**1. Introduction**

208 Soybean Physiology and Biochemistry

Zare, R., Gams, W., Culham, A., 2000. A revision of *Verticillium* sect. Prostrata.

Food security remain an unfulfilled dream for more than 800 million people (Combes *et al.,* 1996) who are unable to lead healthy and active lives because they lack assess to safe and nutritious food. More than 840 million people lack access to enough food to meet their daily basic needs, while more than one third of the world's children are stunted due to diets inadequate in quantity and quality (WHO, 2001). Widespread nutritional problems are steadily reported in less developed countries (LDCS). This is manifested in protein energy malnutrition indicated within vulnerable groups such as infants, children, the elderly, and pregnant and lactating mothers, who often have high nutrient needs.

Anon (2003), reports that the World Health Organization (WHO) called protein energy malnutrition, (PEM), the silent emergency. According to this report, it declared that PEM is an accomplice in at least half of 10.4 million child deaths each year. WHO (2001) reports that malnutrition cast long shadows, affecting close to 800 million people with 20% of all such people in the LDC. Reports of these wide growing nutritional problems have been steadily mentioned even in Nigeria (Smith and Oluwoye, 1988). Majority of this class is found in the rural areas and urban slums where common heritage of poverty, ignorance, poor sanitation and other conditions contribute to the problems of malnutrition, interfere with its solution, and thus perpetuate a vicious cycle.

Most malnourished people live in Asia and Africa; and the staple of most people in Asia and Africa are starchy pastes. These pastes are made from cereals (sorghum, rice, maize, wheat, millet, acha*)* roots and tubers (cassava, yam, sweet potato and plantain). These crops do not only provide marginal nutrition (especially for children) but also require high inputs of time, labour and fuel to prepare. In most cases they are consumed as combinations in the home because the blends provides complementary balance of amino acids (proteins) in the diet (FAO, 1985). That Africa and especially sub Saharan Africa is in danger of food shortages is no longer news. What is news however is the inability of this region to rise to the great danger facing this region in terms of provision of adequate food.

It was in response to this bleak future that the Bill Gate foundations (2007-2009) sponsored recent research on the possibility of development of drought resistant legumes including soybeans for the areas prone to drought. This was in the realization that these legumes would not only provide needed protein there by improving the nutritional status of the farming populations it would also enhance the socio- economic status of the populace through value chain addition.

The broad objective of the soybean component of the study was to **e**nhance promiscuous multipurpose soybean productivity and production in drought-prone areas in sub-Saharan Africa. The specific objectives included: To increase production of soybean by 15%, through increasing on farm yields in drought years by 20%, on 60% of target area planted, and also by increasing value chain marketing by 20%, income by 30% and house-hold consumption by 25%. These objectives were to be achieved through; Testing of promiscuous multipurpose existing soybean breeding lines for drought and low P tolerance. At least 20 promiscuous elite soybean lines with resistance to bacterial pustule, frog-eye spot, rust and shattering were to be evaluated for adaptation to drought and low P tolerance, and for promiscuous nodulation.

Part of the overall goal of the work was to develop soybean value chains to increase income and improve nutrition of smallholder farm families and other rural entrepreneurs. At least ten thousand households across the target countries were to be informed about profitable and environmental friendly value- addition technologies. At least 25% increase in consumption of soybean products and 25% increase in household income for at least 25% of the population in the target areas was envisaged. At least six training courses for soybean processing and utilization was to be organised in each project site in each country . At least 5 pilot sites for community-based soybean value addition operational in each of the target countries was to be established. At least 10 best-bet technologies for value addition in soybean used by at least 10% of households in the target countries was to be developed.

#### **1.1 Effect of drought on the nutritional status of soybean**

A study to evaluate the nutritional qualities of soybean grown under limited rainfall (drought) was carried out. The results showed that drought grown soybeans grains were smaller and ranged between 6.81-7.88 mm in length and 4.42-5.20 mm in width compared to 7.47-8.22 mm in length and 5.15-5.72 mm in width of the rainfed soybeans grains.

The functional properties of drought and rain fed samples( Table 1) showed that packed and loose bulk density of the milled flours were not significant (P>0.05). Water absorption capacity had been reported by Oyelade *et al* (2002) to denote the maximum amount of water that a food material can take up and retain under formulation conditions. It is known to be related to the degree of dryness and porosity. The high water absorption capacities and index showed that incorporation of the drought sample flour to other food supplement would yield similar results as use of rainfed soybean flours. Foaming capacity of the drought samples were significantly different (P<0.05) from the rainfed soybean sample. Though there were no significant differences (P>0.05) in the foaming stability of the drought and rainfed samples, however, drought grown soybean samples had higher foaming capacities but lower foaming stability. Soy protein is used in food formulations for its foaming properties (Iwe, 2003). The results showed that drought materials have potential capacities to be used as foaming agents. Thus it could be a success in replacement or partial replacement of traditional ingredients for foaming such as egg white (INTSOY, 1998).

Emulsion capacity showed no significant differences (P<0.05) between the drought and rainfed samples. However the drought soybeans showed higher emulsion capacities than the rainfed samples indicating that there were no loss of critical functional property.

The least gelation capacity were also not significantly different (P>0.05). Gelation is an important functional property that soy protein can impart to comminuted sausage products. The results showed that even at 1%, the drought soybeans like the rainfed, soybean produced a gel.

The broad objective of the soybean component of the study was to **e**nhance promiscuous multipurpose soybean productivity and production in drought-prone areas in sub-Saharan Africa. The specific objectives included: To increase production of soybean by 15%, through increasing on farm yields in drought years by 20%, on 60% of target area planted, and also by increasing value chain marketing by 20%, income by 30% and house-hold consumption by 25%. These objectives were to be achieved through; Testing of promiscuous multipurpose existing soybean breeding lines for drought and low P tolerance. At least 20 promiscuous elite soybean lines with resistance to bacterial pustule, frog-eye spot, rust and shattering were to be evaluated for adaptation to drought and low P tolerance, and for

Part of the overall goal of the work was to develop soybean value chains to increase income and improve nutrition of smallholder farm families and other rural entrepreneurs. At least ten thousand households across the target countries were to be informed about profitable and environmental friendly value- addition technologies. At least 25% increase in consumption of soybean products and 25% increase in household income for at least 25% of the population in the target areas was envisaged. At least six training courses for soybean processing and utilization was to be organised in each project site in each country . At least 5 pilot sites for community-based soybean value addition operational in each of the target countries was to be established. At least 10 best-bet technologies for value addition in soybean used by at least 10% of households in the target countries was to be developed.

A study to evaluate the nutritional qualities of soybean grown under limited rainfall (drought) was carried out. The results showed that drought grown soybeans grains were smaller and ranged between 6.81-7.88 mm in length and 4.42-5.20 mm in width compared to

The functional properties of drought and rain fed samples( Table 1) showed that packed and loose bulk density of the milled flours were not significant (P>0.05). Water absorption capacity had been reported by Oyelade *et al* (2002) to denote the maximum amount of water that a food material can take up and retain under formulation conditions. It is known to be related to the degree of dryness and porosity. The high water absorption capacities and index showed that incorporation of the drought sample flour to other food supplement would yield similar results as use of rainfed soybean flours. Foaming capacity of the drought samples were significantly different (P<0.05) from the rainfed soybean sample. Though there were no significant differences (P>0.05) in the foaming stability of the drought and rainfed samples, however, drought grown soybean samples had higher foaming capacities but lower foaming stability. Soy protein is used in food formulations for its foaming properties (Iwe, 2003). The results showed that drought materials have potential capacities to be used as foaming agents. Thus it could be a success in replacement or partial replacement of traditional ingredients for

Emulsion capacity showed no significant differences (P<0.05) between the drought and rainfed samples. However the drought soybeans showed higher emulsion capacities than

The least gelation capacity were also not significantly different (P>0.05). Gelation is an important functional property that soy protein can impart to comminuted sausage products. The results showed that even at 1%, the drought soybeans like the rainfed, soybean

the rainfed samples indicating that there were no loss of critical functional property.

7.47-8.22 mm in length and 5.15-5.72 mm in width of the rainfed soybeans grains.

**1.1 Effect of drought on the nutritional status of soybean** 

foaming such as egg white (INTSOY, 1998).

produced a gel.

promiscuous nodulation.

Similarly there were significant (P<0.05) differences in all the proximate parameters measured (Table 2). The results followed already established principles that drought materials are low in moisture but higher in protein percentage. The reduction in moisture content and the hardness of the grain kernel makes oil extraction difficult. But results gotten from this work showed that even fat content of the drought material was significantly (P<0.05) higher than the rain fed samples. The vitamin and mineral contents of the materials showed similar trends in their profile. The amino acid profile further elucidated the nutritional superiority of the drought samples over the rainfed samples. Compared to the FAO recommendations for infants and adults the results showed that drought materials exceeded the recommendations for infant nutrition in all the amino acids.

The implication of this is that while rainfed material may record higher yields due to bigger seed size ,drought materials would be better nutritionally.


Table 1. The Functional Properties of the Drought and Rainfed Soybean


Table 2. The Proximate Composition of Drought and Rainfed Soybean.


Table 3. Vitamin Content of Drought and Rainfed Soybeans


Table 4. Minerals Content of Drought and Rainfed Soybeans


Table 5. Sensory Attributes of Soymilk Produced from Drought and Rainfed


Table 6. The Amino Acid Profile of Drought and Rainfed Soybean Compared to FAO Reference Pattern

Minerals (Mg/100g) Drought Soybean Rainfed Soybean Phosphorus 0.58 04.8 Potassium 0.98 0.98 Sodium 0.51 0.51 Calcium 0.15 0.13 Magnesium 0.62 0.53 Manganese 27.53 70.00 Iron 75.23 60.87

Sample Appearance Aroma Taste Texture Overall

Lysine 7.22 7.46 5.50 2.40 Histidine 3.00 2.32 1.40 - Arginine 6.21 5.87 - - Aspartic acid 8.59 8.96 - - Threonine 4.00 3.11 4.00 1.40 Serine 3.37 3.02 - - Glutamic acid 16.07 15.1 - - Proline 2.97 2.24 - - Glycine 3.99 3.70 - - Alanine 4.32 3.78 - - Cystine 1.32 1.19 - - Valine 5.00 4.36 5.00 2.00 Methionine 1.13 0.94 - - Isoleucine 3.48 3.70 4.00 2.00 Leucine 8.15 7.52 7.00 2.80 Tyrosine 3.22 3.54 - - Phenylalanine 4.90 4.23 - - Table 6. The Amino Acid Profile of Drought and Rainfed Soybean Compared to FAO

Drought 87.5 6.6 6.7 6.6 7.0 Rainfed 8.9 6.6 6.2 6.4 6.9 Commercial 8.0 6.6 7.2 7.0 8.0

Table 5. Sensory Attributes of Soymilk Produced from Drought and Rainfed

(g/100g protein) Drought Soybean Rainfed Soybean FAO Amino

Acceptability

Acid Ref. Pattern

Children Adult

Table 4. Minerals Content of Drought and Rainfed Soybeans

Sensory Attributes

Amino acids

Reference Pattern

Organoleptic properties (Table5) showed that drought soybean samples had higher mean scores for taste (6.7), consistency (6.6) and overall acceptability (7.0) compared to 6.2, 6,4 and 6.9 respectively for rainfed soybeans samples. The results indicated that the only issue of serious consideration is the smaller size of drought soybean seeds which translates to lower yield. Growing soybean under limited rains may reduce its physical size, but have no reduction in its chemical, functional, nutritional or organoleptic properties. It is therefore necessary for increase in yield and to facilitate adoption and incorporation of soybean into both the farming systems and recipes of those in areas prone to drought that drought resistant soybean varieties be developed.
