I emailed Presto (I have 2 of their 6 qt cookers) - got an email and a
tel call.

You can use pressure cookers for canning - two points - do not use
over 3000 ft altitude - and use the instructions for canning in
pressure COOKERS specifically. They emailed them - I've attached them
below.

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CANNING IN THE 4 & 6 QUART PRESSURE COOKERS

Pressure canning is recommended by the United States Department of
Agriculture, Washington, D.C., as the only safe method for canning
low-acid foods - vegetables, meat, poultry, and fish. These
instructions for canning at 15 pounds pressure are according to
research done by the Department of Food Science and Nutrition,
Agriculture Experiment Station, University of Minnesota, St. Paul,
Minnesota.

National Presto Industries, Inc.
3925 North Hastings Way
Eau Claire, WI 54703-3703

1-800-368-2194 Home Economist
1-800-877-0441 Parts and Service

Why Pressure Canning?

Water boils at 212 degrees F. (except in mountainous regions) and this
is
sufficient to arrest or destroy some spoilage organisms - enzymes,
molds,
and yeast. However, a temperature of 240 degrees F. or above is
needed to
destroy harmful bacteria, especially clostridium botulinum. In
pressure
canning, some of the water in the Pressure cooker is converted to
steam
and, after all air is exhausted through the vent pipe and air
vent/cover
lock in the cover, the pressure regulator is placed on the vent pipe.
Expanding steam will close the air vent/cover lock and will then
create
pressure. As pressure within the pressure cooker increases,
temperature
increases to 15 pounds pressure -- 250(F.

Four specific agents produce food spoilage. They are enzymes, molds,
yeast
and bacteria. Three of them (enzymes, molds and yeasts) are easily
destroyed by heat during the processing. Bacteria, especially
clostridium
botulinum, can be destroyed only with temperatures above boiling. And
their destruction is of prime importance. If enzymes are not
destroyed,
the quality of food is lowered. Unchecked mold may spread through the
entire contents of a container of food. Yeast causes fermentation.
Bacteria spoilage fall into four groups:
1) Fermentation, recognized by the formation of gas and acid, which
causes
food to sour
2) Flat Sour, in which acid is produced, but no gas is formed
3) Putrefaction, characterized by gas, bad odor and sometimes by
darkening
of food
4) Toxins or poisonous substances which may show no visible signs of
spoilage unless other spoilage organisms are also present

As a safeguard against using canned foods that may be affected with
spoilage that is not readily detected, heat all low-acid foods (all
meats
and all vegetables) to 15 pounds pressure before tasting or using.

Pour canned food into a pressure cooker. Close cover securely. Place
pressure regulator on vent pipe. When pressure attains 15 pounds,
remove
pressure cooker from heat. Let pressure drop of its own accord.
Another
method to detect food spoilage is to pour canned food into a saucepan
and
boil 10 - 15 minutes before tasting or using.

Many times odors that cannot be detected in the cold product will
become
evident by these methods. If after pressure cooking or boiling, food
does
not smell or look right, discard it without tasting.

Foods, such as fruits and tomatoes, may also be canned in a pressure
cooker.

Canning Vegetables

Young, tender, fresh vegetables, slightly immature, are better for
canning
than overripe produce. As a rule, vegetables are best if canned
immediately after picking, since flavor decreases upon standing and
often
unpleasant color changes take place. Avoid bruising vegetables
because
spoilage organisms grow more rapidly on bruised vegetables than on
unblemished ones.

Wash and prepare garden fresh vegetables as you would for cooking.
Vegetables may be raw packed or precooked before they are processed.
If
raw, pack prepared vegetables into clean jars.

To precook vegetables, cover with boiling water and cook until heated
through. Pack precooked vegetables into clean jars. Leave one inch
head
space in jars.

Can with or without salt. If salt is desired use only pure canning
salt.
Table salt contains a filler which may cause cloudiness in bottom of
jars.
Add 1/2 teaspoon canning salt to each pint jar (1/4 teaspoon salt to
each
one-half pint) if desired. Cover vegetables with boiling water
leaving one
inch head space.

When vegetables are precooked, some of the nutrients dissolve in the
water.
So whenever possible, the precooking water should be used as liquid
to
cover the vegetables. However, do not use the precooking water for
canning
turnips, greens, kale and sometimes asparagus, because the precooking
water
may be bitter.

Adjust cap closure according to manufacturer's instructions. Follow
the
specific directions for the operations of your cooker. Place boiling
water, cooking rack and jars in the cooker. Close cover securely. Do
not
place the pressure regulator on the vent pipe. Exhaust air from the
cooker
and jars by adjusting heat to a relatively high setting to obtain a
free
flow of steam from the vent pipe. Allow steam to flow for 5 minutes.
Place the pressure regulator on the vent pipe. Continue heating
until 15
pounds pressure is reached.

Process vegetables according to chart.

Canning Meat and Poultry

Cut meat or poultry into pieces convenient for canning. Precook meat
until
red color changes to light brown. Precook poultry until medium done.
Precooking can be done by boiling, frying, or roasting.

To precook by boiling, make a concentrated broth from bones and meat
or
poultry trimmings. Heat to boiling and precook meat or poultry in
broth.
Meat should not be browned with flour, nor should flour be used in
the
gravy of meat used for canning.

Pack hot meat or poultry into clean jars leaving one inch head space.
Do
not pack tightly. Salt may be added, 1/2 teaspoon for each pint, or
it may
be added at serving time. Cover with hot liquid broth, meat juice or
water. It is important to leave one inch head space.

Adjust cap closure according to manufacturer's instructions. Follow
the
specific directions for the operations of your cooker. Place boiling
water, cooking rack and jars in the cooker. Close cover securely. Do
not
place the pressure regulator on the vent pipe. Exhaust air from the
cooker
and jars by adjusting heat to a relatively high setting to obtain a
free
flow of steam from the vent pipe. Allow steam to flow for 5 minutes.
Place the pressure regulator on the vent pipe. Continue heating
until 15
pounds pressure is reached.

Process meat and poultry according to chart.

Canning Fish and Seafood

Only fresh fish should be canned and these should be bled and
thoroughly
cleaned of all viscera and membranes when caught, or as soon as
possible.
Canning should be restricted to proven varieties where it is
definitely
known that a product of good quality may be obtained.

Clams, Whole (Littleneck)
Scrub clams and soak overnight in 10% brine. Open clams and wash in
salted
water using 1 tablespoon salt for each quart of water. Cover clam
meat
with boiling water, to which 1/8 teaspoon citric acid crystals have
been
added to each quart of water. Allow to stand 1 minute. Pack loosely
into
clean, hot Mason jars, leaving 1 inch head space. Cover with hot
concentrated clam juice to 1/4 inch from top. Adjust jar lids.
Process
according to chart.

Crab
Place crabs in ice water 1 - 2 minutes. Separate claws from body,
remove
waste portions, and wash thoroughly. Place bodies and claws with 2
cups
water in cooker, and cook 5 minutes at 15 pounds pressure. Cool
cooker at
once. Remove meat from shells. Wash thoroughly in salted water using
1/2
cup salt to 2 quarts water. Drain and dip in solution of 1/2 cup
vinegar
to 2 quarts water. Drain and remove all excess moisture. Pack
loosely
into clean, hot Mason jars, leaving 1 inch head space. Add 1/2
teaspoon
salt and cover with boiling water. Adjust jar lids. Process
according to
chart.

Fish - General Method
Cod, Mackerel, Herring, Lake Trout, Whitefish, and Mullet. Clean fish
thoroughly, fillet large fish or leave small pan fish whole. Cut into
container length pieces and soak in brine, 1 cup salt to 1 gallon
water,
for 1 hour. Drain. Pack with skin side of fish to the outside of the
Mason jar. Leave 1/2 inch head space. Then submerge open jar in a
kettle
containing hot brine, 1/2 cup salt to 1 gallon of water, and boil 20
minutes. Remove, invert and drain thoroughly. Add a bay leaf and a
slice
of onion to each jar, if desired. Adjust jar lids. Process according
to
chart.

Lobster
Plunge live lobsters in boiling, salted water, 2 tablespoons salt to 1
gallon water. Cook 15 - 30 minutes depending on size. Remove and dip
in
cold lightly salted water. Remove meat and wash quickly. Drain. Dip
meat
in solution of 1/2 cup vinegar to 2 quarts water. Drain and remove
all
excess moisture. Pack in clean, hot Mason jars, leaving 1/2 inch head
space. Cover with hot brine, 1 1/2 tablespoon salt to 2 quarts water.
Adjust jar lids. Process according to chart.

Salmon
Clean and wash fish thoroughly. Cut into container length pieces,
leaving
in backbone. Soak in brine, 1/2 lb. salt to 1 gallon water, for 1
hour.
Drain well. Pack solidly in Mason jars leaving 1/2 inch head space.
Adjust jar lids. Process according to chart.

Shrimp
Shrimp should be canned when absolutely fresh as they deteriorate
quickly.
Wash shrimp thoroughly, peel and wash again. Cover with cold brine,
1/2
cup salt to 1 quart water, for 20 - 30 minutes depending on size.
Drain.
Place on cooking rack and cook 6 to 8 minutes in boiling brine,
proportions as above. Dry and cool shrimp. Pack loosely in clean,
hot
Mason jars leaving 1 inch head space. Fill containers with boiling
brine,
1 1/2 tablespoon salt to 1 quart water, leaving 1 inch head space.
Adjust
jar lids. Process according to chart.

Canning Fruits and Tomatoes

Fruits and tomatoes may be canned in a pressure cooker. The pressure
processing method for fruits and tomatoes gives a heat treatment
equivalent
to the much longer processing in boiling water bath canner.

Select firm, fully-ripened but not soft fruit or tomatoes. Do not can
overripe tomatoes. Wash, peel, core, or remove pits, if necessary.
To
loosen skins of peaches, apricots and tomatoes, blanch for 30 seconds
in
boiling water. Dip into cold water and peel. Cherries and plums are
usually canned whole. Prick the skins with a fork to prevent them
from
breaking during processing. Leave fruit whole or cut as desired
(halves,
slices, or chunks).

Some fruits tend to darken while they are being prepared. To prevent
the
darkening, place fruit in an ascorbic acid solution (1 teaspoon
ascorbic
acid to 1 gallon water) or use ascorbic acid or citric acid mixtures
according to manufacturer's instructions.

Although fruit has better color, shape and flavor when it is canned
with
sugar, it may be canned unsweetened if desired. Sugar is used for
flavor.
It is not used in high enough concentration to act as a preservative.

White sugar is preferable to brown sugar for canning. Honey or light
corn
syrup may be used to replace up to 1/2 the sugar. If you wish to use
sugar
substitutes, follow manufacturer's instruction.

The amount of sugar desirable to use in preparing syrups will depend
upon
the tartness of the fruit and on your preference. It should be
remembered
that fruit, when heated, releases some of its juices which will dilute
the
syrup in proportion to the juiciness of the fruit.

Syrups for Canning Fruits

Very Light1/2 cup sugar to 1 qt. Water yields 4 cups
Light1 cup sugar to 1 qt. Water yields 4 1/2 cups
Medium2 cups sugar to 1 qt. Water yields 5 cups
Heavy3 cups sugar to 1 qt. Water yields 5 1/2 cups

Heat sugar with water or juice until sugar is dissolved. Add fruit
and
cook until heated through. Pack fruit into clean jars to within 1/2
inch
of top of jar. Cover with hot liquid leaving 1/2 inch head space.
The
liquid may be syrup, fruit juice or plain water.

If preferred, fruit may be packed raw (except apples, cranberries,
figs and
strawberries) into containers and covered with boiling hot syrup.
When
this is done, processing time need not be increased. When fruit is
packed
cold, it shrinks during processing, and the container is less full
than
when fruit is preheated in boiling syrup before packing.

Pack tomatoes into clean jars to within 1/2 inch of top of jar, press
down
to release juice and fill spaces. Add 1 tablespoon of lemon juice per
pint. Add 1/2 teaspoon canning salt to each pint jar if desired.

Adjust cap closure according to manufacturer's instructions. Follow
the
specific directions for the operations of your cooker. Place boiling
water, cooking-canning rack and jars in the cooker. Close cover
securely.
Do not place the pressure regulator on the vent pipe. Exhaust air
from
the cooker and jars by adjusting heat to a relatively high setting to
obtain a free flow of steam from the vent pipe. Allow steam to flow
for 5
minutes. Place the pressure regulator on the vent pipe. Continue
heating
until 15 pounds pressure is reached. Process fruits and tomatoes
according
to chart.

After Processing Time Is Complete

At the end of processing time, turn the burner to "Off" or remove
cooker
from the heat source. Let the pressure drop of its down accord, do
not
quick cool. When pressure is completely reduced, remove the pressure
regulator from the vent pipe. Allow cooker to stand approximately 10
minutes, then remove cover and jars.

Processing Time Chart
For Use with 4 or 6 Quart
Pressure Cookers

Processing times at 15 pounds pressure apply only to altitudes up to
3,000
feet. Do not use a 4 or 6 quart pressure cooker at altitudes above
3,000
feet. Processing times are for 1/2 pint and pint jars. Use 5 cups
water
in pressure cooker for processing. Exhaust air from the cooker and
jars by
adjusting heat to a relatively high setting to obtain a free flow of
steam
from the vent pipe. Allow steam to flow for 5 min.

FOOD/MINUTES
Fruits/0
Asparagus/25
Beans, lima/40
Beans, snap/25
Beets, whole or sliced/25
Carrots/25
Corn, whole kernel/60
Greens, all kinds/45
Mushrooms/30
Okra/25
Okra and Tomatoes/25
Peas, green/40
Peas, blackeye/40
Potatoes, new-whole/30
Squash, cubed/30
Sweet potatoes/60
Tomatoes/0
Beef/60
Pork/60
Lamb/60
Veal/60
Poultry, with bone/40
Game meat/60
Game fowl, with bone/40
Clams (Littleneck)/35
Crab meat/35
Fish/90
Lobster *use only 1/2 pint Mason jars/45
Salmon/90
Shrimp/30