Putting Food By - Janet Greene [35]
What Foods to Can in Which
Throughout the individual instructions we’ve included the type of can—plain, R-enamel, or C-enamel—to use if you use cans at all. Today, some suppliers of open cans offer white enamel cans instead of R-enamel cans. For most products, the two cans are interchangeable.
However, here’s a rule of thumb to go by if you’re canning a food we don’t go into:
R-enamel or white enamel. Think of “R” as standing for “red” and you’ll have the general idea: beets, all red berries and their juices, cherries and grapes and their juices, plums, pumpkins and winter squash, rhubarb, and sauerkraut (which is very acid), and tomatoes.
C-enamel. Think of “C” as standing for “corn” (which has no acid) and for “cauliflower” (whose typically strong flavor indicates sulfur) and you get: corn—and hominy, very low-acid Lima and other light-colored shell beans (and, combined with corn, succotash); cauliflower—and things with such related taste as plain cabbage, Brussels sprouts, broccoli, turnips, and rutabagas; plus onions, seafood, and tripe.
Plain. This is the catch-all, and may take these foods, as well as others: most fruits, tomatoes, meats, poultry, greens, peas, and green/snap/string/ wax beans, and certain made dishes (like baked beans, etc.).
If you’re canning mixed vegetables, use C-enamel for preference if one or more of the ingredients would go in C-enamel by itself.
Remember, though, that the heavens won’t fall if you mix up plain and C-enamel for fruits and vegetables. Nor will “red” acid foods be bad if they’re not canned in R-enamel: they just won’t have their full color.
What’s Re-usable?
Only the sealer apparatus. No damaged, rusted, dented, bent new can or lid may ever be used in the first place. No can or lid may ever be re-used.
For information on where to get cans and can sealers, see the Appendix.
Preparing Cans, Lids, and Sealer
If cans and lids are to be processed in a Boiling–Water Bath (212 F/ 100 C) or Pressure-processed, they need not be sterilized before filling.
Wash cans in clear hot water, scald; drain upside down on sterile cloths so air in the room cannot contaminate the inside of the can. To sterilize, wash, submerge in hot water and bring to boiling, and boil for 15 minutes; remove and drain as above.
The gaskets of some lids could be of a material that must not be wetted or it won’t seal right; other gaskets are of a rubber-like composition that must be treated as carefully as the compound on non-boilable metal screwband lids. Therefore be sure to ask your supplier for explicit instructions for sterilizing the lids.
Adjust the sealer according to the manufacturer’s directions, and test its efficiency by sealing a can that’s partly filled with water, then submerge the can in boiling water: if any air bubbles rise from the can after a few seconds, the lid is not seamed tightly enough. Adjust the chucks of your sealer until you have a perfect seam joining the lid to the can.
A can of food exhausted to 170 F/77 C should be sealed with the rolling seam. (Drawing by Norman Rogers)
In and Out of the Canner
Unlike jars, cans do not vent during processing: they are sealed completely before they go into the B–W Bath or Pressure Canner. Therefore air in the food’s tissues and in the canning liquid must be driven out before the lid is crimped on perfectly tight—otherwise you wouldn’t end up with a vacuum when the cans are cooled.
So all cans of food require an extra intermediate step that may be bypassed with most jars (the exceptions being jars of meat, poultry, and seafood), and we’ll deal with it now before we turn to the Raw and Hot packs in the general procedure for filling any container with food to be canned.
THE EXTRA STEP: “EXHAUSTING”
To drive out enough air to make the desired vacuum, you heat the food to a minimum of 170 F/ 77 C at the center of the filled