Jam, jellies & marmalade
Practical Action
• For marmalade (which contains strips of peel), or jams which contain fruit pieces, it is
necessary to soak the peel or fruit for 2-3 days in a concentrated (60%) sugar
solution. This causes the peel or fruit to achieve the same density as the preserve and,
as a result, it is evenly distributed through the jar and does not float to the surface.
Boiling
Pour the batch into a stainless steel boiling pan and heat as quickly as possible with constant
stirring to prevent the product burning onto the pan. Use a large pan as this will allow the water to
evaporate more quickly and reduce the time needed for boiling. This saves on fuel and time
needed for production and also produces a better coloured preserve.
It is important to use stainless steel to prevent the acids in the preserve reacting with the pan and
causing off-flavours. However, if this is not available, a large clean pan can be used.
Filling and packaging
In many countries there are laws concerning the weight of food sold in a package and accurate
filling to the correct weight is therefore important. The weight, cleanliness of the container and
appearance of the product after filling should be routinely checked. In particular it is important
to avoid getting preserve around the rim of the jar as this may prevent a vacuum forming, and will
look unsightly and attract insects.
Cool the jam to about 85°C and pour into the hot sterilised jars. The jars should be hot when they are
filled or they may crack. If the jam is hotter than 85°C, condensation will form under the lid. This can
drop down onto the surface of the jam and dilute it, which may subsequently allow mould to grow on
the surface of the jam during storage. If the jam is colder than this, it will be difficult to pour.
Fill the jars to about 9/10ths of their volume. Place the clean lids onto the jars, fasten them loosely
and invert the jars to sterilise the lid with the hot jam.
If you are using plastic jars, leave the jam to cool to about 80°C before you pour into the jars. If the
jam is hotter than this it may cause the plastic bottle to melt and become misshapen. Do not cool
too much though or the jam will be difficult to pour.
The packaging is likely to be one of the main costs involved in production. Ideally glass jars
should be used with new screw-on metal lids. Metal cans are also suitable but very expensive.
Cheaper alternatives include plastic (PVC) bottles or plastic (polythene) sachets. However, these
cannot be filled with hot jam as they will soften or melt. Technical advice should be sought from
the supplier if these packs are being considered. Plastic jars are less expensive than glass, but
the preserve will have a shorter shelf life than glass packaging.
It is possible to use paper, polythene, or cloth tied with an elastic band or cotton, to cover the jam
jars. However, the appearance of the product is less professional and there is a risk of
contamination by insects. This is not recommended unless metal lids are impossible to obtain.
Finally, the jars are held upright and the gel is formed during cooling. This can be done by
standing the jars on shelves, or more quickly using a low cost water cooler. A partial vacuum
should form between the surface of the jam and the lid when the product cools. This can be seen
by a slight depression in the lid. If a vacuum does not form it means that the jar is leaking or the
temperature of filling is too low.
Storage
Jams and jellies that are made according to the correct recipe will have a long shelf life. Jam stored
in glass jars will have a longer storage life (up to 12 months) than those packed in plastic bottles (up
to 4 months). For the optimum storage time, jams should be stored in a cool dry place, away from
direct sunlight.
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