Putting Food By - Janet Greene [26]
If you find your rack impractical, either shop for a better one online or buy several large, round cake-cooling racks. Their wire is more fragile, but for support toward the middle, cluster on the bottom of the kettle five or six screwbands that are no longer fit to use on jar lids. Measure the bottom diameter of your B–W Bath canner (not the top, which usually is about an inch larger), and choose your racks accordingly: ½ inch of leeway all around is about right.
Hot–Water Bath (Pasteurization)
We have bent over backward in referring to the Boiling–Water Bath because it’s necessary to distinguish clearly between the B–W—which maintains a real 212 F/100 C boil at sea level—and the Simmering Hot–Water version, which is a form of pasteurizing.
The Hot–Water Bath is recommended only for certain sweet, acid fruit juices, and as a finishing—as against a complete processing—procedure to help seal preserves and pickles/relishes and sauerkraut.
Despite the casual swapping of these terms in some older manuals, the processes themselves are not interchangeable.
THE WHY OF PRESSURE CANNING
Even in the sea-level zone, every plain vegetable except tomatoes, every meat, every seafood that is canned at home—and almost every mixture containing these—MUST BE CANNED IN A PRESSURE CANNER.
Or put it this way: Pressure Canning is the ONLY process that is able to destroy the tough spores of bacteria like Clostridium botulinum which can grow and produce deadly poison in jars or cans of any low-acid food.
Or this way: dangerous spoilers can live through even a day-long Boiling–Water Bath at 212 F/100 C in containers of low-acid food with a natural acidity rating of a pH higher than 4.6, but they are killed by the higher temperatures reached only in a Pressure Canner.
Please look at the pH ratings of selected foods and the section called Dealing with the Spoilers on page 8.
And before we talk about how to use a Pressure Canner, we’ll make three points:
First, the Pressure Canner we’re talking about is not to be confused with a steamer—either the old-style arrangement that swirled steam at Zero pounds/212 F/100 C around containers of food, or today’s compartmented kettles for cooking clams or lobsters, or the “atmospheric canner” described later in this chapter.
Second, the Pressure Canner we’re talking about is an honest-to-goodness, regular, conventional big Pressure Canner—not the 4-, 6- or 8-quart pressure saucepan that is called a pressure cooker. PFB is leery of processing any containers of low-acid food in a pressure cooker.
Third, being so much smaller and thin-skinned, pressure cookers (usually less than 4- to 6-quart loose capacity) are not designed for processing times researched by food scientists for true canners. The pressure cooker’s heating-up and cooling-down times are too short to do the job without adding processing time. However, if a pressure cooker is the only thing you have for canning low-acid foods, go ahead and use it—with these stipulations:
It is 4- to 6-quart loose contents, and is controlled by a deadweight gauge, using 15 psig.
Process nothing larger than a 1-pint jar or a No. 303 can.
Don’t let the containers touch each other inside the pan; and of course the jars/ cans will be on a rack that holds them up from the bottom of the pan.
Let the pan vent steam for 5 minutes—see The Pressure Canner at Work a few pages later on. Then close the vent and start counting the minutes required for safe processing when the gauge indicates 15 psig.
Add 10 minutes to the processing times given in later chapters for individual foods being Pressure-canned (again, this is to compensate for shorter heating/cooling times in the smaller pot).
Consult Correcting for Altitude in Chapter 3. If you live higher than 3000 ft/914 m, the leading makers of the small pressure cookers warn against processing low-acid food in these pressure cookers. Reason: water needed for extra processing time at a higher altitude will