There are lots of jam recipes as the proportion of fruit to sugar varies depending upon the fruit you are using but the process you follow in the making of jam is the same for all of them. As a general rule 3kg of each fruit and suger should produce 5kg of jam, if you reduce the volume of fruit and suger then the volume of jam will reduce in proportion.5kg of jam will fill 1lb 10 jarswhich are the large jars you normally buy in a supermarket.
Please note that pectin is the secret ingredient to a successful set. Pectin is released from the fruit as it cooks with the aid of the natural acid in the fruit. Fruit that is naturally low in acidity will release less pectin so you may want to add acid to help the process along. You can also buy powdered or liquid pectin and Jam or preserving sugar, which has extra pectin in, to help if you have fruit with a low pectin content.
1 - Prepare the fruit,
Use slightly under ripe fruit if you can. The pectin content lowers as the fruit ripens so avoid any that are past their best and use no more than half the quantity made up of fully ripe fruit to slightly under ripe. The, the same as before remove stones, cores and stems, all the bits you would not want to spread on your taost.
2 - Soften the fruit and adjust the acidity
This means gently cook your fruit untill it is pulpy and the cell walls have broken down releasing the pectin. You are aiming for a reduction to about 1/3 the volume. Avoid adding any more water than absolutely necessary at this stage and keep the heat low so that the fruit doesn't burn. As a guide the more juice your fruit contains the less water you will need to add;
- juicy fruits such as raspberries, strawberries, blackcurrants, blackberries and rhubarb need no water added at all
- Plums and apples need half their weight in water
- Pears and quinces need about the same amount of water to weight
If using strawberries, raspberries, sweet apples, blackberries, peaches or pears you will need to adjust the acid levels add. For every 1 kg of fruit add 9ml gooseberry juice, or 2 tablespoons of lemon juice or 1/2 teaspoon of citric acid
3 - Adjusting the pecin levels
Before you add any sugar test for the pectin levels. This involves a little science and some methylated spirits. Remove a teaspoon of fruit juice from the pan and put it in a glass. Add 3 teaspoons of methylated spirit mix well and leave to stand for a minute. jelly clots should form in the glass.
- 1 big clot and you have plenty of pectin, move on to the next step
- 2 - 3 large clots and you have sufficient pectin to succeed, move on to the next step
- several small clots and you need to add more pectin - the rule of thumb is to add 200ml pectin to every 1kg of fruit
4 - Add the sugar
Add the sugar as directed by the recipe you are following. Don't add extra as your jam will start to ferment. You can add less but your jam wont keep as long. Your jam is hot at this stage. You need to keep the heat in there so your sugar needs to be warm when you add it. The easiest way to do this is to warm it in the oven. Any sugar can be used but brown sugar will add a flavour to your jam that you may not want. Add the sugar and bring your jam back to a rolling boil. Stir occasionally but only enough to make sure the jam is not burning on the bottom of the pan.
5 -Testing for a set
You need to boil the jam until it is able to set adequately. There are 3 tests you can try, if the jam is not ready continue to boil it.
- Flake test - using a wooden spoon scoop out a liitle jam. Allow the jam to cool in the spoon for a minute then tip the spoon on edge. If the jam is ready it will form a flaky crust on the surface.
- Cold saucer test - spoon a little jam onto a cold saucer, leave to cool and then, using your finger, scrape the jam through. If a skin has formed you are ready to go
- Temperature test - using a jam thermometer stir the jam in the pot for a monent allowing time for an accurate reading. If you have reached 105C you should have a good set.
6 - Remove the scum
As the jam boils you will see a scum appear on the surface. You don't want this in the finished jam so using a spoon remove the scum as it appears. Stiring the jam will mix the scum back into the jam so keep the stiring to a minimum
7 - Pot it up and store
- If you have whole fruits in your jam you will want an even distribution of fruit through the jelly so you need to allow it to cool slightly in the pan to avoid having the fruit float at the top of the jar.
- If you are making jelly you will need to strain the jam through a sieve at this stage. Be extremely careful as the jam is hot and there is a high risk you will suffer a burn. Using specialist jam sieves is best but an old pair of tights, that are clean, works too.
I recommend using a jam funnel at this stage as no matter how hard you try you will end up with drips of sticky jam everywhere otherwise. As mentioned before load the jars leaving a 1comgap at the top and put the lids on. As the jam cools the jars will seal tightly. Clean off any stickiness, label with the contents and a date then store your jam until you need it.
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Eat and enjoy!