Morama bean

The Morama Bean (Tylosema esculentum) A Potential Crop for Southern Africa... 

The morama bean is an underutilized leguminous oilseed native to the Kalahari Desert and neighboring sandy regions of Botswana, Namibia, and South Africa (Limpopo, North-West, Gauteng, and Northern Cape provinces), and forms part of the diet of the indigenous population in these countries. It is also known as gemsbok bean. 

There has been very little research conducted on the morama bean, largely because it is found in the wild and only consumed by a small percentage of the population in the coimtries where found. However, in these areas, it is used by indigenous communities as a source of food, feed, shelter, and medicine, thus contributing to improve the quality of life in traditional agricultural and forest systems in various ways. The morama has enormous potential value that needs to be exploited for the... 

The morama bean is presently known only in the wild state. It tolerates the scorching heat and long drought periods of the Kalahari Desert of Botswana and Namibia (Fig. 5.2), where it is an important component of... 

FIGURE 5.1 Morama bean plants and seeds from Southern Africa (T. esculentum and T. fassoglense] (adapted from Maruatona, 2008 and Kayitesi, 2009). 

FIGURE S.2 Current geographic distribution of morama bean in Namibia and Botswana (Agricultural Laboratory Ministry of Agriculture, Water, and Forestry, 2004 as cited by Muuseler and Schonfeldt, 2006). 

There are no varieties of morama bean that have been developed so far. However, there are advanced crop improvement experiments that are designed to produce a variety of cultivars, namely, early maturing culti-vars, using morama that matures after about 18-24 months. Microsatellite markers (Weising et ah, 1998) have been developed and used previously. Current microsatellite markers for morama beans have been developed using a modified procedure by Zane et ah (2002). These markers will be used in marker-assisted selection (MAS) for the morama bean. 

D. Characteristics of soils from morama bean- and nonmorama bean-growing areas... 

The soils from the morama bean-growing sites in Botswana were characterized by brown sand with no dolomite or limestone concretions on the surface or in the soil profile. Of all the sites in Botswana, only Ghanzi was characterized by white sand with dolomite or limestone concretions in the soil profile. Nonmorama soils from Namibia (Sandveld Site 4) were very fine white sands that appeared wet, waterlogged, and clayish, while those from Botswana soils (Groote Laagte Site 2 and Makgobokgobo Site 2) were generally brown sands with no limestone or dolomite concretions in the profile. 

The pH of the morama bean soils (0-120 cm) collected from Namibia ranged from 5.08 0.08 to 6.90 0.26. A significant difference was found between morama bean soils from Sandveld Sites 1 and 2, and Buitepos, and nonmorama bean soils from Sandveld Site 4. The soils from Botswana showed mean pH values of 5.04 0.21 to 7.40 0.25 for morama bean-growing areas and 4.04 0.03 to 4.89 0.16 for... 

Morama beans may be eaten when they are still immature green beans, but most of them are eaten as mature beans when the seeds are surrounded by hard woody seed coats, reddish to brownish in color. Therefore, the morama beans need to be decorticated before use. 

A number of studies have been carried out, describing the main chemical composition of the edible part of the decorticated morama bean (T. esculentum) and few samples of T. fassoglense have also been included. A literature survey of the performed proximate analysis is summarized in Table 5.2. 

The moisture content of the morama bean is very low as the dry matter (dm) content ranges from 93.4% to 98.7% (Bower et al., 1988 Holse et ah, 2010 Wehmeyer et ah, 1969). Variations may arise from external factors such as soil composition, climate, harvest time, and maturation state of the beans. 

The high amoimt of lipids in morama beans is comparable to the content found in seeds used for production of commercial vegetable oils such as sunflower seed (22-36%) and rapeseed (22-49%) and closely approaches that of peanuts (45-55%) (Belitz et al., 2004 Salunkhe and Kadam, 1989). The amoimt of lipids is twice that of soybeans... 

Proximate composition (g/100 g) of the morama bean reported as mean SD or range... 

The principal components of oils and fats on which all the physical and chemical properties depend are the TAG molecules. The TAGs are in turn made up of a variety of fatty acids esterified to the hydroxyl groups on glycerol molecules. TAG profiles of morama bean oil has been carried out by Mitei et ah (2008) who found seven major TAG classes, with the dominating classes being C54 4, C54 3, and C52 3. Occupancy of the sn-1 and sn-3 positions is 45.0% saturated, 38.4% oleoyl, and 16.6% linoleoyl. The sn-2 position is occupied by oleoyl (56.4%) and linoleoyl (43.6%). 

The lipid of morama beans is mainly ( 75%) unsaturated fatty acids, with the principal fatty acid being oleic acid (43%). The beans furthermore contain linoleic (22%) and palmitic acid (13%) as well as stearic, arachidic, linolenic, arachidonic, erucic, behenic, myristic, palmitoleic, and gadoleic acid in lower concentrations (Bousquet, 1982 Bower et ah, 1988 Engelter and Wehmeyer, 1970 Francis and Campbell, 2003 Ketshajwang et ah, 1998 Mitei et ah, 2008). The fatty acid composition resembles that of olive oil (Mitei et ah, 2008). A literature review of the fatty acid composition of morama beans is given in Table 5.3. Less than 5% of the fatty acids are present as free acids (Bower et ah, 1988 Dubois et ah, 1995), which means that the activity of lipases is negligible in dry morama beans. 

Mitei et ah (2009) determined the relative percentage composition of phytosterols in morama bean oil and foimd 4-desmethylsterols to be the most abimdant phytosterols in the oil (77% or 149.15 gg/g). The content of 4-desmethylsterols is comparable to the phytosterols content of olive oil... 

The major fatty adds in the morama bean are in bold. The last column gives the average fatty acid composition (normalized to 100%). 

A significantly higher amoimt of protein is found in beans from South Africa compared to beans from Botswana. The amount of protein in beans from Namibia is between the contents from the two other countries (Holse et al., 2010). The variation in protein content might be due to different concentration of nitrogen in the soils. Bower et al. (1988) found that globulins are the most abimdant (53%) protein constituents in morama beans. The beans furthermore consist of albumins (23.3%), prolamins (15.5%), alkali soluble glutelins (7.7%), and acid-soluble glutelins (0.5%). 

TABLE 5.4 Amino acid composition (% of total amino acids, normalized to 100%) of the morama bean... 

Amino acids present in the highest amounts in morama beans are highlighted in bold. 

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