Jam (Jelly U.S.) is one of the most effective, and tasty, ways of preserving fruit. It can be slightly messy and is a bit more time consuming than other ways of preservation such as drying and freezing but the results are much more satisfying. Homemade jam when done properly is a delicious and a far superior product to any supermarket bought jam.
The three 'rules' to jam making are to a sugar concentration of 60-65% a pectin content of 0.5-1.0 % and a pH of 2.8-3.4. As Alan Davidson points out in his book: The Penguin Companion to Food
'Stated like this it is remarkable that anyone should produce jam successfully outside a laboratory; but centuries of trial, error and experiment with gluts of acid fruit such as gooseberries have fixed jam firmly in the affections of the British'.
As it is always best to learn from the mistakes of others, with Jam I prefer to tap into these centuries of trial and error and follow the quantities in the recipes to the letter. I have improvised jams when I have had no recipe but the effects were disapointing. One year I tried making a low sugar jam for a friend's diabetic Dad and the result was a pot of mould!
In terms of jars I successfully made ten jars of jam using the first recipe bellow, (all taken from, Food From your Garden), after my glut of black currants this year. In terms of weight 3 kg of fruit will make 5 Kg of Jam.
Steps two and three, (setting point and potting) are the same for all recipes and are shown below.
The measurements used are metric and English imperial Americans should adjust accordingly to American pints etc.
weights and measures conversion chart
2 Kg (4lb) Blackcurrants
1.5 litres (3 pints) water
3 Kg (6lb) Sugar
Stem the currents, wash and drain carefully, put the fruit in a pan with water and simmer until reduced by almost half. Stir frequently to avoid burning.
Add the sugar, stir until dissolved; boil rapidly until setting point is reached, (see below).
weights and measures conversion chart
3 Kg (6lb) Loganberries or Raspberries (Or Both)
3 Kg (6lb) Sugar
Simmer the cleaned berries over a very low heat for 15-20 minutes or until reduced to a pulp, stirring constantly. Add the sugar, stirring until dissolved, then boil until setting point is reached.
weights and measures conversion chart
1.5 Kg (3lb) Cultivated or wild blackberries.
1.5 Kg (3lb) Elderberries
3 Kg (6 lb) Sugar
300 - 450 ml (½ - ¾) pint water
Simmer the stemmed and washed elderberries in the water until soft and pulpy; rub through a sieve to remove the seeds. Return the pulp to the pan, with the hulled and rinsed blackberries, and simmer for about ten minutes or until soft.
Add the warmed sugar, stir until dissolved, then boil rapidly until setting point has been reached
weights and measures conversion chart
3kg (6lb) Sharp cooking apples
1 litre (2 Pints) Water
2 Level tablespoons of citric acid
12 Cloves
3 Kg (6lb) Sugar
Wash, dry and slice the apples, but do not peel or core. Simmer to a pulp, with the citric acid and cloves tied in a muslin bag.
Remove the cloves; sieve and weigh the pulp. Return to the pan, with 1 ½ lb of sugar to every 2 lb of pulp (750 g to 1Kg).
Stir until dissolved and boil rapidly to setting point.
Setting point can be judged by pouring a little of the jam mixture onto a cold saucer and leaving to cool. Once cooled (after thirty seconds to a minute or two) run your finger across the top of the jam and if a skin has formed and the jam wrinkles it has reached setting point. If it stays runny and no skin is present then boil for longer.
• Warm up jars by placing them in a pan of boiled water for five minutes or so.
• Leave Jam for 10-15 minutes without stirring once setting point has been reached.
• Remove any scum that may have formed on the top of the jam.
• Dry jars and poor the hot jam into them.
• Cover the top of the jam with a wax disc, (I used cut greaseproof paper)
• Cover the top with cellophane or greaseproof paper, secure with an elastic band and screw the cap on the jar.
• Label and date.
• You can make personalised gifts with the jam, i.e. a printed label with 'this jam was exclusively bottled for (insert name)'.
Jam Facts
• In Victorian England the main source of vitamin C was from Jam. Quite an astonishing fact when you consider that vitamin C is destroyed by both heat and light and Jam needs to be heated to 105 ºC (220 ºF) and is normally kept in clear glass jars.
• Pectin is a carbohydrate found to a greater or lesser degree in the cell walls of all fruits and vegetables.
• Pectin is high in fruits such as apples and citrus fruits lower in cherries, figs and peaches and although strawberries and raspberries do contain it
• The jam making process allows water to evaporate from the fruit. This water loss and the addition of the sugar makes the pectin (added or already in the fruit) form a barrier trapping water within the cells, making the characteristic jelly or gel like substance we call jam.
DH
The Penguin Companion to Food, Alan Davidson 