Elemental Analysis On Edible Leaves Pterocarpus Mildbreadii (Oha) Seed

1.1 Introduction

A seed or mature ovule is a miniature plant with a protective cover in a suspended state of development. Most seeds contain a built-in food supply called endosperm, orchid is an exception. The endosperm can be made up of proteins, carbohydrates and fats.

Seed can also be defined as a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant(Wikipedia).Seed protects a plant embryo so that it can grow into a new plant. Many seeds are edible, such as sunflower seeds, tomato seeds, corn and peas.

Seeds contain three distinct structures. The inside of a seed contains an embryo, which is a baby plant with a shoot and a tiny root. The two halves of a seed are stored food that provides the nourishment necessary for seeds to germinate, or begin growing. Surrounding the seed is a hard, tough seed coat, which protects the seed during dormancy(Anville 2007).

Most seeds contain a built-in food supply called endosperm. The endosperm can be made up of proteins, carbohydrates and fats. Seeds also contain anti-nutrients in their seed coat. These anti-nutrients includes phytin, lectin, trypsin inhibitor activity, tannin and cyanide.

In addition, they also contain minerals such as sodium, potassium, calcium, magnesium, phosphorus, zinc, manganese, iron, selenium and copper.(Balogun 2000)

Oilseeds are energy dense foods; for example, sesame seeds provide 600kcal or 2470kj/1000g.Although oilseeds contain protein(|14-32g/100g)and carbohydrate(ranging from less than 1g/100g to more than 34g/100g),most of the food energy they provide is as fat(which provides 9kcal or 37kj/g).Oilseeds vary widely in their fatty acid composition but tend to be rich in MUFA(e.g peanut)r PUFA(e.g sunflower seeds).Some seed oils contain significant amounts of EFA, ALNA, an n-3 fatty acid, and linoleic acid(LA),an n-6 fatty acid. from these two fatty acids, the body can make all the fatty acids it needs. From LA, arachidonic acid can be produced, and from ALNA the long chain n-3 eicosapentaenoic acid(EPA)and docosahexanoic acid(DHA)can be made.(BNF 1999).

Generally, whole oilseeds are a source of fibre, phosphorus, iron and magnesium; many oilseeds are a source of vitamin E(an antioxidant),niacin and folate. Whole oilseeds also contain phytoestrogens, a group of substances including lignans and isoflavones. Phytoestrogens have a structure similar to the oestrogen hormone oestradiol and can bind to oestrogen receptors.Phytoestrogens may provide a protective effect against coronary heart disease as they have been shown to have a lowering effect on blood cholesterol.Additionally,some phytoestrogens may have antioxidant properties(Goldberg 2003).

In Britain, oilseeds are usually consumed, following processing,as oils and margarines. The fatty acid composition of oils produced from oilseeds varies widely. Vegetable oils do not contain the same levels of macronutrients, vitamins and minerals as whole oilseeds. In fact, apart from fat itself, vitamin E is the only nutrient present in appreciable amounts. Vegetable oils do, however, contain a range of phytochemicals, e.g they are the main source of natural plant sterols in the diet. Plant sterols have a structure similar to cholesterol and hence reduce cholesterol absorption, therefore reducing the circulating levels of total and low density lipoprotein(LDL)cholesterol. Plant sterols can be present as free or esterified forms and the proportions vary, e.g free sterols dominate in soybean,olive and sunflower oil,while in rapeseed and corn oil, free sterols account for only 30% of the plant sterols.Refining vegetable oils decreases the content of sterols(from 10-70% depending on the oil and processing conditions used),thus decreasing their potential to lower serum cholesterol(Goldberg 2003).

1.2 Aim Of Study

To determine the elements present in grinded oha seed(Pterocarpus mildbreadii)

1.3 Research Objective

This study was primarily designed to use grinded oha seed(Pterocarpus mildbreadii) extract for elemental analysis.

Chapter Two

Literature Review

2.1 Elemental Analysis

Elemental analysis is the qualitative detection and quantitative determination of chemical elements(atoms, ions)in a sample(Fritz Pregl 1923).To detect an element, one should fix an appearance of an analytical signal, the formation of precipitate or characteristic crystals, color change, an isolation of gaseous products, an appearance of a definite lines in spectrum, luminescence ,etc. To determine elements quantity, it is necessary to measure a value of an analytical signal: a precipitate mass, intensity of a current, solution absorption, spectrum line, luminescence or radioactivity, a reaction rate and so on. The content of an element is calculated on the base of a functional dependence of the analytical signal value(AS)on a mass or concentration of this element(AS=F©),which is established by calculations or experiments(Mazor L 1986).

To obtain the analytical signal, chemical reactions of different types(acid-base, oxidation-reduction, complex formation),various processes (eg. precipitation) as well as different chemical, physical, biological properties of elements themselves or product of their reactions, are used. Methods for the detection and determination of elements are divided into chemical, physical, biological. The most important characteristics of these methods are the detection limit, sensitivity, selectivity, precision, rapidity and price of analysis. At present, elements are mostly detected with the help of physical methods, which are based on physical phenomena or processes eg. an interaction of elements with an energetic current. Among such methods is the method of atomic emission spectroscopy(AES),based on a thermal excitation of atoms of free elements and registration of the optic spectrum of excited atoms emission (Kellner R.et al. 1998).