Putting Food By - Janet Greene [28]
Checking the Dial Gauge
Each year well before canning season, or more often if you put by large quantities, you should have the dial gauge of your Pressure Canner checked for accuracy against a master gauge. Just because the dial may rest at 2 pounds pressure when the canner is not in use does not necessarily mean that the gauge is simply 2 pounds high, or that it is uniformly 2 pounds off throughout its range: have it checked.
Contact your county Agricultural Extension Service offices. The County Agent in home economics there is likely to have the equipment to do it for you—or at least she can tell you where to go. The director of the EFNEP (Expanded Food and Nutrition Education Program) center for your area might be able to offer similar information.
Presto will check your dial gauge for free. Call 1-800-368-2194 or contact the company at www.gopresto.com.
The Pressure Canner at Work
Here are the mechanics of using a Pressure Canner. And a commonsense rule: don’t leave your canner unattended while it’s doing its job.
Water In
Put about 1½ inches of warm water in the thoroughly clean canner. If you know that your canner leaks steam slightly when the vent is closed, add an extra inch of water to ensure that the canner will not boil dry if the processing time is more than 30 minutes.
Start It Heating
Place the uncovered kettle (bottom section) over heat high enough to raise the pressure quickly after the lid is clamped tight.
Cover on Tight
When the batch is loaded, put the lid in position, matching arrows or other indicators. Turn the cover to the Closed position or tighten knobs, clamps, etc., to fasten the closure so no steam can escape at the rim.
Let It Vent
It is important to consider the Why of this next step, because sometimes it isn’t stressed in the instruction booklet that comes with your canner—and your processing could be thrown off whack.
Air that is trapped in your Pressure Canner will expand and exert extra pressure—that is, pressure in addition to that of the steam—and your gauge will give you a false indication of the actual temperature inside your canner. Therefore, you must make sure that all air is displaced by steam before you close your petcock or vent.
For canners with either type of gauge, leave the vent open on the locked-in-place lid until steam has been issuing from it in a strong, steady stream—7 minutes for small canners, 10 minutes for larger ones. Use your minute-timer here. When your canner has vented, close the vent by the means specified for dial or weighted gauge.
Manage the Controls
For a canner with a dial gauge, close the vent and let pressure rise quickly inside the kettle until the dial registers about ½ pound under the processing pressure that is called for. At this point, reduce the heat moderately under your canner to slow down the rate at which the pressure is climbing: in a minute the gauge will have reached the exact poundage you want, so you adjust the heat again to keep pressure steady at the correct poundage.
For a canner with a deadweight-weighted gauge, set the gauge on the vent and then carry on as for the canner with a dial gauge—but of course keep track of the frequency of the jiggles as the maker’s instructions say to do.
Watch the Gauge
Pressure, once the right level is reached, must be constant.
You’re using a Pressure Canner so your food will be safe, so if the pressure sags you should bring it back up to the mark and start timing again from scratch. Don’t guess—turn your timer right back to the full processing period. Your food will be overcooked, of course—but next time you’ll keep your eye on the pressure, right?
Fluctuating pressure also can cause liquid to be drawn from jars. And this in turn can prevent a perfect seal.
And Watch the Clock
Count the processing time from the moment pressure reaches the correct level for the food being canned. Be accurate: at this high