BELINDA AGYEI- POKU FINAL THESIS.Pdf
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KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY, KUMASI COLLEGE OF SCIENCE DEPARTMENT OF FOOD SCIENCE AND TECHNOLOGY THE EFFECT OF PRE- TREATMENT AND OVEN DRYING TEMPERATURES ON THE NUTRITIONAL, ANTI-NUTRITIONAL VALUES AND COLOUR PROPERTIES OF THE FRUITS OF SOLANUM TORVUM THIS DESSERTATION IS PRESENTED TO THE DEPARTMENT OF FOOD SCIENCE AND TECHNOLOGY IN PARTIAL FULFILMENT OF THE REQUIREMENT OF MASTER OF SCIENCE (MSc) DEGREE (HONS) IN FOOD QUALITY MANAGEMENT By BELINDA AGYEI- POKU JULY, 2017 1 DECLARATION I declare that I have wholly undertaken the study reported herein under the supervision of Mr. Emmanuel Yaw Adu Amankwah and that except portions where references have been duly cited, this dissertation is the outcome of my research. Belinda Agyei-Poku (PG4367715) …………………… ………………….. Student Name and ID Signature Date Mr. Emmanuel Yaw Adu Amankwah …………………… ………………….. Supervisor‟s Name Signature Date Mrs. Faustina D. Wireko Manu (PhD) …………………… ………………….. Head of Department Signature Date ii ACKNOWLEDGEMENT I thank the almighty God, whom I serve, for the grace to finish thesis work. My profound gratitude goes to my supervisor, Mr. Emmanuel Adu Amankwah for his tireless, guidance, patience, constructive criticisms, critical comments and suggestions throughout the course of this study. I am grateful to him for his supervision, guidance and support during my research work. Special thanks should go to my family: My husband Thomas Agyei-Poku, children; Akua, Kwasi, Ama and Kwame Agyei-Poku, my father and mother Ernest and Theresa Owusu-Badu, sister Brenda Biney, and all my siblings whom I shall always remain grateful for their support, kindness, love, prayers and patience during all the time of the study. My deep sincere gratitude also go to friends Apeku Osborn-Jnr, Williams and Redeemer, all at KNUST, for their full time support, assistance and kindness during my thesis at Kwame Nkrumah University of Science and Technology. iii DEDICATION I dedicate this work to my beloved husband Mr Thomas Agyei-Poku for his love and care. To my children Akua, Kwasi, Ama and Kwame Agyei-Poku so that they become greater scholars who will not only be able to understand different aspects of the world but also to change them in appropriate and positive ways. May Almighty God bless them all, Amen. iv ABSTRACT Fruits of Solanum torvum are generally consumed by lactating and nursing mothers, pregnant women and anemic patients when cooked for medicinal and nutritional purposes. Lack of preservation method has led to its high postharvest losses. However processing methods such as drying can affect differently the nutrient, colour and anti-nutrient content of food samples at different temperatures. This work therefore sought to determine the effects of treatment and different temperatures on the nutritional and anti-nutritional composition of the dried fruits. Proximate composition, some minerals (iron, magnesium, and calcium), anti-nutrients (Alkaloid, Oxalate and Tannin) and colour of the fresh and pre-treated dried samples were determined. AOAC (1995) methods were used for the determination of moisture, fiber, fat and ash content. AOAC (1990) method was used for the determination of protein. Minerals were determined using the Atomic Absorption Spectroscopy methods. Oxalate was determined by titrimetric method, Tannins by the spectrophotometric method and Alkaloids by the Gravimetric method. The results indicate that the fresh fruits possess high moisture content of 78.3% and 82 on wet basis. Fat, fiber, ash and protein contents increased with the exception of carbohydrate which decreased for the dried samples irrespective of the drying pretreatment. Minerals determined increased after drying for all temperatures with the effect of the treatments not well established. Vitamin C decreased after drying with the exception of the berries pretreated with ascorbic acid. Alkaloids and Tannins reduced after drying but oxalate was not affected by heat. Boiling reduced the browning effect with the 5% ascorbic acid treated samples recording the highest range of browning values. The high iron content of the fruits proves the fact that the fruits truly have hematinic property. These present research indicate that Solanum torvum fruits boiled and dried at 70oC has the best nutritional qualities, reduced anti-nutritional properties and a better desirable colour properties. v TABLE OF CONTENTS DECLARATION............................................................................................................................ i ACKNOWLEDGEMENT ........................................................................................................... iii DEDICATION.............................................................................................................................. iv ABSTRACT ................................................................................................................................... v TABLE OF CONTENTS ............................................................................................................ vi LIST OF TABLES ....................................................................................................................... ix LIST OF FIGURES ...................................................................................................................... x CHAPTER ONE…………………………………………………………………………………………….…………….………1 1.0 INTRODUCTION ................................................................................................................. 1 1.1 Background ........................................................................................................................... 1 1.2 Problem Statement and Justification ..................................................................................... 5 1.3 Significance of the study ....................................................................................................... 6 1.4 Main objective ....................................................................................................................... 6 1.5 Specific objectives................................................................................................................. 6 1.6 The scope of the study ........................................................................................................... 7 1.7 Limitation of the study .......................................................................................................... 7 CHAPTER TWO .......................................................................................................................... 8 2.0 LITERATURE REVIEW ...................................................................................................... 8 2.1 Introduction ........................................................................................................................... 8 2.2 Origin of solanum torvum ..................................................................................................... 8 2.3 The Solanum torvum plant .................................................................................................... 9 2.4 Varieties .............................................................................................................................. 10 2.5 Health benefits..................................................................................................................... 11 2.6 Nutritional composition of Solanum torvum ....................................................................... 13 2.7 Cuisine ................................................................................................................................. 13 2.8 Food Preservation ................................................................................................................ 14 2.8.1 Drying............................................................................................................................... 14 2.8.2 Fundamentals of Drying ................................................................................................... 15 2.8.3 The Drying Process .......................................................................................................... 16 2.8.3.1.1 Mechanism of Drying................................................................................................. 17 vi 2.9 Oven Drying ........................................................................................................................ 17 2.9.1 Batch Drying Ovens ........................................................................................................ 18 2.9.2 Conveyor Drying Ovens .................................................................................................. 18 2.9.3 Specialty Drying Ovens ................................................................................................... 18 2.10 Nutritive values of dried vegetables .................................................................................. 19 2.10.1 Types of food to dry ....................................................................................................... 19 2.10.2 Equipment for drying ..................................................................................................... 19 2.10.3 Pre-treatment before drying. .......................................................................................... 19 2.11 ANTI-NUTRIENT ...........................................................................................................