ABSTRACT

Seeds of Azadirachta indica were collected and subjected to different extraction methods to obtain neem oil. The study aimed to investigate the production and nutritional composition of neem oil extracted from raw neem seeds and to evaluate the influence of the extraction methods on the acid, saponification, and peroxide values of the resulting oils, particularly regarding their potential application in biodiesel production. Five oil extracts were obtained: the ethanol fraction of the cold ethanolic extract, the hexane fraction of the cold ethanolic extract, mechanically pressed neem oil, pressed neem oil treated with petroleum ether and ethanol, and the petroleum ether fraction of the hot ethanolic extract. The extracted oils were analyzed to establish their respective acid, saponification, and peroxide values.

The hexane fraction of the cold ethanolic extract exhibited the highest acid value of 74.56 for a sample weighing 0.514 g. This was followed by the petroleum ether fraction obtained through hot ethanol extraction, which had an acid value of 60.18. The lowest acid values were recorded for pressed neem oil, the ethanol fraction of the cold ethanolic extract, and pressed neem oil treated with petroleum ether and ethanol, with values of 16.03, 7.66, and 3.23, respectively.

The saponification values ranged from 176.8 to 203.5, with sample masses between 1.404 and 1.427 g. The pressed neem oil treated with petroleum ether and ethanol produced a saponification value of 203.5, which fell within the range reported in the literature. Conversely, the hexane fraction of the cold ethanolic extract recorded the lowest saponification value of 176.8. The peroxide values obtained for the analyzed oil samples were 0.64 for the ethanol fraction of the cold ethanolic extract, 0.63 for the pressed neem oil, and 0.21 for the pressed neem oil treated with petroleum ether and ethanol. No visible blue coloration appeared after the addition of starch indicator during the analysis of the hexane fraction of the cold ethanolic extract; consequently, its peroxide value could not be determined. The findings from the acid, saponification, and peroxide value analyses indicate that a non-polar solvent used under cold extraction conditions may be suitable for extracting neem oil for potential biodiesel production.

CHAPTER ONE

INTRODUCTION

1.0 Plant Description

Throughout history, humans have relied on different parts of plants for treating illnesses, healing wounds, controlling insects, and eliminating other harmful organisms. Various plant species provide materials for food, timber, and traditional medicinal applications. Among these plants is neem (Azadirachta indica), a tropical tree regarded as a valuable natural resource and an important component of traditional African healing practices.

Neem contains biologically active compounds known as phytochemicals. These organic substances are present in mature cells within different plant structures, including the roots, stems, leaves, flowers, fruits, and seeds. Phytochemicals serve as part of the plant's natural defence mechanisms and contribute to its aroma, colour, and flavour. They are also associated with several biological activities, including deterring insects from feeding, disrupting insect growth, killing insects, and controlling nematodes, fungi, and bacteria.

Among the phytochemical substances relevant to this study are limonoids and oils, which are predominantly present in neem seeds. The botanical name of the neem tree is Azadirachta indica. It belongs to the family Meliaceae, commonly known as the mahogany family. The term indica refers to the tree's association with India. Although the botanical name has been adapted into Latin, its components are derived from Persian, or Farsi, terminology:

• Azad means free.

• Dirakht means tree.

• i-Hind means of Indian origin.

Consequently, the name is interpreted as “The Free Tree of India.”

Botanical name: Azadirachta indica

Family: Meliaceae, the mahogany family.

Common names: Neem, nim tree, Indian lilac, nimba, holy tree, and sacred gift of nature.

Local names: Neem, dedua gyeene and dedua kankan in Akan, nym in Ewé, and dogoyaro in Hausa.

The neem tree possesses a straight trunk and can grow to a height of approximately 30 metres or more, although its average height is usually between 15 and 20 metres. It is well known for its ability to withstand drought. Neem is generally evergreen, but during periods of severe water scarcity, it may shed most or almost all of its leaves. The tree produces white, fragrant flowers, while its smooth fruits vary in shape from elongated oval forms to nearly spherical ones.

The fruit has a thin outer skin surrounding a yellowish-white, bitter-sweet mesocarp that is highly fibrous. Inside the fruit is a hard, white endocarp enclosing one, and occasionally two or three, elongated seeds or kernels covered by a brown seed coat.

Habitat: Neem grows in a wide variety of soil conditions but develops most successfully in deep, well-drained, sandy soils. It is widely distributed throughout tropical and subtropical regions, including India, Burma, and Nigeria.

1.0.1 Uses

Various parts of the neem tree are used for medicinal purposes in the regions where the plant grows. The roots, seeds, bark, and leaves contain compounds that have been associated with several medicinal and biological properties, including emmenagogue, fever-reducing, antiseptic, antidiabetic, anthelmintic, analgesic, contraceptive, in vitro spermicidal, lice-killing, antiviral, antipyretic, anti-inflammatory, anti-ulcer, and antifungal activities.

In India, neem leaves are dried and placed inside cupboards to protect clothing from insect damage. The leaves may also be boiled to prepare a decoction that is traditionally consumed for managing malaria and high fever.

In tropical regions, dried neem leaves are burned to repel mosquitoes. The young shoots and flowers of the neem tree are also consumed as vegetables in India. In addition, neem leaves have traditionally been used in treating certain skin conditions, including eczema and psoriasis.

Neem seeds can be ground into powder, soaked in water overnight, and sprayed on agricultural crops to control insect pests. The resulting preparation acts as a feeding deterrent and repellent and discourages insects from laying eggs on treated plants. These effects can reduce crop damage, deprive insects of food, and eventually cause their death within a few days. Neem preparations can also inhibit the hatching of insect eggs. Furthermore, powdered neem seed mixed with honey has been reported as a traditional preparation for promoting hair growth.

In India, Africa, and the Middle East, thin neem twigs are traditionally chewed and used as natural toothbrushes, after which the split ends may serve as tongue cleaners. Neem oil is also used in soap production in India. Neem cake, the residue remaining after oil extraction, is widely applied as fertilizer for commercial crops, particularly sugarcane and vegetables, and has also been used as animal feed.

Despite its numerous applications, neem can have adverse effects. It may cause miscarriage, infertility, and reduced blood sugar levels. Neem oil has potential applications as a biofuel. However, neem oil and other neem products, including neem leaves and neem tea, should not be consumed by pregnant women, women attempting to conceive, or children. Although short-term use of certain neem preparations in adults may be tolerated, prolonged exposure can potentially damage the kidneys or liver, particularly in young children. Neem oil is toxic when ingested, and its consumption can result in death.

The United Nations Organization has described the neem tree as the “Tree of the 21st Century.” Similarly, a report published by the United States National Academy of Sciences in 1992 recognized the tree's potential in addressing global problems.

1.1 Specific Aim

This study aims to investigate the production and nutritional composition of neem oil obtained from raw neem seeds. It involves extracting oil from neem seeds using different techniques and assessing how these methods influence the acid, saponification, and peroxide values of the resulting oils. The investigation also considers the potential suitability of the extracted neem oil for applications such as biodiesel production.