Putting Food By - Janet Greene [37]
Leaving Headroom
In packing jars of food that will be processed in a Hot–Water Bath, Boiling–Water Bath, or Pressure Canner, there must be some leeway left between the lid and the top of the food or its liquid. This space—called headroom in the instructions that follow later—allows for expansion of solids or the bubbling-up of liquid during processing. Without it, some of the contents would be forced out with the air, thus leaving a deposit of food on sealing surfaces, and ruining the seal.
Too much headroom may cause food at the top to discolor—and could even prevent a seal, unless processing time was long enough to exhaust all the excess amount of air.
Important Altitude Note: steam in the headroom expands more at high altitudes than it does in the sea-level zone (1000 feet/305 meters), so we suggest that you increase headroom by ⅛ inch for every 1000 ft/305 m above the sea-level zone, but not to exceed 1¾ inches for quarts, 1 inch for pints, and ¾ inch for ½-pints.
Also, Pressure-processing has steam at a higher temperature than a B–W Bath does, and steam expands more when it’s hotter.
All of which means that you should be prepared to make your own arithmetical adjustments if you live at, say 7000 ft/2134 m, and process at 15 psig.
The right headroom in the sea-level zone for each food and its processing liquid is specified in the individual instructions, with more headroom given to starchy foods—Lima/shell beans, green peas, corn, etc.—because they swell in the canner.
Cans generally require no headroom between liquid and lid—air is driven out in the exhausting step.
Filling, Bubbling, and Capping
Whether it’s in cans or jars, you pack most raw food firmly (except for the starchy vegetables that expand, mentioned above), and most hot foods rather loosely.
Prepare and fill only one container at a time—don’t set them up in a row, standing open to air-borne spoilers. Set the jar/can in a clean pie dish, or whatever, to catch spills and overflows.
As you pack Raw, shake the container or tunk it on the bottom to settle the pieces of food; use a slender rubber spatula to make room for chunks you’re fitting in; don’t compress the food so much that it will spring up again, though, and invade the headroom. Pour in your boiling liquid—syrup, water, juice—to the desired level, keeping track of the headroom you must leave.
Follow directions for headroom in Hot pack. Your wide-mouth funnel is most handy here for controlling dribbles of food that must be wiped away completely.
Removing Bubbles
In either pack in any container, run a slender plastic blade down between the food and the side of the jar/can at several points. There is likely to be more air trapped in the liquid between pieces of food in Raw pack than in Hot; but use your blade with both. Take care not to stir or to fold in more air. Never use a metal blade: it makes the minute scratches inside that cause jars to break.
For insurance, use your blade again—but sparingly—when you “top up” a can with boiling liquid after exhausting it to 170 F/77 C.
Capping
With a fresh section of paper towels, or a scrupulously clean cloth wrung out in boiling water, wipe the sealing rim of cans to remove any liquid, food tissue, or fatty substance, because any of these can interfere with the seal. Wrap a clean, damp cloth around the body of the hot can to make it comfortable to hold; set the can in the sealer. Wipe the lid (rinse it quickly in hot water if, in some way, it has become dusty—and this is the first time it may be wetted), place it on the sealing rim of the can, and crimp it in place according to the directions for making the seal complete. Set the can in the processing kettle and deal with the next one.
Wipe the sealing edges of the jars—rim of the glass, if you’re using two-piece screwband metal lids; rubber ring around the neck of the jar, if it’s a bailed closure. Remove every vestige of food or other substance that would prevent a perfect seal.
Set the