When I was a kid, my neighbor had an enormous garden. Every summer, after we'd all had our fill of fresh, sun-ripened fruits and veggies, she would begin canning. As each fruit reached its peak, she would harvest, wash and preserve it so that come winter, her table was always abounding with tastes of summertime: fresh jam with huge chunks of ripe fruit, crisp pickles flavored with mellow garlic and home-grown dill, rich and velvety tomato sauces, and a fiery hot pepper relish that would warm you up on even the coldest day.
Today, I'm surprised to find that a lot of my friends are daunted by the idea of canning. They think it's too hard, or unsafe, or old-fashioned, but in reality home canning is safe, affordable and easy.
A few weeks ago I was driving through a rural area in southern Illinois when I came upon a young Mennonite couple selling strawberries by the roadside. The berries had just been picked a few hours earlier, were beautifully ripe and about half the price of what I'd pay for them in Chicago. I bought an entire flat (about 6 pounds) and headed home.
I love strawberries, but even I can't eat six pounds of them, so I decided I'd make some jam and can it to share with friends and family. Since we've all been thinking about our favorite summer recipes this week at MNN, I thought I'd share the jam (and the canning process) with you all, as well.
The basics of canning
Canning relies on four simple things to keep food fresh and safe: heat, acid, sugar and an air-tight seal. Heat (applied during the canning process) kills any bacteria that may have gotten into the food, while acid and sugar prevent any heat-resistant spores from growing once the canning is done. And the air-tight seal prevents new contaminants from getting in. Many fruits are already high acid and can be prepared with just a little extra boost from lemon juice, but most vegetables are low acid and so must be pickled in vinegar to keep them safe.
The equipment you need is simple. High acid foods (and those that are pickled in high-acid brines) can be processed in a boiling water-bath canner. This is essentially a big metal pot with a lid and a wire rack that fits inside. The pot must be big enough to hold six or so jars in a single layer without packing them together and deep enough that you can safely cover the jars with at least two inches of water at a full, rolling boil. There should be a little separation between each jar and also between the jar and the bottom of the pot (here's where the wire rack becomes important). This allows hot water to circulate on all sides of the jar, ensuring even heat and safe processing. If you don't feel like investing in a canner, a stock pot with a wire cake rack in the bottom will do, just make sure that the rack doesn't lie flat against the bottom of the pot.
You'll also need to purchase some jars and lids. Canning jars, also called Mason jars, come in a variety of sizes from tiny jam cups to giant pickle jars. There are also two different mouth sizes for canning jars: regular and wide mouth. Regular is fine for jams, jellies, relishes and sauces, but wide mouth is a little easier if you need to pack in big pieces of food, such as whole cucumbers or whole tomatoes. Each jar will come with a metal ring and a flat, disc-like lid. While the jars and rings can be washed and re-used year after year, you'll need to purchase new lids each time. The rubber seal becomes damaged after use and re-using is unsafe. You will also want to avoid using other types of food jars. Don't be tempted to use that pretty mustard jar you emptied last week or a fancy jar left over from store-bought jam. The lids on these are different from home canning jars and require special handling to make them safe.
Make sure to wash and dry all your jars, rings and lids just before use. Jar and rings can go into the dishwasher, but hand-wash your lids to prevent any heat damage to the rubber seals.
How to can strawberry jam
Now you've got your jars and your canner set, it's time to make some jam! Three simple ingredients are all you need: fruit, sugar and lemon juice. Typically the amount of fruit and sugar will be about 2:1 (two parts fruit to one part sugar) in terms of weight, but some recipes call for a ratio closer to 1:1. European jams tend to have less sugar, be slightly less sweet and also looser in consistency. American jams have more sugar and are firmer. A good place to start is with this simple recipe:
(makes about eight 8-ounce jars)
- 4 lbs. fresh strawberries, washed, hulled and cut into one-inch pieces
- 5 cups of sugar (2 1/2 lbs.)
- 1/4 cup of freshly squeezed lemon juice, seeds and pulp removed
This will produce a sweet, soft jam that will really let the taste of the ripe strawberries shine.
Start by heating up the water in your canner, bringing it to a full boil. I also keep a kettle simmering so that I can top off the water in the canner if I need to without lowering the temperature.
Place four or five small plates in your freezer. You will want to use these to test the consistency of your jam as it cooks.
Put your strawberries, sugar and lemon juice into a separate large, heavy pot over medium heat and bring them to a gentle boil. You'll want to crush the berries slightly, but leave some chunks so that when you spread the finished jam, you get bites of fruit. A sturdy wooden spoon or a potato masher both work well for crushing the berries.
As the berries boil, they release a natural thickening agent called pectin. This is what gives jams and jellies their thick consistency. Strawberries are typically lower in pectin (especially very ripe ones) and so they have to be cooked longer to develop the desired thickness. This jam recipe should take between 30-40 minutes to reach the correct consistency.
When your berries have been boiling for about 15 minutes, check your canner. If the water is boiling, drop in your jars and rings (but NOT the lids) and cover the pot. As soon as it's boiling again, set your kitchen timer for 10 minutes and wait. This will sterilize your jars and rings. When the 10 minutes is up, carefully take them out using tongs or a jar lifter and invert them onto a clean kitchen towel. You want to time this so that the jars are still hot when the jam is ready. Put your lids in a separate bowl and cover them with a few inches of hot (but not boiling) water. Let them sit in the water as this will gently soften the rubber seals without damaging them.
Now it's time to start testing the consistency of your jam. Some people rely on a thermometer to tell them when the jam is ready, but I have found that often leads to over-cooked jam. Instead try this old-fashioned trick. Take one of the plates from your freezer and dab a small spot of jam on the plate. Return it to the freezer for two minutes. Now take it out again and hold the plate up in front of you. If the jam runs off the plate it's still too loose and needs more time to cook. If it moves very slowly and forms a soft gel, then it's probably done. I tend to test often, using four or five plates, so that I catch the jam at the right point and don't overcook it.
When your jam is ready, turn your jars right side up and ladle the hot jam into them. You'll want to leave about half an inch of space between the jam and the rim of the jar. This is called the head space and it allows the correct air tight seal to form while the jars are processing. Too much head space or too little can result in a poor seal. Wipe off the rims of the jars with a clean towel if you spill any jam.
With the jars filled, take your lids from the hot water, shake them off and center one each jar. Now put a ring on each jar, tightening just with your finger tips. You want it to be loose enough that small amounts of air can escape, but tight enough that no water can get in. Fingertip tight is just right.
Make sure that the water in your canner is boiling and deep enough to cover the jars. Place the jars in (on the rack) so that they are not touching one another or the walls of the pot. Put the lid on and wait. Once the water is boiling again, set your timer for 10 minutes.
When the time is up, remove the jars with tongs or a jar lifter and set them on a towel-covered counter to cool. Well processed jars will be clean, tightly sealed and the lid will have become concave. Sometimes you'll even hear a little ping as they come out of the water bath; this is the sound of the vacuum drawing the lid in. Throw out any jars that have failed to seal correctly. If your jars have a faint white film on them, don't worry. It just means you have hard water. Next time, you can avoid the film by adding a very small amount of white vinegar to the canner water before you start. Also, your jam may take a day or two to fully gel, so don't panic if it seems a little runny at first. As a rule you'll want to let it sit for a few days before tasting. This way both the flavor and the gel can fully develop.
One quick note of caution: Home-canned foods, if improperly stored or processed, can harbor dangerous pathogens like the bacterium that causes botulism. When you open a jar of home-canned food, always check it for freshness. Make sure that the lid is tightly sealed and concave (when you press your finger to the center of the lid, you should not be able to push it inward). If you see any discoloration, spurting liquid, mold or a bad smell, throw it out — jar and all — and wash your hands right away. Keep spoiled food away from pets and children. It may sound scary, but a bad jar is rare so long as you keep your work space and equipment clean, use fresh ingredients, buy new lids every time, and keep everything hot (think hot food into hot jars with a hot lid).
With a little care, canning is easy, fun and best of all, ensures that you can enjoy truly ripe fruits and veggies all year round.
Photos: Jen Jellen