ABSTRACT
This study evaluated the impact of palm oil and yellow maize addition on composition, antioxidant, physical and sensory properties of biscuits. Five samples of biscuits were produced from wheat-maize flours (50:50%) with different levels of Palm oil substitutions 10% (EI2), 20% (EI3), 35% (EI4), 45% (EI5) and 60% (EI6) for shortening. A control biscuit sample, EI 1 was produced from 100% wheat flour and shortening. The biscuits samples were analyzed for quality characteristics using standard methods. The bulk density (0.78-0.84%), water absorption capacity (0.93-1.13%), oil absorption capacity (1.10-1.30%) and hydrophilic (0.78-0.98) differed significantly (p<0.05). The proximate composition of the biscuits ranged from moisture (6.86-8.32), protein (8.24-11.27), fat (19.65-28.21), crude fibre (1.41-1.88), Ash (1.69-2.14), Carbohydrate (52.06-58.21), Energy level (454.71-495.05) and dry matter (91.69.93.14). The Vitamin A (1.73-151.90 IU/ml), Vitamin C (3.28-6.24 mg/100g) and phytochemical, Flavonoids (0.73-1.45%) and phytate (0.03-0.12%) content of the biscuits differed significantly (p<0.05). Antioxidant activity of the biscuits showed that there were significant difference (P<0.05) among the samples. Dietary fibre of the biscuits showed that there were significant difference (P<0.05) among the samples. The Sensory properties of the biscuits samples also showed that the level of likeness of the sensory attributes: appearance, taste, texture, aroma, crunchiness, and general acceptability reduced in the composite flour substitution were moderately liked but there were no significant difference (P<0.05) in the general acceptability and Control (100% wheat flour) sample was liked extremely by the panelist. Palm oil substituted in the biscuits also contains anti-oxidants like β carotene which prevents food from oxidation and increases the energy levels of children and the elderly because it contains calories.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of content vi
List of tables x
List of figures xi
List of plates xii
Abstract xiii
CHAPTER 1: INTRODUCTION
1.1 Background of study 1
1.2 Statement of problem 4
1.3 Justification of the study 4
1.4 Objectives of the study 4
CHAPTER 2: LITERATURE REVIEW
2.1 History of Biscuits 5
2.2 Maize 6
2.2.1 Nutrient composition of maize 7
2.2.2 Health benefit of maize 8
2.2.3 General uses of maize 9
2.3 Wheat 9
2.3.1 Nutrient composition of wheat 11
2.3.2 Health benefit of wheat 12
2.3.3 General uses of wheat 13
2.4 Palm oil 14
2.4.1 Antioxidant in palm oil 16
2.4.2 Nutrient composition of palm oil 18
2.4.3 Health benefit of palm oil 18
2.5 Baking principle 20
2.6 Ingredients of biscuits 21
CHAPTER 3: MATERIALS AND METHODS
3.1 Materials 26
3.2 Sample preparation 26
3.2.1 Production of maize flour 26
3.2.2 Production of biscuits 26
3.3 Method of Analysis 31
3.3.1 Functional analysis of flour 31
3.3.1.1 Determination of bulk density 31
3.3.1.2 Determination of water absorption of flour 31
3.3.1.3 Determination of oil absorption of flour 32
3.3.1.4 Determination of hydrophilic and lipophilic property of the flour 32
3.3.2 Proximate analysis of biscuits 32
3.3.2.1 Determination of fat 32
3.3.2.2 Determination of moisture 33
3.3.2.3 Determination of crude protein 33
3.3.2.4 Determination of ash content 34
3.3.2.5 Determination crude fibre 35
3.3.2.6 Determination of carbohydrate content 35
3.3.2.7 Determination of energy value 35
3.3.3 Physical analysis of biscuits 36
3.3.3.1 Determination of specific volume 36
3.3.3.2 Determination of spread ratio 36
3.3.3.3 Determination of spread factor 36
3.3.4 Vitamin content of the biscuits 37
3.3.4.1 Determination of Vitamin A 37
3.3.4.2 Determination of Vitamin C (carotenoids) 37
3.3.5 Phytochemical content of the biscuits 38
3.3.5.1 Determination of flavonoids 38
3.3.5.2 Determination of phytate 39
3.3.6 Dietary fibre of the biscuits 39
3.3.6.1 Determination of soluble, insoluble and total dietary fibre 39
3.3.6.2 Determination of resistant starch 40
3.3.7 Antioxidant activity of the biscuits 41
3.3.7.1 Determination of DPPH 41
3.3.7.2 Determination of FRAP 41
3.3.7.3 Determination of TBA 42
3.3.8 Sensory evaluation of the biscuits 42
3.4 Experimental design 43
3.5 Statistical analysis 43
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Pictorial presentation of biscuits samples 44
4.2 Functional determination of the biscuits 45
4.3 Proximate determinations of the biscuits 48
4.4 Physical determination of the biscuits 52
4.5 Vitamin and phytochemical of the biscuits 54
4.6 Dietary fibre of the biscuits 57
4.7 Antioxidant activity of the biscuits 60
4.8 Sensory determination of the biscuits 62
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 65
5.2 Recommendations 65
REFERRENCES
APPENDIX 77
LIST OF TABLES
Table 3.1: Formulation of composite flour % 27
Table 3.2: Formulation of Shortening and palm oil in % 28
Table 3.3: Recipe for biscuit production 28
Table 4.1: Functional determination of the biscuits flours 46
Table 4.2: Proximate determination of the biscuits 49
Table 4.3: Physical determination of the biscuits 52
Table 4.4: Vitamin and phytochemical determination of the biscuits 54
Table 4.5: Sensory determination of the biscuits 62
LIST OF FIGURES
Fig. 3.1: Flow chart for the production of maize flour 29
Fig 3.2 Flow chart for the production of Biscuits 30
Fig. 4.1 Dietary fibre profile of the biscuit samples 58
Fig. 4.2: Antioxidant profile of the biscuit samples 61
LIST OF PLATES
Plate 1: Picture of maize-wheat biscuits substituted with palm oil 44
Plate 2: Picture of packaged maize-wheat biscuits substituted with palm oil 44
Plate 3: Yellow maize 77
Plate 4: Maize flour 77
Plate 5: Wheat flour 78
Plate 6: Palm Oil 78
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
In Nigeria biscuits is one of the most consumed cereals food apart from bread, because they are readily available in local shops as ready to eat, convenient and inexpensive food products containing digestive and dietary principles of vital importance (Kulkarni, 1997). Biscuits belong to the flour confectionery. Biscuit is flat crisp, dry in nature, small, thin and flat shape and may be sweetened or unsweetened according to preference. Biscuit can be made from hard dough, for example crackers, hard sweet dough for example rich tea and short or soft dough for example short bread and short cake (Nwosu, 2013). Biscuit can be defined as a small baked product made principally of flour, sugar and fat (Manley, 1998).
Biscuits are produced as nutritive snacks from unpalatable dough that is transformed into appetizing products through the application of heat in the oven (Olaoye et al., 2007). It is different from other baked products like bread and cakes as biscuit has low moisture content. Its moisture content is usually less than 4% and thus it has long shelf life, perhaps six months or longer. According to Manley (2000), biscuits can be divided into 10 major types: 1. Bread, pizza and crisp bread, 2. Water biscuits and soda crackers, 3. Cream crackers, 4. Cabin biscuits, 5. Savoury crackers, 6. Semisweet/hard-sweet, 7. Continental semi-sweet, 8. Short dough (moulded), 9. Wire cut types, 10. Short dough (sheeted). Wire cut types have the highest fat content in their formulation compared to other types of biscuit (Manley, 1998). Biscuits are the most consumed bakery products due to its nature, good nutritional quality, affordable cost and availability in different varieties (Azza et al., 2016).
Wheat is the main ingredient for biscuit production, though imported; it is a carbohydrate based food raw material and also lack some nutrients. It is used in food production because it has a unique ability to form a cohesive gluten network when worked with water (Peter-Ikechukwu et al., 2018). Wheat flour constitutes the basic ingredients for biscuit production because of its gluten protein, which are not present in the flour of other cereals. Wheat flour is produced than any other flour. Wheat varieties are called soft or weak if gluten content is low and are called hard or strong if they have high gluten content. Gluten protein forms elastic dough during baking and gives high organoleptic quality to the finished product (Rai et al., 2017).
Maize (Zea mays) is also referred to as corn, and both words are used as synonyms. Maize ranks as the second most widely produced cereal crop worldwide. Maize flour contains high levels of many important vitamins and minerals, including potassium, phosphorus, zinc, calcium, iron, thiamine, niacin, vitamin B6 and folate (Watson, 1997). Maize (Zea mays L.) is one of the most important cereal grain and one of the main source of cereals for food, forage and processed industrial products. Maize is one of the earning grain crops and in the world it is perhaps the most versatile. It is used in the human diet in both fresh and processed form. Maize is generally used for animal feed. It is widely processed into various types of products such as cornmeal, grits, starch, flour, snacks, and breakfast cereals (Shah et al., 2016).
Biscuits are prominent ready-to-eat baked snack among the people, globally. The association of wheat consumption with such health problems as celiac disease makes it pertinent to utilize composite flour in biscuit manufacture (Kiin- Kabari and Giami, 2015). The technology of composite flours represents an interesting option for the management of costs associated with importation of wheat flour in developing countries where wheat is not cultivated for climatic reasons (Olaoye et al., 2006).
Composite flour has been defined as a mixture of different ratios of non-wheat flour from cereals, legumes, roots and tubers with or without wheat flour. In many countries, biscuits are prepared with fortified or composite flour to increase their nutritive value (Hasmadi et al., 2014). Maize and wheat flours are frequently used in various pharmaceutical and food formulations all over the world. These flours are used either in their pure form or in the form of their blends with other seed flours such as groundnut and soy bean (Akubor and Onimawo, 2003). In fact, biscuits have been suggested as better use for composite flour than bread due to their ready-to-eat form, wide consumption, relatively long shelf life, and good eating quality (Noorfarahzihah et al., 2014; Bala et al., 2015).
Palm oil is an edible plant oil derived from the kernel of the oil palm, Elaeis guineesis (Poku 2002). Palm oil is an important item in the Nigerian diet and it is used as illuminant, candle, pomade and cosmetics, cooking/baking fat, soap ingredients etc. Palm oil contains carotene, a precursor of vitamin A, a high prized energy vitamin rich food used for cooking in oil producing countries of Africa. Palm oil is a natural vegetable oil which has a bright red colour. It is versatile in terms of utilization. It can be used interchangeable with other oils/fat and it can be used directly without modification. It is healthy in nature and contains natural beta carotene, it a good source of pro Vitamin A and Vitamin E. it is the cheapest oil in the market (Van Stuijvenberg and Benade 2000).
Palm oil is also a rich natural source of carotenoids (500–700 ppm), of which approximately 50% is β-carotene. Furthermore, it also contains tocopherols and tocotrienols (about 1,000 ppm), which have powerful antioxidant properties (Van Stuijvenberg and Benade 2000).
This study was done to ascertain the impacts of yellow maize and palm oil substitutions on composition, antioxidant, physical and sensory properties of biscuit.
1.2 STATEMENT OF PROBLEM
Biscuit is widely and regularly consumed by Nigerian but the conventional biscuit is either low in or lack most bioactive nutrients needed for good health. Also most staples of Nigeria are deficient in these nutrients. These vital bioactive nutrients must be supplied in the diet for adequate nutrition. There is need to make these bioactive ingredients reach the common Nigerians through biscuits which is widely and regularly consumed in the country.
1.3 JUSTIFICATION OF THE STUDY
Substitution of yellow maize and palm oil in biscuits will address most dietary requirement of Nigerians. This will increase Protein, dietary fibre and phytonutrient contents of biscuits and the shelf life of biscuits to reach the rural Nigerians in good form.
1.4 OBJECTIVES OF THE STUDY
The main objective of the study was to produce biscuits with substituted yellow maize and palm oil, and evaluate physicochemical and sensory properties of the biscuits.
The Specific objectives were to:
i. Produce maize and maize-wheat composite flour
ii. Produce biscuits with different substituted levels yellow maize and palm oil.
iii. Determine composition, anti-oxidant, physical and sensory properties of biscuit samples.
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