


Organisation: Centro Internacional de Agricultura Tropical (CIAT) (http://www.cgiar.org/ciat/)
Author: A.L. Jones
Edited by AGSI/FAO: Danilo Mejia (Technical), Beverly Lewis (Language&Style), Carolin Bothe (HTML transfer)

CHAPTER IV PHASEOLUS BEAN: Post-harvest Operations

1.1 Economic and social impact

1.2 World Trade

1.3 Primary Product

1.4 Secondary and Derived Product

1.5 Requirements for export and quality assurance

1.6 Consumer preferences

1. Introduction

The common dry bean or Phaseolus vulgaris L., is the most important food legume for direct consumption in the world. Among major food crops, it has one of the highest levels of variation in growth habit, seed characteristics (size, shape, colour), maturity, and adaptation. It also has a tremendous variability (> 40,000 varieties). Germplasm collection in beans compares well with other important commodities on a worldwide basis.

Phaseolus vulgaris is produced in a range of crop systems and environments in regions as diverse as Latin America, Africa, the Middle East, China, Europe, the United States, and Canada. The leading bean producer and consumer is Latin America, where beans are a traditional, significant food, especially in Brazil, Mexico, the Andean Zone, Central America, and the Caribbean. In Africa, beans are grown mainly for subsistence, where the Great Lakes region has the highest per capita consumption in the world. Beans are a major source of dietary protein in Kenya, Tanzania, Malawi, Uganda, and Zambia. In Asia, dry beans are generally less important than other legumes, but exports are increasing from China (25 and 37).

In Latin America, Africa, and Asia, the bean is primarily a small-scale crop grown with few purchased inputs, subjected to biological, edaphic, and climatic problems. Beans from these regions are notoriously low in yield, when compared to the average yields in the temperate regions of North America and Europe (26). Yet yields can be improved in all zones.

Beans are a nearly "perfect" food. Nutritionally rich, they are also a good source of protein, folic acid, dietary fibre and complex carbohydrates. Further, when beans are part of the normal diet, the use of maize and rice proteins increases since the amino acids are complementary. Beans are also one of the best non-meat sources of iron, providing 23 percentage-30 percentage of daily recommended levels (23) from a single serving.

Consumption of beans is high mostly because they are a relatively inexpensive food (23). For the poor of the world, they are a means of keeping malnutrition at bay (36). Any advances in scientific research that benefit bean yields, particularly in developing countries, help to feed the hungry and give hope for the future.

1.1 Economic and social impact

1.2 World Trade

Statistics for dry bean production are vague. Figures for the biggest producers and consumers in developing countries are underestimated because beans are often intercropped and/ or grown in remote areas. As a result data are often imprecise. Political disturbances or war sometimes makes statistical analysis difficult or impossible to perform as in the case of Kenya, Rwanda, and Eastern Europe. Illegal trading also occurs across various borders. FAO figures for Asian countries include Vigna, of which there are 150 species in the tropics. A climbing or prostrate plant, Vigna is rarely erect and has various, small seeds that are not broad and flat. The most economic species is the cowpea Vigna unguiculata (L.) Walp. aggreg. whose dried seeds are an important pulse crop in the tropics and subtropics. Including Vigna in the statistics means that P. vulgaris has to be estimated. In short, for developing countries, it is best to take field experience into account when interpreting the statistics.

The centre of origin of the crop is attributed to the central Andes, Central America, and Mexico. Pre-Colombian times documented minor trade between regions. In the seventeenth century, returning colonists took beans to Spain. Thence the Portuguese introduced beans to Brazil and East Africa. Beans became useful for travellers both at sea and on land. European bean consumption began and increased to become one of the few foci of stable trade in the world. Other country to country trade is opportunistic and dependent on the vagaries of climate, causing a continually shifting pattern in world marketing. For example, Chile is now exporting only half the dry beans it did in 1990-92. Morocco has shifted from an exporter in the early 1990s to a big importer in the mid 1990s. Previously substantial exports from Tanzania to Europe have evaporated as Rwandan refugees obtain any surplus product (24).

Over 12 million tons of dry beans are produced annually world-wide, with a total production value of US million $5717. Of this production, 81 percentage occurs in tropical countries. Today, Brazil remains the most important country for production and consumption of beans in the world (13), followed by Mexico. These two countries are nearly self-sufficient in the crop, but bean imports can be essential to supplement periodic production shortfalls. The United States has lost its position as top world exporter to China. Unlike rice and wheat, fundamental to the Chinese diet, dried beans are not government controlled in China. Farmers have a valuable cash crop with production almost wholly for export. This has made China the fastest growing supply source in the world although quality control is lacking (25). In 1994, South Africa imported 58,000 tons of beans to supplement its own production, which has been falling since 1990. China provided 89 percentage of these imports (18).

In East Africa and Central America, the bean is an important staple. Throughout sub-Saharan Africa mostly women farmers grow it traditionally as a subsistence crop. Yet the East Africa Bean Research Network's (EABRN) recent economic surveys show that approximately 50 percentage of producers sell part of their harvest, primarily to urban populations. The income-generating aspect of bean production is becoming more significant principally near urban markets, where populations increasingly rely on bean as an inexpensive source of protein (7).

Table 1. Major dry bean production and consumption by areas (Yearly average in 1000 tons) 1993-95.



(US million $)b








- 165

World's biggest producer & consumer

East Africac




- 18

Uganda and Kenya biggest consumers/producers of area

East Asiad




+ 394

China world's leading exporter (+633), Japan imports increasing

N. America




+ 417

Mainly USA, world's 2nd biggest exporter (+353).

South Asiad




- 40

Per capita consumption low





+ 33

Exports recently increasing





- 244

W. Europe biggest importers, UK especially

C. America & Caribbean




- 39

Guatemala biggest consumer/ producer of area

South Africa




- 88

Imports increasing, mainly low-cost from China

W. Asia &
N. Africa




- 9

Iran & Turkey chiefly for export, Egypt & Algeria importing

Southern Cone




+ 214

Chile & Argentina mostly for export





- 63

Venezuela biggest consumer/ producer of area





+ 8

Recent increase for export

Regions are in order of production and defined as:

East Africa

Burundi, Ethiopia, Kenya, Rwanda, Somalia, Sudan, Tanzania, Uganda, Zaire

East Asia

Cambodia, China, Indonesia, Japan, Korea Rep., Myanmar, Philippines, Thailand, Vietnam

South Asia

Bangladesh, India, Nepal, Pakistan, Sri Lanka


Albania, Austria, Benelux, Bulgaria, Czechoslovakia, France, Germany, Greece, Hungary, Ireland, Italy, Poland, Portugal, Romania, Spain, Sweden, United Kingdom, former USSR, Yugoslavia

C. America & Caribbean


South Africa

Angola, Lesotho, Madagascar, Malawi, Republic of South Africa, Swaziland, Zimbabwe

W. Asia & N. Africa

Algeria, Egypt, Iran, Israel, Jordan, Lebanon, Morocco, Saudi Arabia, Tunisia, Turkey, Yemen

Southern Cone

Argentina, Chile, Paraguay, Uruguay


Bolivia, Colombia, Ecuador, Peru, Venezuela

Calculations based on implicit border prices.
Kenya figures calculated from area planted and expected yields, and probably underestimated.
Asian figures adjusted using scientists' information (FAO Asian data includes Vigna in dry beans).

SOURCE: Compiled by author from FAO databases http://www.fao.org/WAICENT/Agricul.htm (9).

Some high quality dry beans are exported to European markets and elsewhere, constituting a significant proportion of export crops in many countries, notably Ethiopia, Zimbabwe, and Tanzania. These crops have considerable foreign exchange value (23).

The Southern Cone countries of Latin America produce beans mainly for export. Argentina prefers meat protein and began producing beans only for export. Grain that is below export quality remains within a country to sell off cheaply. Thus a producer becomes a consumer as well. This is also the case for Bolivia, where local consumption has risen as a result of information campaigns on the nutritional value of beans.

Europe remains the world's biggest importer of high quality beans. In Asia, beans are less important than other pulses and the statistics are unreliable.

Clearly dry bean production and consumption continue to expand at greater and greater rates as populations increase. As a food crop for the poor, beans have big potential, particularly in developing countries.

1.3 Primary Product

Common bean is grown for its green leaves, green pods, and immature and/or dry seeds. The dry seeds of P. vulgaris are the ultimate economic part of the bean plant. They are appreciated throughout the developing world because they have a long storage life, good nutritional properties and can be easily stored and prepared for eating.

Traditional markets have accentuated local preferences in seed colour and size of seed coat, but dry beans have similar composition. The different bean classes give identical total calories per gram. So it is easy to interchange or substitute different bean types within a major seed-coat class in recipes that require milling mashing or mixing. The consumer may not readily discern the bean type.

There are some limits on the use of dry beans and research is finding ways to overcome them. The long preparation time can be inconvenient and expend much fuel. Changes in the product during post-harvest storage can damage the grain including seed hardening, hard shell, hard-to-cook effect, moisture absorption, mould growth, seed discoloration, flavour and odour. Anti-nutrients such as protease inhibitors and lectins can block the digestion process. Factors promoting flatulence are another undesirable effect (30). There is genetic variability for most of these factors.

The major commercial processors of beans are developed countries. Some of their products are found on the supermarket shelves in the cities of developing countries. They are sold as "luxury" items for the middle and upper classes. This may eventually lead to commercial products being produced within developing countries. All have canning factories. South Africa produces a Bantu bean gravy and relish, Brazil a bean puree cake, Chile makes extruded products for infant foods using black beans and Guatemala pre-cooked flour. Mexico uses black beans for products similar to tempeh and pinto beans to manufacture tortillas and tacos (30). Manufacturing of bean products will increase as demands for convenience foods increase. This is a rapidly expanding market for dry beans.

1.4 Secondary and Derived Product

Dry leaves, threshed pods, and stalks are fed to animals and used as fuel for cooking, especially in Africa and Asia (30). In Peru and Bolivia, where high altitudes prolong cooking times and fuel costs, the ancient tradition of toasting grains comparable to corn and peanuts may be the reason why popping or "toasted" beans have been developed. They are cooked similarly to popcorn.

Dry beans are mostly eaten whole in cooked recipes. Some manufactured products use bean flour (see Figure 1). Roasted beans can be pin-milled to produce whole flour or cracked by corrugated rollers for easy removal of hulls by air aspiration. Hulls may be ground as high fibre (40 percentage) flour to desired particle size (30).

1.5 Requirements for export and quality assurance

Dry beans have numerous seed types, a wide spectrum of colours and colour patterns, varying degrees of brilliance and several seed shapes and classes (34). Of about 600 varieties grown in the world, 62 are commercial market classes and 15 of these are internationally recognised.

The United States classifies dry beans as follows: Red Mexican, Pinto, Navy, Small White, Yellow Eye, Great Northern, White Marrow, White Kidney, Cranberry, Dark and Light Red Kidney, Pink and Black. These classes have become international.

Seed size is classified as small (>900 seed kg-1), medium (600 to 900kg-1) and large (>600 seed kg-1). Seed shape also varies among market classes and has become standardised (3).

Photo 1: Some of the great diversity of bean seed types BEAN VARITY

1.6 Consumer preferences

There is always a premium price for traditional, high quality bean varieties. Worldwide more sophisticated consumers are willing to pay for a quality product. In Latin America, colour preferences are still paramount. Local producers grow beans of the area's preferred colour, which they can sell at high prices. Imported beans of other colours will sell for low prices. At the cheaper end of the market, consumers have no strict criteria. In Africa where mixed varieties are preferred, bean colour is not as important as uniformity of cooking.

Cooking time varies regionally and can be a criterion for consumer acceptance. It is less of a factor where pressure cookers are used, as in many Latin American regions but may be more prominent where firewood is the main fuel source in Central Africa and Guatemala (30).

Producers are concerned about risk avoidance and yield of good quality beans. They recognise the importance of good adaptation of cultivars and resistance or tolerance to major negative characteristics. They are also concerned about culinary quality, taste and selected traits such as seed size, colour and plant growth habit (8).

Photo 2: Mixed varieties are preferred in Africa BEAN VARITY IN AFRICA


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