It`s time for the Tigress Can Jam and the rules are clear: thou shalt use a boiling water bath.
I am a rule bender – but not a complete rule breaker. So I did indeed make something that was done in a hot water bath. This just isn`t the post on it (that will come tomorrow). I did want to take a moment and share a bit about pressure canning with hopes to inspire some of the other can jammers who haven`t tried it to give it a go.
Let`s back up a bit and start at the beginning first though… Hot water bath canning is technique which preserves food by adding heat to high-acid foods. The heat kills bad bacteria and the cooling process results in a sealed jar without air (that`s my very technical explanation). High acid food includes most fruit while vegetables are brined as pickles to increase their acidity. Large amounts of sugar are typically added to the non-pickled jars to help increase the stability of their suspended state.
Pressure canning uses a pressure cooker to preserve lower acid food without the giant amount of sugar or acid.
Consider this:
- Water boils and transforms into steam at 212 °F
- At 10PSI water boils at 240 °F (at sea level)
Pressure canners seal the contents of the pot – as the temperature rises, so does the pressure on the outside of the container as well as the surface of the water. Pressure canning essentially produces a much higher heat than a water bath can ever reach (water can never get higher than 212 °F. A pressure canner typically seals jars using much less water (as little as 2-3 inches) and often uses pressurized steam as it`s heat source.
Some of the advantages of pressure canning compared to water-bath:
- Less sugar used
- Less vinegar used
- Faster to bring to a boil and can be more energy efficient (though it`s boiling time tends to be longer)
- Less complicated – no testing for set or complicated ingredients (this could also be a disadvantage)
- Can eat more of it at lower calories
- Closer to taste of original product (in most cases)
There is a lot of fear around pressure canning – much of it is from a combination of the fear of the unknown as well as a lot of horror stories on pressure cookers from the past. A lot of safety improvements have been made in the last 10 years alone and you can vastly improve safety by using a new pressure canner. Resist, at all costs, buying a `deal`from a garage sale or using a freebie that was handed down across the generations.
Pressure canning inverts a lot of the logic that you use in water-bath canning. The recipes are simple. The full details for asparagus from the National Center for Home Food Preservation lists the full details here but it is essentially uncooked asparagus with a bit of salt that is loosely packed in sterilized jars and covered with boiling water. It is then placed inside the pressure canner and steamed for a prolonged period (about 30 minutes) and the result is home-canned asparagus.
We`ll post a few tips on buying a canner on Friday.
This allows us to eat beans, peas, asparagus and more through the winter. It`s an awesome addition to your preserving pantry and a relatively easy technique to learn. It can also be a lot less work and less measuring and all of your hard work will pay off through reduced labour and increased local options through the winter.
Peas were our absolute best pressure canning last year.
We`d be pleased to answer any questions (some answers may be in the form of posts in the next week or so) and encourage you to do your research and consider expanding to this relatively easy option and grow your pantry further. But be warned – this can be very habit-forming and you may end up with your own great wall of preserves (our pantry with 400 of our 700 or so jars) to redecorate your house with!