A new sweetener thaumatin – A process for the utilization of an African cultured plant

Figure 1: Katemfe plants (Thaumatococcus) in their natural habitat.

In Ghana, West Africa, the timber company Samartex has initiated a project to cultivate on a sustained basis former areas of forestry clearance for the purpose of preserving the biodiversity and to create additional sources of income for the rural population.

This Oda-Kotoamso Community Agroforestry Project, or OCAP for short, is run in collaboration between the landowners, tenants, the state authorities and with the technical support of the German development Service. Financial support is provided by Deutsche Investitions- und Entwicklungs-GmbH.

Thaumatin – 3000 times sweeter than saccharose

Figure 2: Fruits of the katemfe plant.

A useful plant that is easy to cultivate under plantation trees is the katemfe shrub (Thaumatococcus daniellii), which is native to the African rain forest. The protein thaumatin can be obtained from the seed shells (arili) of its fruits. It is around 3000 times sweeter than saccharose and can be used in many areas of foodstuff technology as a sweetener and taste enhancer, e.g. in chewing gum and desserts. Thaumatin is approved as a food additive throughout the entire European Union and in many other countries throughout the world. The sweetener is currently marketed by an English company. Its plant material comes from Ivory Coast, but is processed in Great Britain.

A new method allows processing in the country of origin

Figure 3: Seeds of the katemfe plant with arili (white).
Figure 4: The product – freeze-dried thaumatin.

In order to make the best possible use of the thaumatin plant in the context of the OCAP idea and to achieve a high value added in the country in question, the plan is not only to intensively cultivate and harvest the fruits, but also to process the plant material and purify the protein in the country of origin. This requires a processing and purification method with scale-up capability, which can also be carried out under the conditions prevailing in the producer country.

Using frozen plant material, a laboratory-scale method was developed in an initial project phase at Fraunhofer IGB, with which thaumatin can be extracted from the seed shells of the fruits and purified.

The method includes the mechanical dissolution of the fiber parts containing thaumatin and, since the protein is very easy to dissolve in water, the aqueous extraction. Modern membrane technologies are used to separate other attendant materials extracted at the same time. In the final process step, the protein is dried to make it suitable for storage and transport. The cleaning steps result in a product that fully conforms to the quality requirements listed in the Foodstuffs Approval Ordinance.

Construction of a production plant

If the sweet fruits of the katemfe shrub are already processed in Ghana, the country of origin, new jobs are created there.

On the basis of the laboratory results, the construction and operation of a small plant in Ghana was conceived in a second project phase for the purpose of producing materials locally in order to supply primary customers.

The plant went into operation at the beginning of 2004.

Further information