Jam, jellies & marmalade
Practical Action
general, the amount of pectin in fruit decreases as the fruit matures. Fruits that are high in
pectin can be mixed with those that are lower, for example, strawberry and apple, to make a
mixed fruit jam.
Although it is possible to make a
Making your own pectin solution
good preserve using the pectin
already in the fruit, a higher
Slice the skins of passion fruit, lime, lemon, orange
quality product can be made by
or grapefruit and boil in water for 20-30 minutes.
adding commercial pectin powder Filter the solution before adding to the fruit pulp.
or solution. This will produce a
The amount of solution to be added depends on the
standardised gel each time and
type of fruit and a number of other factors, and must
there will be less risk of a batch
be found by trial and error.
failing to set. However,
commercial pectin may not be available in all areas or may be too expensive for small scale
processors. If this is so, a pectin extract can be made at home from fruits that are naturally rich
in pectin.
There are several different types of pectin available, but for preserves, a slow setting type is
needed so that the gel forms in the jar during cooling. However, in larger containers (eg 5-10kg
jars of jam) or for preserves in which peels or pieces of fruit are suspended in the gel, a faster
setting pectin in needed. In both types, the concentration of pectin varies from 0.2-0.7%
depending on the type of fruit being used. Pectin is usually supplied as '150 grade' (or 150 SAG)
which indicates the ratio of the weight of sugar to weight of pectin that will produce a standard
strength of gel when the preserve is boiled to 65% soluble solids. 5 SAG is normally enough to
produce a good gel.
How to calculate the amount of pectin to add
Assume the commercial pectin is 150 SAG. This means that if you use 100g of this pectin
per 100g jam you would get a pectin strength of 150SAG. This is too strong for jam, which
only needs a strength of 5SAG. Therefore the commercial pectin needs to be diluted to 5
SAG, (ie it is diluted 30 times).
Therefore 3.3g (100/30) pectin would be used for every 100g of material.
Acid
Acids are added to fruit juice to bring the pH within the range 3.0-3.3 which is necessary for jam
making (pH is a measure of acidity – the lower pH means greater acidity). As the acidity varies in
different types of fruit and also in different samples of the same fruit, it may be necessary to
check for the correct acidity if different fruits are used. Limes are very acidic and have a pH
lower than 3.3. Sodium bicarbonate may need to be added to the fruit juice to reduce the
acidity.
The only acids that are allowed to be added to jam are citric acid, tartaric acid and malic acid. In
practice citric acid (which is found in lemon juice) is usually used and this is widely available
from chemists or pharmacies. If citric acid is not available, lemon juice is often used instead.
Food colours and preservatives
During boiling, fruit pulps and juices usually darken in colour. Some fruits only change a small
amount and produce a colour which is still acceptable for jam making. Other fruits darken too
much and produce a dark brown preserve which is not very attractive to consumers. Processors
may consider adding some artificial colour to these products to improve their appearance. It is
better if natural fruit colours can be used – for example, adding dark red fruits or berries can give
a more attractive and natural colour to jams. Most consumers prefer to eat preserves that are free
from artificial colourings. As a processor, you are likely to get a higher price for products that are
more natural and free from colours. If you do need to add colour to your preserve, it is important
to check with the local Bureau of Standards to see which colours are allowed in your particular
country and the permitted levels.
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