A Jam Inspired By My Son’s Favorite Children's Book

When my son was small, I made a lot of jam. More accurately, I was obsessed with jam. It was a great distraction from the daily grind of first-time motherhood, and it was good to eat too. We were hard-core berry pickers back then—it was the perfect activity for a young child when the days were long, and my brain was tapped out for ideas to keep him entertained.

Our favorite book back then was Each Peach Pear Plum, by Janet and Allan Ahlberg. It inspired the combination of fruit in this jam—peaches, pears, and plums. We made it both for immediate consumption and gift-giving throughout the fall and winter. We named it Tom Thumb’s jam based on a character in the book. My holiday gifts were covered, and we feasted on jam and toast in the meantime.

How to Select the Best Fruit for Jam

Peaches, pears, and plums hang around through mid-September and they make a stellar combination for preserving into this unique jam. When you are making jam, select the best fruit available. Firm and perfectly ripe or slightly underripe fruit has the highest level of acidity and pectin, which will give you the best results.

Relegate overripe or blemished fruit to the blender for smoothies with a good squeeze of lemon if you want to avoid waste. Too underripe, your jam will lack flavor. Sample the fruit and you will have an idea of what your jam will ultimately taste like. 

You can also use frozen fruit—either store-bought or fruit you freeze yourself—if you have the fruit but don’t have the time to do anything with it, freezing is a great option. You can get to your jam-making when the spirit moves you later. 

Specific Fruit Recommendations 

For this jam, you can really use any variety of peaches, pears, and plums that are available to you. That said, here are some of my recommendations: 

Peaches: I like to use yellow peaches because they are tangy and sweet. White peaches are sweeter, softer, and have less acidity. Freestone peaches, available mid to late season are the easiest to pit.

Pears: Red and green Anjou pears, golden brown Boscs, and green Comice pears are readily available and hold their shape well when cooked—it’s better than it turning to mush, which makes the jam muddy. Choose firm but ripe pears and peel, core, and cut them into 1-inch pieces.

Plum: There are too many varieties of plums to count, ranging from green and red to almost black. Dark-skinned plums will give your jam the prettiest color, but all plums are good candidates. No peeling necessary!

Tips for Cooking the Jam

• Unfortunately, there is no magic number on the thermometer to indicate that the gelling point for your jam has been reached. This is just a matter of practice. The fruit syrup starts out runny and gradually thickens until it sheets from a spoon. A perennial second-guesser, I like to test it in a cold saucer just to be sure.
• The time it takes to cook the jam depends on how the acidity and pectin in the fruit interacts with heat and sugar.
• Start by using a large pot and fill it only halfway. As the jam cooks it tends to bubble up—so give it plenty of room.
• You may notice foam rising to the surface as the fruit cooks. Don’t skim it! Just ignore it—if you start skimming early there will be no jam left. Instead, wait until it reaches the gelling point, and if there’s still foam around the edges you can skim it.

Can Your Jam for Longer Storage

In the unlikely case you eat all the jam within a few weeks, you can store it in the fridge. But that takes up a lot of real estate. Instead, use the water bath canning method below and your jam will keep for up to 1 year outside the fridge.

More Canning Recipes to Try

• Apricot Riesling Jam
• Rose Hip Jelly
• Meyer Lemon Marmalade
• Seville Orange Marmalade
• Chia Seed Jam with Berries

Prep your jars:

Sterilize the jars using the technique you prefer.

Make the jam:

In a large (6-quart) heavy-based pot, combine the peaches, plums, pears, sugar, lemon zest, and lemon juice. Slowly bring the mixture to a simmer over medium heat, stirring to dissolve the sugar.

Meanwhile, place saucers in the freezer:

For the final jam test, you will need 2 or 3 cold saucers. Place them in the freezer while the jam bubbles away.

Continue cooking the jam:

Raise the heat to medium-high and continue to cook, stirring occasionally until the syrup deepens in color and the fruits begin to look translucent. Reduce the heat as necessary if the jam is bubbling exuberantly. The jam will need more stirring towards the end because the fruit sinks to the bottom of the pot as it becomes heavily saturated with syrup. This can take 20 to 40 minutes, so be patient.

Test the jam:

Test the jam using a spoon: When the syrup, which is initially quite thin and runny, begins to thicken, dip a large spoon into the pot. Hold it over the pot so that the bowl of the spoon is facing you and let the syrup fall back into the pot. Notice how it falls off the spoon. As it approaches the gelling point, two distinct thick drops will hang onto the rim of the spoon, and after a few minutes the drops will merge, and the jam will sheet off the spoon. 

Test the jam using a saucer: For second-guessers, use the saucer method to confirm the gelling point. Spoon a small puddle of the syrup onto a cold saucer from the freezer. Put it back into the freezer for about a minute. Remove it and draw your finger across the middle to form a channel. If the surface of the jam wrinkles and the channel does not close immediately, your jam is ready.

Fill and can the jars:

Ladle the hot jam into the clean jars, leaving a 1/4-inch space between the top of the jam and the rim of the jar. Wipe the rims with a wet paper towel and place the lid on top. Screw on the band, but don’t screw it on too tightly.

Process the jars in a boiling water bath for 10 minutes using the guidelines below. 

Store the jam:

Canned jars of jam will keep outside the fridge for up to 1 year. Once open, store them in the fridge for up to 3 months. If you want to skip canning the jars in the water bath, refrigerate the jam for up to 3 months.

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