ABSTRACT
Physicochemical, microbiological and sensory properties of bread spreads produced from blends of peanuts, cashew nuts and avocado pear was evaluated. Bread spreads were produced from different slurry blends (100:0, 80:10:10, 70:20:10, 60:30:10 and 50:40:10) of peanuts, cashew nuts and avocado pear. Bread spread made from 100 % peanut slurry served as the control. Physicochemical properties, proximate composition, mineral content and microbial quality of the bread spread were evaluated using standard laboratory procedures. The data generated were statistically analysed by One Way Analysis of Variance (ANOVA) using Statistical Product of Service Solution (Version 22). The result of proximate composition showed the moisture (6.80 to 8.48 %), fat content (18.04 to 27.01 %), ash (2.10 to 3.00 %), crude fibre (2.26 to 2.80 %), crude protein (15.90 to 20.20 %) and carbohydrate content (40.49 to 52.68 %) of the bread spreads. The physicochemical properties of the bread spreads showed that its pH and total solids ranged from 6.01 to 6.23 and 64.00 to 65.02 % respectively. In terms of mineral content, bread spread made from 100% peanut had the highest zinc (11.16 mg/100g) and phosphorus content (236.89 mg/100g) whereas bread spread made from 50 % peanut, 40 % cashew nuts and 10 % avocado pear blends had the highest calcium (48.20 mg/100g), magnesium (140.31 mg/100g), iron (7.12 mg/100g) and potassium content (38.60 mg/100g). The result of microbial analysis showed that the total bacteria count of the bread spreads ranged from 2.00x104 to 4.00x104 whereas the total fungi count ranged from 1.00x103 to 5.00x103. Furthermore, presence of coliform count was not detected in the bread spread samples. The sensory properties of the bread spreads ranged from 6.25 to 8.15, 6.40 to 7.55, 6.00 to 7.70, 5.40 to 7.90 and 6.00 to 8.05 for appearance, taste, spreadability, mouth-feel and general acceptability with bread spread made from 50 % peanut, 40 % cashew nuts and 10 % avocado pear having the highest mean scores in all the assessed attributes.
TABLE OF CONTENTS
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of contents vi
List of tables ix
List of figures x
List of plates xi
Abstract xii
CHAPTER 1: INTRODUCTION
1.1 Background of the study 1
1.2 Statement of the problem 2
1.3 Justification of the study 3
1.4 Objectives of the study 4
CHAPTER 2: LITERATURE REVIEW
2.1 Peanuts 5
2.1.1 Nutritional value and health benefits of peanuts 5
2.1.2 Processing and utilization of peanut in food system 7
2.2 Avocado pear 9
2.2.2 Processing and utilization of avocado pear 11
2.3 Overview of cashew nut 12
2.4 Bread spread 13
2.5 Microbial food safety 14
CHAPTER 3: MATERIALS AND METHODS
3.1 Sources of raw materials 22
3.2 Sample preparation 23
3.2.1 Production of peanuts slurry 23
3.2.2 Production of cashew nuts slurry 23
3.2.3 Production of avocado pear slurry 23
3.2.4 Production of bread spread 29
3.3 Methods of analyses 32
3.4 Determination of physicochemical properties of bread spread 32
3.4.1 pH 32
3.4.2 Total solid 32
3.5 Determination of proximate composition of bread spread 32
3.5.1 Moisture content 33
3.5.2 Crude protein 33
3.5.3 Ash 34
3.5.4 Fat 34
3.5.5 Crude fiber 35
3.5.6 Carbohydrate 35
3.6 Determination of mineral content of bread spread 36
3.6.1 Calcium and magnesium 36
3.6.2 Phosphorus 37
3.6.3 Potassium 37
3.7 Evaluation of microbial quality of bread spread 38
3.8 Sensory evaluation 38
3.9 Experimental design 39
3.10 Statistical analysis 39
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Pictorial representation of bread spreads 39
4.1 Proximate composition of bread spreads produced from blends of peanuts, avocado pear and cashew nuts 40
4.2 Physiochemical properties of bread spread samples produced from blends of peanuts, avocado pear and cashew nuts 46
4.3 Mineral content of bread spreads produced from blends of peanuts, avocado pear and cashew nuts 48
4.4 Microbial quality of bread spreads produced from blends of peanuts, avocado pear and cashew nuts 54
4.5 Sensory properties of bread spread produced from blends of peanuts, avocado pear and cashew nuts 56
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 60
5.2 Recommendations 60
REFERENCES 62
LIST OF TABLES
Table 3.1: Preparation of the different sample blends (%) 27
Table 3.2: Recipe for production of bread spread 28
Table 4.1: Proximate composition of bread spreads produced from blends of peanuts, avocado pear and cashew nuts (%) 41
Table 4.2: Physiochemical properties of bread spread produced from blends of peanuts, avocado pear and cashew nuts 47
Table 4.3: Mineral content of bread spread samples produced from blends of peanuts, avocado pear and cashew nuts (mg/100g) 49
Table 4.4: Microbial quality of bread spreads produced from blends of peanuts, avocado pear and cashew nuts 55
Table 4.5: Sensory properties of bread spread produced from blends of peanuts, avocado pear and cashew nuts 57
LIST OF FIGURES
Figure 3.1: Flow chart for production of peanuts slurry 24
Figure 3.2: Flow chart for production of peanuts slurry 25
Figure 3.3: Flow chart for production of avocado pear slurry 26
Figure 3.4: Process flow chart for bread spread 30
LIST OF PLATES
Plate 1: Cashew nuts 22
Plate 2: Groundnuts 22
Plate 3: Avocado pears 22
Plate 4: Bread spread made from 100% peanut 31
Plate 5: Bread spread made from 80% peanut, 10 % cashew nuts
and 10 % avocado pear 31
Plate 6: Bread spread made from 70% peanut, 20 % cashew nuts
and 10 % avocado pear 31
Plate 7: Bread spread made from 60% peanut, 30 % cashew nuts
and 10 % avocado pear 31
Plate 8: Bread spread made from 50% peanut, 40 % cashew nuts
and 10 % avocado pear 31
CHAPTER 1
INTRODUCTION
1. BACKGROUND OF STUDY
Increasing search for nutritious food products has led to the substitution of animal based foods with plant based foods (Gorrepati et al., 2015). Recently, consumers are looking for products that are not only nutrient dense but provide health benefits (Jnawali et al., 2016). Many households use margarine as bread spread but due to the concerns raised by health practitioners about trans-fats in margarine, its consumption is being discouraged (Amevor et al., 2018), thereby leading to production of spread from crops like cashew nut, avocado pear and peanut.
Cashew (Anacardium occidentale L.) belongs to the genus Anacardium, a member of the family Anacardaceac. In Nigeria, cashew is known among Igbo, Yoruba and Hausa tribes as “Kashuu”, “Caju” and “Kadinnia” respectively (Nwosu et al., 2014). Cashew nut contains 2.88 % crude fibre, 28.20 % crude protein and 1.44 % carbohydrates (Okonkwo and Ozoudee, 2015). It is a rich source of minerals like manganese, potassium, copper, iron, magnesium, zinc and selenium (Olife et al., 2013). Cashew nut does not have relatively high cholesterol (Olife et al., 2013). It contains essential fatty acids which are necessary for the proper functioning of the body and play an important role in the regulation of several metabolic processes (Soares et al., 2013). Cashew nut can be processed into numerous food products. According to Shakerardekami and Karim (2012), utilization of cashew nut in production of spread has potential to improve the food uses of cashew nuts and introduce consumers to a healthier novel food product.
Peanut (Arachis hypogea L.) is a very popular crop cultivated across Africa. In Nigeria, it has many local names like epa (Yoruba), ayayaa (Hausa), opapa, asibpko (Ibo), omizaguo (Owan) and isagwe (Benin) (Abdulraham et al., 2014). Peanut is technically considered as pea and belongs to the family of legume. Although a legume, it is generally included amongst the oilseeds due to its high fat content (Suchoszek-Lukaniuk et al., 2011). Peanut contains all the 20 amino acids in variable proportions and it’s the biggest source of arginine (USDA, 2014). Peanut is referred to as poor man’s protein as they are available at an affordable price (Settaluri et al., 2012). Peanuts possess 92.00 mg/100g calcium, 1.14 mg/100g copper, 4.58 mg/100g iron, 168.00 mg/100g magnesium, 1.93 mg/100g manganese, 76.00 mg/100g phosphorus, 3.27 mg/100g zinc and 7.20 µg/100g selenium (Ayra et al., 2016). They can be processed into numerous food products by boiling, roasting, milling, pounding, and so on.
Avocado pear (Persea americana) is derived from the Aztec word “ahucatl”. It is a member of the family Lauraceae. Avocado pear is also called Alligator pepper, reflecting its shape and the leather like appearance of its skin (Orhevba and Jinadu, 2011). Avocado pear is a nutrient dense fruit with the composition depending on cultivar, degree of maturity and growing conditions (Schaffer et al., 2012). Nwaokobia et al. (2018) showed that avocado pulp contains fat (31.64 %), protein (1.62 %), carbohydrate (53.74 %), crude fibre (1.08 %), magnesium (40.77 mg/100g), calcium (27.13 mg/100g), phosphorus (31.63 mg/100g) and potassium (28.02 mg/100g). Avocado pear contains 66.67 % monosaturated, 14.29 % saturated fatty acid and 12.24 % polyunsaturated fatty acid (Gillingham et al., 2011). Avocado pear possess numerous health benefits like reduction in risk of cataracts (Sen et al., 2015).
1.4 STATEMENT OF PROBLEM
Margarine is widely used by many households as bread spread. However, margarine contains trans-fats which are detrimental to human health. Consistent consumption of food high in trans-fat results to cardiovascular diseases, breast cancer, shortening of pregnancy period, disorders of nervous system and vision in infants, colon cancer, diabetes, obesity and allergy (Vandana et al., 2011). These prompted the need for an alternative plant based spread. A high quantity of Avocado fruits which possess the potential to be utilized in spread production are loss to spoilage due to that they respire after harvest. More so, protein malnutrition is a major public health problem in most developing nations in the world; most diets in these parts are predominantly starchy, the major food crops being roots and tubers. Animal products representing high concentration and quality of protein are either unaffordable or too expensive thus, increasing the dependence on tuber, roots and cereal crops. This results to inadequate intake of protein leading to malnutrition in both children and adults.
1.3 JUSTIFICATION OF STUDY
Processing of peanut seeds, cashew nuts and avocado pear pulp into bread spread will go a long way to promote their use in food system, hence encourage famers to produce more of the crops, preferably on a commercial scale and in turn contribute in curbing postharvest loss of avocado fruits. Bread spread produced in this study will not only introduce consumers to a healthier breakfast product devoid of trans-fat but will also add to the varieties of bread spread available in the market for consumers. More so, frequent consumption of spread produced in this study remains one of the most practicable option to ensure accessibility of protein developing nations like Nigeria.
1.5 OBJECTIVES OF THE STUDY
The main objective of the study was to evaluate the quality characteristics of bread spread made from blends of peanut seeds, cashew nuts and avocado pear fruits.
The specific objectives were to:
i. produce bread spread from peanut, avocado pear and cashew nuts blends
ii. determine the physicochemical properties of the bread spread
iii. determine the proximate composition of the bread spread
iv. evaluate the microbiological quality of the bread spread
v. evaluate the sensory properties of the bread spread.
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