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Prebiotics / Probiotics
Untapped health promoting
potentials of indigenous cereal
based African fermented foods
and beverages
Anno 17 - No. 3
May/June 2006
AgroFOOD industry hi-tech
36
Perspective Paper
VICTOR OLUSEGUN OYETAYO
Federal University of Technology
Department of Microbiology
P.M.B. 704, Akure, Nigeria
INTRODUCTION
Food fermentation is regarded as one of the oldest ways of
food processing and preservation (3). All over the world, man
has known the use of microbes for preparation of foods
products for thousands of years. Hence, a wide range of
fermented foods and beverages contributed significantly to the
diets of millions of people.
Fermentation has been defined as a complex chemical
transformation of organic substances brought about by the
catalytic action of enzymes either native or elaborated by the
microorganisms fermenting the raw materials (18). Some
advantages of food fermentation include: preservation of
foods, nutrient enhancement, flavor development and other
qualities that are associated with edibility (11, 18). Most
researchers have been more concerned about the
preservative and nutrient enhancing properties of fermented
foods. This has resulted to dearth of information especially on
the health promoting potentials of cereal based fermented food
indigenous to Africa. Ironically, as early as 1907, the Nobel
price winning Elie Metchnikoff had advocated that the
consumption of fermented milk products by Bulgarian
peasants might be responsible for their long and healthy lives.
In the last 3 decades there has been reports of health
promoting properties of fermented milk products such as
yoghurt in stimulating the immune system of germ free rats
(21), stimulation of the immune system in humans (1);
reduction of cholesterol (9), alleviation of lactose intolerance
(10). The big question is that "is this peculiar to fermented milk
products alone and not others such as cereal based fermented
food products"? This paper highlights the health promoting
effects of Lactobacillus plantarum isolated from fermenting
corn (Ogi) and the potentials of the slurries of indigenous
cereal based African fermented foods and beverages in
maintaining gut health.
FERMENTED AFRICAN FOODS
Fermented foods traditionally constitute a significant proportion
of African diet. Achi (2005) classified fermented food products
into four groups based on the main substrates or raw materials
into the following:
- Fermented cereal e.g Ogi, pito, burukutu
- Fermented starchy foods e.g garri
- Fermented legumes and oil seeds e.g Dawadawa, iru, ogiri
- Fermented animal proteins e.g nono, yoghurt
Fermented cereal products are very common parts of African
diets. Some examples of these are: Ogi (fermented corn
product), Burukutu (fermented sorghum / millet beverage),
Kunnu zaki (Fermented sorghum) etc. Lactic acid bacteria
(LAB) are mainly responsible for the fermentation of these
cereal products. LAB produce metabolites such as organbic
acids, bacteriocins and hydrogen peroxide (7, 12). These
metabolic products have been reported to possess
antagonistic effect on enteropathogens (6, 12). Lactobacillus
species is a well known member of the LAB. They are
important in the maintenance of intestinal microbial ecosystem
(20) and hence an effective biotherapeutic agent called
probiotic. The presence of lactobacilli in the gut is believed to
have the following benefits: growth enhancement of farm
animals, protection from enteropathogen, alleviation of lactose
intolerance, relief of constipation, anticholesterolaemic effect,
immunostimulatory effect (FAO/WHO, 2001).
HEALTH PROMOTING PROPERTIES OF
LACTOBACILLUS PLANTARUM ISOLATED FROM
FERMENTING OGI
Lactobacillus plantarum is one of the bacteria associated with
the fermentation of corn in the production of ogi (4, 15). In a
study by Oyetayo (16), Lactobacillus plantarum isolated from
fermenting corn was found to have the following health
promoting effects.
Antimicrobial activities
Lactobacillus plantarum inhibited the growth of pathogenic and
food spoilage bacteria (Table 1). Figure 1 shows the inhibition
of Staphylococcus aureus by untreated supernatant of
Lactobacillus acidophilus isolated from Ogi.
Table 1. Antimicrobial activities of Lactobacillus
plantarum isolated from fermenting Ogi against
indicator bacteria
goats. This slurry is usually decanted as waste water after
fermentation of these cereals. Therefore, there is need to
conduct research on the metabolic products present in the
slurry. The new study will answer the following questions.
Are these metabolic products different from the already
known antagonistic products of LAB? Are there novel
metabolic products in the slurry? Definitely, there are lots
of questions to answer in future studies.
In the nearest future, maintaining a sound
Table 3. Differential leucocytes counts of rats orogastrically dosed with different
concentrations of Lactobacillus plantarum
gut health may entail drinking this slurry
as beverage. This may sound absurd at
the present, but with further research into
purification, flavouring and toxicological
assessment, human consumption of the
improved slurry will be encouraged. This
may ultimately open a new door for
effective maintenance of gut health.
Table 2. Serum biomarkers of rats dosed with Lactobacillus plantarum
Isolated from Fermenting Corn Slurry
Anticholesterolaemic Effect
The serum cholesterol also reduced significantly in wistar rats
dosed with Lactobacillus plantarum as compared with the
control (Table 2). It has been reported that reduction of serum
cholesterol can prevent various ischemic heart syndrome.
REFERENCES AND NOTES
1.
2.
3.
4.
5.
6.
13.
The potentials of probiotic LAB isolated from cereal based
fermented Afican foods and beverages as biotherapeutic agent
is a very promising area of research. Lactobacillus plantarum
isolated from fermenting corn (Ogi) gave good characteristics
of a promising probiotic candidate with the following benefits:
antimicrobial activities against important pathogenic and food
spoilage bacteria, hepatoprotective effect as a result of of
ability to lower serum aminotransferase level,
immunostimulatory effect and antichilesterolaemic effect.
Other more efficacious LAB with better probiotic effects may
still be present in cereal based fermented foods indigenous to
Africa. The yet to be explored health benefit of cereal based
fermented African foods and beverages is the use of their
slurries in the treatment of bacterial induced gastroenteritis. In
Nigeria, peasant farmers use the water obtained from
fermenting corn slurry in treating incidences of diarrhea in
11.
12.
14.
15.
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17.
18.
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Anno 17 - No. 3
FUTURE PERSPECTIVE
10.
9.
May/June 2006
Other Benefits
Lactobacillus plantarum isolated from fermenting corn slurry
also displayed the following benefits: reduction of the fecal
level of enteropathogens, increse in the level of beneficial
bacteria (lactobacilli), protection of the intestinal ileal epithelial
cell in wistar rats challenged with enteropathogenic E. coli and
orogastrically challenged with Lactobacillus plantarum.
8.
7.
37
AgroFOOD industry hi-tech
Immunostimulatory Effect
differential leucocyte counts in wistar rats dosed with
Lactobacillus plantarum reveal a significant increase in
lymphocyte counts as compared with the control (Table 3). The
primary role of lymphocytes is in the humoral antibody
formation and cellular immunity (5).
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Prebiotics / Probiotics
Hepatoprotective Effect
Serum biomarkers in experimental animals after orogastric
dosing with Lactobacillus plantarum reveal a significant
reduction in aspartate aminotransferase (AST) and Alanine
aminotransferase (ALT) levels as compared with the control
(Table 2). Serum AST and ALT are important enzymes used in
monitoring liver damage (13). An increase in the level of these
enzymes in the serum is an indication of hepatocellular (liver
cell) damage.