I’ve always liked to cook and bake, but one thing I’ve never done until the last couple of weeks is canning, the practice of preserving foods like jams or pickles in heat-treated airtight cans or jars. Confession #1 is that I’ve always found the idea a bit intimidating! Despite many years working in biology labs and confidently maintaining sterile solutions to prevent contamination of cultured cells, I think there was still part of me that worried about getting the food safety aspect of canning right. But I’ve finally taken my first baby steps into the world of canning and it really wasn’t as complicated as I thought it might be! While there are certainly some key steps to doing it safely, it isn’t difficult, at least for simple things like jam. So today I’d like to share a few things I’ve learned about jam-making and canning from books we have in our collection and some reading online.

Last summer, I came across sour cherries at one of the small, fancier grocery stores in the area. Whenever I see fruits I haven’t had before — plumcots! sugar-apples! Manzano bananas! — I’m always curious to give them a try and that was the first time I’d seen sour cherries for sale. Sour cherries, also known as tart cherries, are a bit too sour for most people to want to eat raw, but they are great for making jams and baked goods. They also tend to have a very short season, typically only a few weeks in July here in Ontario, so if you see them, act fast!

Based on seeing contestants on The Great British Baking Show quickly whipping up batches of jam to use for cake fillings and other treats (often while making many other things in parallel), I felt like jam-making couldn’t be that hard. Well, I can now confidently say it is pretty easy to make jam! And if you aren’t planning on canning the jam, it can be very quick to make and doesn’t require any special equipment. Freshly-made jam put into clean jars can generally be stored in the fridge for several weeks or frozen for several months. If you’re freezing jam, just make sure to use wide-mouth jars and leave a good amount of space at the top of your jars to keep them from cracking when the jam expands as it freezes. You can freeze traditional cooked jams and then there’s also a type of jam referred to as freezer jam, which is uncooked or barely cooked, thus tending to have a very fresh flavour and often having a looser consistency than longer-cooked jams.

For my first time making jam, I used a cherry jam recipe by David Lebovitz (who wrote several books we have in our collection) and it’s very easy to make. You simply cook the fruit for a bit until it’s softened and has released a lot of its juices, then add sugar and lemon juice and continue to cook it until you’ve evaporated off enough water for the jam to be a good consistency. After the jam is sufficiently cooked, he recommends adding a small amount of almond extract and/or kirsch (a type of brandy made from cherries) or another liqueur. He does note that this jam will be on the runny side — expect to use a spoon rather than a knife! — since cherries are low in pectin and he doesn’t call for adding packaged pectin. What is pectin exactly? It’s a natural carbohydrate present in fruits in varying amounts and which helps jams set into a thicker consistency. Packaged pectin isn’t necessary to make jam, but if you don’t use it, you will likely have to cook your jam longer to get it to thicken and it may still be on the runnier side, though still delicious! One of the main things I’ve learned from reading all about jam-making is that there are lots of different ways to do it, it’s just that you’ll end up with different styles of jams. Uncooked freezer jams, traditional cooked jams without added pectin, or briefly-cooked jams with packaged pectin can all be great!

So how can you tell when a jam has been cooked enough? Checking the temperature can be a helpful guide, but Lebovitz and many others suggest an old-fashioned test called the frozen plate test. Once you think your jam might be ready, dollop about a teaspoon of jam on a frozen plate, put the plate back into the freezer for a couple of minutes, and then run a spoon or a finger through the jam. The jam should be ready if is stays in place for a few moments rather than quickly spreading back across the cleared area.

That first batch of cherry jam I made last year was really tasty, so this year I decided to make another batch, but this time ventured into the world of canning so the jars could be stored long-term at room temperature. As it turns out, canning of jam using a water bath is also surprisingly easy! The basic process involves filling hot canning jars with your jam, putting on canning lids and rings, immersing the jars in hot water, and then boiling the water until the jam in the jars is sterile. There are lots of little details to make sure you get right (how much space to leave at the top of the jars, how tight to make the lids, how long to boil the jars, etc.), so for anyone wanting to do canning for the first time, I would definitely recommend the books The All New Ball Book of Canning and Preserving and America’s Test Kitchen’s Foolproof Preserving. In addition to many recipes, they have detailed instructions and guidelines for canning with lots of pictures to make the process really clear. These books are great guides for doing canning safely, which involves making sure your jam has enough acidity and is heat-treated sufficiently to prevent the growth of bacteria and mold. As explained in these books and others, sugar also acts as a preservative, so it’s particularly important to get the acidity and heat treatment right when making low-sugar jams and preserves, which are more likely to spoil.

Anyway, the cherry jam that I made and canned this year also turned out really well and the process really went quite smoothly. My only “mistake” was that I was so focused on making sure I got everything right for the canning process that I forgot to make sure I’d followed the jam recipe all the way through to the end and left out the kirsch I had sitting out right in front of me on the counter. So that’s confession #2: Despite being a big believer in the idea of mise en place when cooking, I still sometimes manage to miss an ingredient!

For my second time doing canning, I made the classic strawberry jam from Foolproof Preserving. One interesting thing about this recipe is that it doesn’t use packaged pectin, but calls for adding grated Granny Smith apple, which contributes a lot of natural pectin. I was a bit skeptical of this, thinking that it might make the finished jam taste like apple, but since I haven’t yet tried using packaged pectin (that’s confession #3), I thought it was worth a shot. And the finished jam was quite good and very thick, so the natural pectin in the apples did its job without contributing a noticeable apple flavour.

So, what will I be making next? Well, I’ve got more sour cherries in the freezer and have some cherry plums, so next up will be a mixed stone-fruit jam from the book Food in Jars. Then for my first foray into using packaged pectin, the nectarine vanilla bean jam from the book The Canning Kitchen sounds really good. After that, who know?! But for those of you out there who have never tried jam-making or canning before, now is a great time for it with lots of great fresh Ontario produce available at farmers markets and grocery stores. For those interested in making or canning jams or condiments like chutneys and relishes, check out the books Canning in the Modern Kitchen, Bernardin’s Complete Book of Home Preserving, The New Homemade Kitchen, or some of our many other books on canning and preserving. Happy canning!