pressure canning

Pressure Canning – basic principles

Posted on September 14, 2011 at 7:20 am

If you want to know how to preserve food by pressure canning, this article is what you need. You may want to check out my boiling water bath article as well.

First, what foods must you pressure can? Low-acid foods. In this context, low acid is defined as “pH 4.7 or higher”. Vegetables, meat, fish, stocks, and finished foods like stews or soups all need to be pressure canned. Tomatoes are a special case as they are right on the cusp of pH 4.6, so they can be canned using either the boiling water bath method (with added acid like lemon juice or citric acid) or by using pressure.

Second, what is a pressure canner? Can I just use my pressure cooker?

Pressure canner and jiggle weight

Pressure canner and jiggle weight ( jiggle weight is the column to right of pressure gauge with ring either side)

The simple answer is “no”. Most domestic pressure cookers are not rated or constructed to take the sustained pressures for which a pressure canner is designed. When processing beans with my easy prepare method, for example, I am canning at 10psi for 90 minutes. Unless your pressure cooker specifically states it is rated for pressure canning, it is not suited to this task. Canners like the Presto 23qt canner I have (see picture) cost around $80 and are a worthwhile investment – you can use it as a pressure cooker, pressure canner, AND as a boiling water bath canner.

A note on pressure canner gauges. If you intend using the pressure gauge, you must get the gauge checked for accuracy every year. This is a free service by most county extension services in the USA. I use a jiggle weight because I can always tell when the canner is at the right pressure – I listen for the “pshht pshht” noise of the jiggle.

Third, you need lids and bands. New jars come with lids and bands, but you should pick up extra lids when you can get them at a good price. The bands are reusable for many canning sessions – they only need to be discarded if they show signs of rust or corrosion.

And finally, you need something to put in the jars – the “jar contents”.

PREPARATION STEPS

If you’ve already read my article on boiling water canning you already know the first few preparation steps, and can skip down to Putting on the squeeze.

JARS
To start a pressure canning session, first clean the jars you are going to use. Running them through the dishwasher works well; if you don’t have a dishwasher you can wash them in the sink. Once they have been cleaned, put them in the canner, fill the canner with hot tap water to the appropriate fill line marked on the inside of the canner (see your canner’s instruction sheet) and put a little hot tap water into the jars to keep them from falling over. Once the jars are resting in the hot tap water, put the lid on the canner to retain heat, put the canner on the hob, and set it to a medium-low temperature.

This is all before you do anything to the “jar contents”. You are aiming to have the jars at a good hot temperature before filling them with the “jar contents” – too much of a temperature difference between the jar and the contents leads to thermal shock, also known as “glass shrapnel and incendiary contents spread across the kitchen”. Thermal shock is generally considered A Bad Thing(TM) and is definitely to be avoided.

Once the “jar contents” are starting to cook, increase the heat under the canner with the aim of getting it to a boil once the “jar contents” are ready. It’ll take you a little practice to know exactly when to turn the heat up, but don’t sweat it too much – you can keep the “jar contents” nicely hot for a few extra minutes if needed, and it doesn’t really matter if the empty jars are heating for longer than needed.

LIDS
Give the lids a good clean with plenty of soap and hot tap water and then rinse thoroughly. I have seen many people saying to boil the lids and then keep them in the hot water straight after boiling, but according to the Ball Complete Book of Home Preserving (which I cannot recommend strongly enough – it is absolutely essential for a home canner), all that is needed is to keep them to a simmer – 180F/82C.

Once your lids and jars are ready, you can ladle in your jar contents (the soup, stock, stew, beans, etc.) and then seal the jars.

SEALING THE JARS
Once each jar is filled to the appropriate level (usually within 1/2 to 1 inch of the top of the jar depending on the recipe) you should wipe off the rim of the jar to make sure that there is nothing on the rim to interfere with a proper seal. Use a paper towel sprayed with a 50/50 mix of white vinegar and water to wipe off the rim. Lift lids out one by one and place on the rim. Screw down the bands to “finger tight”: use your fingertips to screw the lid down until you can’t tighten it any more, but do not tighten the lid as tight as you possibly can. The purpose of this step is to secure the lid on, not to seal it completely – there needs to be a little looseness in the band to allow air to escape, but equally you don’t want water to get into the jar. The jar seal comes from the vacuum you will create in the water bath stage.

PUTTING ON THE SQUEEZE
Once your jars, lids, and “jar contents” are ready, it’s time to put them into the canner on the rack at the bottom.

Place the lid on the canner, bring the canner to a full boil, and vent the canner for 10 minutes. Count the 10 minutes from when the stream of steam is running full blast – on my canner I get a whistling noise at this point. You can tell that the appropriate point is reached when the steam is a solid column – this is when you start your timer.

Once the 10 minute vent is completed, put the weight on the vent and process for the amount of time specified in the recipe. Once the processing time is up, take the pot off the heat and walk away. You need to let the pressure canner return to normal pressure. This will take a variable amount of time, but you cannot hurry this step – remember thermal shock! Once the pressure gauge has dropped to normal, leave the canner for an additional 10 minutes then take the lid off the canner. Use your jar lifter or tongs to take the jars out of the hot water to cool.

COOLING THE JARS WITHOUT THERMAL SHOCK
The best way I have found to cool jars without having any danger of thermal shock (hot jars and cool countertops do not mix) is to use a cookie rack. This allows free air circulation around the jars without putting them onto any surface which could turn them into bombs.

Leave the jars overnight; the next day you can take the screw bands off and test the seal.

TESTING THE SEAL
Testing the seal is easy. If you can lift the jar up by the lid, the seal is good. If you can’t, the seal is bad! If a jar didn’t seal properly, treat it as an eating jar and just finish the contents within a few days or freeze the jar and its contents for later use.

RULE OF THUMB
The rule of thumb when calculating how long to pressure can for: look up each ingredient on the USDA list separately. Note the longest time any single ingredient requires. Pressure can for that amount of time – the longest amount of time required by any single ingredient.

You were waiting for me to say what the jar contents are? Well… that’s up to you. Go for it!

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Easy canning dried beans

Posted on May 17, 2011 at 10:24 am

Canning dry beans can seem like a real pain. The rinsing, sorting, soaking overnight, changing the water rigmarole. There’s the “quick cook” method – boil for 2 minutes, soak in the hot boil water for 1 hour, drain, fresh water, bring back to a boil – pfft, what a pain!

So here’s the super easy way to do it!

Put your pint jars into your pressure canner with hot tap water to the appropriate fill line. Start heating the water with the jars in it. Put your electric kettle on to boil. If you don’t have an electric kettle – why not?!? – boil the water in a pan instead.

Rinse and sort the beans. Put 1/2 to 2/3 cup of rinsed sorted beans in each pint jar, producing an approximate yield of 4 to 5 pint jars from each pound weight of dry beans. Pour in boiling water to 1/2 inch of the top (just about where the screw threads start).

Cap your jars and process at the appropriate pressure for your altitude for 90 minutes. Follow the usual steps for pressure reduction and cooling as specified in your pressure canner user manual.

There you go! Between four and 10 pint jars of pressure canned/cooked beans in about 100 minutes, more or less, ready and waiting for you to deploy them in all sorts of interesting manners.

The beans I canned this way were chickpeas(garbanzo) and pinto beans… you’ll see why later this week.

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Pressure canning – beans

Posted on April 14, 2011 at 2:43 pm

Beans are a powerful ally in living frugally. They have the best “bang for the buck” in terms of nutritional return for money: insoluble and soluble fiber, high in protein, complex carbohydrates, folate, and iron. Once you get a stockpile of dried and canned beans in your pantry you are opening up new vistas of frugal, healthy, and stupidly cheap food.

Start with 2lbs of dry beans – any type, any combination. I started with 1lb of dried black beans and 1lb of dried kidney beans. Sort through the dried beans discarding any that are broken or that are stones masquerading as beans. Wash them in lots of cold water and place them in a large pot with enough water to cover them by 1 inch / 2.5cm. Bring to a boil and boil for 2 minutes. Allow the beans to stand for 1 hour in the hot water.

You now have a choice: discard, or don’t discard, the water. Many recipes recommend discarding the water and starting again with fresh as this reduces the amount of oligosaccharides, which are responsible for the… fragrant!… reputation that beans have. The water also contains trace minerals and nutrients, so I leave it up to you to decide which is more important for you.

Two pounds of dried beans will yield you between 6 and 10 pint jars of ready-to-use beans, depending on which ones you go for. The black/kidney bean mix I did yielded 8 pint jars, at a cost per jar of 25 cents. Most of the cans in the stores are done by weight rather than volume, but they probably contain about 1.5 cups of cooked beans, usually at around 50 cents to over a dollar in price.

Put the squeeze on those bad boys for 75 minutes per pint jar, 90 minutes per quart jar. The National Center For Home Food Preservation is an absolutely essential reference for those of you above 1000ft.

Beans. Full of nutrition. Good for you in multiple different ways. Work well with vegan, vegetarian, and omnivore cuisine. Laughably cheap and stupidly easy to prepare. What more do you need to know?

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Basic meat sauce – pressure canning

Posted on April 2, 2011 at 9:48 am

I like having modular components as well as finished items. What I mean by a “modular component” is something which is not complete in and of itself, but that can very quickly become a tasty meal. In the case of this basic meat cause it can become chilli, curry, spaghetti sauce, or even a pizza topping depending on what spices, seasonings, or other supporting ingredients I add to it.

Basic meat sauce
Ground meat, approximately 3 to 4 lbs (1.5 to 2kg)
6 large (28oz/800g) cans crushed tomatoes

Cook the ground meat (I used beef and venison) with olive or other healthy vegetable/fruit oil until nicely browned. Add the 6 large cans of crushed tomatoes to the meat and heat thoroughly until nice and bubbly.

Portion into quart (litre) jars, leaving 1inch/2.5cm headroom in the jar (fill jar to the point just below where the shoulders narrow) and process in your pressure canner for 70 minutes. Follow the instructions for your pressure canner for time adjustments if you live 1000ft / 300m or more above sea level.

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leftovers

Posted on November 26, 2010 at 5:05 pm

Ah, Thanksgiving. One of the leading causes of leftovers along with Christmas! But leftovers is where the home canner can really shine.

The turkey carcass? Boil it up to make a bone stock and put the squeeze on it. Same with the leftover veggies, you can put them up for later use. You could add some of your freshly made stock to make the vegetables into a rich and nutritious soup. Put that soup on the shelves for later in the year when you can’t be bothered cooking, or even when you are ill.

Got a ham? What are you waiting for – boil those bones and make a stock – then pressure can that bad boy! Yes, even things like Collard or Mustard Greens which are frequently made with pork stock or bacon can be canned.

What about all these lovely buttery, creamy sauces? Can you can them? The answer, sadly, is a categorical NO. Dairy products can’t be canned in any way that the USDA deems “safe”. If you have some butter or cream or milk in there, please don’t even take the chance – freeze it, and avoid that whole “dying from botulism” thing. That’s a once in a lifetime experience of suck!

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