PHYTOCHEMICALS, PHYSICAL AND SENSORY QUALITIES OF BREADS SUPPLEMENTED WITH FERMENTED SWEET ORANGE PEEL FLOUR

PHYTOCHEMICALS, PHYSICAL AND SENSORY QUALITIES OF BREADS SUPPLEMENTED WITH FERMENTED SWEET ORANGE PEEL FLOUR

ABSTRACT The study investigated the quality of bread supplemented with fermented sweet orange peel flour. Flour was prepared from sweet orange peels. Fermented sweet orange peel flour and unfermented sweet orange flour were analyzed for proximate composition and phytochemical contents.  Fermented sweet orange peel flour was   used to substitute 5, 10, 15, 20 and 30% wheat flour in breads which was analyzed for proximate composition, phytochemical contents, physical and sensory properties. The fermented sweet orange peel flour had slightly higher protein content than the unfermented sweet orange peel flour. The moisture, fat, ash and carbohydrate contents of the fermented and unfermented sweet orange peel flour were not significance different (p0.05).The levels of flavonoids, saponins, carotenoids and total phenol were not significance different (p0.05) in the breads supplemented with fermented sweet orange peel flour. The bread containing 5% fermented sweet orange peel flour were not significance different from the 100% wheat flour bread in all sensory attributes studied. The volume, weight, height and length of the breads decreased steadily with increased levels of fermented sweet orange peel flour in breads.   

TABLE OF CONTENTS                                                                 PAGES

Title Page —————————————————————– i

Certification ————————————————————– ii

Declaration ————————————————————— iii

Dedication —————————————————————- iv

Acknowledgement ——————————————————-          v

Abstract ——————————————————————- vii

Table of Contents ——————————————————–         viii

CHAPTER ONE

1.0     Introduction ——————————————————–        1

• Statement of the Problem ————————————— 3

1.2     Objectives ——————————————————— 3

1.2.1  Broad Objective —————————————————        3

1.2.2  Specific Objectives ———————————————–         4

1.3     Significance of the Study —————————————-        4

CHAPTER TWO

2.0     Literature Review ————————————————–       5

2.1.    Origin and Distribution of Sweet Orange————————   5

2.2     Morphology of Orange Fruit ————————————–    5

2.3     Chemical Composition of Orange Peel and Pulp —————  7

2.4     Phytochemical Composition in Orange Peel —————————– 10

2.5     Uses of Orange Peel ———————————————————     11

2.5.1  Orange Zest ——————————————————————-     11

2.5.2 Preserve Brown Sugar ——————————————————    11

2.5.3 It is used in Dipped in Chocolate ——————————————- 11

2.5.4 Deodorizer ——————————————————————–      12

2.5.5 Citrus Cleaner —————————————————————-     12

2.5.6 Lower Blood Pressure —————————————————–      12

2.6     Health Benefits of Orange Peel ——————————————-     12

2.7     Wheat (tricium aestulum) ————————————————–     13

2.7.1  Chemical Composition of Wheat ——————————————   14

2.7.2  Phytochemical Composition of Wheat Flour —————————– 16

2.7.3  Uses and Baking Property of Wheat Flour ——————————–         16

2.8.    Composite Flour ————————————————————–   17

2.9     Bread ————————————————————————–      17

2.9.1. Types of Bread —————————————————————    18

2.10   Bread Preparation ———————————————————–     19

2.10.1 Chemical Composition of Bread ——————————————  21

2.10.2         Physical Properties of Bread ———————————————–  23

2.11   Fermentation —————————————————————        23

2.11.1 Types of Fermentation —————————————————      24

2.11.2 Alcoholic Fermentation —————————————————     24

2.11.3 Lactic Acid Fermentation ————————————————-     24

2.11.4 Butyric Acid Fermentation ————————————————   25

2.11.5 Acetone-Butyl Alcohol Fermentation ———————————-    26

2.11.6 Fermentation of Proteins ————————————————-       27

2.11.7 Propionic-Acid Fermentation ——————————————–    27

2.11.8 Acetic-Acid Fermentation ————————————————     28

2.11.9 Gluconic-Acid Fermentation ——————————————–     28

2.12   Importance of Fermentation ———————————————-     29

2.13. Health Benefits of Fermented Foods ————————————     31

CHAPTER THREE

3.0     Materials and Methods —————————————————-      32

3.1     Source of Raw Materials ————————————————–      32

3.2     Preparation of Orange Peel Flour —————————————-    32

3.3     Preparation of Fermented Orange Peel Flour —————————  32

3. 4 Flour Blending ————————————————————– 34

3.5     Preparation of Bread ——————————————————-     34

3.6     Analytical Methods ———————————————————     36

3.6.1  Physical Evaluation of Breads ——————————————-     36

3.6.1.1 Determination of Length and Height ———————————–   36

3.6.1.2  Determination of Weight ————————————————     36

3.6.1.3 Determination of Volume ————————————————    36

3.6.1.4 Determination of Density ———————————————–      36

3.6.1.5 Determination of Oven Spring —————————————–     37

3.7     Senesory Evaluation of Breads —————————————–       37

3.8     Determination of Proximate Composition ——————————-  37

3.8.1  Determination of Ash Content ——————————————–    37

3.8.2 Determination of Moisture Content ————————————–    38

3.8.3 Determination of Fat Content ———————————————     38

3.8.4 Determination of Crude Fiber Content ———————————-    39

3.8.5 Determination of Protein Content (Micro Kjeldehl Method) ———- 40

3.8.6 Determination of Carbohydrate Content ———————————  40

3.9    Determination of Phytochemical Composition ————————–  41

3.9.1  Determination of Flavonoids Content ————————————  41

3.9.2   Determination of Carotenoids Content ———————————-  41

3.9.3  Determination of Total Phenol ——————————————-    41

3.9.4 Determination of Saponins ————————————————-    42

3.10   Statistical Analysis ———————————————————      43

CHAPTER FOUR

4.0     Results and Discussion —————————————————-      44

4.1     Proximate Analysis ——————————————————–      44

4.2.    Phytochemical Analysis of Wheat Flour, Fermented and Unfermented      Sweet Orange Peel Flours ———————————————–         46

4.3     Sensory Properties ——————————————————-         48

4.4     Physical Analysis ——————————————————–         49

CHAPTER FIVE

5.0     Conclusion and Recommendations ————————————-      52

5.1     Conclusion —————————————————————- 52

5.2     Recommendations ——————————————————–        52

References —————————————————————– 53

Appendix ——————————————————————-        57

CHAPTER ONE

1.0     INTRODUCTION

Bread and other baked products are widely consumed throughout the world. Bread has been an important food and energy source throughout human history. Bread has for years gained consumers acceptance in Nigeria. It is basically made from wheat flour, water, yeast and salt by a series of processes involving mixing, kneading, proofing, shaping and baking (Dewettink, et al., 2008).

Recently, Nigeria introduced 10% cassava bread (Act,2005), which results in the reduction of the protein content of bread. Food fortification has become a popular method of addressing problems of micronutrient deficiencies and has been used in many countries (Bowley, 2003). However, most effective approach is the use of natural sources of micronutrients such as fruits, vegetable, eggs, mushroom and legumes instead of synthetic supplement materials (Badifu, et al., 2005).

A typical conventional bread loaf is high in carbohydrate (51-60%), low in protein (5-7.2%), low in micronutrients like (Fe, P, Ca, Zn) and supplies about 240kcal of energy per 100g (Shakuntala and Shadaksharawsi, 2006) which  is derived mainly from its wheat carbohydrates and protein. The use of orange peel which is abundant in vitamins, phytochemicals, dietary fiber and fair in protein (which are almost absent in bread) to fortify bread would help to improve the nutritional and organoleptic quality.

Phytochemical literally means “plant chemicals”,  are naturally occurring chemicals produced by plants. They are biologically active and may affect health. However unlike vitamins and minerals, they are not considered to be essential nutrients. Some of the best known phytochemicals include, carotonoids, flavanoids, terpenes, inositol, polyphenols, etc.

Wheat (Tricicum Spp) is a cereal grain. It is the world third most produced cereal in 2015 (FAOSTAT, 2015). Globally, wheat is the leading source of vegetable protein in human food, having higher protein content than other major cereals, such as maize (corn) or rice. Wheat is very rich in many nutrients which make it a source of many foods in the world. Raw wheat can be ground into semolina, germinated and dried, creating malt. Wheat is a major ingredient in such foods as bread porridge, crackers, biscuits, cakes, cookies, muffins, boza (a fermented beverage) pies, pastries, gravy breakfast cereals (e.g. wheaten, cream of wheat, shredded wheat) etc.

Sweet orange Citrus sinensis is the world most commonly cultivated fruit tree. It belongs to the Rutucea family which comprises of mandarins, lemons, limes, grape fruits, sour and sweet oranges (Karoui and Marzouk, 2013). Citrus fruit are of immense economic value; occupying the top position in fruit production. Orange trees are widely cultivated in tropical and subtropical climates. The fruit is composed of an external layer (peel) formed of flavedo (epicarp or exocarp) and albedo (mesocarp) and inner material called endocarp that contains vesicles with juice (Liu et al., 2007).

However, orange contains substantial vitamin C, potent water soluble vitamins essential for healthy living. The consumption of orange peel confers some protection against diseases such as cardiovascular diseases and cancer (Baghurst, 2003; Guimareaset al., 2010; Atolaniet al., 2012).

• STATEMENT OF THE PROBLEM

Wheat is low in phytochemicals but sufficiently available in orange peels. Substitution of wheat flour with orange peel flour in baking can save foreign exchange spending since its use will discourage importation of large quantity of wheat flour. The rate of loss of orange peel annually is high. It is therefore, hoped that with an appropriate level of orange peel flour incorporated into wheat flour for bread, will prevent these high losses. Certain individuals with celiac disease react to high level of cereal protein particularly gluten in wheat. Bread from orange peel flour which is very low in gluten content is solution to this chronic disease.

1.2     OBJECTIVES

1.2.1  Broad Objective

The broad objective of this study was to determine the quality of bread supplemented with fermented sweet orange peel flour.

1.2.2  Specific Objectives

The specific objectives of the study are to determine the:

1. Chemical composition and functional properties of wheat flour and fermented sweet orange peel flour
2. Chemical composition and phytochemical contents of bread supplemented with fermented sweet orange peel flour.
3. Sensory characteristic of bread supplemented with fermented sweet orange peel flour.

1.3 SIGNIFICANCE OF THE STUDY

Orange fruit is readily available almost all through the season. Orange peels are by products of fruits processing and are usually regarded as waste. These products are rich in phytochemical, fibers and nutrients. The incorporation of orange peel flour into bread would deliver significant levels of nutrients and phytochemicals to Nigerian diets. The use of the peel in bread would help to solve waste disposal problem associated with orange fruit processing in addition to conserving foreign exchange on wheat importation.

The flow chart for the production of orange peel flour is given in Fig .1

Orange fruit

Sorting

Washing

Peeling

Slicing

Sun drying

Milling

Sieving

Packaging

Storage

Fig.1: Flow chart for the production of orange peel flour

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