PHYSICAL PROPERTIES OF OGI PROCESSED BY INDUSTRIAL METHOD

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 (H₂S_o-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+2H₂BO_3.

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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