Semi-processing of tomatoes
Practical Action
Solids
The total soluble solids content (TSS) of the juice is measured. It should be a minimum of
5°Brix and is usually about 6-7°Brix. If it is lower than 5°Brix, the juice can be mixed with juice
recovered from tomato which has a higher Brix value. It should be noted that the refractometer
should only be used with juice at ambient temperature. Juice at high temperatures will give an
incorrect reading.
Heating
The juice is heated in a large stainless steel pan to 90ºC, for about 45 minutes, using an
industrial gas stove.
Filling
The hot juice is poured into clean, food grade, plastic drums. Just before use the drums should
be thoroughly washed with clean water. It is recommended to use boiling water or, ideally, 35%
hydrogen peroxide solution for the final rinse. Cleaned, empty drums should be stored upside
down on racks.
Preservative
Preservative (700ppm) of either sodium or potassium metabisulphite is added to the drum of
pulp and the drum is quickly sealed. The metabisulphite is mixed by shaking the barrels after
sealing.
Sealing
The drums should be sealed as quickly as possible to minimise the loss of the preservative. As
the juice cools down, if there is a good seal, a slight vacuum will be formed. This helps with
preservation of the pulp.
Storage
The sealed drums must be carefully moved and stored in a clean space at ambient temperature
(25-30ºC). Care should be taken not to damage the seal while moving the drums. If the seal is
broken the levels of sulphur dioxide will start to decrease and there will be no vacuum. This will
cause the juice to ferment and be unacceptable for the consumer and for further processing.
Dispatch
The price per litre of tomato juice is negotiated with the buyers. The drums are transported in a
lorry from the processing unit. Members are paid for the supply of tomatoes. The profits left
after covering the costs are divided according to the quantity of tomatoes supplied by each
member. These are then deposited into individual bank accounts at the Regional Rural Bank in
Matale.
References and further reading
Tomato Processing, Practical Action Technical Brief
How to grow tomato and peppers: Agrodok 17: M. Amati et al, Agromisa, 1989
Starting a Small Food Processing Enterprise by Peter Fellows, Ernesto Franco & Walter Rios
Practical Action Publishing/CTA 1996
Small Scale Food Processing 2nd Ed. P Fellows & S Azam Ali, Practical Action Publishing, 2003
Tomato and Fruit Processing, Preserving and Packaging: An example of a village Factory, G.
Klein, CIEPAC/TOOL, 1993.
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