Abstract
Microbial
succession of some fermented cereals was carried out using standard microbiological
methods. The results revealed higher bacterial count from sample fermented in
plastic container A (6.4 to 1.44 x 105 cfu/ml), B (6.1 x 104cfu/ml
to 1.22 x 105 cfu/ml), C (3.9 x 104cfu/ml to 1.03 x 105cfu/ml),
Samples fermented with earthen pot, showed lower bacterial count with sample D
(2.7 x 104cfu/ml to 9.2 x104cfu/ml), E (3.3 x 104cfu/ml
to 1.15 x 105cfu/ml) and F (4.2 x 104cfu/ml to 9.0
x 104cfu/ml ). The total fungal count results revealed higher fungal
count from samples fermented with plastic container with sample A (0.4 x 103cfu/ml
to 1.7 x 104cfu/ml), B (0.4 x 103cfu/ml x 103cfu/ml
to 1.9x 104cfu/ml), while C (0.2 x 103cfu/ml x 103cfu/ml to 1.6
x 104cfu/ml ). The results of samples fermented with earthen pot,
showed lower bacterial count with sample D (0.2 x 103cfu/ml to 1.0 x
104cfu/ml), E (0.1 x 103cfu/ml to 1.4 x 104cfu/ml)
and F (0.4 x 103cfu/ml to 1.8 x 104cfu/ml). The study
revealed microorganism associated with progressive fermentation of cereals at
day one in plastic container to include Bacillus,
Streptococcus sp and Staphylococcus sp
for day 1 and 2, while day 3 showed Streptococcus
sp, Lactobacillus sp and Leuconostoc sp. Earthen pot revealed the
presence of Lactobacillus sp and E. coli for day 1, day 2 had Lactobacillus sp and Micrococcus sp, while day 3 had Lactobacillus sp respectively. Fungal
included Penicillin sp for day
plastic. Day two include Bacillus sp, Streptococcus sp, Staphylococcus
sp, Lactobacillus sp and Micrococcus sp while fungal were Penicillin sp and Apergillus sp, while day three recorded bacterial isolated to
include Streptococcus sp, Leuconostoc sp, Lactobacillus sp and Lactobacillus
sp as bacterial and fungal as Candida
sp. Streptococcus sp and Lactobacillus
sp recorded the highest frequency distribution 3(23.1%) each, Bacillus
sp and Staphylococcus sp
recorded 2(15.4%), while E. coli,
Leuconostoc sp and Micrococcus sp recorded the least
frequency occurrence 1(7.7%) each respectively. Penicillium sp recorded the highest frequency distribution
4(44.5%), followed by Candida sp
recorded 3(33.3%), while Aspergillus sp
recorded the least frequency occurrence 2 (22.2%) each respectively. Therefore
this study significantly shows that prolonged fermentation is good since it
inhibits the growth of pathogenic bacteria leaving behind only the lactic acid
bacteria (LAB) which are beneficial to the body due to their activities as
probiotic, thereby increasing the nutritional content of the fermented food,
reducing the toxicity of the food, forces
digestion and palatability of the food.
CHAPTER ONE
1.0
INTRODUCTION
Fermentation of cereal based foods is a
common practice in Africa for food preservation. It is a technology that is
simple; home based and has fed millions of people. Currently, a variety of
fermented foods are produced from cereals at house hold and semi industrial
scale. These foods are used as weaning food for infants and children (Lei and
Jacobsen, 2004; Kalui et al., 2008) and also for adults. A wide range of
cereal-based fermented foods and related processes is a testimony to cultural
diversity and to the ability of humans to find ways to produce foods in
different contexts. The beneficial effects are the preservation of foods and
the increase in their organoleptic characteristics because of the production of
lactic acid and other metabolites synthesized by lactic acid bacteria (Guyot,
2012).
Cereals which include maize (Zea mays),
Sorghum (Sorghum bicolor), millet (Peninsetum americanum) and
acha etc are used in the production of gruels which is used as complementary
food for babies and serves as breakfast for adults. Functional foods are
defined as foods that, in addition to their basic nutrients, contain
biologically active components, in adequate amounts, that can have a positive
impact on the health of the consumer. These foods generally contain health
promoting components beyond traditional nutrients (Berner and O′Donnell, 1998).
Recently, people have realized that
fermented foods have a role beyond provision of energy and body maintenance.
Scientific investigation has shifted to research on the fermentation benefits
(Kalui et al., 2010). Investigation has revealed that fermentation
processes have been discovered to produce active substances (Grajek et al., 2005),
flavor enhancing compounds, important enzymes and amino acids. Some
fermentation microorganisms are known to produce anti–microbial substances
which lead to safe and long shelf life of food products (Corgan et al.,
2007; Kalui et al., 2009; Kalui et al., 2008; Parvez et al., 2006;
Steinkraus, 2000). Useful microorganisms which have health benefits are
associated with fermentation. Predominant among these organisms are Lactic acid
bacteria (LAB) which produce lactic acid during fermentation (Holzapfel and
Schilinger, 2002; Shah, 2007).
These organisms are generally regarded
as safe (GRAS). Human’s need for natural health enhancing foods is a reason for
research development in functional and traditional foods. Many workers have
undertaken research into the probiotic potency of many traditional fermented
foods (Grajek et al., 2005, Reid, 2008; Vasiljevic and Shah, 2007).
These foods contain phytochemical compounds called bioactive substances that
prevent the initiation, promotion and development of allergies and diseases,
rather promote the nutritional and health benefits of the food products
(Sanders, 2003; Pisulewski and Kostogrys, 2003; Pervez et al., 2006; Lei
et al., 2008; Vasiljevic and Shah, 2007).
Cereals are considered major component
of human food in Africa including Nigeria. Nutritionalists have given more
concerned and attention to cereal based foods from maize, sorghum and millet
sources. These cereals have high content of soluble non-starch polysaccharides
such as beta glucan which has a health promoting role. Clinical and
epidemiological studies indicating that beta glucan from barley or oat based
products control cardiovascular disease in humans as reported by Beck et al.
(2010), Shimzu et al. (2008);
Karmally et al. (2005)
and Keogh et al. (2003).
Duchonova et al. (2013) suggested
that the multiple beneficial effects and health benefits of cereal can be
exploited in different ways hence design of novel cereal foods or ingredients
can be targeted at a specific population. Furthermore, cereals are good
fermentable substrates for the growth of probiotic microorganisms (Kochova et
al., 2011 and Kedia et al., 2007; Charalampopoulos et al., 2009).
Cereals can be used as sources of non- digestible carbohydrates. This
selectively stimulates the growth of colonic lactobacilli and bifidobacteria
which act as probiotics (Charalampopoulos et al., 2002; Chavan
and Kadam, 2009; Duchonova and Sturdik, 2010).
Growth of lactic acid bacteria (LAB) in
cereal based fermentation has led to a variety of cereal-based fermented foods
like burukutu, pito, ogi etc. Hence incorporating human-derived probiotic
strains in cereal substrates under control conditions would produce essential
health benefits. There is thus increasing awareness among consumers (users) about
the health benefit and pharmacological properties of diets with high fibre
content. Cereal-based fermented food products contain bioactive ingredients
like dietary and functional fibres. Prolong lactic acid
fermentation of cereal products is the cheapest method of safely preserving
weaning food, the contamination of which is a major cause of disease and
associated malnutrition (FAO/WHO, 1997).
During
the fermentation process, a change of naturally occurring microorganisms resulted
in a population dominated by lactic acid bacteria during prolong fermentation
process (Steinkraus et al., 2003;
Hounhouigan et al., 2003; Johansson et al.,
2005). In order to demonstrate the role of these organisms in the
fermented products, it is essential to quantify the predominating groups of
organisms and to investigate thermodynamics of the overall community. In
addition, the final quality as well as the storage of the product strongly
relies on the way the fermentation was carried out. Studies have shown that
phenotypic identification of fermentative microflora is time-consuming and
often problematic due to ambiguous biochemical or physiological traits (Hugas et al., 2003; Sierra et al., 2005). Therefore, the aim of this research work
is to assess the microbial changes associated with fermented cereal based foods
at different stages of the fermentation, in order to promote health issues.
Aim and objectives of the Study
The
aim of this study is to investigate the microbial succession during cereals
fermentation using earthen pot and plastic bowel. Therefore, the objective of
this study is to:
i. Identify and characterize naturally
occurring microorganisms in fermented cereals using earthen pot and plastic
bowel.
ii. To investigate the microorganisms associated
with the spontaneous fermentation of the cereals samples both in earthen pot
and plastic bowel.
iii. To assess the occurrence of microbial
changes during fermentation of cereals samples both in earthen pot and plastic
bowel.
iv.
To predict a quality control measures
on microbial changes during fermented cereals samples in earthen pot and
plastic bowel.
1.2 Significant
of the Study
This
study will be of significant to food nutritionist as it will highlight some
micro organism (lactic acid bacteria) present in the fermentation of cereals at
different stages, as these bacterial act as probiotics which its presence in a
fermented food leads to the preservation of the food samples. The study will be
of emerge benefits to food industries in the process of preserving their food
product with the use of these naturally occurring lactic acid bacteria (LAB) obtained
from the fermentation of cereals which are cheap and could be easily obtained
from cereals food products.
General
public consuming cereals grains will also benefited from this work, since it
will educate the public on the need for the consumption of prolonged fermented
cereals food which contain lactic acid bacteria (probiotics), which has the
potential and capability of preserving the cereals food products as well as
increasing of the nutritional and health benefits of the food. More specially,
this study will also add to the already existing literature on the
microbiological changes on fermentation of some cereals grain.
1.3 Scope
and Limitation of the Study
The
scope of this study is to isolate, identified and characterized microorganisms
(bacteria and fungi) associated with different stages of fermentation of
cereals grain. Individual organisms’ isolated and microbial loads at different
stages of the fermentation are to be considered. This study is limited only to
bacteria and fungi as well as their colony count obtained from different stages
of the fermentation of the cereals such as maize (Zea mays), Sorghum (Sorghum bicolor), millet (Peninsetum
americanum) due to time factor and also due to the financial
constraint as all the financial burden involved in the research work are solely
on the research student.
