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.
