Contents - Previous - Next
The chibuku beer consumed in southern Africa is basically a thin fermented porridge, usually made from sorghum.
Breads and other baked products
Flat breads are made by baking batters made with flour and water on a hot pan or griddle. Almost any flour may be used. The batter can be based on sorghum, millet or any other cereal and it may or may not be fermented. These flat breads are known by many local names: roti and charpatti in India, tuwo in parts of Nigeria, tortillas in Central America, etc.
Unfermented breads include roti and tortillas. Roti and chapatti made from sorghum or millets are common foods in India, Bangladesh, Pakistan and Arab countries. More than 70 percent of sorghum grown in India is used for making roti (Murty and Subramanian, 1982).
Tortillas, which are prepared in Mexico and Central America, are similar to roti except that the grain is lime-cooked and wet milled. Although corn is the preferred grain for making tortillas, sorghum is widely used and is well accepted in Honduras (Dewalt and Thompson, 1983). Sometimes tortillas are made by mixing sorghum and corn. White sorghum is the preferred sorghum for making tortillas. Sorghum can be dehulled to reduce the off-white colour of the product. Tortillas prepared from blends of yellow maize and pearled sorghum (15 percent) had lighter colour than 100 percent yellow maize tortillas and were found acceptable (Choto, Morrad and Rooney, 1985). Sorghum cultivars Dorado, Sureno and Tortillero from Central America and two hybrids from the Texas Agricultural Experiment station gave tortillas with the best colour and texture (Almeida-Dominguez, Serna-Saldivar and Rooney, 1991). Sorghum kernels with thick white pericarp and yellow endosperm from plants with tan colour and straw-coloured glumes have excellent potential for the manufacture of tortillas.
TABLE 32: Proximate composition of maize and sorghum ogi obtained from study villagesa
|Type of ogi||Moisture (g)||Protein (g)||Fat (g)||Crude fibre (g)||Carbohydrate (g)||Ash (g)||Energy (kcal)||Protein energy (%)|
|Per 100 g wet weight|
|Per 100 g dry weight|
a Mean ▒ SD.
Source: Brown et al., 1988.
Injera (Ethiopia) and kisra (the Sudan) are the major fermented breads made from sorghum flour (Gebrekidan and Gebre Hiwot, 1982). Teff is the preferred cereal for injera preparation. However, sorghum and teff can be mixed, and sorghum alone is also often used. The quality of injera is determined in part by the extent of fermentation. In general, children are given lightly fermented injera with mild sourness. Kisra is a traditional and staple food of the Sudan, prepared from sorghum and millet (Bad), Bureng and Monawar, 1987). It is made with a fermentation starter which shortens the time required for fermentation to less than 16 hours (Bad), Bureng and Monawar, 1988).
A comparison of sorghum and millet flours and bread (roti) made from them (Tables 33 to 35) indicated that baking did not affect the chemical composition including the fatty acids (Khalil et al., 1984; Sawaya, Khalil and Safi, 1984). A slight increase in tyrosine, lysine and methionine content was observed when sorghum flour was made into fermented bread. Baking at 300░C for 15 minutes decreased arginine, cystine and lysine content in pearl millet bread.
Eggum et al. ( 2983) compared the nutritional quality of sorghum grain and kisra made from it. Sorghum is deficient in lysine and therefore has a low biological value. On the other hand, the true digestibility of protein, as well as digestible energy, is very high, with values above 90 percent. Variety was observed to have only a minor influence on the nutritional quality of kisra when preparations from several sorghum varieties were compared (Tables 30 and 31).
Many studies have been done to explore the potential for making loaf bread with composite flours that include either sorghum or millet, and there are no technical difficulties in using any of these flours. Casey and Lorenz (1977) reported that a breed made with part millet flour had excellent texture and a flavour similar to that of whole wheat bread. There is always a steady deterioration of bread quality as the percentage of non-wheat flour is increased. If the flour is coloured (as is the case with pearl millet and abrasively decorticated sorghum that contains too many brown sorghum seeds), it is usually the extent of discoloration that limits the amount of non-wheat flour that can be used. In most other cases the limiting factor is the density of the loaf. Unless other additives (usually expensive imports) are used, about 10 percent of non-wheat flour is the limit most people will accept, although many reports have claimed that breads made using much higher rates of addition were acceptable. Cakes and biscuits can be made using flour with much higher levels of non-wheat flour, but again, as with bread, the quality of the product deteriorates as the substitution level increases. Composite flour has been used commercially in bread in several countries, but it is usually accepted only when there is a shortage of wheat flour, and even then unwillingly.
TABLE 33: Proximate composition and tannin content of sorghum flour and breada
|Product||Moisture (%)||Crude protein (Nx6.25)||Crude fat (% )||Crude fibre (%)||Ash (%)||Carbohydrate (by difference) (%)||Tanninsb (%)|
|Reddish -white sorghum, fermented||35.4||16.4||4.9||2.9||2.2||73.6||0|
a Means of duplicate determinations (variatÝon
< 5%) expressed on dry-weight basis. except moinsture which
was determined in fresh samples.
b Expressed as catechin equivalents (CE)
Source: Khalil et al., 1984.
TABLE 34: Mineral composition of sorghum flour and bread (mg %)a
|Reddish -white sorghum||160||308||23||256||54||5.0||2.3||0.6||2.3|
|Reddish-white sorghum, fermented||174||300||27||187||57||4.2||2.5||0.7||2.8|
a Means of duplicate determinations (variation
< 5% ) expressed on dry-weight basis.
Source: Khalil et al., 1984.
TABLE 35: Proximate compositions and tannin content of pearl millet flour and breada
|Product||Moisture (%)||Crude proteine (Nx6.25)||Crude fat (%)||Crude fibre (%)||Ash (%)||Carbohydrate (by difference) (%)||Energy (kcal/100g)||Tanins (%)|
|As-is basis||9,7 ▒ 0,8||15,7▒0,3||5,7▒0,2||2,5▒0,7||2,0+0,1||64,4▒2,1||372▒10,5||0,17▒0,05|
Pasta and noodles
Pasta products (noodles) such as spaghetti and macaroni are usually made from semolina or from flour of durum wheat or common wheat or a mixture of both. Wheat has a unique property of forming an extensible, elastic and cohesive mass when mixed with water. Sorghum and millet flours lack these properties when used alone.
Sorghum is inferior to wheat for making pasta, both because it contains no gluten and because its gelatinization temperature is higher than that of wheat. Miche et al. (1977) made pasta from mixtures of sorghum with wheat. They found that to obtain products of good cooking quality it was necessary to add some gelatinized starch to the sorghum flour before extrusion. The pasta quality is influenced by the quality of both the sorghum flour and the starch. White sorghum is preferable for pasta products as its colour is similar to that of wheat flour. A composite flour consisting of 70 percent wheat and 30 percent sorghum produced acceptable pasta.
Noodles made with 20 percent prove millet flour were acceptable (Lorenz and Dilsaver, 1980). The reduction of flour mass during cooking (cooking loss) at this level of addition was similar to that of wheat noodles used as a control. Cooking loss increased with 40 or 60 percent millet flour.
Faure (1992) made pasta from mixtures of sorghum, millet and wheat. He found that the quality of the pasta was strongly related to the characteristics of the flour that was used and particularly to the way the flour was dried. There should be less than I percent ash and I percent fat in any material that is used. Proper hydration is necessary. Regrinding and intensive shearing during mixing and extrusion improves hydration. It is difficult to hydrate large pieces of corneous endosperm.
Desikachar ( 1977) prepared noodles by extruding boiled sorghum dough through a press and then steaming and drying it. In China, sorghum noodles are made using a special device.
Germinated sorghum flour, called "power flour" (kimea in the United Republic of Tanzania), reduces the viscosity of the food product. It is thus possible to use double the quantity of flour to make a product of similar consistency, so the energy density of weaning foods can be increased (Seenappa, 1988). Sorghum and millets are used in weaning foods in countries such as Ethiopia, India, the United Republic of Tanzania and Uganda. Seenapa (1988) described sorghum and millet weaning foods that are being promoted in a number of African countries.
Use of sorghum- and millet-based weaning foods prepared using extrusion and malting techniques has been found successful. These foods have been promoted as high-energy or high-protein foods but would have better acceptance and be more popular if the cost could be reduced.
The quality of weaning foods prepared from cowpea and malted or rollerdried sorghum was evaluated (Malleshi, Daodu and Chandrasekhar, 1989). The weaning food formulation based on malted sorghum and malted cowpea was nutritionally superior to roller-dried weaning food prepared using the unmelted raw materials. The available Iysine content was 3.85 percent in the malted food and 2.95 percent in roller-dried sorghum food. The protein efficiency ratio of malted food was 2.26, significantly higher than that of the roller-dried food ( 1.87). The cooked paste viscosity of malted sorghum was considerably lower than that of the roller-dried sorghum.
Though beverages are not major foods, they serve as a source of energy in several countries. Thin fermented porridges are commonly prepared and used as a drink in African countries. They are considered foods and provide important nutrients. Traditional beer, amgba, and a wine, affouk, prepared from sorghum in Cameroon were found to be nutritionally superior to sorghum flour (Chevassus-Agnes, Favier and Joseph, 1976) as they provide additional riboflavin, thiamine and lysine. Derman et al. (1980) found that iron absorption from maize and sorghum beer was more than 12 times higher than that from the constituents that were used to prepare the beer. In traditional sorghum beer, most of the thiamine and about half of the riboflavin and niacin are associated with beer solids which contain the yeast (van Heerden and Glennie, 1987). The beer with the highest total solids contained the highest amounts of minerals and trace elements (van Heerden, Taylor and Glennie, 1987). Thus the beer is a source of vitamins, iron, manganese, magnesium, phosphorus and calcium. The beer contained 26.7 g starch and 5.9 g protein per litre.
Lager beer can also be produced from sorghum. In Nigeria, sorghum has been tested as a barley malt substitute for producing beer (Obilana, 1985). Beer has been produced successfully by blending equal amounts of sorghum and barley. Lager beer was brewed from sorghum malt using the three-stage decoction method and 30 percent sucrose as an adjunct (Okafor and Aniche, 1987). In Rwanda, a new type of beer is produced using local sorghum and barley (lyakaremye and Twagirumukiza, 1978). Up to 40 percent sorghum mixed with barley malt makes acceptable beer.
Amylopectin starches are not suitable for lager as they cause difficulty in filtration. Varieties with low starch gelatinization temperature may be suitable. Good malting barley or cereal usually has white floury or starchy endosperm. Similarly, sorghum with predominantly floury endosperm is preferred for malting. Sorghum and corn grits are similar in amino acids, proteins and starch composition (Canales and Sierra, 1976), and sorghum may confer additional oxidative stability because of its fatty acid composition.
Distilled alcohol can also be produced with suitable modifications and sorghum may have good potential in the industry. Distilled spirits are produced from sorghum in China, where the alcoholic beverage industry is a major consumer of sorghum grain.
Traditional opaque beer, for which sorghum and millets are valuable raw materials, is a popular beverage in several countries in Africa. It is called chibuku in Zimbabwe, impeke in Burundi, dolo in Mali and Burkina Faso and pito in Nigeria. The main attributes of this product are short shelf-life of about one week, low alcohol content, acidic nature, suspended solids and a characteristic taste and colour (Chitsika and Mudimbu, 1992). Opaque beer is more a food than a beverage. It contains high proportions of starch and sugars, besides proteins, fat, vitamins and minerals. In its manufacture white sorghum with less polyphenols is preferred, although red and brown sorghum varieties are also used. Red sorghum imparts a pinkish-brown colour to the beer. Hightannin sorghum is not desirable for beer production. The malt used for the manufacture of beer should have high diastatic activity and solubility. Malts are also sources of lactobacilli and essential nutrients.
Extrusion is being used increasingly often for the manufacture of snack foods. In extrusion processes, cereals are cooked at high temperature for a short time. Starch is gelatinized and protein is denatured, which improves their digestibility. Antinutritional factors that are present may be inactivated. Microorganisms are largely destroyed and the product's shelf-life is thereby extended. The products are easily fortified with additives.
So far, sorghum and millet extrusion products have not yet been produced on a commercial scale. Fapojuwo, Maga and Jansen ( 1987) used two low-tannin sorghum varieties in extrusion studies. Extrusion improved the digestibility of one variety from 45.9 to 74.6 percent and of the other from 43.9 to 68.2 percent. The cooking temperature was the variable that most influenced digestibility. Youssef et al. ( 1990) used two varieties of sorghum (one brown, one white) to make 16 different extrusion products. The proportion of sorghum in the formulations ranged from 45 to 97 percent. These studies showed that sorghum can be used with other cereals to make acceptable extruded products.
Contents - Previous - Next