CHAPTER ONE
1.0 INTRODUCTION
Ogi-acid-fermented cereal gruel is a
staple food of several communities in Nigeria. It is traditionally made from
maize, sorghum or millet. Several reports had identified steeping and souring
as the two fermentation stages involved in the traditional process of Ogi. It
is prepared by steeping clean grains in water at room temperature (25±20C) for 48-72h. The steep water is
decanted and the fermented grain is washed with clean water and then wet-milled.
The bran is removed by wet sieving and the sierate is allowed to settle for
another 24-48h, a process referred to as souring during which time fermentation
also proceeds and the solid starchy matter, Ogi, sediments (AKinrele, 1970.
Banigo and Muller, 1972, Akingbala et al,
1981). The wet Ogi usually has a smooth texture, a sour flavour resembling that
of yoghurt and a characteristics aroma that differentiate it from starch and flour.
The color of Ogi depends on the type of cereal used. Cream for maize, light
brown for sorghum and greenish to grey for millet (Banigo and Mullerm 1972).
Lactic acid bacteria (LAB) are the most
prominent non-pathogenic bacteria that play a vital role in our everyday life,
from fermentation, preservation, and production of wholesome foods, and
vitamins to presentation of certain diseases and cancer due to their
antimicrobial action. Lactic acid fermentation is generally inexpensive often requiring
little or no heat in the process, making them fuel-efficient as well (Keith,
1991). Lactobacillus plantarum frequently occurs spontaneously, in high
numbers, in most lactic acid fermented foods, especially when the food is based
on plant materials, for example, in brine olives (Fernandez Gonzalez et al., 1993), Capers (Caper berries;
Palido et al., 2005), Sauver-kraut
(Dedicatoria et al., 1981), salted
gherkins (McDonald et al., 1993),
sour-dough (Lonner and Abrne 1995), Nigeria Ogi (made from maize or sorghum)
(Johannson 1995a). Thus, it is obvious that individuals consuming lactic
fermented products of plant origin also consume large amounts of L. plantarum.
Lactococcus lactis, a model lactic acid
bacterium that is widely used in the diary industry, which proves beneficial
due to its easy protein secretion and purification. It is also a potential host
for the production of therapeutic recombinant proteins (Biomedical Research,
2012 volume 23 Issue 1).
The purpose of the research work presented
in this paper is to study the effect of these ‘LAB’. L. Plantarum, L. Lactis and schizosaccharonyeces rouxii on the
qualify of maize Ogi, with the aim o providing a rational basis for the
improvement of processing techniques and thus the nutritional quality of Ogi
for its use as complementary food for infants and young children.
1.1 Objectives
1. To evaluate the physical
properties of Ogi processed by industrial method.
2. To determine chemical
properties of the product, Ogi processed by industrial method.
CHAPTER TWO
2.0 LITERATURE
REVIEW
Lactic acid bacteria in the last fifteen
years has been increasing in term of researches, and industrial attention has
been used both in alcoholic and lactic fermentations. Cereals such as maize is
important in Ogi production because it is considered as habitats for microbial
growth, such microbial growth as lactic acid bacteria infractions during Ogi
production will be discussed below.
All lactic acid bacteria ferment various
sugars into lactic acid in amount large enough to inhibit or kill most other
microorganisms. But with very few exceptions, including some streptococci,
lactic acid bacteria are harmless to humans, and the metabolic products of
lactic acid bacteria have a pleasant taste. These properties enables us to use
lactic acid bacteria to prepare and preserve food. The food must contain enough
sugars for the lactic acid bacteria to produce inhibiting amounts of lactic
acid. Also air must be excluded so that aerobic microorganisms, which
metabolize more rapidly, cannot use the sugar before the LAB have a chance to
develop. Usually, it is not necessary to add lactic acid bacteria to the food
because most plant materials and diary products contain an adequate natural
population.
2.1 Lactic
Acid Bacteria Metabolism During the Fermentation of Ogi
There are two main hexose fermentation
pathways that are used to classify lactic acid bacteria genera according to
Axelssion, (1998), under the condition of excess glucose and that of united
oxygen. Homo-fermentative lactic acid bacteria catabolize one mole of glucose
in Emelem-Mayherh of parnas (EMP) pathway to yield two moles of private.
Intracellular redox balance is maintained through the oxidation of lactic acid.
This process yields two moles of ATP per glucose consumed. Representative
homopfermentative lactic acid bacteria include; Lactococcus, Enterococcus,
streptococcus, pedicoccus and group 1 lactobacillus.
The second fermentative pathway as described by MC
Granth et al, (2007) is the pentose phosphate pathways which are utilized by
the heterofermentative lactic acid bacteria. This pentose phosphate pathway is
alternatively referred to as the spentose phosphoketolase pathway. One mole of
glucose. 1-6- Phosphate is initially dehydroqenated to 6-phosphoglucante and
subsequently decarboxylated to yield one mole of CO2 .The resulting
pentose 5-phosphate is cleared into one mole glyceraldehydes phosphate (GAP)
and one mole acetylphbsphate. GAP is further metabolized to lactate as in
homofermentation with the acetyiphosphate reduced to elthanol via acctyl-COA
and acctaldchyde intermendiates. Theoretically, end products (including ATP)
are products in equimolar quantities from the catabolism of one mole glucose
obligate heterofermentative lactic acid bacteria during the fermentation of
African cereals are; leuconostoc, weissella and group III lactobacilli.
Therefore, during the lactic fermentation
of cereal gruels, these two important pathways described above are involved,
both the homo and heterofermentative lactic acid bacteria are usually found
present at the end of the fermentation with different species of pedicoccus
acidiolactic, lactobacillus and lactobacillus brevis. This was contrary to the
report of Iwuona and Eka (1996), who found that all bacteria isolates from the
final sour dough were homofermentative lactobacillic and pedicoccus species. Such
variations in the composition of microflora can be accounted for by differences
in incubation time and temperature, type of cereal used.
2.2 Bateriophages of Lactic Acid Bacteria
During Ogi Production
A broad number of cereals used for the
production of Ogi, manufactured industrially by large-scale bacteria
fermentation of various organic substrates. Because enormous amounts of lactic
acid bacteria are being cultivated each day in large fermentative vats, the
risk that bacteriophage, contamination rapidly brings fermentation to a half
and causes economical set back which is a serious threat in the food
industries. The relationship between bacteriophges and the lactic acid bacteria
host is very important in the context of the food fermentation industry.
Sources of phages contamination, measures to control their propagation and
dissemination, and biotechnology defense strategies developed to restrain
phages are of interest (Nicholas, 2007).
2.3 Bacteriophage
Interaction in Lactic Acid Bacteria During Ogi Production
According to Nicholas (2007), the first contact
between an infecting phage and its bacteria host is the attachment of the
phages to cell wall. This attachment is medicated by the phages receptor
binding site (BBS), which recognize and bind to• a receptor on the lactice acid
bacteria surface. RBS’S are also referred to as; host determinant and
anti-receptor. For simplicity, RBS will be used here. A variety of molecules
have been suggested to act as host receptors.
2.4 Bacteriophages Infecting Lactic Acid
Bacteria.
For bacteriophages infecting lactic acid
bacteria, among those who are polysaccharides, roles (lipo) techioe acids as
well as a single membrane protein, a number of receptor binding proteins of
lactic acid bacteria phages have been identified by generation of hybrid phages
with altered host range. These studies, however, also found additional phage
infection. Analysis of the crystal structure of several RBP’S indicated that
the these proteins share a common tertiary folding as well as supporting previous
indications of the saccharide nature of the host receptor.
The Gram-positive lactic acid bacteria have a thick
peptidolycan layer, which must be transversed in order to infect the phage
genome into the bacteria cytoplasm. Peptidoglycan degrading enzymes are
expected to facilitate this penetration and such enzymes have been found as
structural elements of number of lactic acid bacteria phages. (Nicholas et al,
2007).
2.5 Probiotics and Lactic Acid Bacteria In
The Fermentation Of Ogi
According to Tannock, G. (2005), the two
principle kinds of probiotic/prebiotic bacteria, members of the genera
lactobacillus and Bifidobacterium that had been studied in the course of the
fermentation of cereals. A more common definition of probiotics according to
Nicholas, (2007) is that, it is a live microbial feed supplement which
beneficially affects the host by improving it intestinal microbial balance. The
world ‘probiotic’ is derived from the Greek word “pro” meaning life and has
been define in many different ways, however, it designates a bacteria product from
fermented foods, which would benefit the health of the host.
Probiotics today are officially defined as; oral
probiotics which are living microorganisms which upon digestion in certain
numbers, exert health benefits beyond inherent basic nutrition. The main aspect
of definition are: The microorganisms (bacteria) which are alive, the bacteria
are administered orally, the bacteria cells should be capable of reaching the
intestine alive, in order to have an influence on the microbial balance (that
is, resistant against acid) and capable of growing under anaerobic conditions
and non-toxic.
The probiotics produced during the course of cereal
fermentations are claimed to have beneficial effects on consumers health in the
various ways produced from fermented Ogi production helps to manufacture
specific vitamins, it helps to regulates pessistalsis and regulate bowel
movement. Probiotics assist immune functions by keeping the colon at the proper
pH level and break down and rebuild hormones. His qualities and usefulness of
probiotics makes Ogi a good weaning food as it provides adequate nutrient for
infant growth and development. Such strains of lactobacillic include
lactobacillus rhamnosus, lactobacillus casei and lactobacillus us
jensenci (Nicholas, 2007).
2.6 Potential Benefits of Lactic Bacteria
Consumed in Ogi
There are numerous potential beneficiaries
of lactic acid bacteria when consumed in Ogi. The original observation of the
positive role played by certain bacteria was first introduced by Russian
scientist Noble Laureate Eli Metchikoff, who in the beginning of 20th century
suggested that it would be possible to rnodifyThe gut flora and to replace
harmful microbes by useful microbes. It was reasoned that bacteria originating
from the gut were more likely to produce the desired effect in the gut, and in
1935 certain strains of lactobacillus acidophilus were found to be very active
when implanted in the human digestive tract. Trait where carried out using this
organism, and encouraging results were obtained especially in the relief of
constipation (Elimet Chikoff, 1935).To this end, other benefits of lacticacid
bacteria includes prevention of colon cancer, lowering blood pressure,
improving infection, reducing inflammation, improving mineral absorption and
managing lactose tolerance (Wollowski et al, 2001).
2.7 Prevention of Colon Cancer
According to Wollowski et a!, (2001) some
strains of lactic acid bacteria have demonstrated anti-mutagenic effect though
to be due to their ability of bind with heterocyclic amines, which are
carcinogenic substances formed in fermented cereals. Animal studies have
demonstrated that some LAB can protect against colon concern in rodents though
human data, is limited and conflicting. Most human traits have found that the
strains tested may exert anti-carcinogenic effects by decreasing the activities
of an enzyme called B-glucorondiase (which can generate carcinogense in the
digestive system). Source: Wollowski et al
(2001).
2.8 Lowering Blood Pressure
Several small clinical traits have shown
that consumption of Ogi with various strains of LAB can result in modest
reduction in blood pressure. It is thought that this is due to the inhibitor
like peptides produced during fermentation (Wollowski et al, 2001).
2.2.0 Improving Immune Function And Preventing Infections.
Lactic acid bacteria are thought to have
several presumably beneficial effects on immune function. They may protect
against pathogens by means of competitive inhibition (that is, by competing for
growth) and there is evidence to suggest that they may improve immune function
by increasing the number of immunoglobulin producing plasma cells, increasing
of improved phagocytosis as well as increasing the proportion of T lymphocytes
and Natural killer cells. Clinical traits have demonstrated that probiotic
organisms such as lactobacillus rhamnosus and lactobacillus casei isolated from
maize may decrease the incidence of respiratory tract infections and dental
cares in children. LAB food and supplement have been shown to be effective in
the treatment and prevention of acute diarrhea, and in decreasing the severity
and duration of rotavirus infections in children and travelers diarrhea in
adults. Helicobacter pyloriclactic acid bacteria are also though to aid in the
treatment of Helicobacter pyloric infection (which causes pecic ulcers) in
adult when used in combination with standard medical treatment (Wollowsk et al,
201).
2.2.1 Reducing Inflammation
Lactic acid bacteria food supplement in
Ogi production have been found to modulate inflammatory and hyper sensitivity
responses, an observation thought to be at least in part due to the regulation
of cytosine function, clinical suggestion and detail states that they can
prevent reoccurrence of inflammatory bowel disease in adults (Wollowski et al,
2001).
2.2.2 Improving Mineral Absorption
It is hypothesized that probiatic
lactobacilli may help correct malabscorption of trace mineral found
particularly in those with diet high in phytate content form whole grains
(Wollowski et al 2001).
2.2.3 Cholesterol Lowering
Animal studies have demonstrated the
efficacy of a range of lactic acid bacteria to be able to lower serum
cholesterol level, presumably by breaking down bile in the gut thus inhibiting
its reabsorption (which enters the blood as cholesterol). Some but not all
human traits have shown that consumption of Ogi with specific lactic acid can
produce modest reductions in total cholesterol level in those with normal
levels to begin with however, traits in hyperlipidemic subjects are needed (Wollowski
et al, 2001).
2.2.4 Origin
of Maize
Maize (zee mays) is believed to have been
originated in Guatemala and southern where it was cultivated by the Indians
long before the arrival of the Columbus (Muller, 1980).
According to Lake, (1980), maize was
originally grown in the USA but it is now grown in Africa, India, Australia and
parts of Europe. However, the USA produces 70% of the world maize.
Initially, maize growing was limited to
the central areas until the 20 century where sellers introduced new varieties
before suited to inland climate from then onwards maize spread very rapidly in
part of Africa suitable for its growth particularly in Kenya, Nigeria, Malawi,
South Africa, Cameroon and it has replaced traditional starchy food stuff such
as mallet and sorghum (FAQ, 1989).
2.2 Climatic
Requirement of Maize
Maize is essentially a crop of warm
countries with adequate moisture. It thrives well in area which has a
reasonable rainfall of 60 – 100m Rainfall of 15— 20in is enough, provided it is
evenly distributed over the growing season On the other hand, it will not
thrive well in areas of excessive rainfall of 100m to 200in or more (Adebago,
1988)
Maize can be cultivated in a wide range of
environmental conditions from sea level to over 300in (FAO, 1989).
2.3
Classification of Maize
The classification based on the different
applications of maize, due to its different sites of origin and application.
They are segregated gene pools as shown below:
Waxy Corn
• Origin:
South-East Asia.
• Contains
100% amylopectin starch
• Starch is used as
stabilizer/thickener in food industries and as an adhesive in the paper
industry.
• Very
little is currently grown.
Flint and
Dent Corn
• Dent corn is softer
compared to flint. They are used as livestock feed and also make processed food
Yellow Dent
Corn (Field Corn)
• Most United
States corn crop is yellow dent
• Has high vitamin A
content, high feed value and availability of adapted superior hybrids account
for its extensive use.
• It has the highest
carotene content (vitamin A) of all cereal grains
• It
contains 75% amylopectin and 25% amylose starch.
Flint Corn
• Early
maturing maize with a hard aleurone coat.
• Has good storage
potential and resistance to insect damage due to hard coat.
• Contains
little soft starch
• It
contains earlier in temperate zones.
• It has better
germination and early plant vigour than dent corn.
Soft Corn.
• Well
adapted for starch production.
• Kernels
consist almost entirely of soft starch.
Pop or Puff
Corn
• Limited
production volume
• Produced mainly for
snacks but also has potential for packaging materials. Natural moisture inside
the kernel turns to steam when heated, the outer coat is so hard that the
moisture is trapped Steam builds up the pressure and causes the kernel to
explode
• We
produce almost all the world’s pop corn
Oil Corn
· Contains
7-8% oil, 2 mOre than dent corn.
· Also
has enhanced protein qua and quantity.
Sweet Corn
• Synthesizes low
molecular weight polymers and sugars. Contain almost 70% water
· Contain
more natural sugar than other types of corn.
· Grown
almost exclusively for human consumption (fresh or processed).
· Comes
in three colours- yellow, white and bicolour (yellow and white).
White Corn
• Appears to be
replacing some yellow corn in food applications. Preferentially used for dry
milling (cereal products). Can also be used for wet milling to produce
specialty starch products with very bright whiteness.
High Amylase
Corn
· Specialty
corn producing kernels with more than 50% amylase content.
· Starch
is used in textiles, candies and adhesives.
• Have increased levels
of two amino acids that are essential for non- ruminant diets.
• The
two amino acids are lysine and tryptophane.
Source: International
center for the improvement of maize and wheat, (2007).
2.4 Physical Composition of Maize
The maize grain is larger than those of
other cereals. It possesses a broad apex, and a narrow scutellum are contained
within a hull, comprising pericarp and tasta (lhekoronye and Ngoddy, 1985).
Figure: 1
Structure of maize grain
2.5 Chemical
Composition of Maize
The chemical composition of different
varieties of maize differ slightly (Aseidu, 1989)
TABLE
1:
Average
chemical composition of major components of typical
Nigerian
dent corn variety.
Components Weight OIL Protein Ash
9%) (%) (%) (%)
(Either) (NX5.7)
Whole corn 100.00 4.6 9.5 1.2
Endosperm 81.20 0.7 7.8 0.2
Bran 5.00 2.1 5.1 1.1
Germ 12.7 33.0 19.8 9.1
Tipcap 1.2 4.0 10.2 1.2
Source: lhekoronye and Ngoddy, (1985).
This result shows that the endosperm
constitutes above 80% of the
total kernel weight, the bran is low (5%) and the germ
is larger than the
bran (12%)
Typical analytical figures for the maize grains
Starch 65 - 84%
Protein 9-10%
Moisture 12-15%
Fat 3-5%
Fibre 2-3%
Ash 3%
Food energy 4% calories
Source: lhekoronye and Ngoddy, (1985).
2.5 Protein
Zein is the predominant protein of maize.
This prolamine-zein is found mainly in the endosperm. The total protein of
maize grain ranges from 6-15% with the germ protein ranging from 15-25% of the
total protein of maize. The germ may contribute 25-40% of the total kernel
lysine amino acid (Enwere, 1998).
2.5. 2 Oil
and Related Compounds
Maize contain 1.2% - 5.7% lipid depending
on the variety. Varieties developed particularly for high oil contents are
known to yield as much as i4% (Enwere, 1998). Fatty acids contained in maize
which have been reported by various investigators are 56%unoleic, 30% oleic,
0.7% linoleic, small quantities of stearic, palmitic and arachidic fatty acids.
Fat soluble substances such as vitamin E, phosphatide and lecithin occur in
their percentages as 0.03%, 0.3% and 0.5% respectively.
2.5.3
Minerals/Ash Content
The whole maize kernel contains about 3.5%
ash which consists of sodium, potassium, copper, calcium, phosphorus, magnesium
and others. Maize has low calcium content of less than 0.03%, 0.0005%ppm
sodium, 0.02mg iron, 3.4mg copper, 4.1mg manganese and 0.4mg zinc (Enwere, 1998).
TABLE 2: Mineral Composition of Maize
Mineral
elements Maize
Calcium (mg/100g) 6.00
Phosphorus (mg/100g) 300.00
Magnesium (mg/100g) 160.00
Potassium (mg/100g) 400.00
Sodium (mg/100g) 50.00
Chlorine (mg/100g) 70.00
Sulphur (mg/100g) 140.00
Iron (mg/I OOg) 2.50
Manganese (ppm) 6.83
Source lhekoronye and Ngoddy, 1985
2.5.4
Moisture
Maize grain contains 12-15% moisture which
accounts for it good storage stability and shelf-life (lhekoronye and Ngoddy,
1985). Relative humidity and temperature affects moisture content. At a
constant temperature the relative humidity in creases, the ability of the air
to extract water from the grain decreases.
2.5.5
Vitamins
Maize seeds contain a useful concentration of vitamin
B or thiaminand yellow maize B-carotene, a precursor of vitamin A (Enwere,
1998).
The vitamin content of maize is show in the table
below:
TABLE 3:
Average Vitamin Content of Corn
Vitamin Yellow
Corn mg/lb White Corn mg/lb
Carotene 2.20 -
Vitamin A 19.90 -
Thiamine 2.06 2.22
Riboflavin 0.60 0.61
Niacin 6 40 6
04
Panthonic actd 3.36 -
Vitamin
E 11
21 13
93
Source
lhekoronye and Ngoddy, 1985
2.5.6
Carbohydrate
According to Asiedu, (1989), the
carbohydrate and related compounds found in maize is mainly starch and
pentoglycan in the cell wall. Maize grain contains 0.1-0.3% raffinose 0.9 -1.9%
- succrose, 0.2-0.5% g(ucose 0.1-0.4% fructose and small amount of inositol and
glycerol in sound maize kernel. Maltose and other sugar may appear during
germination while raffinose disappears.
26 Utilization of Maize
Maize is used as animal feed, for human
consumption, for the manufacture of starch, syrup and sugar, industrial spirit
and whisky. The product from milled maize include maize flour, meal grits and
corn steep (Kent, 1975).
Besides the direct consumption of maize as
feed for animals and food for man, maize is utilized industrially in the
production of:
• Flour
for bakery, meals, cornflakes and golden morn
• Oil
for cooking, margarine, mayonnaise, salad dressing
• Starch for adhesives,
paper industries and beverage industries Alcohol for wines and spirits
(Guy,1987, Olatunde,1988)
• Ethanol can also be
derived from maize which is combined with gasoline to be used as fuel (Potter
and Hotchkiss 1995)
2.7 Typical Maize Foods of the Tropics
The consumption of maize in the tropics
varies from one area to the next as shown below:
2.7.1 Ogi (Maize Pap)
Ogi is a porridge prepared from fermented
maize in West Africa. It is a staple of this region and serves as a weaning
food for infants. It can be prepared both traditionally and industrially. Ogi
is often marketed as a wet cake wrapped in leaves or transparent polythene
bags. It is diluted to a solid content of 8-10% and boiled into a pap or cooked
and turned into a stiff gel called “Agidi” or “Eko” prior to consumption
(Odunfa,1985,Akinrele,1 970).
2.7.2 Koga
It is a popular camerounian food prepared
by mixing ground corn kernels, palm oil, salt and ground red pepper. The
mixture is rolled and steamed in a plantain leaf (lhekoronye and Ngoddy, 1989).
273 Kenkey
It is the principal dish made from maize
in Ghana The corn is washed, soaked, ground and made into dough and let to
stand for a day or two The dough is divided into two parts and one part is
cooked and combined with the uncooked part. It is then wrapped in dried corn
husks or plantain leaves before steaming for about two hours until ready to eat
(lhekoronye and Ngoddy, 1985).
2.7.4 Banku
It has similar process as Kenkey made by
boiling dough, then stirring and shaping but not wrapping it (lhekoronye and
Ngoddy, 1985).
2.7.5 The
Tortilla
It is for the majority of the population
of Central America and Mexico, the substitute for wheat bread. The mature corn
is prepared using an alkaline precook, called “nixtamalizado” which prepares
the corn for grinding, given a dough and made into bread or this leathery corn
cakes known as tortillas (lhekoronye and Ngoddy, 1985).
2.7.6 Taco
It is another popular food prepared from
the tortilla. It is a sandwich
made of a tortilla rolled up with a filling and
usually fried (lhekoronye and Ngoddy, 1985).
2.7.7 Tamale
It is another highly esteemed food in
central and South-America. it meat or beans enclosed in a corn pepper. It is
then wrapped in corn husk or leaf and then boiled or steamed (lhekoronye and Ngoddy,1985).
2.8
Ogi fermentation
Fermentation is the conversion of a carbohydrate such
as sugar into an acid or an alcohol, by use of yeast (Ihekoronye and Ngoddy,
1985).
Ogi is traditionally made from maize and it is
prepared by steeping clean grains in water at room temperature (25 + 20c)
for 48-72 hour (Banigo and Muller, 1972; Akingbala et al, (1981). The steep water is decanted and the fermented grain
is washed with clean water and then wet-milled the bran is removed by wet
sieving and the sievate is allowed to settle for 24-48 hours, a process
referred to as souring during which
fermentation also proceeds and the solid starchy matter, Ogi sediments
(AKinele, 1970; Akingbala et al, 1981).
The physical and biochemical qualities of
ogi are influenced by the type of cereal grain, fermentation or souring periods
and the milling method (Banigo and Muller 1972; Da et a!, 1982; Hounhouigan et
a!, 1993).
Periods
of fermentation or souring had been found to scientifically affect titrable
acidity of Ogi, which increases with periods of fermentation (Adeyemi and
Beckley, 1986; Osungbaro, 1990).
2.9 Improved Technology for Ogi
Production
Attempts have been made to modify the traditional
methods of fermenting cerea’ grains for Ogi manufacture. Such attempts involves
inoculating dry milled cereal grains with starter cultures of micro organisms.
Ogi had been successfully prepared using dry milled sorghum and maize flours
(Umoh and Fields, 1981; Adeyemi, 1983; Osungbaro,
dry
milling was considered more convenient than wet milling the flour could be
dispensed and packaged to consumers
subsequent
steeping and fermentation.
Diagram for Dry Milling of Corn
Kernels
¯
Condition to 21% moisture
¯
Decorticate :To
loosen hulls and germs from
Endosperm
¯
Dry mixture to 15% moisture
¯
Aspirate to remove hulls
¯
Endosperms and germs
¯
Pass thr rollers : To flatten germs and crush
endosperm.
¯
Sieve to remove germs
¯
Coarse grits or porn meal
¯
Grinding
¯
Cornflour
Source:
lhekoronye and Ngoddy, (1985).
Ogi fermented traditionally has been
observed to have shelf-life of 40 days (Ohenhen and lkenebomeh, 2007). In an
attempt to prolong the Shelf-life of Ogi, they modified the fermentation method
of Ogi preparation by steeping maize grains in previous steep water with an inoculums
load of 2,60 x 106 cfu/mI for 72 hour at 28 + 2°c and grains were we milled and
wet [ The result of the investigation showed that the shelf-life of Inoculated
fermented Ogi has well over 60 days compared with the shelf-life of 40 days for
uninoculated fermented Ogi.
Large-scale industrial production of Ogi involves
sophisticated : including drum drying, spray drying and extrusion cooking FAO,
1997).
Flow Chart of Ogi Production
Corn
¯
Steep for 2-3 days
¯
Wet mill
¯
sieve and discard pomace
¯
ferment filtrate and allow to sediment for 1-3 days
¯
Ogi
Figure 1: Source: FAO, (1997)
The physical and biochemical
qualities of Ogi are influenced by the type of cereal grain, fermentation or
souring periods and the milling method (Banigo and Muller 1972; Da et al. 1982; Hounhouigan et al, 1993).
Periods of fermentation of souring
had been found to scientifically affect titrable acidity of Ogi, which
increases with periods of fermentation (Adeyemi and Beckley, 1986; Osungbaro,
1990).
2.10 Microbiological
Study of Ogi
Fermentation studies on cereal grains revealed
important micro organism in Ogi production. Those isolated and identified
include: Moulds like Fusarium, Aspergillums and pen/c/hum surface micro flora
of fermenting maize include cephalosporium sp, 0’ Ospora sp, cercospora sp, all
which are eliminated within 6 hours of steeping (Ohenhen,2002). Aerobic
bacteria isolated include Corynebacterium sp, Aerobacter and lactic acid
bacteria (Fields, .1981 ;:Akinerele, 1980; Banigo,1 972).
The yeasts implicated in the fermentation are Candida
Mycoderma, Saceharomyces Cerevisac and Rhodotorula (Andah and Muller, 1973;
Fields et a!, 1981).
Major fermentation products include lactic, acetic,
and butyric acids. All contributing to the flavour of Ogi. Odunfa (1985)
determined that L. planetarium was predominant organism in fermentation
responsible for tactic acid production. Coiynebacterium ghdroiysed maize starch
to
:Organic acids while S. cerevisae and C. Mycoderma
contributed to flavour development.
2.11
Nutritional Properties of Ogi
A lot of nutrient losses occur during
processing of maize for Ogi. These loses include fibre, protein, calcium, iron,
phosphorous and vitamins uch as thiamin, riboflavin niacin folic and pathogenic
acids (Adeniji and porter, 1978). According to Lagunna and Carpenter (1951),
considerable nutrient losses like place during steeping, milling and sieving.
These losses are inevitable because much of the protein in cereal grains is
located in the testa and germ, which are usually sifted off during processing
(Oke, 1967; Banigo et a!, 1974; Chavan and Kadam, 1989).
Reductions in net protein utilization and efficiency
ratio and biological values have also been reported during Ogi processing
(Akobundu and Hoskins, 1982). Discarding steeping water over fails and Ogi wash
water head to serious losses in minerals and other nutrients F Muller, 1980). A
minimal use of water in wet sieving is recommended to rninimize losses of
soluble nutrients during Ogi preparation (Amoa and Muller, 1976).
The amount of nutrient losses depend on the exact
method of Ogi J preparation. The traditional process has been shown to result
in lower means protein and fat with a higher mean starch content when compared
with Ogi product obtained by experimental milling (Akingbala et a!, 1981). Also
dehydration of Ogi by drum or tray drying has been found to prolong its shelf
life, but the method has been found to destroy heat sensitive nutrients in Ogi
(Labuza, 1972). Adeniji and Potter, (1978) reported appreciabie loss in the
valuable lysine content of drum dried Ogi.
2. 12
Improvement of Ogi as Food
The major drawback to the use of Ogi as a staple food
is its low nutritional value. It is of great importance that Ogi is improved
because it serves as a weaning food for infants in West Africa, which will
affect their growth rate and as food for adults, which might cause a particular
nutrient deficiency.
Several attempts have been made to improve
the nutritional status of Ogi, by fortifying it with protein rich substrates
(Anon, 1970; Banigo, 1972; Bamiro et al, 1994; Osungbaro et al, 2000). A
protein enriched Ogi containing 10% Soya flour was developed by the Federal
Institute of Industrial Research Organization (FIIRO) Lagos, Nigeria (Akinrele,
1970). The utilization of high lysine maize for the manufacture of Ogi using
improved processing system had also been attempted (Bango et al, 1974; Adeniji
and Potter, 1978). The development of an Ogi (dogit), having the therapeutic
properties on the basis of its ability to control diarrhea among , infants has
been reported (Olukoya et al, 1994).
In an attempt to improve the nutritive composition
and sensory. of Ogi, Aminigo and Akingbala, (2004) fortified maize Ogi with
okra seed meal. Okra seed fortification at 20% level using defatted and meals
increased crude protein content by 122 and 106% respectively. They were also
able to raise ash content by 2-5 folds and fat was increased by 1.5-2.2%. Also
working on fortification of Ogi with okra seed flour, Otunola et al (2007) were
able to achieve substantial increases in the levels of protein in maize Ogi
samples obtaining up to 100% increment.
Microbiological and nutritional studies
show how organisms responsible for fermentation of Ogi could be majority
responsible for its: nutritional improvement. Working on Ogi fermentation,
Odunfa et al (1994),
utilized mutants as starter culture resulting in a
three fold increase in the lysine content of Ogi Fifty mutants from L plantarum
and seven mutants from a yeast strain were selected from thialysine-resistant
cultures capable of over producing lysine After analysis for lysine production,
a 12-fold increase in lysine production was observed for L plantarurn and 3 -4
fold increase for yeasts was observed.
Heating Ogi over a period of time impacts
greatly on its physical techs as the cooked maize starch gels to solid state on
cooling. Cooking of white maize Ogi at concentration of about 1 5% total solid
for 15 minutes, followed by cooling produces a stiff gel, agidi (Osungbaro,
1990). Agidi is used as weaning solid food and staple break fast cereal for
people
In West Africa The nutritive quality of
Agidi will definitely be a reflection of the themtcal composition of Ogi the
base material The presence of other non-I starch component like fat, protein
and crude fibre reduces the tendency of starch to form gels (Muller, 1980)
2.13
Physical Properties of Ogi
Textural quality of Ogi porridges depend
on many factors which include the type of cereal grains, variety, milling
technique, particle sizes, steeping and fermentation periods (Amon and Muller,
1976; Klaus and Hinz, 1976; Adeyemi, 1983; Adeyemi and Beckley, 1986;
Osungbaro, 1990). Working on maize for Ogi fermentation, Osungbaro, (1990)
found that varieties of maize exhibit different pasting viscosities. This trend
was attributed to the fact that maize varieties were found to contain varying
amount of amylase ranging from 29 — 34% (Adeyemi and Beckley, 1986).
Particle size distribution has been found
to influence rheology, heat and mass transfer, mixing and consistency of starch
pastes in cereal porridges (Kruger and Murray, 1976). Penetrometer and adhesion
tests had been used to evaluate textural qualities of Ogi porridges (Da et al,
1981; Cagampang et al, 1982).
The swelling characteristics (thickening)
of Ogi have been found to be influenced by fermentation period. Banigo et al,
(1974) have o an increase in swelling characteristics of maize flour, It was
also established that two-day fermentation of maize is best for Ogi manufacture
in farms of pasting viscosities and consistencies. Fermentation beyond four
days was found to result in Ogi porridge exhibiting poor stability, gelling
tendency and consistency (Osungbaro, 1998).
Fortifying Ogi with protein rich food has
also been found to influence Its rheolagical properties (Edema et al, 2007).
Addition of okra seed flour to maize Ogi samples indicated a reduction in
amylograph starch stability values (Otunola et al, 2006). However, Ogi
supplemented with roasted okra seed meal had higher viscosities during heating
and cooling cycles samples fortified with the defatted meals. Also Ogi
fortified with okra seed meals had lower sensory texture ratings (Aminigo and
Akingbala, 2004). Lowering the viscosities in the process of fortification of
fermented cereal foods has implications on the consistency of the gruels
prepared.
Agidi, the stiff gel prepared from Ogi is
traditionally eaten with fingers, and so the main quality for acceptance by the
consumer is related to its physical (textural) properties. These textural
characteristics have been mostly evaluated by subjective methods (Umoh and
Fields, 1981, Osungbaro, 1998). These workers showed that agidi samples
produced from wet-milled Ogi (pH 5.3) were of firmer texture than those
produced from dry-milled unfermented maize flour (pH 6.7). fermentation
therefore plays a prominent role in textural qualities of agidi which is made
from fermented maize-Ogi.
CHAPTER
THREE
MATERIALS AND METHODS
3.1 Source
of Raw materials
The maize use for this work shall be
purchase from main market in Abakaliki, Ebonyi State.
3.2 Preparation
of Samples
The maize grain sample shall be
destone, clean, and weigh. Afterward, shall be divide into two equal parts,
sample A and sample B respectively. Each portion shall be steep in portable
water for 24hrs respectively. After steep time, the steep samples shall be mill
into paste.
Sample
A, after wet-milling, sieving, homogenizing, filtering with a membrane, I shall
inoculate my with a chemical (sulphur dioxide/propionate), which acts as an
inhibitor against the activities of others microorganism. Thereafter, I shall
inoculate my starter culture (L.plantarum, L. Lactis, schizos accharomyces
rouxii) into the filtrate and allow it to stand for 24hrs, and after ward, I
shall decant and have my product, Ogi.
While for sample B (my control)
after wet-milling, sieving, homogenizing, I shall filter using a membrane and
collect my filtrate. After collecting the filtrate, I shall allow it stands for
24hrs. thereafter, I shall decant and have my final product, Ogi.
Maize Kernels
¯
Destining
¯
Cleaning
¯
Weighing
¯
steeping (for 24 hrs)
¯
Milling
¯
Sieving
¯
Homogenizing
¯
Filtering
¯
Introduce chemical (sulplur dioxide/propionate)
¯
inoculants
¯
Decanting
¯
Ogi
Fig 1: Flow chart for ‘industrial’ production of Ogi.
¯
Maize Kernels
¯
Destining
¯
Cleaning
¯
Weighing
¯
steeping (for 24 hrs)
¯
Milling
¯
Homogenizing
¯
sieving
¯
Filtering
¯
Ogi
Fig 2: The control flow chart (for local processing method)
3.3 Analysis
of the Sample
The different samples obtained shall
be subjected to analysis. The wet Ogi samples shall be subjected to sensory and
chemical analysis.
3.3 Chemical
Analysis
3.3.1 Mineral
Element Analysis
3.3.2 Calcium
and Magnesium Determination
Extraction by the wet-acid digestion
for multiple nutrient determination may be used (Onwuka, 2005).
About 0.2g of the processed sample
material shall be weigh into a 150ml pyren conical flask. About 50 ml of the
extraction mixture (H2So-selenium-salicyclic acid) shall
be add to the sample and allowed to stand for 16 hours.
The sample mixture may be place on a
hot plate on a hot plate set at 300c and allow to heat for about 2
hours. About 5.0ml of concentrated perchloric acid shall be introduce to the
sample and heat vigorously until the sample dipeate into a clear solution.
About 20ml of distilled calcium and magnesium shall be determined. About 10ml
of the digest shall be pipette out into a conical flask. Then a pinch of
potassium cyanide (KCN) and potassium ferro-cyanide shall add to the digest to
mark the in termination.
Calcium and magnesium forms complex
compounds at a pH of 10.00 hence, NH4 buffer solution (10ml) may be
add to raise the pH of the system to ten, with solochrome black 1 indicator.
The system shall be titrate with 0.02N EDTA to get a greenish end point form
original colour.
Calcium shall or may be determine
alone by using ten percent sodium hydroxide, water may be add and mix thorough
for about a minute. The digest shall be allow to cool and transfer into a 50ml
volumetric flask and numbered up to the
mark with distilled water.
The digest shall be use for the
determination of calcium and magnesium by EDTa vassonate comlexometry titration
method. The heavy metals zinc used as buffer to raise the pH to twelve at which
EDTA form complex with calcium alone using solochrome dark-blue indicator. A
blank determination shall be carry out and titrate with 0.02N EDTA reagent.
3.3.3 Determination
of Potassium and sodium Using Flame Photometer
About 5ml of the sample digest may
be pipette into a 50ml volumetric flask and dilute to 50ml with distilled
water. A set of potassium (k) and sodium (Na) may be prepare containing Oppm,
2ppm, 4ppm, 8ppm and 10ppm, of the element in the solution. The flame
photometer shall place on and the scale calibrator with 6ppm adjust to 60. the
standard solutions shall be test and their values recorded.
The appropriate filter (Photocel)
may be select for each element. The atomizer of the instrument shall be dip
into the sample solution and the meter reading taken. The values obtain form
the standards shall be use to plot the calibration curve for each test elements
and the concentrations of the sample element determine by estrapulating form
the graph as ppm off curve.
3.3.4 Determination
of Trace Metel
The trace metals (heavy element):
Zine, copper and lodine shall be determine. Using the atomic analysiger method.
Atomic absorption spectrometer 969 instrument. The appropriate cathode lamp
shall be fixe for each element and the sample is introduce to the atomizer and
the value core of the element shall be print as mgx/litre. The actual
concentrations shall be converted after the standization of the instrument and
the sample.
3.3.5 Iron
Determination by Atomic Absorption
Spectrophotometer
From the multiple-nutrient digest,
the iron (fe0 content of the samples shall be determine using the spectro 92 uv
atomic absorption spectrophotometer. The iron cathode lamp shall be select and
the equipment shall be power by an automatic ignition process. The sample shall
be place in place and the atomizer dip into the sample. The optical digest
taken and convert to a correct concentration values, then print out with the
computer machine.
3.3.6 Determination
of ascorbic Acid by AOAC (1990) Cuso4 Titration
About 10g of the sample may be
weighed with an extraction tube and mixed with 100ml of the extraction solution
(metaphosphoric acid-acetic acid solution and shake for 30 minutes in a
mechanical shaker. The sample shall be pilfere through a W2 Whitman
filter paper into 100ml volumetric flask and make up to mark with the
extracter.
About 20ml of the extract shall be
titrate with 0.02N CUSO4 solution using 10Ml of potassium 10dide and
starch as indicator A blank sample shall be carry out using the extracting solution and the
indicator. The values of the samples shall be subtracted form the blank for
calculation.
3.3.7 Determination of Vitamin using Sepectrophotometer
Described in AOAC, (1990)
About 5g of the sample may be
homogenized with 100ml of diethyl ether for 10 minutes in a shaker and filter
another 100ml of 95% ethanol may be add to the residue and shake for 30 minutes
and filter. The two extra shall be mix together and transfer into a separating
funnel, distilled water shall be added gradually form the walls of the funnel
until a separation phase occur the aqueous layer shall be run into a 25cm3
beaker and the yellowish layers shall be recorded and its absorbance measured a
452nm wavelength in the spectrophotometer. The blank reading shall also be
taken.
3.3.8 Determination
of Riboflavin
Five gramme of the sample may be
weighed into a pyren beaker, 50ml of O.IN HCl shall be add and heat over a hot
plate to boil for about one hour. The sample shall allow to cool and filter
through a number I Whitman filter paper into fifty ml volumetric flask and make
up to the mark.
About 5ml of the extract shall
pipette into a 50ml flask. 10.ml of glacial acetic acid shall add then lml of
3% KMn04 and IN of 1% H202 and makes up to
mark will distilled water.
The colour shall be allow to develop
and the absorbance reading taken at 479 nm wavelength. The value obtain shall
read off the standard curve for calculation.
3.3.9 Determination
of Thiamin
The method described by Onwuka,
(2005) shall be use five gramme of the sample shall be weigh into 250ml conical
flask and boil for 30 minutes. The sample shall be allow to stand overnight and
filter with into a 50ml volumetric flask. This shall be transfer into a flask
extraction tube and the following regents shall be added 5ml acidic kcl, 3ml of
potassium ferrocyanide solution and 5ml of isobutanol and shake for 5 minutes
in mechanical shaker.
About 5ml of the extract flask. 50ml
of 10% NaOH shall be add and makes up to measurement. The absorbance shall be
measure in a spectrophotometer at 450nm wavelength.
3.3.10 Determination
of Niacin
The method described by Onwuka,
(2005) shall be use. About 5g of the sample shall be extract with a solution of
potassium bromide (10%) in a 50ml extraction tube and filter into 50ml
volumetric flask and make up to mark with extracting solution. Ten ml extract
shall be pipette into a 50ml volumetric
flask 10ml of 10% NaOH and 5ml potassium cyganide and makes up to mark and read
at 470nm wavelength.
3.3
Proximate chemical Analysis
3.4.1
Protein Determination AOAC, (1990)
This shall be done using kjeldahl method. About 5g of
the sample shall be transfer into a micro digestion flask and 8g to mixed Naso4/Cuso4
catalyst will be added. 25ml of concentrated H2SO4
shall also be added and the flask shall
be heat up on a Bunsen burner in a fume cupboard for I hour to obtain a clear
mixture, then cooled. 400ml of ammonia free water shall be added to the cleared
mixture while 50ml of 2% boric acid plus 1 ml screen methl red indicator shall
be add in the receiving flask. This digestion makes alkaline by addition of
75ml of 50% NaoH and the distillate shall be collected. The distillate will
titrate with NiOHSO4 and recorded.
The
principal of this test is:
2NH4BO3
+ H2SO4 →(NH4)2SO4+2H2BO3.
When
I
mole H2SO4 = 2moles N = 28g N OR
I
mole HCL = I mole N = 14g
N.
I
ml 0.1 NH2SO4 =
0.0028g N
I
ml 0.1. M Hcl = 0.0014g N
3.4.3 Ash Determination
The percentage ash shall be
determine by the method described by the National Science and Technology Forum,
(2004).
Five gramme of the sample shall be
weigh into a clean, dried crucible which was previously weighted. The crucible
shall be transfer into a furnace at 550C for 2 hours until a white
grey or light gray ash result s. then cool in a desiccators and weight.
3.4.5 Fat
Determination
The fat content of the sample shall
be determine using soxhlet extraction method as described by Onwuka, (2005).
About 2g of the sample shall be
weigh into a thimble in a soxhlet extractor; 300ml of petroleum ether shall be
measured into the weighted round bottom flask. The apparatus shall be set-up
and shall allowed to reflux for about 6 hours. The solvent shall be distilled
off and the fat extract dry at 1050c for I hour in an oven, cooled
in a desiccators and weight.
3.5 Sensory
Analysis
The sensory analysis shall be
determined by the method described by Onwuka, (2005). Sensory evaluation of wet
Ogi produced from sample A and Sample B shall be carryout by ten semi-trained
panelists for taste, flavour, texture, colour, gelation and general acceptance.
Scoring shall be done with a nine point hedonic scale, where 1 represents
“Dislike”, 5 represent “Neither like nor dislike” and 9 represented like
extremely.
3.5.1 COLOUR
ATTRIBUTE
The colour of the two samples of Ogi
from different method of processing shall be examine using the sight. Each
panelist shall report base on their judgments on each of the Ogi products
depending on how appealing the product seems to them.
3.5.2 TASTE
ATTRIBUTE
The taste attribute shall be examine
by each of the panelist with the aid of the taste bud. Each of the Ogi sample
shall be score base on their natural taste.
3.5.3 FLAVOUR
ATTRIBUTE
The panelists shall base their
description on the flavour and aroma of the Ogi prepare by both methods. The
perceptible factor the intensity of each factor, the oder in which the factors
were perceived, aftertaste, and over al impression of the penalist shall be
score base on their judgment of each of the products.
3.5.4 CONSISTENCY
ATTRIBUTE
The Ogi porridge shall be examine of
their consistency quality shall be score bas eon the panelists judgment.
3.5.5 GENERAL
ACCEPTABILITY
The test shall be carryout to
Judgment choice of the consumers for each of the Ogi made from both methods
(Local and Industrial methods).
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