ABSTRACT

Antrinutitional factors re compounds which reduce the nutrient utilization or food intake of plant or plant products (seeds) used as human foods and they play a vital role in determining the use of seeds for human. This paper is aimed to review the updated scientific information regarding the potential health benefits and adverse effects associated with major antinutritional factors found in edible seeds. Antinutrients in these edible seeds are responsible for deleterious effects related to the absorption of nutrients and micronutrients. However, some antinutrients may exert beneficial health effects at low concentration. This review will focus on phytic acid, Tannin content, cyanide content and oxalate content which are found in edible seeds. Antinuttitional substance from nutritional point of view interferes with normal growth, reproduction and health when consumed regularly in amount existing in a normal component of diet therefore should be considered as harmful and toxic. A significant part of human population relies on legumes as staple food for substance particularly in combination with cereals. They are unique food because their rich nutrient content includes starch, protein, dietary fibre, phytochemicals and minerals so, the knowledge regarding various anti-nutritional substances present in food as well as technique to reduce them in the diet is essential for health and wellbeing of population.

KEYWORD: Dietary fibre, Antinutritional factors, potential health benefits, adverse health effects.

TABLE OF CONTENTS

Title page

Declaration

Certification

Dedication

Acknowledgements

Abstract

CHAPTER ONE: INTRODUCTION

1.1     Background of the Study

1.2     Statement of Problem

1.3     Aim of Project

1.4     Research Questions

1.5     Scope of the Study

CHAPTER TWO: LITERATURE REVIEW

2.1     Nutritional Substance

2.1.1  Pumpkin Seed

2.1.2  African Bush mango Seed

2.1.3  Walnut

2.1.4  Garden Egg

2.1.5  Wheat

2.1.6  Beans

2.1.7  Maize

2.1.8  Watermelon Seed

2.19   Unpolished Rice

2.1.9  Pawpaw Seed

2.2     Antinutritional Substance

2.2.1  Tannins

2.2.2  Phytate

2.2.3  Oxalate

2.2.4  Saponins

2.2.5  Lectins

2.2.6  Alkaloids

2.2.7  Protease Inhibitors

2.2.8  Cyanogenic Glycosides

CHAPTER THREE: METHODS

3.1     Sample Collection and Treatment

3.2     Methodology

3.2.1  Oxalate Determination by Titration Method

3.2.2  Phyticacid (phytate)

3.2.3  Tannins

CHAPTER FOUR: RESULTS

Discussion

CHAPTER FIVE: SUMMARY, CONCLUSION AND RECOMMENDATIONS

5.1     Summary

  5.2   Conclusion

5.3     Recommendations

5.4     Contribution of the Work to Knowledge

References

CHAPTER ONE

INTRODUCTION

1.1     Background of the Study

          Food is described as any substance consumed to provide nutritional support for an organism. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals taken into the body to keep it alive and enable it to grow. It is a substance which when consumed is able to supply energy, maintain life and stimulate growth, since it nourishes the body.

       Today’s scientific understanding of human hmm nutrition is one of the most important contributions of biochemistry. It has saved numerous human lives or improved their quality (Lenninger 19987). It shows that nutrition is essential for the maintenance of good health and for increasing productive capacity (Lehninger 187).Some food is obtained directly from plants; but even animals that are used as food sources are raised by feeding them food derived from plants. Cereal grain is a staple food that provides more food energy worldwide than any other type of crop. Corn (maize),wheat, and rice – in all of their varieties – account for 87% of all grain production worldwide. Most of the grain that is produced worldwide is fed to livestock.

        Seeds of plants are a good source of food for animals, including humans, because they contain the nutrients necessary for the plant’s initial growth, including many healthful fats, such as omega fats. In fact, the majority of food consumed by human beings are seed-based foods. Edible seeds include cereals (corn, wheat, rice, et cetera), legumes (beans, peas, lentils, et cetera), and nuts. Oilseeds are often pressed to produce rich oils – sunflower, flaxseed, rapeseed (including canola oil), sesame, et cetera. Seeds are typically high in unsaturated fats and, in moderation, are considered a health food. However, not all seeds are edible. Large seeds, such as those from a lemon, pose a choking hazard, while seeds from cherries and apples contain cyanide which could be poisonous only if consumed in large volumes.

Nutritive Values of Foods

         The nutritive values of a food are measure of the usefulness of the food for the purpose of providing correct nutrients. As it is normally seen, the requirements for carbohydrates and fat are never considered critical, because of their abundance in nature. Protein content of food and its quality is usually used as a measure of the quality of the food or it nutritive value.

Chemical analysis alone may not suffice as some nutrients may be in a form not biologically available. Hence, if a nutrient in a food is in a form which renders it unavailable to human, then its nutritional significance is zero; irrespective of the concentration of the nutrients at the point of sale or consumption of the food.

Anti-Nutritional Factors (Plants’ Secondary Metabolites)

        The abundance of anti-nutritional factors and toxic substances in plants used as human foods and animal feeds certainly calls for concern. Therefore, ways and means of eliminating or reducing their levels to the barest minimum should be discovered. It could be wrongly argued that since the African cultural method of preparing food involves cooking, there is no cause for alarm. This is not entirely correct because although the toxic effects of most anti-nutritional factors present in plant food and feedstuffs can generally be eliminated by proper heat treatment, it should be appreciated that conditions may prevail whereby complete destruction may not always be achieved. For example, it has been reported that phytic acids (phytates) are not destroyed by being cooked even in boiling water. The mixtures of ground beans and ground cereals prepared under the field conditions prevailing in Africa, the haemagluttinins not always completely destroyed, and that cooked products produced diarrhea and other toxicity signs. A reduction in the boiling point of water in mountainous regions could also result in incomplete destruction of toxicity or incomplete elimination of the lectins. Also, people do not patiently prepare or process beans to the recommended level to destroy the anti-nutrients because of the high and prohibitive cost of energy sources like kerosene and gas and the scarcity of firewood, especially during the rainy season. As a result of this, people are forced to eat improperly cooked nutritionally toxic beans. There has also been some press reports of food poisoning leading to mortality in humans after consumption of bean meal. The adverse effect of excessive cooking on protein denaturation is also an important factor to be considered during food / feed  processing. A review of the occurrence of nitrate in unprocessed foods showed that high concentrations are frequently found in vegetables. Nitrates are present in all plants and are an essential source of nitrogen for normal growth. The increasing incidence of various forms of cancer in the world at large and in Nigeria in particular may be attributed to the levels of certain chemicals in our foods and drinks. The consequences/implications of toxic factors in plants used as food/feedstuffs are not their direct toxicity to man and animals alone, but also the inconvenience and the economic loss associated with poisoning of domestic animals and the cost of preventing or reducing such happenings. It is worthy of note that plant poisons can either be accumulated in the animal or in certain organs or they are metabolized and excreted in milk.  Ruminants may convert cyanide to the less toxic thiocyanate, which is goitrogenic. By this food chain, toxins or their metabolites thereof may become harmful to man. Nutrition education should emphasize adequate and thorough preparations of human foods and animal feeds, especially in humans where there are increases in reported cases of renal diseases. Oxalate, which is an anti-nutritional component of plant, if consumed in large quantities is associated with blockage of renal tubules by calcium oxalate crystals and development of urinary calculi. All these can lead to renal disease and hence death in susceptible individuals. There is also the need to re-visit studies on the levels of anti-nutritional factors in our common foods due to the influence of soil, fertilizer, pesticides, and other chemicals and environmental conditions on the levels of these anti-nutritional factors in plants.

Anti-Nutition and Health

Positive effects of anti-nutritional factors in human nutrition

       The anti-nutritional factors found to have effect on gastrointestinal tract and affect the microflora count of the intestine by promoting the growth of beneficial bacterias. Lupinuscampestris seed found to have anti-mutagenic activity and prevents the mutagenic process involved in development of cancer. Anti-nutritional factors decreases levels of heat shock protein 70 and 90 in gut epithelial cells after exposure to plant lectins. Lectins present in legumes assessed to  act as a mucosal adjuvant. Beneficial outcome in hypercholesterolemia after intake of heat treated chickpea in rats have been observed (Price et al., 1987; Friedman, 2001; Young, 2011).  

Negative effects of anti-nutritional factors in human nutrition

        Low toxic substances in legumes produce serious pathological conditions. They are the factors in kesari dhal which cause lathyrism and haemolytic factor in Viciafaba associated with disease favism.

Lathyrism: Lathyrism is a paralytic disease affecting the lower limbs. The incidence of the disease is higher in males than females and recovery from the condition does not usually occur. The disease has been known since early times and there is reference to it in early Indian medical writing. Serious outbreak of lathyrism has occurred in this country quite a few times. The disease has been associated with consumption of kesari dhal and is commonly noticed in poor families who regularly eat considerable quantity of the dhal. However, lathyrism develops only when the consumption of dhal is high(300 g daily) and the diet does not contain adequate quantities of cereals and is used for long time (six months or more). In lathyrism, the toxic substance interfaces with the formation of normal collagen fibre in the connective tissue. The disease can be prevented by ensuring reasonable balance between kesari dhal and other material and its replacement by other pulses where practicable. Lathyrogens i.e. Beta N oxayl, Beta diamino propionic acid (BOAA), a naturally occurring amino acids, possess potent neurotoxic activity and has been shown to be responsible for outbreaks of neurolathyrism following consumption of Lathyrussativus. BOAA occurs naturally as two isomeric forms with the Beta N oxayl L form being approximately 5% of the total. The level of BOAA in dry seeds varies considerably according to genetic factors and environmental conditions. Lathyrussativus grown in nutrient solution that are zinc deficient or rich in ferrous iron, produced seeds with elevated levels of BOAA (Burbano,1999). 

Favism: Favism is a disease characterized by haemolyticanaemia which affects certain individuals following the ingestion of fresh or cooked broad beans. The victims suffer from an inherited biochemical abnormality which affects the metabolism of glutathione in red blood cells and is the result of decreased activity of the enzymes glucose-6-phospate dehydrogenase. In person with his abnormality, the red cells are more prone to injury and destruction by certain drugs, such as sulphonamide and this raises complications in the treatment of infectious disease (Dmello et al., 1991). 

1.2     Statement of Problem

          Seeds in general, contain antinutritive phytochemical which prevents the availability of some minerals in the body, due to its chelating activities, thereby resulting in mineral deficiencies. So this project deals with the comparative studies on phytic acid, Tannin, cyanide and oxalate contents in wheat, pawpaw seed, African bush mango seed, walnut, watermelon seed, rice, garden egg, maize, Beans, Pumpkin seed for the purposes of diet formulation for maximum benefit.

1.3     Aim of Project

          Considerately, less is known of the chemical constituents of edible seed. It has become necessary to evaluate the anti-nutrient content of these edible seeds, in order to protect the health and well being of the consumers.

         However, this project was therefore designed to determine the anti-nutrient content in some edible seeds found in Akwa-Ibom and it is expected that the result of this research project will provide useful information to justify the continued consumption of these seeds.

1.4     Research Questions

1.     Is the any concentration of oxalate, cyanide, tannin and phytic acid in these samples?

2.     If it is high, which of them have the highest value?

3.     If it is low, which of them is having the lowest value?

4.     Is the concentration of oxalate, cyanide, tannin and phytic acid in eah of the samples the same?

1.5     Scope of the Study

          The scope of this project covers the following:

a.     Collection of samples:

b.     Determination of oxalate content, phytic acid content, Tannin content and cyanide contents in

1.     Wheat

2.     Pawpaw seed

3.     African bush mango seed

4.     Walnut

5.     Watermelon seed

6.     Rice

7.     Garden Egg

8.     Beans

9.     Maize

10.                      Pumpkin seed

C.   Comparison of the phytic acid content, Tannin content, Cyanide content, Oxalate content of these 10 edible seeds