Semi-processing of tomatoes
Practical Action
The advantages of semi-processing tomatoes are as follows:
The pulp can be produced when there is a glut of tomatoes and processed later in the
season, thus spreading the processing season throughout the year
If tomato pulp is sold on for further processing, it cuts out the need for packaging
materials such as glass bottles and jars and for bottling equipment.
The details in this technical brief are based on the experience of a farmers group in Sri Lanka
who process the tomato pulp and sell it on to a processor for further processing (contact
Practical Action Sri Lanka for further details). The procedure can be varied to suit local
conditions, but the quality control points must be adhered to to ensure a high quality product.
Quality Assurance guidance notes
Acceptance
Farmers deliver the tomatoes to the processing unit between 3.00 and 5.00pm on a daily basis.
Processing takes place up to about 12.00 midnight everyday during the season. If there are
messages that need to be conveyed (minimum, maximum of supply, changes in working hours
etc.) to the farmers (suppliers) these messages are put up on a notice board at the delivery point,
so that the person who delivers tomatoes can take the message back. Farmers are not allowed
inside the processing area.
The farmers are asked to supply fully ripe tomatoes which cannot be sold as fresh tomatoes.
Tomatoes of any shape, size and variety and without split skins are accepted. Bruised tomatoes
are accepted provided that the skin is fully intact. The farmers, who are members of the society,
have been given thorough instructions and they have agreed upon the quality of the raw material.
Farmers understand that bringing unsuitable fruit will increase the production cost. They bring
the tomatoes packed in boxes.
Weighing
The tomatoes are accepted through a half door, weighed and a receipt given to the farmer which
indicates the weight of the tomatoes (minus the individual rejects of the previous day). The
farmers have requested that the seeds extracted from a previous days production are returned to
them for preservation for use in next season.
Sorting
Sorting is done by putting tomatoes onto a sorting table which has a slight gradient at one end.
The good quality tomatoes gently roll into a basin of water and the rejected tomatoes (spoilt,
damaged with broken skins) are collected and weighed. Each delivery is sorted separately to
identify accepts/rejects for each farmer.
Washing
The good quality tomatoes are thoroughly washed in clean water to ensure they are free of soil
and other foreign matter.
Pulping
The clean tomatoes are fed into an electrically driven mechanical pulper with a 1-1.5 HP motor.
This separates the juice from seeds and skins. The tomatoes are rubbed against a perforated
drum by two brushes which are fixed to the central shaft driven directly by the motor. The juice
passes through the perforated drum into the outer stationary drum and is collected through an
outlet. The remaining seeds and skins are pushed out through an outlet connected to the inner
perforated drum.
Acidity
The acidity of the juice is checked to ensure that it is below pH 4.5. If it is higher than pH 4.5,
citric acid is added until the desired acidity is achieved.
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