Basic steps to canning
How to lose your fear of hot-water baths and begin putting up summer's glorious produce
Nothing last forever. With produce, once it's separated from its plant, it's a fairly quick downhill slide. Canning, though stops spoilage in its tracks. (Alex Garcia/Chicago Tribune)
If you've always wanted to preserve some of summer's greatest glories, but you've never quite had the know-how or courage to do it yourself, read on. Today we introduce the novices among you to the wonderful world of canning.
Why you need to learn this
As I'm reminded every time I look in the mirror, nothing lasts forever. With produce, once it's separated from its plant, it's a fairly quick downhill slide. Bacteria, ever-present in small numbers on all living things, feed on picked produce and reproduce exponentially, causing it to spoil. Food is rendered first unpalatable and unsightly, then inedible and possibly poisonous. Canning, though, stops spoilage in its tracks, leaving this summer's harvest ready for next winter's table.
The steps you take
One caveat: Most Prep School articles concern methods and techniques that you can implement immediately in your kitchen. Canning's a little different, though. For one thing, there's some specialized equipment that, while readily available and relatively inexpensive, you nevertheless probably don't have. For another thing, you'll want to go to the library or bookstore and get a good book on canning. To start off, think about canning pickles or fruit jams and preserves. Here's why:
There are two types of home canning: hot-water-bath canning and pressure canning. We're going to stick with the former. For one thing, a simple hot-water-bath canning pot or "canner" (a very large, covered pot containing a metal rack that holds the jars) is cheaper than its pressurized cousin (under $50 for the former versus closer to $100 for the latter). For another thing, the types of food canned by hot-water-bath method, high-acid foods like fruit and pickles, tend to carry less risk of food poisoning than low-acid foods that require pressure canning.
(For both kinds, you'll need canning jars: pint- or quart-size glass jars with flat, rubber-ringed lids and separate screw tops. )
Understanding how canning works explains the relationship between food type and canning method. And in order to understand how canning works, we should first talk about why it's necessary.
The purpose of all canning — indeed, of all methods of preservation — is to interfere with a microorganism's ability to reproduce. Two methods (among many) for doing this are exposure to extremes of heat and acid.
For example, with canned food, the microorganism we fear most is Clostridium botulinum, the bacterium responsible for botulism. Unlike most bacteria, which are destroyed as temperatures go above 140 degrees Fahrenheit, Clostridium botulinum can survive very high temperatures, even higher than boiling (212 degrees). That's where pressure canning comes in; foods preserved by pressure canning reach temperatures above 240 degrees.
Clostridium botulinum cannot survive, however, in highly acidic environments. That's why some foods like pickles and fruit jellies, which are highly acidic, can be processed with a simple hot-water-bath treatment.
For today's discussion, we'll use pickled cucumbers. Here's what you do and why:
1. Thoroughly wash and sterilize canning jars and their lids in boiling water.
2. Wash cucumber pickles and stuff them whole (or cut) into sterilized jars.
3. Following a trustworthy recipe, bring a pickling brine to a boil.
4. Pour boiling brine over cukes to come within about 1/4 inch from top of jar.
5. Wipe the jar with a clean, dry cloth, then top with the lid, rubber side down. Screw the top on until just tight. Don't force it; it needs to be loose so air can escape during processing.
6. Place jars in rack and lower them into simmering water. Water needs to cover jars by at least 1 inch. Consult your recipe for water temperature and immersion time. Some recipes call for boiling water, while others want it simmering. When the food heats up, it kills the bacteria, while water vapor forms and forces air out of the jar. (That's why it's important not to screw the cap on too tightly.)
7. After the jars are processed for the time dictated by the recipe, usually 30 to 45 minutes, remove them and set them aside. As the contents cool, the water vapor inside condenses and a vacuum forms, pulling the rubberized seal tight against the lip of the jar. Tap on the lid. It should be slightly concave and not in the least bit loose. If it is, the seal didn't take and you should refrigerate the jar immediately and use the contents within a week.
8. Once the jars cool to room temperature, store them in a cool, dry place for up to a year.