CHAPTER ONE
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.
Objectives
i. To produce Ogi using locally and industrially
method.
ii. To
determine mineral content of produced Ogi by both method (locally and
industrial)
iii. To evaluate the sensory properties of
Ogi.
CHAPTER TWO
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.
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.
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).
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.
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).
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.
11
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).
POTENTIAL BENEFITS OF LACT4 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).
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).
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).
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).
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).
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).
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).
2.1 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).
Figure 1
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
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 a!, 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 a!, 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 a!, 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 a! (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% totdl 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 a!, 1981; Cagampang eta!, 1982).
The swelling characteristics (thickening) of Ogi have
been found to be influenced by fermentation period. Banigo et a!, (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 a!, 2007). Addition of
okra seed flour to maize Ogi samples indicated a reduction in amylograph starch
stability values (Otunola et at, 2006). However, Ogi supplemented with roasted
okra seed meal had higher viscosities during heating and cooling cycles
p
than 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
destine, clean, and weigh. Afterward, shall be divide into two equal parts,
sample A and sample B respectively. Each portion shall 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
incorporate with a chemical (sulphur dioxide/propionate), which acts as an
inhibitor against the activities of the microorganism. Thereafter, I shall
microorganisms. 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 2: Flow chart for ‘Control’ production of Ogi.
Maize Kernels
¯
Destining
¯
Cleaning
¯
Weighing
¯
steeping (for 24 hrs)
¯
Milling
¯
Homogenizing
¯
sieving
¯
Filtering
¯
Introduce chemical (sulplur dioxide/propionate)
3.3 Analysis
of the Sample
The different samples obtained shall
be subjected to analysis. The wet Ogi samples shall subjected to sensory and
physio chemical analysis.
3.3.1 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.
3.3.2 Mineral
Element Analysis
3.3.3 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.
3.3.4 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.
3.3.5 Determination
of Trace Metel
The trace metals (heavy element):
Zine, copper and lodine shall 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.
3.3.6 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.
3.3.11 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.
3.4
Proximate chemical
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.