ABSTRACT
The physicochemical composition, antioxidant and sensory properties of melon-seed coconut cheese was studied. The proximate composition mean values ranged from 51.45 to 59.93 % moisture, 9.84 to 20.15 % protein, 0.11 to 0.73 % crude fiber, 3.79 to 7.47 % fat, 1.41 to 2.10 % ash, 10.76 to 32.73 % carbohydrate and 190.77 to 204.33 Kcal energy. The mineral composition mean values ranged from 702.26 to 982.13 mg/100g calcium, 311.91 to 674.17 mg/100g sodium, 65.16 to 104.05 mg/100g magnesium, 35.25 to 50.12 mg/100g phosphorus, 129.13 to 160.22 mg/100g potassium, 2.82 to 5.87 mg/100g iron and 2.88 to 5.12 mg/100g zinc. The vitamin composition mean values also ranged from 371.03 to 440.27 mg/100g vitamin A, 0.38 to 0.76 mg/100g vitamin B1, 1.13 to 2.68 mg/100g vitamin B2, 1.38 to 3.81 mg/100g vitamin B3 and 0.38 to 0.62 mg/100g vitamin E. The mean values of the chemical composition of the cheese samples ranged from 6.13 to 6.97 pH, 0.07 to 0.19 % TTA and 40.08 to 48.55 % total solid. The antinutrient mean values ranged from 0.41 to 1.87 % alkaloid, 0.19 to 1.42 % saponin, 1.05 to 2.06 % tannin, 0.87 to 1.48 % phytate and 0.07 to 0.95 mg/kg cyanide. The result of the correlation coefficient showed that, flavonoid correlated (R2 = 0.671) positively with DPPH and FRAP assays while there was a strong negative correlation (R2 = -.873) between phenol and antioxidant activities (ABTS and FRAP). The sensory evaluation mean scores ranged from 5.10 to 7.14 appearance, 5.20 to 7.35 tatse, 6.10 to 6.90 flavour, 5.40 to 7.80 texture and 6.00 to 7.45 general acceptability. The study concludes that producing cheese from melon and coconut milk blend (30 % melon:70 % coconut cheese) may be a promising means of value addition and to further promote the utilization of coconut and melon milk beyond the traditional usage.
TABLE OF CONTENTS
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables xi
List of Figures xii
List of Plates xiii
Abstract xiv
CHAPTER 1: INTRODUCTION 1
1.2 Statement of Problem 2
1.3 Justification 3
1.4 Objective of the study 3
CHAPTER 2: LITERATURE REVIEW
2.1 Cheese 5
2.1.1 Cheese Producing Potential of Milk 5
2.1.2 Composition of Cheese 5
2.1.3 Classification of Cheese 6
2.1.4 Selection of Milk for Cheese-Making 8
2.1.5 Manufacture of Cheese, Role of Enzymes, Proteins and Fat 9
2.1.5.1 Coagulation of Milk 9
2.1.5.2 Cutting 13
2.1.5.3 Cooking 13
2.1.5.4 Draining 14
2.1.5.5 Salting and Milling 14
2.1.5.6 Forming and Pressing 15
2.1.5.7 Curing or Ripening 15
2.1.6 Changes in Cheese during Ripening 16
2.1.7 Spoilage of Cheese 17
2.1.8 Storage and Preservation of Cheese 19
2.1.9 Need for Cheese Analogues 20
2.2 Coconut 21
2.2.1 Description and origin 21
2.2.2 Coconut fat 22
2.2.3 Coconut meat 23
2.2.4 Coconut milk 24
2.2.5 Nutritional and medicinal importance of coconut milk 25
2.3 Melon (Citrullus colocynthis l.) 27
2.3.1 Origin and Distribution 27
2.3.2 Consumption and Uses 28
2.3.3 Nutritional Information 28
2.3.4 Nutritional Benefits 28
CHAPTER 3: MATERIALS AND METHODS
3.1 Source of Raw Material 31
3.2 Preparation of Coconut Milk 31
3.3 Preparation of Melon Seed Milk 31
3.4 Preparation of Cheese 37
3.5 Proximate Analysis of the samples 41
3.5.1 Determination of Moisture content 41
3.5.2 Determination of Crude protein 41
3.5.3 Determination of Ash content 42
3.5.4 Determination of Fat content 43
3.5.5 Determination of crude fiber 44
3.5.6 Determination of Carbohydrate content 45
3.5.7 Determination of Energy value 45
3.6 Determination of Mineral Elements 45
3.7 Determination of Vitamins 46
3.7.1 Determination of Vitamin A (carotenoid) 46
3.7.2 Determination of Thiamine (Vitamin B1) 47
3.7.3 Determination of riboflavin (Vitamin B2) 48
3.7.4 Determination of Niacin (Vitamin B3) 49
3.7.5 Determination of vitamin E 50
3.8 Physicochemical Composition of the Samples 51
3.8.1 Determination of pH 51
3.8.2 Determination of total solid 51
3.8.3 Determination of Total Titrtable Acidity (TTA) 51
3.8.4 Determination of Minerals 52
3.9 Determination of Phytochemical Composition 52
3.9.1 Determination of tannin 52
3.9.2 Determination of phytate 53
3.9.3 Determination of Alkaloids 54
3.9.4 Determination of Saponin 54
3.9.5 Cyanide content determination 55
3.10 Determination of the Antioxidant Composition of the Samples 56
3.10.1 Determination of DPPH (2,2-Diphenyl-1-picrylhydrazyl) 56
3.10.2 Determination of FRAP (Ferric Reducing/Antioxidant Power) 56
3.10.3 Determination of Antioxidant Activity Using the ABTS Free Radical Scavenging Method
3.11 Sensory Evaluation 57
3.11 Statistical analysis 58
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Proximate composition of the samples 59
4.2 Mineral composition of the samples 63
4.3 Vitamin composition of the samples 68
4.4 Physiochemical Composition of the samples 71
4.5 Antinutrient composition of the samples 74
4.6 Antioxidant composition of the cheese samples 77
4.7 Correlation coefficient of antioxidant activity of the cheese samples 79
4.8 Sensory evaluation of the samples 81
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 83
5.2 Recommendations 83
References 84
LIST OF TABLES
Table 2.1 Composition of cheese 7
Table 2.2 Classification of Cheese by Fat Content 8
Table 2.3 Countries where coconut is abundant 22
Table 2.4 Composition of coconut milk 25
Table 3.1 Milk blend formulation 38
Table 4.1 Proximate composition of melon seed-coconut milk cheese 60
Table 4.2 Mineral composition of melon seed-coconut milk cheese 64
Table 4.3 Vitamin composition of melon seed-coconut milk cheese 69
Table 4.4 Physiochemical Composition of melon seed-coconut milk cheese 72
Table 4.5 Antinutrient composition of melon seed-coconut milk cheese 75
Table 4.6 Correlation coefficient of antioxidant activity of the cheese samples 80
Table 4.7 Sensory evaluation of melon seed-coconut milk cheese 82
LIST OF FIGURES
Figure 3.1 Flow chart for the production of coconut milk 34
Figure 3.2 Flow chart for the production of melon seed milk 36
Figure 3.3 Flow chart for the production of melon seed-coconut cheese 39
Fig. 4.1: Antioxidant and antioxidant activity of melon seed coconut milk cheese 78
LIST OF PLATES
Plate 3.1: unshelled Coconut seed 32
Plate 3.2: Deshelled melon seeds 33
Plate 3.3: Blended melon seeds 35
Plate 3.4: 100% Cow milk cheese 40
Plate 3.5: Melon seed coconut cheese sample 40
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Cheese is a dairy product derived from milk that is produced in a wide range of flavours, textures and forms by coagulation of the milk protein casein. It comprises proteins and fat from milk, usually the milk of cows, buffalo, goats or sheep (Balogun et al., 2016).
In many parts of tropical Africa, milk and milk products are scarce and unaffordable by the majority of the populace (Ekanem and Ojimelukwe, 2017). The high and unaffordable cost of milk in some developing countries like Nigeria has made it necessary to source less expensive plant products that could be used as substitutes for milk products or to augment the use of milk products for effectiveness in fighting protein malnutrition.
Coconut is much cheaper than cow milk and using it for substitution will reduce the cost of the cheese product. Coconut milk is a sweet rich tasting, nutrient dense white fluid derived from the meat of the coconut fruit. It is rich in oil, protein and sugars (Ekanem and Ojimelukwe, 2017). It is cheaper than cow milk and has the potentials to act as a cow milk complement in milk products.
Nowadays, consumers prefer not only natural, healthy and delicious food, but also environmental friendly produced foods. In underdeveloped and/or developing countries, food producers have focused on researching and developing alternative milk and milk products obtained from vegetable sources due to the inadequacy of dairy milk source, variety of consumers diet preferences (vegan/vegetarian diet, special diet for religious reasons) and allergen and sensitivity of dairy products (lactose intolerance, milk allergies) (Heyman, 2006). Vegetable milk was used for different purposes; such as raw material or flavour enhancing for beverage/drink productions, thickening or emulsifying agents for soup. Soy, almond, rice, and coconut milk were widely produced and consumed as vegetable milks in the world (Belewu and Belewu, 2007). The other vegetable milk sources such as wheat, sunflower seed, pumpkin seed and melon seed also draw researchers’ attention (Diarra et al., 2005).
Melon seed was qualified as a waste product containing high amount of protein, fat, carbohydrates and other metabolites such as minerals (Ogunwa et al. 2015). Obi and Offorha (2015) reported that the melon seeds could be used for emulsifying, flavoring, thickening in soups or as a snack after frying. The melon seed milk (MSM) which was one of the plant derived milk, had the potential to be nutritious and healthy beverage for vegan/vegetarian diet and/or people who have lactose intolerance.
Hence, the production of melon seed-coconut-like cheese will ensure a safe and economic product due to its natural ingredients which can be sourced locally.
1.2 STATEMENT OF PROBLEM
Over the years, the importation of extremely large quantities of milk to satisfy the consumer demands for milk and other dairy products such as cheese has been the source of genuine concern for the governments, processors and consumers alike because the imported milk is expensive and it drains large sums of foreign exchange reserves. It is therefore regarded as urgent and timely to develop dairy-type products from less expensive alternative sources of indigenous raw materials, such as melon seeds and coconuts.
The existing problem is also, the result of companies’ heavy reliance on additives, synthetic nutrients, and other unhealthy ingredients to sustain and sell their products.
Too much intake of this processed food contributes to the declining ability of the body to absorb potential antioxidants, which the body needs in order to self – heal sufficiently. Antioxidants play a vital role in the maintenance of the different body systems to run smoothly, and when insufficient, the natural defense mechanism would abruptly go down with higher risks of accelerated aging in a short amount of time. Hence, there is need to produce cheese-like product from natural and indigenous raw material such as melon seed and coconut.
1.3 JUSTIFICATION
Traditionally, coconut was manufactured as an intermediate product for food-based uses in the form of coconut protein, powder and canned coconut milks. Successful development of new products, such as melon seed-coconut cheese, would bring substantial economic benefits to the melon and coconut industry. The new product developed from melon seed and coconut could potentially be of desirable nutritional composition especially in relation to cholesterol inducing fat levels, being as it is that the saturated fat content in coconut milk has been shown to be a good saturated fat, easily metabolized to give the body quick energy. Production of melon seed-coconut-cheese will help to diversify the utilization of melon seed and coconut and these crops being our local produce, will help improve the agricultural sector. This research work is also expected to help in the production of new inexpensive type of dairy-like foods from coconut and melon seed.
1.4 OBJECTIVE OF THE STUDY
The main objective of this work was to evaluate the physicochemical, antioxidant and sensory properties of melon seed-coconut cheese.
The specific objectives were to:
i. produce coconut and melon seed milk
ii. produce cheese product from melon seed and coconut milk of different formulations
iii. determine the physicochemical properties of the cheese product
iv. determine the antinutrient composition of the cheese
v. determine the sensory properties of the cheese
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