packed foods.
Put the filled jars, with lids and rings on, onto the canner rack and
use the handles to lower the rack into the water. Or you may fill the canner, one
jar at a time, with a jar lifter. Obviously, you'd need to be quick, or
the first jar could be in the bath for substantially longer than the last
jar you add. If you don't use a jar rack, then a
flat rack on the bottom helps to reduce break. One of these comes with
each canner.
Always add more boiling water, if needed, so the water level is at least one
inch above the tops of the jars.
Turn heat to its highest position until the water boils vigorously, and
then set
a timer for the minutes required for processing the food.
Cover the canner and if necessary, lower the heat setting to maintain a
full but gentle boil
throughout the processing time. Generally, I find I need to keep the burners
on high.
If one burner doesn't produce enough heat to keep the water boiling, you
can usually straddle two burners with the canner.
When the jars have been boiled for the recommended time, turn the
heat off and use a jar lifter to remove the jars and place them on a towel
in an area that is not drafty, leaving
at least one inch between the jars during cooling.
Do not retighten the jar lids - it may break the seal.
Do not leave the jars in the boiling water after processing time is done,
because the food will become overcooked.
Check the jar seals 12-24 hours after processing for leaks and broken
seals. Just press down on the lid. If it seals, it will be
sucked down tight. If it did not seal, it will flex and make a popping
sound each tip. See this page
for more information.
To store, remove the screw bands and wipe the jars clean. Otherwise, the
rings may rust tight to the jar!
Any jar that
fails to seal can be reprocessed in a clean jar with a new lid. Reprocess
within 24 hours. Generally, it is better to refrigerate the jar and use it within several
days. The jar may also be stored in the freezer if the headspace is adjusted
to 1-1/2 inches to allow for the expansion of the product.
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Remember to ALWAYS call the farm or orchard BEFORE you go - weather, heavy picking and business conditions can always affect their hours and crops!
