Clean the fruit well and remove all stalks and leaves. Place the fruit in the mixing bowl and then heat for the time shown in the Tables below. The heating is necessary to soften the fruit and extract "Pectin" from the fruit. Pectin is essential for making the jam set firm. In scientific terms it increases the viscosity of the jam so that it can be spread easily, but not run too easily. Blackcurrants are high in Pectin and hence the recommendation that you use Granulated White Sugar.
After the initial heating take the bowl from the microwave oven and crush the fruit with a potato masher or liquidiser. Once the fruit has been crushed add the sugar to the bowl and mix thoroughly. Make sure all the sugar is dissolved. At this point the mixture appears to be partly clarified, with seeds and skins floating in a relatively clear liquid.
The mixture is now ready for its final heating and boiling. The times suggested, should work OK for the quantities shown in the Tables. Judging the setting point for Blackcurrant jam is relatively easy. The times quoted in the tables seem to be about right to give a reasonably good setting point. A good guide to the correct heating time is the point where the boiling mixture starts to rise up to the top of the mixing bowl. When the bubbling mixture gets within 1/2 inch or 1 cm of the top of the bowl, it is likely to be ready to bottle. This has been found for many different fruits over the years.
Although Blackcurrant jam sets relatively easily, it is a good idea to test it for setting first time around. Take a small sample of the mixture and place it on a plate or saucer and cool it in a refrigerator. If it is ready to set, the sample will form a "skin" on the top of the sample and will become more viscous.
Once the setting point has been achieved, take the bowl out of the microwave oven and use a ladle and funnel to fill your jam jars. It is a good idea to have plenty of clean sterile jars available before taking the mixture out of the oven. Clean the jars well and then place them in hot water (as hot as you can stand) just before you need to use them. Take a jar out of the water, dry well and fill with jam immediately. Do the same with the screw tops and fit the tops as quickly as you can after filling with jam. This helps avoid contamination with mould spores and creates a vacuum over the jam when the jars cool. When done correctly the tops often shrink inwards towards the jam and you have to exert some force to open them when you come to use them. This is just like commercially produced jams and preserves.
Finally when the bottles are cool, label them and store in a cool dry place. Most Jams made this way will last for at 12 months, perhaps longer. However it might be unwise to keep them much longer than 12 months.
A suggested amount of fruit is shown below in the Table. About 1½ pounds is about the maximum suitable for a batch of blackcurrants. It is possible to use frozen blackcurrants if no fresh fruit is available, and the initial heating time must be increased if they are cooked from frozen. However it has been noted that frozen fruit needs less boiling than fresh fruit to reach the setting point. In the recipe below a cooking time of only 8 minutes rather than 12 minutes might be needed to achieve the setting point.
|Item||Weight oz||Weight gms|
|Method||Initial Heating Time||Final Heat & Boil Time|
|Heat Fruit & Water||10fl oz||290ml||5min|
|Crush/Puree Fruit||Add sugar||Stir until clarified|
|Test for setting||Take sample||Cool & check|
|If not at set point||Heat Mixture again||-||2min|
|Test for setting||Take sample||Cool & check||Repeat heating||If not set|
Good luck with your Blackcurrant jam!