FRUIT JUICE PROCESSING
Introduction
•A wide range of drinks can be made using extracted
fruit juice or fruit pulp as the base material.
•Many are drunk as a pure juice without the addition of
any other ingredients, but some are diluted with sugar
syrup.
•
•The types of drink made from fruit can be separated
into two basic types;
•- those that are drunk straight after opening
•- those that are used little by little from bottles
which are stored between use
Types of Fruit Juices
Each of the above products is preserved by a
combination of natural acidity, pasteurisation and
packaging in sealed containers. Some drinks (syrups
and squashes) also contain a high concentration of
sugar which helps to preserve them.
Preparation of raw material
•Select mature, undamaged fruits. Any fruits that are mouldy or
under-ripe should be sorted and removed.
•Wash the fruit in clean water. It may be necessary to chlorinate
the water by adding 1 tablespoon of bleach to 5 litres of water.
•Peel the fruit and remove stones or seeds. If necessary, chop the
fruit into pieces that will fit into the liquidiser or pulper. Remember
that at this stage, you are exposing the clean flesh of the fruit to
the external environment.
•Make sure that the utensils are clean.
•Do not leave the cut surfaces exposed to the air for long periods
of time or they may start to turn brown and this will discolour the
juice. The fruit pieces can be placed in water that contains lemon
juice (250ml lemon juice per litre of water) to stop them browning.
Juice extraction
There are several methods to extract juice
depending on the type of fruit you use.
For citrus fruits which are naturally juicy, the best
option is to use a hand presser (see figure 1) or a
revolving citrus 'rose'.
Some fruits such as melon and papaya are steamed
to release the juice.
Apples are pressed and
Fruits such as mango, guava, sour sop, pineapple,
strawberry must be pulped to extract the juice. The
fruit pieces are pushed through a perforated metal
plate that crushes and turns them into a pulp.
•Some fruits can be pulped in a liquidiser and then filtered to remove the fruit
pieces. There is a range of equipment available that varies in size and in the type of
power supply (some are manual while the larger ones require electricity).
•For the small scale processor, the Mouli Legume or a hand-powered pulper/sieve
which force the fruit pulp down through interchangeable metal strainers (figures 2
and 3) is sufficient.
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%.
The Pearson Square
The Pearson Square is a method that processors can use to
calculate the amounts of two components that should be mixed
together to give a final known concentration.
For example, it can be used to calculate the amounts of fruit
pulp and sugar syrup to make a fruit drink.
The method can only be used for blending two components.
When more than two components are involved, it becomes more
complex.
Pasteurisation
•All the products mentioned above need to be
pasteurised at 80-95°C for 1-10 minutes prior
to hot-filling into bottles.
•At the simplest level, this may be carried out
in a stainless steel, enamelled or aluminium
saucepan over a gas flame, but this can result
in localised overheating at the base of the
pan, with consequent flavour changes.
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.
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.
Another option is to pasteurise the juices once they
have been bottled. The bottles are placed in a hot water
bath which is heated to 80°C. The bottles are held in the
hot water for the given amount of time until the
contents reach the desired temperature.
The next industrial jump in pasteurisation is an
expensive option that involves the purchase of a
double-jacketed steam kettle in stainless steel and a
small boiler.
Filling and bottling
In all cases, the products should be hot-filled into
clean, sterilised bottles.
A stainless steel bucket, drilled to accept a small
outlet tap, is a very effective bottle filler. The output
can be doubled quite simply by fitting a second tap on
the other side of the bucket.
After filling hot, the bottles are capped and laid on
their sides to cool prior to labelling.
Quality control
Production of fruit juice
concentrates and powders
THANK YOU!
