Canning in a Boiling Water Bath

Almost every local eater in the Northeast is going to want to ‘preserve the harvest;’ pack away the bounty of the growing season at it’s peak of freshness and flavor, and store it against the coming winter. Even if you are lucky enough to have a convenient winter farmer’s market near you, homemade preserves break up the monotony of a winter diet and it’s also the most economical way to eat – strawberries, blueberries & tomatoes might be $2/pound in peak season, but winter berries are notoriously expensive ($6 or $7 for a pint or half-pint) and winter tomatoes are expensive and tasteless.

There are many ways to preserve the harvest: freeze, dry, ferment, root cellar, pickle and can. Here I’ll offer basic instructions for boiling water bath canning, taken directly from the Ball Complete Book of Home Preserving (a worthwhile investment if you get serious about canning).

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Canning in a Boiling Water Bath (BWB)

FOODS

Not all foods can be safely preserved by boiling water heat processing. The safest bet is to follow trusted recipes. The basic rule of thumb is that highly acidic foods, such as fruit and pickles, are safe to can in a boiling water bath. Low acid foods, such as green beans, carrots and spinach, or neutral foods, such as peas and corn, MUST be processed in a pressure canner or you run the risk of botulism poisoning. (I do not personally own nor use a pressure canner, so I will not discuss those techniques here.) Anything with meat (chicken soup, chili) must also be canned in a pressure canner. Tomatoes fall into the middle of the “acid” category and so are always canned with extra acid (lemon juice, vinegar or citric acid) in order to ensure food safety. The best way to ensure safe home-canning is to stick with tested recipes, especially when you are starting out.

SAFE to Can in BWB: All fresh fruit, any type of pickles, salsas with sufficient vinegar, tomatoes & tomato sauces with added acid.

NOT SAFE to Can in BWB: Most vegetables, anything with meat or fish, pureed pumpkin, basil pesto, anything with added oil or butter (a slight amount of oil or butter can be used in canning fruits to reduce foaming).

EQUIPMENT

For my first canning experiment, homemade tomato sauce, I used nothing more than pint-sized Ball jars and my stockpot (with a kitchen towel in the bottom to prevent the jars from rattling). This works fine, but if you find yourself doing a lot of canning, the following equipment will really help to streamline the process. Generally you can find all of the below at any well-stocked hardware store and in larger supermarkets.

• Canner. Make sure you get one that is at least 2, preferably 3 inches higher than the largest jar you intend to use and has a rack for holding the jars away from each other. Jars must be covered by 1 inch of water, and the additional space is to allow room for a vigorous boil during processing.
• Glass canning jars. A.K.A. “Ball jars” or “Mason jars” – easy to find in your local hardware store. The gasket-and-lid type of jar is not recommended by the USDA as it is more difficult (though not impossible) to tell whether or not you have achieved a tight seal. There are also cool (and spendy) German Weck jars and Leifheit jars, Italian Fido jars and Quattro Stagioni jars and vintage jars all over eBay. These jars are all a bit more finicky to use than the standard, hardware store Ball jars, so beginners should stick with standard Mason jars with 2-piece metal lids until comfortable with the process. You can get jars, lids, rubber gaskets and other hard-to-find canning supplies at Lehman’s.
• Funnel. For filling jars.
• Jar lifter. As the name implies, for lifting jars. With the 8-oz jars, I often simply use kitchen tongs, but a jar lifter comes in handy for pint jars and is a real necessity for quart jars.
• Kitchen tongs. Indispensable in any kitchen!
• Ladle.
• Kits, with canner or without. You can also find ‘beginner’ kits that may give you a deal on a canner plus other equipment.

METHODS

1. Examine jars for any nicks, cracks, uneven rim surfaces or other damage – do not use damaged jars. Wash jars, lids and screwbands in hot, soapy water. Rinse well and drain.
2. Place required number of jars into canner on canner rack (if possible I always include 1 or 2 extra jars, as yields vary). Fill with filtered water (hard tap water can cause a white residue to coat your jars) or spring water to at least 1 inch over the top of the jars.If you must use unfiltered, hard water, a little vinegar (2-3 tbsp) added to the water will prevent the white film of mineral deposits from collecting on your jars. Bring to boiling on high heat, then either turn the heat to low and keep the water simmering or boil for 15 minutes to sterilize jars. A 15-minute bath in boiling water, prior to filling, will sterilize jars (I always do this step even though the Ball book says it is not necessary). Time this such that the jars will be ready upon completion of your recipe.
3. Place the jar lids, but not the screw bands, into a small saucepan filled with water. Bring to a low simmer, but do not let boil. Set screw bands aside. Place funnel and ladle in the simmering water in this pan.
4. Prepare recipe.
5. While recipe is cooking, set up your canning area; I clear a good spot on the countertop, place a cutting board topped with a kitchen towel, and line up a wooden spoon, regular teaspoon, clean paper towel, tongs, screwbands and potholders.
6. Fill jars: Working one jar at a time, remove a jar from the canner, pouring hot water back into the canner (keep the heat beneath the canner on low, so as to keep the canner water at a low simmer while filling jars). Place the jar on a cutting board or heat-proof work surface (or hold in your hand with an oven mitt or potholder). Place funnel in the top of the jar with tongs (try to minimize touching anything with your hands that will also touch the food, lest you contanimate the jars). Ladle the prepared food into the jar, leaving the amount of headspace specified in the recipe (usually 1/4 or 1/2-inch). Keep a clear plastic ruler for use in the kitchen if you are bad at judging lengths. Headspace is the space between the top of the jar and the top of the food. If possible, keep the recipe on low heat throughout the filling of the jars; if the recipe will burn, periodically re-heat the food if the canning takes a while, or if the food is no longer steaming hot.
7. Tap the bottom of the jar on your work surface a few times (this is where a kitchen towel or wooden board comes in handy) to pack the food into the jar. Slide a non-metallic utensil, such as a wooden spoon handle, down between the food and the edges of the jar, moving the handle up and down as you rotate the jar. This releases any air pockets that may cause seal failure; adjust headspace if necessary.
8. Dip the edge of a paper towel or clean kitchen towel into the simmering lid water; wipe the jar rim and threads. Any food remaining on the jar rim will interfere with achieving a tight seal.
9. Using tongs (or a magnetic lid lifter), lift a lid out of the simmering water and place on the jar. Seat the lid on the jar top but try not to handle with your hands.
10. Place the screwband on the jar and tighten until it is just fingertip tight (if it is too tight, pressure built up inside the jar from the boiling food will not be able to release).
11. Using tongs or a jar lifter, return the jar to the canner pot. Repeat the process until the food is gone, or until the food remaining will not completely fill a jar. Do not process jars that are not completely full (with recommended headspace); store this food in the fridge and use within a few weeks.
12. Once all jars are full and loaded into the canner, replace the canner lid and turn the heat up to high to bring the water back to a full boil. Once boiling, start your kitchen timer and process at a rolling boil for the time specified in the recipe (often 10 or 15 minutes for jams, chutneys and salsas, longer for tomatoes and tomato sauces.)
13. When the timer goes off and the jars have processed for the prescribed time, turn off the heat, remove the canner lid, and let the jars rest in the canner water for 5 more minutes. Then, using tongs or a jar lifter, remove the jars from the hot water, being careful not to tilt the jars excessively (at this point you do not want any food to touch the jar lid, as it may interfere with the jar producing a tight seal). Try to pull the jars out of the canner straight up, and place on a kitchen-towel-lined cutting board or work surface. You should start hearing the “ping” that signals a jar lid sealing within minutes, but for different recipes, it takes different amounts of time. Allow the jars to rest undisturbed for 24 hours; if at this time the jars did not produce a tight seal (evidence by the jar lid pressed downward, into the jar – you cannot move it by pressing on the lid), then either put that jar into the fridge and use within a week or two, or re-process (in a clear jar, with new lids, etc).
14. After the 24 hour rest, label your jars with the contents and the date and store in a cool, dark place. (Light will tend to discolor the food over time; a standard kitchen cabinet is perfect storage.)

If this all seems like far too much work and far too many details to remember, it’s simply because I’ve written down very complete, step-by-step instructions. In reality, once you get used to it, the process is more like: Heat jars. Make food. Fill jars. Process. The first few times I canned anything, it took forever, I got several burns and it seemed like a ridiculous expenditure of energy for a few jars of tomato sauce. But, surprisingly quickly, I got used to the whole process, and now it is simple, almost automatic. I recommend starting with an easy recipe – tomato sauce or salsa is a good place to start, and don’t worry if it takes a long time or you make mistakes. Even in my first canning attempt, the jars sealed, the sauce lasted and I was ridiculously proud to open a jar of that sauce in the dead of winter. That feeling alone is worth the effort of learning to can, and once you do, the “process” is nearly effortless.

The above is exactly the process I use, every time I can. I’ve never had a jar that did not seal, never had food mold or otherwise spoil and certainly never had any issues with botulism, salmonella, or other dangerous food-bourne illness. I’m pretty anal about cleanliness and preventing contanimation and some people would likely say that all of the above steps are not necessary – but given the potential consequences, the least of which is wasting the time, money and hard work of preserving the harvest in the first place – I think it’s worth it.

TIPS & TRICKS

A few things learned in my 4+ years of canning.

• As noted above, a little white vinegar in the canner water will prevent a white, filmy residue (hard water mineral deposits) from collecting on & in your jars. Filling the canner with water and letting it sit overnight is also effective.
• The standard, 2-piece lid Ball jars are a cinch to use: they seal easily, are a cinch to move in & out of the canner, are designed to work with US equipment. I love using a variety of jar types: but some of them can be tricky.
  • Weck jars seal beautifully; I’ve never had a problem. But the larger ones can be a bit unwieldy to lift in & out of the canner, and they don’t fit the canner rack dimensions very well.
  • I’ve had trouble getting a good seal with Quattro Stagioni jars; the instructions are a bit convoluted (translation issues, I assume) but they instruct you to fill room temperature jars with room temperature food, then process, then let the jar sit until the water cools. I usually fit hot, sterilized jars with hot food, then let the jar sit in the water bath until cool. The last few times the jars have sealed. I typically only use 1 or 2 of this type of jar per batch, however, in case the seals fail.
  • When using a Ball, Fido or Leifheit jar with a rubber gasket, move the little rubber tab away from the sealing clamp in the bail, such that you can see it easily (the rubber tab should point slightly down if you’ve achieved a good seal) and so that it is easier to open the jars when it comes time to enjoy your preserves (pull lightly on the tab, away from the jar, and the rubber gasket will release, releasing the lid).
  • While a seal generally happens within minutes (or seconds) of removal from the canner, jars can take up to 24 hours to seal. Try not to disturb jars, especially those of jams or jellies that need to ‘set’ for about a day. If a jar does not seal, you can stick it in the fridge and use within a month, or re-heat the preserve to boiling and process again in clean, sterilized jar.
• Do taste your preserves prior to canning; I often forget this part and then wish I had added a pinch of salt, a bit of cayenne pepper, or a splash of lemon. Taste as you go, remembering that as preserves age, certain flavors mellow & blend, while others will come to the forefront. It’s always interesting to me to see how a preserve changes over time; I’m always learning.
• Once you’ve established a good seal, do protect your preserves from light while in storage. Light will leach the color out of many bright jams, salsas & chutneys which leaves them looking surprisingly unappetizing.
• Always, always label & date, even if it is just a scrawl on masking tape. I often find myself making a small batch, 1 jar maybe, and sticking it in the fridge, only to come across it (some unspecified amount of time later) and have no idea what it is or when I made it.

As mentioned, a cool dark place is the best for storing your canned jars. Try to use home-canned food within one year (hence dating the labels is key). While I do have some jars on my shelf that are older than a year, I definitely do not keep them 2 years; home-canned foods are not heated to the high temps of industrial foods (250 degrees F) and are not intended to last forever. Remember, you are preserving the harvest against the coming winter, not stocking up for nuclear winter.

SEASON

You can can (ha!) year-round, but most canning happens between June-October, following the harvest as berries, peaches & plums, tomatoes, cucumbers, apples and other goodies ripen and mature.