Chapter One

1.0 INTRODUCTION

The edible fruit of watermelon (Citrullus lanatus) belongs to the family Cubitaceae. The fruit contains many obovate, smooth compressed seeds thickened at the margin and of a black or yellowish white colour. Watermelon plays a very important role in Africa as it is used to quench thirst when there is shortage of water. The seed of watermelon (Citrullus lanatus) can be bruised and rubbed up with water to form an emulsion, which can be used to cure catarrhal infections, disorders of the bowels, urinary passage and fever. It is also being used as worm expeller, in recent years it has been used to expel tape worm (Abiodun and Adeleke, 2010). In Nigeria, the watermelon seed is often discarded after the juicy part has been eaten. The seed constitutes a public nuisance because the sellers of watermelon do not dispose of these in a hygienic manner. Therefore, this project work when successfully completed will convert waste into wealth. From previous studies on watermelon seed oil, it is light penetrating and rich in essential fatty acids (Abiodun and Adeleke, 2010). As a result of importance of drying techniques, this research was designed to observe the effect of two drying methods on the physico-chemical properties of the seed oil and also to determine its edibility and effectiveness in soap making. In Africa, Watermelon seeds have been prized for the highly nutritive oil that they contain. Traditionally, the seeds are removed from the rind and then allowed to dry outside in the sun. Once dried, the seeds are then pressed to extract the beneficial oil. Natural Sourcing provides the most superior watermelon seed oil available. It is carefully processed and packaged to maintain the purity, freshness and beneficial properties of this exceptional watermelon seed oil.

The fatty acid profile of edible oils plays an important role in their stability and nutritional value. Monounsaturated (18:1) and polyunsaturated (18:2) fatty acids have been found to be effective replacements for saturates as part of cholesterol-lowering diets (Mattson and Grundy, 1985). However, it is also known that the oils with substantial amounts of unsaturation, particularly 18:2 fatty acids, are susceptible to oxidation and may produce products that contribute to arteriosclerosis and carcinogenesis. Some studies with experimental animals indicate that excessive amounts of linoleic acid promote carcinogenesis

(Kubow, 1990).Watermelon seed oil, rich in linoleic acid (~64.5 %), is used for frying and cooking in some African and Middle Eastern American countries owning to its unique flavour (Akoh and Nwosu, 1992). Much research has been published on the oxidative stability of some vegetable or fruit oils, but a little has been reported on the stability of watermelon seed oil. The modification of watermelon seed oil fatty acid composition by incorporation of oleic acid (18:1) has been explored (Charment et al., 1997). The modified watermelon seed oil was produced with the better balance of monounsaturated (18:1) and essential Fatty acids (18:2), and also improved the seed oil oxidative stability and nutritional value (Charment et al., 1998).The watermelon family Cucurbitaceae is the most popular fruit in Serbia, with a traditional name ″lubenica″. Unfortunately, there is no information of domestic application or medicinal values of this seed oil for cooking and or frying as useful source of oil with good nutritional value. Thus, watermelon seed oil composition (physical and chemical) shall be evaluated in this present study, which has not been previously investigated. The data generated in the work may help in the future selection of watermelon seed oil for use in human diet.

The light texture, moisturizing capabilities and stable shelf life of watermelon seed oil makes it a highly suitable emollient in natural baby care formulations and light body emulsions. Unlike mineral oil that is a common ingredient in commercial skin projects, watermelon seed oil does not clog pores or prevent the body from natural elimination of toxins through the skin. The rich composition of essential fatty acid contained in watermelon seed oil nourishes and restores elasticity to the skin (Akoh and Nwosu, 1992). It may be recommended for use in skin care formulations for all skin types including dry, oily and maturing skin. Watermelon seed oil may also be a perfect choice for inclusion in hair care formulations as it is non greasy yet highly moisturizing. Grinding the dry seed, flaking or rolling of the seeds to carry out extraction of oil, this is then subjected to mechanical processing to liberate the oil or the use of chemical solvent.

1.1 Aims and Objectives

The aims and objectives of the project are;

Ø Determine the oil content in the watermelon seed using soxhlet extractor.

Ø Determine the physico-chemical characteristic properties of the extracted oil.                                    

Ø Use of normal hexane and petroleum ether as an extractive solvent.

Ø Effect of two drying methods on the physico-chemical properties of the watermelon seed oil.

Ø Determine its edibility and effectiveness in soap making.

Ø Determine the proximate analysis of the seed. 

1.2 Scopes

Ø Collection of the watermelon seeds from road side hawkers.

Ø Drying and removal from the shell.

Ø Drying proper (oven drying and sun drying).

Ø Cleaning of the seed.

Ø Weighing of the watermelon seed.

Ø Grinding of the seed.

Ø Proximate analysis of the seed.

Ø Sieving to obtain particle sizes of varying dimensions.

Ø Extraction using soxhlet method, petroleum ether and hexane as solvent.

Ø Characterization of the oil (physical and chemical).

1.3 Problem Statement

In Nigeria, the watermelon seed is often discarded after the juicy part has been eaten. The seed constitutes a public nuisance because the sellers of watermelon do not dispose of these in a hygienic way. Therefore, this project work when completed will succ