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Organisation: International Development Research Centre, Canada (IDRC)
Author: O.G. Schmidt
Edited by AGSI/FAO: Danilo Mejia (Technical), Beverly Lewis (Language&Style), Carolin Bothe (HTML transfer)

CHAPTER V OILSEEDS: Post-harvest Operations


2.8 Storage


2 Post-Production Operations

Small to Medium Scale Processing of Oilseeds

In Tanzania, starting in the mid-80's, a manual press for sunflower oil extraction was developed, which in the next twelve years reached very high levels of dissemination in many countries. This was the technology, which spawned many rural enterprises and began to affect planting patterns. The US Appropriate Technology International (ATI, 1828 L Street NW, Suite 1000, Washington, D.C. 20036 USA) was the prime mover, attracting the interest and financial participation of other agencies, including IDRC.

In South Asia including India and Pakistan, IDRC funded work aimed at improving the efficiency and cost-effectiveness of the ubiquitous motorised screw expellers. This work contributed to a collaborative research and dissemination network.

Manual oilseed crushing-the Bielenberg ram press

In late 1984, ATI and Lutheran World Relief (LWR) initiated a program to help Tanzanian village groups to establish, own and manage small-scale sunflower seed oil extraction enterprises. A year later, ATI staff engineer Carl Bielenberg designed the ram press. In early 1989, a small workshop was convened to review the ATI progress to date, and to exchange experiences about the technology's manufacture, design and dissemination (ATI 1989).

A further workshop in September 1990, with a much larger number of participants, again took stock of progress with the technology (Kamau, John Mugeto 1990) and its dissemination (ATI 1990). By then, dissemination of the ram press was active in Zimbabwe (the ATI-led Zimbabwe Oil Press Project, 132 Harare Street, P.O. Box 1390, Harare, Zimbabwe; Africare, PO Box 508, Harare, Zimbabwe), in Zambia (Africare, PO Box 33921, Lusaka, Zambia), in Kenya (Action Aid and ApproTech, PO Box 10973, Nairobi, Kenya). (See also Zulberti, C. 1990.; Navarro, L., J. Muthaka. 1990; Zulberti,C., O. Schmidt and J.Mugeto. 1990)

Concurrently in Zimbabwe, the Intermediate Technology Development Group (ITDG, Gorland House, 7 Jason Moyo Ave., PO Box 1744, Harare) accrued valuable technical information and collected detailed business-performance on several pilot installations of the Tinytech mechanised systems applied to sunflower at the medium-scale enterprise level.

ATI then developed the concept of a regional OILS project, to which IDRC made a financial contribution between mid 1993 and mid-1995. The regional project was to facilitate the interaction among national groups which were disseminating ram presses in their own countries, to enable support visits from the technical resource people, particularly those in the Tan-Press project of ATI's located at the Centre for Agricultural Mechanisation and Rural Technology (CAMARTEC) in Arusha. (ATI June 1994; ATI 1995).

A further regional workshop on the theme of small scale oil expressing technologies and enterprises was organised by AGROTEC (UNDP/OPS Programme on Agricultural Operations Technology for Small Holders in East and Southern Africa) 4-10 September, 1994, in Arusha, Tanzania. The proceedings of the workshop are extensive, and can be obtained from AGROTEC (P.O. Box BW 540, Borrowdale, Harare, Zimbabwe). By the time of that workshop, the number of ram press enterprises in Tanzania exceeded 1000, the low hundreds in Zambia and Zimbabwe, were just beginning to reach 100 in Uganda and numbered over 100 in Kenya.

One of the important features of that workshop was the declaration by the dissemination agencies that they were positioning themselves as midwives, not manufacturers, of the ram press technology. They gave descriptions of the kind of efforts being undertaken to devolve manufacture, sales and service of the ram press to indigenous companies and commercial agencies, to ensure maximum prospects of sustainability after the end of the short-term intervention projects.

In Kenya, ApproTech is pioneering a new approach to franchising the manufacturers of the ram press. The manufacturer is permitted to place a sticker from the Kenya Bureau of Standards (KBS) on each ram press built, as long as the workshop meets the qualifications and standards "policed" by ApproTech. At the same time, prospective buyers of the press are counselled to buy a ram press only if it carries the sticker of the KBS.

(Also, at the meeting the UK Natural Resources Institute (NRI, Central Avenue, Chatham Maritime, Chatham, Kent, UK ME4 4TB) provided an excellent keynote on technical issues of oilseeds processing. They proposed a protocol for systematic studies in Tanzania and Zimbabwe on protein cake-quality, and rural utilisation in feed for different farm animals. NRI was shortly going to publish a comprehensive manual on processing of oilseeds and utilisation of co-products in sub Saharan Africa. (See also Gordon, A. and A. Swetman, 1990))

Motorised expelling of oilseeds

The most common screw expeller being manufactured in South Asia is based on a design dating from 1906. Little change was made to the design by the many foundry and metal working shops building the machine. In the mid-80s, IDRC supported applied research work with the Pakistan Council for Scientific and Industrial Research (PCSIR) and with the Indian Council for Agricultural Research (ICAR), aimed at improving the performance of the technology. Other agencies began to show interest, and post-IDRC support led towards multi-country and interagency collaboration:

Improvement of the screw configuration in to increase the yield of oil while decreasing the energy consumption; reducing the machine's weight to make it more portable for the hills of Nepal, and other distant locales with few or no roads);

Improved heat treatment processes for the parts in order to reduce the operating costs;

Redesign of the cage lock and gear drive for weight reduction and facilitation of local manufacture;

Improvement of the cone adjustment mechanism in order to allow the processing of a greater range of oilseeds while avoiding jamming of the system.

The main collaborators were the Germany-based FAKT (Association for Appropriate Technologies in the Third World, Gaensheidestrasse 43, 1000 Stuttgart 1, Germany), the PCSIR of Pakistan, the Tinytech company in India (Tinytech Plants Private Limited, Rajkot--360 002, India). and the Nepalese Development and Consulting Services (DCS) in Butwal.

By 1990, substantial progress had been achieved (Dietz et al, 1990):

Machine weight reduced from 1000 kg to 230 kg while maintaining an hourly throughput of 20 kg of rapeseed;

Drive power requirement reduced from 6 kW to 5 kW;

Energy consumption reduced from 100 Whr/kg to 65;

Basic design of the machine had switched from foundry casting to welding.

Documentation can be obtained from FAKT, while the expelling machinery can be obtained from Tinytech (who have been marketing the equipment in Southern Africa, particularly in Zimbabwe).

2.8 Storage

A major rural problem is how to store the press cake produced by ram press operations on sunflower. If a buyer for the feed cake, containing the crushed hull is not easily found the product could become rancid. The buyer of the cake will also have to know which formulation to use to compensate for the high level of husk/hull fibre.

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