WATER AND ENERGY SUPPLIES FOR AFRICAN DRYING UNITS

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Water is needed for cleaning of rooms and equipment and for washing and treatments of raw material. If no public water-supply systems are available, which is the case in many places in Africa, water has to be obtained from other sources, e.g. wells, drillings or streams. This requires pumping, which can be done manually or by pumps powered by electricity or combustion engines, windmills or animal powered norias (scoop wheels). Turbid water can be cleared by means of sand filters.

Energy - Complementary drying (temperatures above 60 C) requires heat, which can be produced by burning of wood or fuel oil provided the latter can be obtained at low cost, which is the case in Nigeria.

Electricity is required for lighting' ventilation of drying cabinets, pumping, fuel oil burners, small type equipment like grinders etc. Unless electricity can be obtained from centrally generated supply systems it will have to be produced by the plant itself by generators powered by combustion engines, windmills (only for limited needs), photovoltaic cells (high investment costs) or hydraulic energy.

EQUIPMENT FOR TESTING OF RAW MATERIAL DELIVERED

• Scale, 0-50 kilos or 0-200 kilos, according to average weight of deliveries
• refractometer 0-30°C
• simple hot-air stove
• scale 0-200 g (0,01 g sensibility)
• aluminium cups (70 mm diameter)
• containers and filter paper

Equipment for humidity analysis requires electrical power; if unavailable, analysis has to be done at suitably equipped laboratories.

EQUIPMENT FOR PREPARATION AND PRETREATMENT OF RAW MATERIAL

• Tables for cutting, knives, planes, electrical cutters
• tubs or other containers for sulphitation, basketry, pulley on suspended rail
• plastic tents (6 m³) for SO2, BrCH3 and phosphine fumigations.

DRIERS AND DRYING CHAMBERS

Seesaw driers (Figure 2) and indirect driers (Figures 1, 3, 4, 5, 6) are sufficient in most cases. Solar drying alone, however? is insufficient if drying procedures require temperatures exceeding 55-60 C. In this case complementray heating must be done in a drying room or cabinet with air heated by firewood, biogas or fuel oil. In general heating by fossil oil is economically feasible in Africa only in oil producing countries.

It is considered that a drying chamber suitable for African conditions should have the following characteristics:

• capacity: 4 trolleys each carrying 50 trays, 100 x 50 cm
• heating: wood heater furnished with an adapting device to make oil or gas burning possible
• ventilation: fan powered by a 5 CV diesel engine or an engine capable of using low quality gas
• structure - masonry (bricks or breeze blocks) or metal frame with glass wool insulation, metal doors.

ADDITIONAL FURNISHINGS AND EQUIPMENT

• building for housing the drying chamber, if metal type (ground dimensions 6 x 2,5 m)
• concrete area in front of the drying chamber for loading and unloading trolleys (minimum size: 20 m )
• 8 trolleys (4 in the drying chamber' 4 being loaded or unloaded)
• 400 trays (200 in the drying chamber, 200 being loaded or unloaded
• constructions for loading and unloading and for storing treating material (wood)

ESTIMATED COSTS

STORAGE

Stored dried products should be protected against rehydration, dust, odours, attacks of insects? mites and rodents.

Bulk storage of the products prior to packing should be in airtight containers: multilayer plastic bags, metal containers' plastic buckets with airtight bids etc. Storage rooms should be solidly build and provide complete darkness.

METHODOLOGICAL APPROACH FOR SETTING UP A SMALL SCALE INDUSTRIAL DRYING PLANT

1. Basic data collection

In order to design a new drying plant it is necessary to obtain the following data

2. Agricultural products to dry

• list of variety of products
• quantities to dry
• harvest periods
• cost price of products
• analysis of samples of products

3. Monthly climatic data

• temperatures - maximum - minimum - average
• dry bulb temperatures at 0600 h and 1200 h
• dew point temperatures at 0600 h and 1200 h
• rainfall in mm - maximum - minimum - average
• hours of daily sunshine - maximum - minimum - average
• wind speed

4. Food consumption habits

• preparation of raw products
• usual packings
• recommendations regarding marketing aspects

5. Data for lay-out

• plan (drawing) of available area
• main data concerning:

• water (quantity, quality, coat)
• electrical power
• fuel supply possibilities (oil, gas, wood)

6. Outline of procedures

• estimate of recoverable solar energy
• required drying time for each product (laboratory teats)
• choice of drier type
• flow sheet (preparation, drying, packing)
• ratio raw material/utilized material
• equipment specifications
• staff required (by function and by category)
• technical data to calculate production costs, including amortization
• programme implementation and time schedule

7. Financing

• total investment cost
• proposed capital structure and financing
• production cost
• estimated operating coat
• cash-flow and profitability

8. Feasibility study and decision regarding investment

9. Detailed engineering

This includes all estimates of production Methods, sufficiently detailed to implement the project, purchase equipment, to start construction work and to initiate plant operation:

• plant operation
• equipment and supplies (purchase and delivery)
• staff training
• initiation of plant operation
• time schedule and programme of work.

APPENDIX 1

DRIED PRODUCTS IN AFRICA 1, 2, 3, 4

APPENDIX 2: FOOD LOSS PREVENTION IN PERISHABLE CROPS

RECOMMENDATIONS

An international action programme of post-harvest food loss prevention in perishables of plant origin should be initiated. A proper balance should be maintained between post-harvest scientists and economists, engineers and food technolgists in project formulation and implementation.

All projects designed to increase food production or improve food marketing should give consideration to the post-harvest implications of the project including both project development and project monitoring phases.

All post-harvest food loss reduction activities should consider the environmental impact of that activity. Environmental and health issues should be part of the documentation of project proposals and the planning process.

Each country should attempt to identify the principal problem areas affecting losses in perishables of plant origin occurring in its own post-harvest system with a view to establishing appropriate priority areas for action. Since the value of the product may be doubled in the postharvest period, these value changes need to be assessed for specific crops. The scale of priorities should be compiled on the basis of the magnitude of the losses, their economic and nutritional importance and the feasibility of applying effective remedial action that is operationally and economically reasonable. A system's approach should be used in this process taking into account biological, physical, economic and social factors with reference to the various economic groups including the rural poor. There should be full participation of the expected beneficiaries in the planning of food loss reduction activities. Traditional technologies should not be ignored.

The use of proper temperature management procedures should be promoted. This includes simple cooling systems such as shading from direct sunlight and use of evaporative cooling. Where appropriate, more cool stores and better utilisation of existing cool stores should be promoted. The International Institute of Refrigeration should co-operate with national and international organisations to organise training in refrigeration management, design, operation and maintenance of suitable for conditions experienced in developing countries.

The search for low cost cooling systems should be intensified. This should include the application of solar energy and other renewable sources of energy to power cooling systems. Practical research programmes should be drawn up by national and international agencies and institutes to adapt refrigeration techniques to the needs of developing countries.

There should be development and promotion of gentle handling of horticultural produce at all steps in the harvesting and marketing system when it is technically feasible and economically viable. This includes the development and use of improved market and field containers that are used to harvest, transport and store horticultural produce. All training manuals should emphasise that mechanical damage is the major factor in providing pathways for infection of produce by micro-organisms. The avoidance of mechanical injury should be an essential criterion on the design of harvesting and handling machinery. The importance of efficient marketing systems as a factor in the prevention of post-harvest losses particularly the less durable fruits and vegetables hats also to be recognised and such systems adapted to suit the requirements of efficient perishables' marketing.

There should be active encouragement of rigid sanitation and public health procedures of all produce handling and operation areas, sanitary operation of equipment, containers and stores, and sorting out and proper disposal of diseased and damaged units from the produce.

The relevant International Agricultural Research centres of the Consultative Group for International Agricultural Research in collaboration with national and other international institutes should be encouraged to initiate or expand a co-ordinated programme of research to resolve outstanding problems related to post-harvest factors and storage behaviour of horticultural crops, e.g., root crops. Plant breeders in these institutions should consider long inherent storage life as an important criterion of selection in the breeding of fruits, vegetables, roots, and tubers.

Research to develop small scale drying technology or other suitable appropriate technologies for transforming horticultural crops should be promoted. The use of these technologies should be promoted where their benefits have been clearly demonstrated.

Every country should be cautioned against the use of hazardous protective agricultural chemicals until the following actions have been accomplished:

• analytical laboratories and inspection services have been established to monitor the proper use of pre- and post-harvest agricultural chemicals;
• guidelines have been developed and are being applied to educate farmers and food handlers in the proper and safe use of hazardous compounds and safe disposal of empty containers.

Information should be available in each country as to which national and regional laboratories have the facilities to identify decay organisms.

A variety of types of training programmes in prevention of losses in horticultural crops should be initiated. These should be designed to suit the differing needs of the people in different parts of the harvesting and marketing chain. While most training should be provided within their own country exchanges with other countries may be beneficial in some cases. The transfer of existing good storage technology fro M national and international institutes to potential users should receive priority in the programmes of these institutions.

The following publications should be prepared:

• technical loss prevention manuals for commodities or groups of commodities;
• a world-wide directory of institutions and training programmes involved with prevention of losses in perishable crops;
• guidelines for loss assessment.

An international information network on food losses in horticultural crops should be established making as much use as possible of existing national and international programmes to facilitate technical co-operation between similarly oriented institutions. The information to be collated in a World Directory (13b) should form the basis for establishing International and Regional co-operation in improvement of training at all levels.

APPENDIX 3: PROJECT IDENTIFICATION CARRIED OUT BY THE SECOND PREPARATORY MISSION

KENYA

1. Solar fruit and vegetable drying - pilot plant to teach and train farm women in this technology in order to save seasonal over-production, in collaboration with the Ministry of Health (KAREN Center for Research and Training).
2. Kenyan Fruit and Vegetable Sun Drying Project to maintain production in PERKERA Scheme at Mariat, in cooperation with:

• the National Irrigation Board
• the Keryo Valley Development Authority

SUDAN (in collaboration with the Food Research Center in Khartoum)

1. Solar drying pilot plant for hibiscus flowers, vegetables and tobacco leaves in "Djebel Mahra" zone (West Sudan).
2. Solar drying pilot plant for green limes in South Sudan.

UPPER VOLTA

1. Solar drying pilot plant for fruits (mango, tomato ...) and vegetables in order to save and utilize the seasonal overproduction, in collaboration with the Ministry of Rural Development (O.R.D.) at Bobo Dioulasso.
2. If feasible, solar drying pilot plant for onions and other vegetables as a substitute for importations during the dry season, in collaboration with the same Ministry at Boguende or Garango (east).
3. Possibly a solar drying pilot plant for mangoes and green beans in the Export Cooperative Center at Ouagadougou to save nonexportable products in collaboration with I.R.F.A.

ZAIRE

1. Project for five (5) solar drying pilot plants to save the seasonal overproduction and to teach and train:

• women shopkeepers in Kinshasa (one center)
• market gardeners in the "green belt" of the Kinshasa area (one center)
• cooperative of vegetable producers in the Mbansa N'Gungu zone (3 centers)

in collaboration with the "General Secretariat for Women in Development".

2. Drying pilot plant (combining solar heat and pinewood) to be set up in Kiwu province in order to utilize fruits and vegetables which cannot be marketed due to the remoteness of this rich area, in collaboration with the Ministry of Agriculture (CECOPANE).

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