HISTORY
(The historical information is adapted from www.thecharmedkitchen.com)
The first known pressure cooker was invented in 1679,
believe it or not, by Denis Papin, a French physicist and mathematician. His
invention was a large cast iron pot with a lockable lid that raised the boiling
point of water. At this higher temperature,
bones softened and meat cooked in quick time. It was promoted as a “digester”
because it cooked food so quickly. Sadly, it was difficult to control the
pressure and explosions were common. Eventually he added a valve to release
extra pressure.
In 1795, Napoleon Bonaparte offered a reward for whomever
could develop a safe, reliable food preservation method for his constantly
traveling army. Nicholas Appert took on the challenge, and about 15 years later
introduced a method that involved heat-processing food in glass jars reinforced
with wire and sealed with wax.
The next breakthrough with tin cans occurred in or around 1810. Englishman Peter Durand sealed
food in “unbreakable” tin cans… but the can opener was not invented until 48
years later! Before that cans were opened with hammer and chisels! The first
commercial canning establishment in the U.S. was started in 1912 by Thomas
Kensett.
It wasn’t until Louis Pasteur was able to
demonstrate how the growth of microorganisms causes food to spoil that people understood WHY canning methods preserved edible food.
At the time of the U.S. Civil War glass food preservation
jars with metal clamps and replaceable rubber rings had been invented. These
jars are still available today, although they are no longer recommended for
canning, just for storing dry goods.
In 1858, John Mason invented a glass jar with a screw-on
thread molded into its top, and a lid with a rubber seal. Most canning jars are
still referred to as Mason jars.
Meanwhile in the late 1800’s, William Charles Ball and his
brothers got into the food preservation jar business and began buying up
smaller companies. They quickly became leaders in the industry. Ball jars are
today one of the most widely used jars for canning (and their cookbooks are wonderful
– LE).
HOW TO
I regard pressure canning as an essential skill for anyone
wanting to increase self-sufficiency and resilience. Power outage from a tornado, hurricane, flood? A huge harvest from the garden, hunting, or
fishing? Can’t get to a supermarket
during a week-long blizzard or after surgery?
Enjoy the convenience of meat, cheese, vegetables and fruits you pressure
canned in advance!
If someone has never seen the equipment, it may be hard to
imagine how this works, especially since the process requires some specialized
equipment. For one thing, as conveyed above, you do not use cans! ???
The containers are tempered glass mason jars with metal, two part lids –
a flat disk and a round lipped sleeve that fits over the disk and screws around
the top of the jar. The pressure canner
is a specialty kitchen item, not a normal pot. It is super heavy duty steel,
designed with a unique lid. The top locks in place with six screwable locks and
three L shaped brackets and has a steam valve like a mini chimney that you top with
a round, metal regulator. Covering the
steam vent with the regulator enables the temperature within to rise and remain
above the boiling point (usually 240 degrees for my canning), thus killing most
bacteria over the designated duration of cooking. We bought the All American brand for about
$275 in a size that fits 7 quart jars at a time.
After processing, the cook lets the hot water and steam
pressure cool before lifting the lid to pull the jars out of the hot water bath
and set them on an appropriate surface to cool.
The temperature difference between the interior and exterior of the jars
causes pressure by which the disk tops suck inward (concave), thus creating an
air tight seal to protect the food within.
When you want to consume the food, months or years later, you break the
seal with a gentle twisting movement on the edge of the disk, with a fork or
other utensil.
EXAMPLE of METHOD and TIMING
This week, I canned 21 jars of brassica (cabbage, broccoli,
and cauliflower) leaves.
1. 1.
First I assemble the equipment in the
kitchen. I fill the pressure canner with
water high enough to fill and barely top 7 quart jars (they are about 8 inches
tall). I lay the disk lids on top of the
jars. As the water heats, it cleans the
containers and tempers the glass for the boiling temperatures ahead. On another burner, I heat water in a large
pot to blanch the leaves. (Blanching is
quickly boiling the vegetables to turn bright green, then plunging them in a
nearby large bowl of cold water to stop the cooking.) On the counter, I place a big bowl full of
cold water, a smaller empty bowl, a sharp knife, long tongs, a soup ladle, a
sieve, and a special canning tool that looks like short tongs but with a
circular clamp, to lift the round jars in and out of the hot water.
2. 2. Then I go
out to the gardens to harvest enough leaves to fill 7 + quarts (about 15 leaves
per jar or about 100 leaves total). This
pleasant task takes me about 30 minutes.
3. 3.
Upon returning, my prep works takes about an
hour. I fill one sink full of cool
water, rinse the leaves in the other and then lay them in the bath. I gather 8 leaves, roll them up like a green
log, cut crosswise into sushi sized pieces, and then long wise, resulting in
rectangular confetti of leaves. Any long
or thick stems or spines, I snap off and drop in the empty bowl. Every time I
amass 24 or 32 leaves, I blanch them for maybe 10 – 20 seconds. Then I fish the leaves out with the sieve and
dump them into the pot of cool water to stop the cooking.
4. 4.
During the next set of 24 – 32 leaves I chop, I
blanch the stems and spines, which, being thicker, take more time – often a
minute.
5. 5.
Some people flavor the vegetables with herbs,
onions, etc at this point, but I prefer to store mine plain, so I can be more
spontaneous when I eventually prepare meals.
I pull out a hot jar from the
pot, empty the water, and with the long tongs, fill the jar with the blanched
and cooled leaves or stems, pressing down occasionally to fit more. Then I ladle hot blanch water over the
leaves, poking with the tongs to open up any air pockets. Every canned food recipe has a suggested airspace
at the top, such as half an inch. When I
have left overfilled jars in an unheated outbuilding in winter, the liquid
expanded and cracked the jars. So I carefully
assess the space at the top. I wipe the
top edge of the jar with a clean towel and then place the lid and ring on,
finger tight, not tighter, for reasons that relate to the cooking process and
subsequent self-sealing.
6.
The science and safety of canning, as well as
recipes, are well explained in Bell’s Book
of Canning, which is sort of the “Bible” of canning.
7. 6.
When all 7 jars are immersed in the simmering
water bath, with about 1 inch of water covering the lids, I lock on the lid,
crank up the heat, and watch until steam vents out of the top for several
minutes. Then I place the regulator on
top and set the timer.
8. Acidic foods, like berries, tomatoes, and citrus
are processed very quickly (15 -20 minutes for quart jars). Non-acidic foods, like meats, tubers, and
other fruits and vegetables take MUCH longer, such as 90 minutes for quart jars
of leafy greens.
9. 7. It also takes another 60 – 90 minutes for the
water and steam in the pot to cool down enough to remove the regulator and then
the lid. So when I can vegetables or bear meat, I can only process two batches
in a day. During berry harvesting
season, I can process more sets… if I want to spend all day at it. Otherwise, I pop the berries in gallon bags
in the freezer to deal with during inclement weather.
108.
I place the hot jars on the stone surface that surrounds
our wood stove. I can see the liquid
still bubbling/boiling through the glass. I leave them there overnight, hearing
“pings” when internal pressure seals the jars when the lids go concave.
119.
The next morning, I test each jar’s seal by
poking the lids gently with a finger.
Those that sealed are firm and do not lift free of the jar. Those that did not seal for some reason (like
a bit of food on the lip of the jar, or a dented lid) wiggle and lift easily. The sealed ones go on the pantry shelf,
labelled with contents and date. The
unsealed ones go in the freezer or refrigerator to consume sooner or to can
again with a different lid.
During the summer, of course, we gather fresh vegetables for
salads and side dishes each day. But since
brassicas grow so easily here, our winter rice, stews, stir fries, and other
dishes often feature a hefty portion of brassica leaves for color, nutrients,
and roughage. We generally open one
quart per week. By the end of summer, I
will have canned more than 100 jars of summer fruits and vegetables (and
hopefully, bear meat) to enjoy through the winter and into next year.
Yes, this takes a long time, especially if a reader is able
to order foods on line, delivered to the door.
On the other hand, I enjoy a sense of pride in each mouthful. I not only grew this food from tiny seeds, I
also preserved it for my family’s consumption in a tasty dish.
