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< prev - next > Food processing Preserves KnO 100247_Jams jellies and marmalades (Printable PDF)
Practical Action
Jams, jellies and marmalade can be made from a variety of fruits and some vegetables such as
carrot and pumpkin. They are sometimes referred to collectively as preserves. The products are
typically luxury items that are purchased by consumers in affluent urban areas.
As with all food products, it is essential to carry out a
market and technical feasibility study before starting
to make preserves, to assess the level of demand for
the products in your area. Please remember that jam
making requires a large amount of sugar and making a
high quality product requires some technical
knowledge, the correct equipment and good packaging
materials. A surplus of (over-ripe) fruit is not a good
reason for starting a business making preserves.
The preservation principles of jam, jelly and
marmalade production are quite complex, but in
essence involve the correct combination of acidity,
sugar level and pectin content. All three must be
correct to obtain a satisfactory product.
One important feature of preserves is the high acidity
which prevents the growth of food poisoning bacteria
and also helps maintain the colour and flavour of most
fruits. However, some moulds and yeasts are able to
grow at levels of high acidity and these can spoil the
food. They are prevented from spoiling jams by
ensuring that the sugar content of the preserve is at
least 68%. If for any reason the sugar content is lower
than this (eg if water condenses on the lid of the jar
and falls onto the jam during cooling or if the jam is
not boiled for long enough to reduce the moisture
content) the sugar content will be diluted and moulds
will start to grow on the surface of the product.
Figure 1: Testing for the end point of
jam. A food processing training
course in Bangladesh. ┬ęSue Azam
Ali/Practical Action
This technical brief describes the principles and process of jam making. Generic formulae are
given which the more technical processors can use to create their own recipes. In addition, some
tried and tested recipes for various fruits are included.
Types of Products
Jams are solid gels made from fruit pulp or juice, sugar and added pectin. They can be made
from single fruits or a combination of fruits. The fruit content should be at least 40%. In mixed
fruit jams the first-named fruit should be at least 50% of the total fruit added (based on UK
legislation). The total sugar content of jam should not be less than 68%.
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