POTENTIALS OF Piper guineence (Schum and Thom) AND Mondora myristica (Gaertn) FOR THE PROTECTION OF STORED MAIZE (Zea mays) AGAINST Sitophilus Zeamais

Undamaged and uninfested maize grains were hand picked, packaged in moisture proof package and disinfested in the deep freezer for 96 hours. Thirty six sets (500g per set) of disinfested maize were weighed into prepared containers. Each set of maize was infested with 200 live maize weevils (Sitophilus zeamais). The weevils were reared on whole maize at room temperature inside a plastic bucket covered with muslin cloth. Graded levels (0 to 10%) of coarsely ground spices Monodora myristica and Piper guineense were introduced into the infested maize samples. The content was mixed and covered with cotton material held in place with rubber bands. Contents were stored for a period of one month. Protein content of the stored samples was monitored weekly. Results show that significant differences (P<0.05) existed between samples. After storage treated samples were analysed for the effect of the spices on seed viability and extent of damage done by the weevils. Results show that Piper guineense offered more protection to the maize grains than Monodora myristica. Significant differences (P<0.05) existed amongst the spice treated samples and the control. Effect of the spice treatment on the acceptability of the products made from the spice treated maize was assessed subjectively using two products namely fermented maize gruel, pap (akamu) and toasted corn. Products were scored for colour, taste, flavour and general acceptability by a 20 member untrained panel, using a 5 - point hedonic scale, where 5 represents the most desirable attribute (very desirable) and 1 represents the least desirable attribute (very undesirable). The result of sensory evaluation revealed that treatment did not affect the colour of the products, since there were no significant differences in colour (P>0.05) between samples. There were significant differences (P<0.05) in flavour, taste and general acceptability. The control and the sample treated with 2% concentrations of Monodora myristica received the highest panel scores on taste, flavour and general acceptability.

Title page
Table of content
List of Tables
List of Figures

1.1       Cereals
1.2       General Objective
1.3       Specific Objectives
1.4       Justification for the Study

2.1       World Maize Production
2.2       Maize and the Developing World
2.3       Maize Storage
2.4       Chemical Composition
2.4.1    Carbohydrate
2.4.2    Protein
2.4.3 Lipids and Related Compounds
2.4.4    Minerals
2.4.5    Vitamins
2.4.6    Pigments
2.5       Uses of Maize
2.6       Post harvest Losses in Maize
2.7       The Maize Weevil
2.7.1    Ecology
2.7.2    Damage
2.7.3 Life History
2.8       Harmful Effects of Synthetic Pesticides
2.9       Higher Plant Products as Alternatives to Synthetic Pesticides
2.9.1    Monodora myristica
2.9.2    Piper guineense

3.1       Materials
3.2       Preparation of Samples
3.3       Culturing of Weevil
3.4       Preparation of Spices
3.5       Storage of Maize
3.6       Proximate Analysis
3.6.1    Determination of Moisture Content
3.6.2    Determination of Ash Content
3.6.3    Determination of Crude Protein
3.6.4    Fat Determination
3.6.5    Crude Fibre Determination
3.7       Damage Assessment
3.8       Seed Viability
3.9       Production of Maize Products
3.9.1    Production of Fermented Maize Product
3.9.2    Toasted Corn Production
3.10 Sensory Evaluation
3.11 Statistical Analysis

4.1       Proximate Composition of Untreated Maize sample before Storage
4.2       Effect of Spice Treatment and Storage Time on Protein Content of Maize
4.2.1  Effect of Concentration of Monodora myristica and Storage
            Time on Protein content of maize
4.2.2  Effect of Concentration of Piper guineense and Storage time on Protein
            Content of Maize
4.3       Effect of Spice Treatment on Seed Viability after Storage
4.4       Effect of Spice Treatment on Damage of Maize by Weevil during Storage
4.5       Sensory Quality of Products from Spice Treated stored Maize
4.5.1    Sensory scores of Pap Produced from spice Treated stored
            Maize Sample
4.5.2    Sensory Scores of Toasted Corn Produced from Spice Treated
            Stored Maize Samples

5.1       Conclusion
5.2       Recommendation

1.1         Cereals
Cereals are monocotyledons belonging to various tribes of the grass family and they constitute various crops which serve as industrial raw materials and staple foods the world over. World cultivated cereals include wheat, maize, rice, barley, oat, rye sorghum, millet, among others. Some of the important characteristics of cereals include the following, high carbohydrate, low fat, and a fair content of protein. The functionality of these components in the different cereals determines, to a large extent, their uses as food and industrial raw materials. (Enwere, 1998).

Structurally, there are a few important features that cereals have in common and these form the basis for subsequent milling and processing operations. All cereals are plant seeds and as such contain a large centrally located starchy endosperm which is also rich in protein, a protective outer coat consisting of two or three layers of fibrous tissue, and an embryo or germ usually located near the bottom of the seed (Ihekoronye and Ngoddy, 1985).

Cereals have an easy-to-preserve advantage over other plant crops, in their being able to dry to a safe moisture level naturally in the field. In humid environments, cereals can be dried by artificial means. For the safe storage of cereal, the following conditions need to be implemented.

(1)   Grains must be dried to an appropriate moisture content within a reasonable period for safe storage.

(2)   Grains, once dried to a safe moisture level must be protected from excessive moisture generation and uptake.
(3)   Grains for storage must be made free of insect pests by pre-storage chemical or physical treatment followed by insect proofing to suppress insect proliferation or attack (Okaka 2005).

Cereals are generally referred to as grains due to their granular nature.

Maize (Zea mays) originated in the Western hemisphere, but is now cultivated in many parts of Africa, North, South, and Central America, Europe and Asia (Matz 1969, Obi 1991). According to Purseglove (1992) there are different varieties of maize examples include pod corn, popcorn, flour or soft maize, sweet corn or sweet maize, waxy maize, flint maize and dent maize. The last two are also known as field corn or maize..

Spices have been defined by the Food and Drug Administration as aromatic vegetable substances used for the seasoning of food, and from them, no portion of any volatile oil or other flavouring portion has been removed, and are free from artificial colouring matter, adulterants and impurities. (Enwere,1998).

Spices add flavour to foods. They consist of rhizomes, barks, leaves, roots, flowers, fruits, seeds and other parts of a plant (Parry, 1969). Most are fragrant, aromatic and pungent. The flavouring agent in spices constitute only a small fraction of the dry matter. The bulk of the materials consists of carbohydrates, such as cellulose, starch, sugars, pentosans and mucilages. Spices also contain proteins, tannins, resins, pigments, mineral matter, volatile oils, terpenes, alcohols, sesquiterpenoids, esters, aldehydes, ketones, phenols, ethers among others. These and other compounds vary in different spices and flavouring agents (Enwere, 1998).

Published research on the use of plant materials, extracts and oils for the control of stored products pests show that over the past 12 years, a large number of plant species from a wide range of families have been evaluated. Jacobson, (1989), suggested that the most promising....

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