Traditional cereal processing in Nigeria and Ghana

Traditional cereal processing in Nigeria and Ghana
H. G. MULLER
Procter Department of Food and Leather Science, University of Leeds, Leeds LS2,
9JT, England
SUMMARY
The stone and pestle-and-mortar mills currently used
are illustrated and traditional milling processes are
described. A review of the literature concerning cereal
fermentation introduces a new classification of traditional
cereal products which is rheologically based, covering
six beverages, seven porridges, 10 dumplings and three
baked or fried products. The paper includes a sieving
analysis of stock from traditional sorghum milling, and
four flow-charts show the procedures followed in milling
sorghum and in preparing Kaffir beer, ogi and koko
porridges and Fanti kenkey.
RESUME
H. G. MULLER: Le traitement de transformation traditionnel
des cereales au Ghana et au Nigeria. La meule et
Ie pilon et mortier habituellement utilises sont evoques
et les procedes traditionnels de mouture sont decrits
dans cette etude. Une revue des ouvrages traitant de la
fermentation des cereales presente une classification
nouvelle des produits traditionne1s obtenus des cereales
sur une base rheologique et comprend six boissons, sept
farines, dix pates a boulettes et trois aliments cuits au
four ou frits. L'etude comporte une analyse du tamisage
de la farine de sorgho traditionnelle, et quatre tableaux
d'ecoulement montrant Ie procede employe pour
moudre Ie sorgho et preparer la biere kaffir, les farines
d'ogi et de koko, et Ie kenkey Fanti.
Introduction
As in most developing countries, little transportation
of food over large distances exists at
present in Nigeria and Ghana. Exceptions are
cocoa and oilseeds for export, but these do not
concern us here. Generally food is consumed where
it is produced.
Hence cereal technology is maize-based in the
forest and forest-savanna mosaic zones where
maize grows well, and based on sorghum and millet
in the guinea and sudan savanna zones to the north.
The main cereals eaten in the area are maize,
rice, sorghum, wheat and findi. The only place
in West Africa where the latter grows is not far
from Zaria in the Jos Plateau. Table 1 gives an
analysis of these cereals.
The milling
process
Two types of mill are found throughout the
area, the stone mill (Fig. 1) and the pestle-andmortar
mill (Fig. 2). Both types are exceedingly
ancient and were used in Egypt from at least
2500 B.C. onwards (see Fig. 3) but nothing is known
of their performance and detailed use.
The modern stone mill consists of a baseplate,
often fluted, and a roller. Before use it is placed on
three levelling stones so that it slopes away from
the operator who sits, squats or kneels behind the
TABLE 1
Analysis of Various Grains Consumed in West Africa (%)
(after Platt, 1968)
I
carbo-I
Protein Fat hydrate Fibre
Findi (D. exilis) 7·7 1·8 71 6·8
Maize (Z. mays) 10·0 4·5 71 2·0
Finger millet
(E. coracana) 6·0 1·5 75 3·0
Bullrush millet
(P. americanum) 11·0 5·0 69 2·0
Sorghum spp. .. 10·4 3·4 71 2·0
Wheat
(T. vulgare) .. 11·5 2·0 70 2·0
Rice (0. sativa) 8·0 1·5 77 0'5
Accra: Ghana Universities Press I

mill. A dish or raffia mat is placed in front of the
baseplate to receive the ground material. The
roller is originally round in cross-section but
becomes flattened after some use.
The pestle-and-mortar mill is carved from wood.
The mortar is about 60-70 cm high with a diameter
of about 30 cm. The pestle weighs about
3 kg, is about 1·20 m long, 6 cm in diameter and
has bulbous ends, one rather more pointed than
the other.
The grain is pounded by one, two or three
women, each working at about 60 strokes per
minute. There are three types of stroke: (1) up
and down; (2) down, across and up; and (3) down,
"rotary scrape" and up. Both the stroke across
in 2 and the rotary scraping motion in 3 serve to
knock the side of the mortar to prevent bridging
of the cereal. During grinding the women vary
these three patterns and, since each produces a
different sound, the effect is similar to that produced
on a drum.
Usually the stone mill is used for harder
materials, the pestle and mortar for softer ones.
On one occasion the writer saw dry maize being
ground in a mortar with a 5-6 cm diameter iron
rod as a pestle. The wear on the mortar in this
case would be severe.
Normally, maize is soaked for 24 h before
grinding. As an example of the milling process,
the reduction of sorghum to flour may be described
as observed near Kano. 2-3 kg of grain was
placed into the mortar with about 250 ml of water
and gently pounded with the more pointed end
of the pestle (Fig. 2) and so dehusked. (If the tip
is too pointed the seeds tend to jump out of the
mortar during the process.) The husk was then
separated from the grain by winnowing on a plate
or mat (Fig. 4). The husk was discarded and the
grain returned to the mortar where it was pounded
vigorously with the flattened end of the pestle.
The material was then sieved (Fig. 5). The overtails
were ground on a stone mill (Fig. 1) and the
resulting flour combined with the throughs of the
sifting operation. The flow diagram of the traditional
milling process is given in Fig. 6 and the
sieving analysis in Table 2.
P~stl~ & mortar
sh~1I ing
I
Winnowing
I
P~st I~ & mortar
grinding
I
Siev i ng
I
Stone milling
Bran
Flour
,
TABLE 2
Sieving Analysis of Stock from Traditional Sorghum Milling (%)
Mesh:
5 18 36 40 60 80 100

The traditional process described above is now
being replaced in the larger towns by dieselpowered
grinders (Fig. 7).
Fig. 7. Machine-grinding of steeped maize (Accra, Ghana.
Courtesy A. Andah).
Cereal fermentation
In very many of the traditional West Mrican
processes the cereal is fermented as grain, as a
slurry of ground material, or as a dough. Knowledge
of the microorganisms involved and the
types of acids produced during fermentation in
West Mrica is exceedingly sketchy (Christian,
1966; Platt, 1964; Schweigert & Fellingham,
1963; Akinrele & Bassir, 1967).
It is noteworthy that the type of spontaneous
sour fermentation of cereals, so ubiquitous in
Mrica today, was not at all uncommon in Europe
up to the end of the 19th century. Maloin in 1767
referred to sour dough fermentation in France,
while Parmentier in 1776 described the isolation
of both alcohol and acid from such a dough. The
latter also mentioned oxycrat, a sour, low-alcohol
drink taken in France by poor country folk during
hot weather and similar to the Mrican kaffir beer
(see below). Maurizio (1924) referred to the fermented
porridges of the Slavs and Letts, while the
Russian drink kwass, German sour bread and
Scottish, Irish and Danish barm bread are all sour
cereal products which are still consumed in
Europe today.
The most thorough investigation of any sour
cereal product is that on German sour rye bread,
from which 106 different strains of lactobacillus
and many acids have been isolated (Spicher,
1959; Spicher & Stephan, 1964; 1966). There is
no reason to assume that Mrican fermented cereals
contain fewer.
Ankinrele & Bassir (1967) and W. F. K. Christian
(personal communication) made preliminary studies
of the bacterial flora of ogi and koko respectively.
Akinrele also found lactic and acetic acids in ogi,
while work at present in progress at Leeds showed
additionally butyric, propionic and traces of
formic acids. G.L.c. analysis is demonstrating
several more.
Classification of traditional
cereal products
Three surveys, which include cereal foods, have
been made in Ghana by Whitby (1968) and Dovlo
(undated; 1968). None has yet been made for
Nigeria but the writer has collected a sufficient
number of cereal recipes to be able to suggest a
possible system of classification.
Whitby and Dovlo have classified cereal
products either according to geographical distribution
or according to the cereal used. A different
approach is adopted in this paper.
There is little doubt that eventually the manufacture
of cereal products in West Mrica will be
mechanized. This will require mechanical handling
systems such as fermenters, mixers, pumps and
conveyors. The choice of equipment depends on
the physical properties of the cereal product used
and, therefore, the following classification is
rheologically based. There are beverages, porridges,
dumplings and fried or baked products and each
group is discussed briefly in turn. Table 3 summarizes
the products referred to.
Beverages
These are low-viscosity liquids with a water
content of more than 94%. With mechanization,
they would be processed in the usual beer or soft
drink plant.
The most important beverages are the beers
made from kaffir com (sorghum) and referred to

Traditional cereal processing in Nigeria and Ghana
TABLE 3
Classification of Some Typical Ghanaian and Nigerian
Cereal Products
Baked or
Beverages Porridges Dumplings fried products
Kaffir beer Ogi Hura Bread
Pito Koko Eko Atshomo
Burukutu Ekuegbemi Banku Togbei
Kunnutsaki Tuo Fula
Aliha Garin acha Kenkey
Iced kenkey Ablemamu Akporhe
akasa Nsihu
Kunnu
tsamia
Kokui
Abolo
Sweet
kenkey
as kaffir beer. The alcohol content appears to
vary from 1°/., to 4% and, in addition, there are
significant amounts of lactic and acetic acids. It
must be similar to the French oxycrat and the
Russian kwass.
For the manufacture of kaffir beer the sorghum
is allowed to germinate and is then sun-dried.
It is mixed with unsprouted ground sorghum,
boiled and fermented. The relevant flow diagram
is given in Fig. 8. The boiling, which is interposed
between the I-day and 2-5-day fermentation
periods, is curious. As with many traditional
processes it may be a spurious step; it is possible,
on the other hand, that boiling in the presence of
lactic acid, produced during the first fermentation,
causes a degradation of the starch since lactic acid
is not volatile. Hence more substrate for bacterial
fermentation would become available.
Often the brew is consumed warm, as is the
Hausa beer pito. Sometimes the sediment is
stirred up before drinking (kunnu tzaki), and sometimes
the liquid is carefully decanted (burukutu).
The Ewes, Fantis and Gas of Ghana use maize
rather than sorghum and may sweeten the drink
with sugar or colour it with caramel (aliha).
There are also non-alcoholic beverages such as
iced kenkey (see below) dispersed in water and
sweetened, or roasted maize (ablemamu) treated in
the same way.
Porridges
The moisture content of these is about 90%
and they would be processed like soups or yoghurt.
The most important porridge is ogi which is eaten
all over Nigeria and in parts of Ghana. The Ewes
of Ghana and the Ibos and Yorubas of Nigeria
prepare it from maize, the Hausas and Fulanis
from sorghum or millet.
Essentially the cereal is steeped, ground wet,
sieved wet and allowed to sediment and ferment
in water. The sediment is known as ogi and the
boiled aqueous porridge as ogi porridge. Fig. 9
shows the wet-sieving of ogi.
The Ghanaian koko is prepared in much the
same way, except that it is fermented as a dough
(referred to as mbor) and not as a suspension.
Since less is discarded, the nutritional loss with
koko is not as high as it is with ogi. Fig. 10 shows
the flow diagrams of both these porridges.

Soak i ng
12 hrs
Soakin\l
3- 72 hrs
Doughing
mbor
Wet
sieving
Fermentation
1- 3 days
Fermentation
1-3 days
Fig. 9. Wet-sieving of ogi (Kano, N. Nigeria. Courtesy
E. O. I. Banigo).
There are several other porridges: ablemamu
akasa, like koko but prepared from roasted maize;
ekuegbemi, and the very important Rausa tuo,
are both unfermented porridges, the first prepared
from maize, the second from sorghum. Tuo is
made from wholemeal findi, millet or sorghum;
hence its analysis is identical with that of those
cereals given in Table 1.
Garin acha or 'powdered findi' is a peculiar
Rausa porridge, a mixture of sugar or honey and
unground findi. The mixture is allowed to ferment
briefly and eaten raw. To the writer's knowledge, it
is the only raw cereal product eaten.
Fig. 11 shows the mixing of kunnu tzamia, a
boiled preparation of ground millet and tamarind
water.
Dumplings
These preparations are distinct from porridges
in that they have a yield value: the material can
be formed into balls which do not flow under
gravity. The moisture content is of the order of
65-80%. In Europe dumplings are eaten relatively
rarely and fermented ones appear to be unknown.
In West Mrica there are many: banku refers to
koko dough (mbor) which is rolled into balls and
boiled. Ogi may also be boiled down and gelatinized
into eko or agidi, a popular invalid food. Hura
are dumplings made from millet and sold in
Northern Nigerian markets. Pula is similar. Both
may be mashed in sour milk or water and consumed
as a rather lumpy soup.
The most important of the dumplings are the
various types of Ghanaian kenkey. Maize is soaked,
ground and subjected to fermentation. One-third
of the fermented dough is cooked and mixed with

Traditional cereal processing in Nigeria and Ghana
the remaining uncooked dough referred to as
afiata (Fig. 12). This is then moulded into balls,
wrapped and steamed. Fig. 13 shows several types
of kenkey: plantain-wrapped Fanti ken key on the
Fig. 13. Kenkey: Fanti (left); akporhe (centre and right)
(Accra, Ghana).

H. G. Muller (1970) Ghana Jnl agric. Sci. 3, 187-195
There are a few fried traditional products.
Atshomo is a sweet wheat flour pastry flavoured with
aniseed or nutmeg and fried in oil. And Fig. 15
shows the preparation of togbei. This is a wheat
flour pastry containing sugar, palm wine and
beaten egg. The dough is rolled into balls and
fried.
Conclusion
Although cereals are typical carbohydrate
foods, their protein content is far higher than that
of the tubers. Whereas the latter have a protein
content of the order of 2-3%, that of the cereals
is about 10% and they will generally sustain an
adult but not growing children. Hence protein
deficiency in adults is rare in the cereal-eating
north of Nigeria and Ghana and more common in
the south where tubers are the staple diet.
Cereals are generally deficient in lysine. Maize
is additionally deficient in tryptophan and finger
millet in threonine (Oyenuga, 1968).
There. exists little information on the effect of
processing on the nutrient content of traditional
cereal dishes. Work in Leeds has shown that wet
sieving and steeping, for instance, have considerable
effect on the protein losses in ogi.
Similarly, there are few analytical data of these
foods: those available are summarized in Table 4.
left, akporhe wrapped in corn sheaths on the right.
Here the corn husk wrapping is typically pushed
into the dumpling from below, leaving part of it
exposed at the top.
Several other types of kenkey exist differing in
additives (sugar, salt, sweet potato), fermentation
time, flour extraction and method of wrappiug.
The flow diagram of kenkey manufacture is given
in Fig. 14.
Baked or fried products
Bread baking is not indigenous in West Mrica.
The local bread resembles English bread but
tends to be sweeter and of a finer texture. The latter
is the result of the use of dough brakes rather than
the conventional European moulder. A good description
of Nigerian bakery practice is given by
Kilby (1965).
TABLE 4
Analysis of Various West African Fermented Cereals
(% D.E.)
Carbo-
Protein Fat hydrate Fibre W'ater
I
--
Kaffirbeer l .. 15'0 Trace 75 - 96
Sorghumogi .. 11·3 2·7 84 1·8 41
Millet ogi · . 9·1 7·5 81 1·5 41
Maizeogi · . 7·7 4·0 87 0·5 48
Maizeogi
porridge · . 7·7 4·0 87 0·5 91
Agidi . . .. 7·7 4·0 87 0·5 82
Maizembor .. 10·5 4·2 83 1·9 53
Koko porridge .. 10·5 4·2 83 1·9 93
Banku ·. 10·5 4·2 83
70
1'91
Kenkey2 .. 9·7 2·1 86 0·8 66
I
1 Mter Platt (1968); 2 From FAD data.
All other data by the author.

Traditional cereal processing in Nigeria and Ghana
Acknowledgement
The financial assistance of Leeds University
and the Ministry of Overseas Development,
London, which made this study possible, is
gratefully acknowledged.
REFERENCES
Akinrele, I. A. ; Bassir, O. (1967) The nutritive value
of ogi, a Nigerian infant food. J. trop. Med. Hyg.
70, 279-280.
Christian, W. F. K. (1966) Fermentedfoods of Ghana.
Accra: Food Research Institute (mimeo.).
Dovlo, F. E. (undated) Traditional methods of processing
and preserving food in Ghana. Accra: Food Research
Institute (mimeo.).
Dovlo, F. E. (1968)Maize ..its processingand preparation
for food in Ghana. Accra: Food Research Institute
(mimeo.).
Kilby, P. (1965) African enterprise: The Nigerian
bread industry. Stanford: Stanford University.
Hoover Imtitutional Series 8.
Maloin (1767) Description des arts du meunier,
du vermicellier et du boulanger. Paris.
Maurizio, A. (1924) Nahrungsmittel aus Getreide,
vol. 1. Berlin: Parey.
Oyenuga, V. A. (1968) Nigerian food andfeeding-stuffs.
Ibadan: Ibadan University Press.
Parmentier, A. A. (1776) Experiences et reflections
relatives it l'analyse du ble et des farines. Paris.
Platt, B. S. (1964)Biologicalenoblement: Improvement
of the nutritive value of foods and dietary regimens by
biological agencies. Fd Technol. 18,662-670.
Platt, B. S. (1968) Tables of representative values of
foods commonly used in tropical countries. London:
HMSO. Spec. Rep. Ser., med. Res. Counc. 302.
Schweigert, F. & Fellingham, S. A. (1963) A study
of the fermentation in the production of mahewu, an
indigenous sour maize beverage of Southern Mrica.
Milchwissemch. 18,241-246.
Spicher, G. (1959) Die Mikroflora des Sauerteiges, 1.
Zentralbl. f. Bact. Paras. Inf. u. Hyg. II Abt. 113,
80-106.
Spicher, G. & Stephen, N. (1964; 1966)Die Mikroflora
des Sauerteiges, 2 and 3. ibid. 118, 453-471; 120,
685-702.
Whitby, P. (1968) Foods of Ghana. Res. Bull. Fd Res.
Inst., Ghana 1, 1-31.