Description

ABSTRACT

The most common form of utilization of sesame seed is its roasting, which supplies nutrients to the diet. The objective of this study was to determine the effect of different roasting techniques (using open pan and microwave) on the chemical composition physico-chemical properties of its oil and glycemic index. The raw sesame flour (RSF), open pan roasted sesame flour (ORSF) and microwave roasted sesame flour (MRSF) were analysed for proximate composition, minerals, vitamins, anti-nutritional factors and colour, and the seed oils were analyzed for peroxide and iodine values. The ranges of proximate composition of the flours were: protein 24.3-27.5 g/100g, fat 52.4-59.0 g/100g, crude fiber 3.86- 6.13 g/100g, ash 2.88-3.67 g/100g, carbohydrate 5.4-13.2 g/100g and energy value 552.5 -576.6 kcal/100g. Crude fat, ash, fiber and energy values were significantly higher in MRSF and ORSF compared to RSF. However, protein and carbohydrate values were significantly lower in roasted seeds compared to RSF. Calcium, potassium, phosphorus and magnesium ranged from 439.25-445.02, 342.14-346.77, 427.81-434.77 and 357.38-364.03 mg/100g respectively with the RSF having the least value. Whereas micro elements such as iron, manganese and zinc ranged from 3.06-6.42, 0.76-1.50 and 2.78-3.62 mg/100g. Thiamine values for RSF, ORSF and MRSF were 40.23, 20.56 and 4.52 mg/Kg respectively; riboflavin values were 21.08, 15.33 and 2.60 mg/Kg respectively while niacin values were and 28.28, 17.30, 2.01 mg/Kg respectively. Roasting in open pan caused significant reduction in phytate and oxalate contents in sesame than roasting in microwave oven. Colour values (L*) of seed flour significantly decreased, whereas a* and b* values increased (P ≤0.05) in ORSF and MRSF compared to RSF. The peroxide values of RSF, ORSF and MRSF were 1.43, 11.21 and 10.02 mEq O2/kg oil respectively while the iodine values were 118.65, 106.44 and 109.71 g I/100g oil for RSF, ORSF and MRSF respectively. The glycemic indices of raw, open pan roating and microwave roasting are 92.36, 84.88, and 78.67. The effect of roasting techniques with regard to loss and retention of the nutrients and the effect on their glycemic index differed significantly (P ≤ 0.05).

Keywords: chemical composition, microwave irradiation, open pan roasting

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE STUDY
• PROBLEM STATEMENT
• AIM AND OBJECTIVES OF THE STUDY
• RESEARCH HYPOTHESIS
• SIGNIFICANCE OF THE STUDY
• SCOPE OF THE STUDY
• LIMITATIONS OF THE STUDY
• RESEARCH QUESTION
• THESIS ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• REVIEW OF THE STUDY
• ORIGINS AND HISTORY OF SESAME SEED
• PHYSICAL DESCRIPTION OF SESAME
• CULTIVATION OF SESAME SEEDS
• PROCESSING OF SESAME SEEDS
• NUTRITIONAL INFORMATION OF SESAME SEEDS
• HEALTH EFFECTS OF SESAME SEEDS
• CHEMICAL COMPOSITION OF SESAME SEEDS
• SESAME FLOUR
• REVIEW OF RELATED STUDIES
• CARBOHYDRATE
• DIETARY CARBOHYDRATE
• TOTAL CARBOHYDRATE
• SUGARS
• STARCH
• DIETARY FIBRE
• AVAILABLE CARBOHYDRATE
• CARBOHYDRATE DIGESTION
• GLYCAEMIC INDEX CONCEPT
• DETERMINATION OF GLYCAEMIC INDEX
• GLYCAEMIC LOAD AND HEALTH
• GLYCAEMIC LOAD AND DIABETES
• GLYCEMIC LOAD AND CORONARY HEART DISEASES

CHAPTER THREE

• MATERIAL AND METHODS
• SAMPLE MATERIALS
• SAMPLE PREPARATION
• RAW SESAME FLOUR (RSF)
• OPEN PAN ROASTED SESAME FLOUR (ORSF)
• MICROWAVE ROASTED SESAME FLOUR (MRSF)
• BREAD PRODUCTION
• PROXIMATE ANALYSIS
• DETERMINATION OF MINERAL CONTENTS
• DETERMINATION OF VITAMIN CONTENT
• DETERMINATION OF ANTI-NUTRITIONAL COMPOUNDS
• DETERMINATION OF SEED OIL CHARACTERISTICS
• DETERMINATION OF CARBOHYDRATE
• METHODOLOGY FOR BLOOD GLOCOSE DETERMINATION
• DETERMINATION OF BLOOD GLUCOSE RESPONSE
• CALIBRATION OF ONE TOUCH GLUCOMETER
• DETERMINATION OF GLYCEMIC INDEX
• STATISTICAL ANALYSIS

CHAPTER FOUR

4.0      RESULT AND DISCUSSION

CHAPTER FIVE

• CONCLUSION

REFERENCES

 

CHAPTER ONE

1.0                                                           INTRODUCTION

1.1                                                  BACKGROUND OF STUDY

There has been immense expansion in oil seeds production as a result of increasing demand for food applications. Sesame seeds are small, the size, form and colour vary with the thousands of varieties known (Oplinger et al., 2010). Sesame seeds occur in many colours depending on the cultivar (Langham, 2018). The most traded variety of sesame is off-white coloured. Other common colours are buff, tan, gold, brown, reddish, gray, and black. Through the ages, sesame seeds have been a source of food and oil. Sesame is also grown for its leaves that are used in stews, and the dried stems may be burnt as fuel with the ash used for local soap making, but such uses are entirely subordinate to seed production. Sesame seeds contain 47-50% fat, 25-27% protein, 10-12% carbohydrate, 3.7-6.4% fiber and 3.7- 4.6% ash (Makinde and Akinoso, 2013). The seeds are rich in mono-unsaturated fatty acid (oleic acid) and equally rich sources of many minerals such as calcium, phosphorus, manganese, zinc, magnesium and potassium which play vital roles in the body (Makinde and Akinoso, 2014). The seeds also contain B complex vitamins such as niacin, folic acid, thiamine, riboflavin and pyridoxine with some health benefiting compounds such as sesamol, sesamolin and sesamin (Nakai et al., 2013). Phillips et al. (2015) however reported that the seeds contain phytic and oxalic acids, which are anti- nutrients.

The effects of various processing methods in the preparation of oilseeds for human consumption are of utmost importance. Roasting is the most important practice for sesame seed processing in Nigeria and is commonly carried out in open pan over fire with continuous stirring, however, such roasting process takes about 20 min or more, which may adversely affect sesame constituents such as lipids, protein, vitamins and other essential nutrients. Meanwhile, social changes and rapid lifestyle make the working women search for a rapid method for preparing food with microwave oven especially those needed a long time for cooking or roasting. Microwave operation have been applied with increasing success in oil extraction, pasteurization, sterilization, baking, blanching, roasting, cooking, drying, and thawing of different food products (Tan et al., 2011; Mariod et al., 2013) and it is accomplished by means of electromagnetic waves, which penetrate deeply and heat rapidly (Schlegel, 2012). Electromagnetic waves are of electrical and magnetic energy moving together through space. They include gamma rays, x- rays, ultraviolet radiation, visible light, infrared radiation, microwaves and the less energetic radio waves. Although there is no formal definition of the frequency range for microwave radiation, these electromagnetic waves occur in the 300MHz – 300GHz region. Nevertheless, and in accordance with the industrial, scientific and medical (ISM) frequency bands for non- communication purposes, only 915 MHz and 2.45MHz are used for food applications, especially the second due to its worldwide availability (Malheiro et al., 2011). Numerous advantages boosted the use of microwave heating making it in many cases a technique preferred in the processing of food. These advantages include precise timing, rapidity, and energy saving. Moreover, it has been found to be safe; there was no toxicity or adverse effects on microwave treated foods (Miller et al., 2019).

Many researchers have been concerned with the evaluation of the effect of roasting on sesame seeds; these include: anti oxidative activity of roasted sesame seed oil and the effect of using the oil for frying (Fukuda et al., 2016), influence of seed roasting process on the changes in composition and quality of sesame oil (Yen, 2010), oxidative stability of sesame oil prepared from sesame seed with different roasting temperatures (Yen and Shyu, 2019) and microwave roasting effects on the composition and oxidative stability of sesame oil (Yoshida and Kajimoto,2014). However, there is paucity of information on the effect of roasting techniques on chemical composition of sesame seeds. This study was designed to determine the effect of roasting (open pan and microwave roasting) on the chemical composition of sesame flour,  physico-chemical properties of its oil and glyceric indices.

1.2                                                      PROBLEM STATEMENT

Diabetes mellitus is one of the most common metabolic disorders, affecting over 420 million individuals worldwide (WHO, 2016).) is condition was responsible for 28.8 million deaths in 2016 (Naghavi, 2017). Type 2 diabetes is characterized by insulin resistance and is diagnosed by biochemical parameters such as high concentrations of serum blood sugar, insulin, and glycosylated hemoglobin (Unwin et al, 2002). Finding a practical approach to reduce the prevalence of diabetes is essential for global public and economic health.

Sesame (Sesamum indicum L.) has been used as a traditional plant-based therapy worldwide, most commonly in Northern regions of Nigeria. Sesame seed and its products (oil, flour,and dietary supplement) are good sources of lignan compounds (sesamin, sesamolin, sesamol, and episesamin).) ese lignans are responsible for most medicinal actions of sesame, including antioxidant activity [Kamal-Eldin et al, 2011], anti-inflammatory actions, and hypoglycemic effects. Additionally, sesame contains high amounts of other beneficial components such as α-tocopherol, polyunsaturated fatty acids (PUFAs), monounsaturated fatty acids (MUFAs), and fiber.) e hypoglycemic effects of sesame may be due to the action of its bioactive lignans which have been shown to improve insulin secretion from B cells of the pancreas (Makinde et al, 2012).

Some animal studies have found that sesame consumption could reduce insulin resistance and enhance the glucose metabolism (Makinde et al, 2012). In human studies, sesame consumption has produced beneficial effects on serum glucose, and insulin concentrations in diabetic patients (Makinde et al, 2012).

However, this study was carried to bring to the knowledge of the reader the effect of roasting on physico-chemical properties and glycemic indices of sesame (sesamun indicum) seeds on white bread.

1.3      Aim and objectives of the Study

The main aim of this study was to determine phytochemical properties and the glycemic indices of roasted sesame on white bread. To achieve this, the study sought to;

1. Determine the glycemic load of roasted sesame (open pan roasted sesame flour (ORSF) and microwave roasted sesame flour (MRSF) ) on white bread.
2. To carry out a comparison test of glycemic index between raw sesame flour and roasted sesame flour.
3. Perform proximate analysis of roasted sesame on white bread.
4. Carryout the sensory analysis of the roasted sesame on white bread.
5. Make a recommendation for food to be consumed moderately in a diet

1.4      Research Hypothesis

H0 = There is no significant high glycemic load of sesame on white bread

H1= There is a significant high glycemic load of roasted sesame on white bread

1.5      Significance of the Study

Essentially, the glycemic load, which is the product of the glycemic index and the carbohydrate content of a given food, may be more useful than only the glycemic index. This is because the glycemic load takes into account the portion size of the food as well as the carbohydrate content. Glycemic load is a significant factor in dietary programmes aiming at the metabolic syndrome, insulin resistance, and weight loss.

It is hoped that this study will come up with the optimal size of glycemic indices of composite roasted sesame on white bread meal which when consumed will have no effect on the blood glucose level. Knowledge of the glycemic load of glycemic indices of composite roasted sesame could serve as a guide to diabetics to choose these stable foods with the best glycemic load.

This study may also inform nutritionists, dieticians and diet therapists on the glycemic indices of composite roasted sesame on white bread meal recommend to prediabetics and diabetics when they counsel their clients.

This study will also help the reader to understand the nutritional and chemical properties of roasted sesame.

This study will solve the problem of high intake of food containing large amount of carbohydrates. The study also will also make important contribution to future research by contributing to the existing literature particularly on nutrition.

1.6        Scope of the study

The research focused on glycemic indices of composite roasted sesame seeds on white bread and their impact on the blood glucose. This study investigated all the possible roasted sesame seeds meal that are consumed in the country and also analyzes the extent to which each of these affect the blood glucose level.

1.7      Limitations

The study determined the phytochemical properties and glycemic load of roasted sesame seeds. Findings cannot be easily generalized for other carbohydrate foods. The study focused on the effect of roasted sesame seeds has on blood glucose level after it has been digested and so healthy individuals were used for the study.

1.8      Research Question

1. What is the glycemic index for roasted sesame seeds?
2. What is the major cause of diabetes mellitus?

• Do roasted sesame seeds have high glycemic index?

1.9  Project Organisation

The work is organized as follows: chapter one discuss the introductory part of the work,   chapter two presents the literature review of the study,  chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.