Mary Berry Recipes

Home / Baking / Homemade Blackberry Jam: A Taste of Summer

Oh, the joy of a perfect summer's day spent foraging for those plump, juicy blackberries! It's a cherished memory for many, and bringing that taste of the hedgerow into your kitchen is one of life's true delights. Making your own jam might seem a little daunting to some, but I assure you, with a few simple steps and a little patience, you'll be rewarded with jars of glorious, jewel-toned preserve that will see you through the colder months.

This recipe for Classic Blackberry Jam is wonderfully straightforward and relies on the natural pectin in the fruit, alongside a touch of lemon juice, to achieve that beautiful, firm set. There's no need for any fancy equipment, just a good, sturdy preserving pan and a keen eye. The aroma that fills your kitchen as the berries bubble gently with the sugar is simply heavenly – a true sensory experience.

Imagine spreading this vibrant, fruity jam on a warm scone with clotted cream, or perhaps stirring it into your morning porridge for a burst of sunshine. It's a taste of home, a labour of love, and a true testament to the simple pleasures of seasonal cooking. Let's get those aprons on and create some sheer perfection together!

Why You'll Love This Recipe

Utilises the natural pectin found in blackberries, ensuring a good set without added commercial pectin.
A balanced ratio of fruit to sugar enhances the natural flavour of the blackberries, avoiding excessive sweetness.
The step-by-step instructions are clear and precise, making jam-making accessible even for beginners.
Includes a crucial tip for achieving the perfect setting point, guaranteeing success every time.
Produces a generous batch, perfect for sharing or enjoying throughout the year.

Ingredients

1.5 kg (3 lb 5 oz) ripe blackberries, freshly picked and cleaned
1.5 kg (3 lb 5 oz) granulated sugar or preserving sugar
Juice of 1 large lemon
25g (1 oz) unsalted butter (optional, to reduce foam)

Equipment Needed

Large, heavy-bottomed preserving pan (or very large saucepan) • 6-8 standard (340g/12oz) jam jars with lids • Small saucers (for testing setting point) • Ladle • Jam funnel (optional, but highly recommended) • Heatproof gloves or oven mitts

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Step-by-Step Instructions

First, you must sterilise your jam jars. Wash the jars and lids thoroughly in hot, soapy water, then rinse well. Place the wet jars upside down on a baking tray in a cool oven (140°C/120°C fan/Gas 1) for at least 15 minutes, or until completely dry. Keep them warm until you're ready to fill them.
While the jars are sterilising, prepare your blackberries. Pick through them carefully, removing any leaves, stalks, or unripe berries. Give them a gentle rinse if necessary, but avoid soaking them.
Place the cleaned blackberries into a large, heavy-bottomed preserving pan or a very large saucepan. Add the lemon juice.
Heat the berries gently over a low heat, stirring occasionally, until they start to soften and release their juices. This should take about 10-15 minutes.
Once the berries are soft, add the sugar to the pan. Stir continuously over a low heat until all the sugar has completely dissolved. It's crucial not to rush this stage, as undissolved sugar can lead to crystallisation in your finished jam.
Increase the heat to a rolling boil. Boil vigorously, stirring occasionally to prevent sticking, for approximately 15-25 minutes. This is where the magic happens and the jam begins to thicken.
To test for a set, you'll need to use the 'crinkle test'. Before you start boiling, place a few small saucers in the freezer. After about 15 minutes of boiling, take the pan off the heat. Spoon a small amount of jam onto one of the chilled saucers. Let it cool for a minute or two, then push your finger through it. If the surface wrinkles, the jam has reached its setting point. If not, return the jam to the boil for another 5 minutes and test again with a fresh saucer. Repeat until a good set is achieved.
Once the setting point is reached, remove the pan from the heat. If you've used the butter, stir it in now to disperse any foam that has risen to the surface. Skim off any remaining foam with a metal spoon.
Carefully ladle the hot jam into your warm, sterilised jars, filling them right to the brim. A jam funnel can be a great help here to keep things tidy and prevent spills.
Immediately seal the jars with their sterilised lids. As the jam cools, the lids will 'pop' or indent, creating a vacuum seal that helps preserve the jam.
Leave the jars to cool completely at room temperature. Once cool, label them with the date and store them in a cool, dark place. Enjoy your wonderful homemade blackberry jam!

Perfect Substitutions

Granulated Sugar: While preserving sugar is ideal due to its larger crystals which dissolve slowly and help prevent scorching, standard granulated sugar works perfectly well. Just be sure to stir diligently until fully dissolved.
Blackberries: This recipe can be adapted for other high-pectin fruits like raspberries or a mix of summer berries, though cooking times may vary slightly.
Lemon Juice: Essential for setting and flavour. Do not omit. If you don't have fresh, bottled lemon juice can be used in a pinch.

Serving Suggestions

This delightful blackberry jam is an absolute dream on freshly baked scones with a dollop of clotted cream – a true British classic! It's also utterly superb spread generously on warm toast, crumpets, or even stirred into natural yogurt or porridge for a simple yet delicious breakfast. Don't forget, it makes a wonderful filling for sponge cakes or a tart too! If you enjoyed this, you might also love our Mary's Golden Syrup Flapjacks: A Timeless Treat and Simply Perfect Rich Chocolate Cake.

How to Store \u0026 Reheat

Once sealed and cooled, store your homemade blackberry jam in a cool, dark cupboard. It will keep beautifully for at least 12-18 months. Once opened, store the jar in the refrigerator and consume within 6-8 weeks. Jam is not typically 'reheated' but rather served at room temperature or slightly warmed if used in a dessert.

Mary's Secrets to Success

My dears, the secret to a truly magnificent jam lies in two key areas. Firstly, good quality fruit! Use fresh, ripe blackberries – those foraged from the hedgerows are always the best, but good market ones will do splendidly. Secondly, do not rush the setting point test. It truly is the most important step to ensure your jam is sheer perfection. Patience, my friends, is a virtue in the kitchen!

Frequently Asked Questions

How do I know if my jam has reached the setting point?

The most reliable method is the 'crinkle test'. Place a small amount of hot jam onto a chilled saucer. Let it cool for a minute or two, then push your finger through the jam. If the surface wrinkles, it's ready. If not, return the pan to the heat for another 5 minutes and test again with a fresh saucer. A sugar thermometer can also be used; jam usually sets around 104-105°C (219-221°F).

Can I use frozen blackberries for this recipe?

Absolutely! Frozen blackberries work wonderfully. There's no need to thaw them beforehand; simply add them to the preserving pan directly from the freezer. You might find they release more liquid initially, so the simmering time before adding sugar might be a little longer to reduce some of that moisture.

Why is my jam too runny or too stiff?

A runny jam usually means it hasn't boiled long enough to reach the setting point. You can return it to the pan and boil again, re-testing for a set. If it's too stiff, it's likely been over-boiled. Unfortunately, an over-set jam is harder to rectify, but you can sometimes loosen it by gently reheating with a splash of hot water or lemon juice, though it may affect the shelf life.

Do I need to add commercial pectin?

No, not for this blackberry jam recipe. Blackberries are naturally rich in pectin, especially when slightly under-ripe. With the addition of lemon juice, which aids pectin extraction and setting, you should achieve a lovely set without any commercial pectin. This keeps the flavour wonderfully pure and natural.

How long does homemade blackberry jam last?

When properly sterilised and sealed, homemade blackberry jam can last for 12 to 18 months in a cool, dark place. Once a jar is opened, it should be stored in the refrigerator and consumed within 6 to 8 weeks to maintain its freshness and quality. Always check for any signs of spoilage before consuming.