Putting Food By - Janet Greene [36]
Fill the cans according to the instructions for the specific food and put them, still open, on a rack in a large kettle; add hot water to about 2 inches below the tops of the cans. Cover the kettle and boil the whole business until your pencil-shaped food thermometer, stuck down in the center of the food until its bulb is halfway to the bottom of the can, registers 170 F/77 C. You can get the same result by boiling open cans in a Pressure Canner at Zero pounds pressure (as described for jars in “Canning Seafood,” Chapter 11).
COOLING THE CANS
Cans must be cooled quickly after their processing time is up, lest their contents cook further (this is why, if you’re using cans, you vent your Pressure Canner to hasten its return to Zero pounds).
Fill your sink or a washtub with very cold water and drop the processed cans into it. As each can is removed from the canner its ends should be slightly convex, bulging from the pressure of the hot food inside it; if the ends don’t bulge, it means that the can was imperfectly sealed before it went into the processing kettle. The ends will flatten to look slightly concave when the contents have cooled and shrunk, indicating that the desired vacuum has formed inside.
Change the water when it warms, or add ice, to hasten cooling. Remove cans when they’re still warm so the internal heat will hasten air-drying.
GENERAL STEPS IN CANNING
Let’s see how to fill the jars/cans with food before they go into the Boiling–Water Bath or the Pressure Canner, and how to treat them afterward.
Raw Pack and Hot Pack
Many foods may be packed in their containers either Raw (in some manuals they used to be designated as “Cold”) or Hot. The food is trimmed, cleaned, peeled, cut up, etc., in the same manner for both packs. The same amount of canning liquid is added to the container of solid food, regardless of whether it’s Hot pack or Raw—roughly ½ to ¾ cup for pints or No. 303 cans, 1 to 1½ cups for quarts or No. 401 cans; also the liquid should always be very hot. The optional seasoning is added just before processing either pack. And with both packs the containers are handled identically after being removed from the canner and cooled.
Raw Pack
Today, Hot pack for low-acid (or borderline) foods is stipulated across-the-board, for safety’s sake. Raw pack, though, may still be used for some fruits—mainly to protect their texture—and for many pickled foods.
Boiling syrup, juice, or water is added to raw foods that require added liquid for processing.
Jars of Raw-packed food must start their processing treatment in hot but never boiling water, otherwise they’re likely to crack. Even when ajar has been exhausted, the water in the processing kettle should not be at a full boil.
Raw-packed foods usually take longer than Hot packs to process in a Boiling–Water Bath; this is especially true for the denser foods.
Hot Pack
An increasing number of foods are processed by Hot pack. Food that is precooked a little or almost fully is made more pliable, and so permits a closer pack. (Foods differ in the amount of preheating they need, though; spinach is merely wilted before it’s packed Hot, but green string beans boil for 5 minutes.)
In a Boiling–Water Bath, Hot-packed food generally requires less pro cessing time than Raw does, because it is thoroughly hot beforehand. However, there generally is no difference in the time required for Pressure Canning either pack: by the time you start counting—for example, the minute pressure reaches 10 pounds (240 F/116 C)—Raw-packed food has become as hot as if it had been packed Hot to begin with. (One of the interesting exceptions is summer squash, which needs longer Pressure-processing for Hot pack, because