Fruit juice processing
Practical Action
At slightly higher production levels, it is necessary to use a power source to achieve a higher
throughput of juice. The multi-purpose Kenwood Chef food mixer, is strongly recommended.
This has a pulping attachment that is similar to the Mouli Legume and it can also be used for
other operations such as liquidising and mixing.
Figure 2: Hand powered pulper
Figure 3: Hand powered pulper
For large-scale production, an industrial pulper-sieving machine is necessary. This also acts by
forcing the fruit pulp through a fine cylindrical mesh. However, these cost in excess of £2,500.
Filtering
To make a clear juice, the extracted juice or pulp is filtered through a muslin cloth or a stainless
steel filter. Some of the larger filter presses have a filter included. Although juice is naturally
cloudy, some consumers prefer a clear product. It may be necessary to use pectic enzymes to
break down the pectin and to help clear the juice. Pectic enzymes may be difficult to find and
expensive and therefore should only be used if really necessary and readily available.
Batch preparation
When the juice or pulp has been collected, it is necessary to prepare the batch according to the
chosen recipe. This is very much a matter of choice and judgement, and must be done carefully
to suit local tastes. Juices are sold either pure or sweetened. Fruit squashes would normally
contain about 25% fruit material mixed with a sugar syrup to give a final sugar concentration of
about 40%. Squashes are diluted with water prior to use and, as the bottle is opened, partly
used and then stored, it is necessary to add a preservative (for example 800ppm sodium
benzoate).
Another popular product is fruit nectar, which is a sweet mixture of fruit pulp, sugar and water
which is consumed on a 'one shot' basis. Essentially, these consist of a 30% mix of fruit pulp
and sugar syrup to give a final sugar level of about 12-14%.
All fruits contain sugar, usually around 8-10%. The actual levels vary from fruit to fruit and with
the stage of ripeness of the fruit. They also vary within the same fruit grown in different parts of
the world. The addition of sugar to the fruit pulp to achieve the recommended levels for
preservation must take into account the amount of sugar already present in the juice. It is
important to achieve the minimum level that will prevent the growth of bacteria, however, once
that level has been achieved, it is possible to add more if the consumers require a sweeter
product. The amount of sugar added in practice is usually decided by what the purchasers
actually want. The Pearson Square is a useful tool to use to help with batch formulation (see the
appendix) and to calculate the amount of sugar to be added for preservation.
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