African Journal of Food Science Vol. 3(4). pp. 113-116, April, 2009
Available online http://www.academicjournals.org/ajfs
ISSN 1996-0974 © 2009 Academic Journals
Ful Length Research Paper
Effect of dry and wet milling processing techniques on
the nutrient composition and organoleptic attributes of
fermented yellow maize (Zea mays)
Grace, T. O. Otitoju
Department of Home Science Nutrition and Dietetics, University of Nigeria, Nsukka. E-mail: email@example.com.
Accepted 29 January 2009
The Study compared the chemical composition and sensory attributes of fermented yellow maize (Zea
mays) processed by two methods. The grains were divided into two equal portions and fermented for 48
h. One portion was drained, sun-dried, dry-milled and subdivided into two equal parts: one was
unsieved-dried-milled flour (UDM) and the other was sieved-dried-milled flour (SDM). The second
portion of the grains was drained, wet-milled and subdivided into two equal parts unsieved-wet-milled
flour (UWM) and sieved-wet-milled flour (SWM). The flours of UDM, SDM, UWM and SWM were analyzed
for crude protein, crude fat, carbohydrate, crude fibre and ash. Gruels were prepared from the flour
samples and their organoleptic attributes were tested for colour, texture, flavour and general
acceptability. The nutrient content of UDM and SDM flour were significantly higher than the UWM and
SWM in terms of protein, fat, ash and fibre contents. There was no significant difference in the
carbohydrate levels based on the processing techniques used. Organoleptic attributes of gruels also
showed no significant difference for SDM, UWM, and SWM. However, the effect of dry-milling without
sieving seems to offer more benefits in conserving and improving the proximate (nutrient) levels of
fermented maize – ‘ogi’.
Key words: Nutrient composition, fermented maize, organoleptic attributes.
Cereals, such as maize, sorghum, mil et, rice among oth-
content and concentrates nutrients (Baiyeri, 2004). Sun-
ers are processed to detoxify the anti-nutritional factors,
drying of foods such as fermented maize is a cheap tradi-
increase palatability and improve bioavailability of nutri-
tional method of food preservation, because solar radia-
ents. There are many household food technologies used
tion (free gift of nature from sunlight) does the drying and
in the processing and preparation of foods and they inclu-
enhances the shelf life of foods products.
de soaking, fermentation, mil ing (dry and wet mil ing),
However, a greater loss of nutrient has been found as-
and sun-drying among others (Eka, 1984).
sociated with wet-mil ing of maize-ogi. Akingbala et al.
Fermentation is one of the household food technologies
(1981), found a decrease in protein, fat, ash and crude
reviewed extensively as means by which the nutritive val-
fibre in wet-mil ed maize-ogi as compared with maize-ogi
ue of plant foods could be improved (Obizoba, 1998;
that was processed by dry-mil ing: Dry-Mil ing of fermen-
Nnam 2000; Obadina et al., 2008). Food samples such
ted maize has shown that the nutrient content of comple-
as maize, sorghum, mil et, rice can be fermented to incre-
mentary foods can be improved by conserving the nutri-
ase the nutrient content, carbohydrate digestibility, and
ent contents as wel as enhancing the shelf life while wet-
energy densities of gruels, increase the bio-availability of
mil ing results mostly into nutrient-loss, yield mainly star-
amino acids and also improve their shelf life under con-
ch and al ows contamination from dirty water. It is there-
trol ed environment (WHO, 1998). Fermentation can also
fore advisable to dry-mil fermented maize because, it is
reduce the high bulk of the traditional complementary
more hygienic, retains nutrient contents and improves
foods by reducing the viscosity of the cereal gruel or por-
shelf life. (Ruud and Rosa, 2002; Dal et al., 2007) Maize
ridge (Potter and Hotchkiss, 1995).
(Zea mays) is an important cereal crop produced exten-
Sun-drying of food removes water, reduces moisture
sively in Nigeria. Maize is the third most important cereal
114 Afr. J. Food Sci.
crop in the world and ranked the second most important
poured into the cold paste and covered for 5 minutes.
cereal crop in Nigeria (Enwere, 1998). In some countries,
maize constitutes a substantial part of the diet of most of
the population (FAO, 1992). The carbohydrate levels of
maize grains are very high and the protein quality of com-
The sensory evaluation of the gruels was conducted in the Maternal
mon maize is similar to that of rice and wheat with lysine
and Child Health Centre (MCHC) of Bishop Shanahan Hospital,
as the most limiting amino acids (FAO, 1992). Maize is
Nsukka. During one day, a panel of 20 nursing mothers was used
reasonably fair in sulphur containing – amino acids (met-
by random sampling from the MCHC to determine the organoleptic
hionine and cystine) and vitamin A precursor, beta-caro-
attributes of the products. Each of the panelists was seated com-
fortably with window open for proper ventilation, fluorescent lighting
tene (Obi, 1991; Obiakor, 2001). However, maize-ogi is
and free from distraction. The judges evaluated the samples using
stil the usual first traditional complementary food given to
a nine point hedonic scale, where 9 was the highest score and 1
children in Nigeria. It is cal ed ogi, akamu, koko, pap (En-
the lowest score. The degree to which a product was liked was
were, 1998). Adequate processing and preparation of fer-
expressed as like extremely (9 points), like very much (8 points),
mented maize-ogi using dry-mil ing method wil reduce
like moderately (7 points), like slightly (6 points), neither like nor
loss of nutrient, and improved the shelf life as wel as
dislike (5 points), dislike slightly (4 points), dislike moderately (3
points), dislike very much (2 points), dislike extremely (1 point). The
decrease the antinutrient factors hence, the objective of
gruels were presented to each of the panelist as coded in the hedo-
nic scale. Each panelist was given a take-away serving bowl, with
spoon and a cup of water to rinse the mouth at interval of testing
the gruels to avoid carry over effect. An ambient room temperature
MATERIALS AND METHODS
was maintained throughout the testing sessions. The 20 panelists
Preparation of samples
for flavor, texture, colour and general acceptability evaluated the
four products (tests and control).
Two kilograms of yel ow maize that were purchased at Nsukka mar-
ket in Enugu State, Nigeria, were cleaned by hand picking to remo-
ve dirt, stones and unwanted materials. Furthermore, maize grains
were steeped in deionised water in a ratio of 1:3 (w/v) and al owed
to ferment at 28 + 2oC for 48 hr. At the end of fermentation, grains
Data obtained from the study were analyzed statistical y. Analysis of
were divided into two equal portions; one portion was drained, sun-
variance (ANOVA) was used to test for treatment effect (Obi, 1986).
dried, dry-mil ed and sub-divided into two equal parts, one part was
Duncan’s New Multiple Range Test (DNMRT) was used to test the
not sieved (unsieved dried-mil ed flour) UDM while the other part
significance of the differences among means (p < 0.05).
was sieved (sieved dried mil ed flour) SDM. Both flours were pac-
kaged separately in airtight polythene. The second portion of the
fermented maize was also drained, wet-mil ed and sub-divided into
two equal parts. One portion of the wet-mil ed flour was wet-sieved
(using 70mm mesh screen) and the bran was washed away from
the endosperm with adequate water. The filtrate col ected (corn-
Table 1 presents the proximate composition (% dry mat-
starch sediment) was poured into a muslin bag, tied and pressed to
ter) of dried and wet-mil ed fermented yel ow maize flo-
urs. The protein levels of the flours ranged from 0.89% in
Both sieved and unsieved samples were dried to produce unsie-
SWM (control) to 11.48% in UDM (unsieved dried-mil ed
ved wet-mil ed flour (UWM) and sieved-wet-mil ed flour (SWM) res-
pectively. These were also packaged separately in airtight polythe-
flour) of the fermented yel ow maize. The dried-mil ed
ne for chemical analysis and sensory evaluation.
flours of the fermented yel ow maize (UDM and SDM)
had higher crude fat levels of 3.57% and 3.55% than the
wet-mil ed flours (UWM and SWM) having low crude fat
levels of 1.67% and 0.67%.
The proximate composition of the flours (UDM, SDM, UWM and
The carbohydrate levels ranged from 80.4% to 99.22%.
SWM) was determined by AOAC (1995) procedure. Protein deter-
The wet-mil ed flours (UWM and SWM) had higher levels
mination was done by micro Kjeldahl procedure, crude fat was by
of carbohydrate (99.22% and 98.22%). The crude fibre
soxhlet extraction, carbohydrate was determined by difference. Ash
was determined by dried ashing method in a muffle furnance and
levels of sieved dried mil ed flour and sieved wet-mil ed
crude fibre by a modified Weende method.Gruel (pap) was prepa-
flour (SDM and SWM) was in trace amount (0.00%) whe-
red from the flour samples for organoleptic evaluation.
reas, the unsieved dried-mil ed flour and the unsieved
wet-mil ed flour (UDM and UWM) had appreciable quan-
Preparation of gruels for organoleptic evaluation
tity of crude fibre (0.66% and 0.50%). Ash levels of the
four samples (tests and control) ranged from 0.22% in
A recipe was developed and used to prepare gruel from the four
SWM flour (control) to 1.89% in UDM. Ash level was low
samples of fermented maize flour of UDM, SDM, UWM and SWM
in the wet-mil ed flours of UWM and SWM (0.22%). How-
respectively. 100g of flour was mixed with 100 ml of deionised cold
ever, the highest level of ash was 1.80% to 1.89% found
water to make the paste; then slurry was made by boiling with 500
ml of deionised water. The deionised water was boiled and samples
in the unsieved-dried-mil ed flours (UDM and SDM).
were mixed with cold deionised water. The hot water was then
Table 2 showed the sensory scores of gruels made
Table 1. Proximate composition of dried and wet-mil ed floursmade from fermented
yel ow maize (% dry matter)
Nutrient 100 g/samples
For each nutrient, values with similar letter in each row are statistical y similar (p > 0.05) while
those with different letters are significantly different (p< 0.05).
Table 2. Sensory scores of gruels made from dried and wet-mil ed flours of fermented yel ow maize
Means not fol owed by the sample letter in a row are significantly different.
UDM- Unsieved dried-mil ed flour made from fermented yel ow maize; SDM- Sieved dried mil ed flour made
from fermented yel ow maize; UWM -Unsieve wet-mil ed flour made from fermented yel ow maize; SWM*-
Sieved wet-mil ed flour made from fermented yel ow maize (control).
from dried and wet-mil ed flours of fermented yel ow mai-
of nutrient through wet-mil ing. Nnam (2002), showed that
ze. The flavour of the gruels was statistical y similar for
vital nutrients are leached in the residue sieved out,
tests and control and the products were liked moderately
leaving the sediment (filtrate) as cornstarch. Nkama,
by the judges. There was no significant difference in fla-
(1994) also reported the same loss of nutrients during the
vour among the samples. The texture of UDM was liked
production of ‘0gi’ with wet mil ing and sieving. This leads
moderately while SDM, UWM and SWM texture were
to considerable loss of essential nutrients, especial y pro-
liked very much. The colours of SDM, UWM and SWM
tein and dietary fibre of the food content. The lower levels
gruels were significantly different from that of UDM. How-
of crude fat in the wet-mil ed flours (UWM and SWM)
ever, judges liked SDM, UWM and SWM very much. The
than the dried-mil ed (UDM and SDM) could be attributed
general acceptability of gruels in terms of flavour, texture
to effect of processing on the fermented maize – ‘ogi’ flo-
and colour attributes were comparable (P>0.05). Alth-
ur. But, adequate preparation and processing through dry
ough, UDM acceptability was significantly different from
-mil ing conserved the crude fat levels of UDM and SDM.
others, yet the judges like the products moderately.
Crude Fibre was trace in the wet-mil ed samples because
of sieving, leaving the residue with bulk of fibre and the
sediment as corn-starch. The same loss of crude fibre
was observed by (Baiyeri, 2004) when maize ‘ogi’ was
The higher crude protein levels of the dried-mil ed fer-
used as a negative control of complementary foods.
mented yel ow maize flours (UDM and SDM) than the wet
Ash levels of al the samples varied. This could be attri-
-mil ed flours (UWM and SWM) was attributed to the
buted to the low level of mineral contents of maize. Altho-
beneficial effect of dry-mil ing processing method. This
ugh UWM and SWM flours had higher quantity of carbo-
agreed with the observation made by (Akingbala, 1981;
hydrate, the difference was not significant in al the sam-
Olatunji, 1982; Obizoba and Atti 1991; Baiyeri, 2004) that
fermented maize nutrients can be improved and conser-
The varying degrees of sensory scores observed for
ved when processed adequately. The low levels of pro-
flavour, texture and colour of the gruels made from fer-
tein in the control (SWM) and (UWM) flours may be due
mented yel ow maize (dried and wet-mil ed) offers promi-
to processing and preparation method of fermented mai-
se for their use at household level. However, the accept-
ze – ‘ogi’. As a result, UWM and SWM had a greater loss
ance of al the gruels made from the four samples indica-
116 Afr. J. Food Sci.
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