ABSTRACT
The physicochemical and organoleptic properties of gruels made from sieved and unsieved maize paste was studied. All the analysis carried out was subjected to standard methods. Sieving operation reduced the proximate composition of the gruel product. The proximate mean values ranged from 86.66 to 87.62% moisture, 12.38 to 13.34% dry matter, 0.46 to 0.50% ash, 1.17 to 1.22% protein, 0.27 to 0.34% fat, 0.19 to 0.23% crude fiber and 10.10 to 11.29% carbohydrate. There were significant differences (p<0.05) in the mineral content of the sieved and unsieved gruel samples with mean values ranging from 3.82 to 4.76mg/100g calcium, 2.15 to 2.35mg/100g sodium, 5.92 to 6.50mg/100g phosphorus, 3.87 to 4.66mg/100g magnesium, 5.51 to 6.82mg/100g potassium, and 0.66 to 0.77mg/100g iron. There was no significant difference (p>0.05) in the vitamins B1, B2, B3, E and A with mean values ranging from 0.03 to 0.04mg/100g, 0.02 to 0.02mg/100g, 0.06 to 0.06mg/100g 0.32 to 0.36mg/100g and 1.75 to 1.84mg/100g respectively. However, the vitamin C level increased in the sieved sample with mean value range of 1.47 to 1.64mg/100g. There was no significant difference (p<0.05) in the phytate, tannin and flavonoid content of both the sieved and unsieved gruel samples with mean values ranging from 0.01 to 0.02mg/100g, 0.02 to 0.02mg/100g and 0.07 to 0.07mg/100g respectively. Presence of phenol was not detected in both the sieved and unsieved samples. Sieving operation was observed to decrease the caroteniod level with mean value range of 1.49 to 1.64mg/100g. The sensory evaluation result showed that, sieving as a method of gruel processing reduced the organoleptic property of the gruel product. The sensory mean values ranged from 6.80 to 8.73% taste, 6.53 to 8.40% appearance, 6.27 to 8.40% mouthfeel, 6.47 to 8.47% texture and 6.13 to 8.60% general acceptability.
TABLE OF CONTENTS
Title page i
Certification ii
Dedication iii
Acknowledgement iv
Table of contents v
List of Tables viii
List of figures ix
Abstract x
CHAPTER 1
1.1 INTRODUCTION 1
1.2 Statement of Problem 3
1.3 Objectives of the Study 5
1.3.1 General objective of the study 5
1.3.2 Specific objectives of the study 5
1.4 Significance of the Study 5
CHAPTER 2: LITERATURE REVIEW
2.1 History of Maize 6
2.2 Utilization of Maize 7
2.3 Chemical Composition 10
2.3.1 Carbohydrate 10
2.3.2 Protein 10
2.3.3 Lipids and related compounds 11
2.3.4 Minerals 11
2.3.5 Vitamins 11
2.4.6 Pigments 12
2.4 Deficits and Anti Nutritional Factors in Maize 12
2.5 Historical Evaluation of Maize Gruel ( OGI) Production 13
2.6 Physical Properties of Gruels 15
2.7 Nutritional and Chemical Properties of Gruels 16
2.8 Importance of Fermentation in Gruel Production 17
2.9 Complementary Feeding 17
2.9.1 Amount of complementary foods needed 20
2.9.2 Food consistency 22
2.9.3 Meal frequency and energy density 22
2.9.4 Nutrient composition of adequate complementary foods 24
2.9.4.1 Micro nutrient content 24
2.9.4.2 Fat content 27
2.9.4.3. Protein 28
2.9.4.4 Carbohydrates 29
CHAPTER 3: MATERIALS AND METHODS
3.0 Scope of the study 30
3.1 Source of raw material 30
3.2 Sample preparation 30
3.3 Preparation of the pap 30
3.4. Physicochemical analysis 33
3.4.1 Proximate composition 33
3.4.1.1 Determination of Moisture content 33
3.4.1.2 Determination of Ash content 33
3.4.1.3 Determination of Crude fibre content 34
3.4.1.4 Determination of Protein content 35
3.4.1.5 Determination of Fat content 36
3.4.1.6 Determination of Carbohydrates content 37
3.4.1.7 Determination of Energy 37
3.4.2 Mineral analysis 37
3.4.2.1 Determination of calcium and magnesium content 37
3.4.2.2 Determination of Potassium and Sodium content 38
3.4.2.3 Determination of magnesium content 39
3.4.2.4 Determination of phosphorous 39
3.5.3 Vitamin analysis 40
3.5.3.1 Determination of Niacin content 40
3.5.3.3 Determination of Riboflavin Content 41
3.5.3.5 Determination of vitamin E 41
3.5.3.5 Vitamin C determination 43
3.5.4 Antinutrient and Phytochemical analysis 44
3.5.4.1 Determination of Phytate 44
3.5.4.3 Determination of Tannin 44
3.5.5.3 Phenol determination 45
3.5.5.4 Determination of carotenoids 46
3.4 SENSORY EVALUATION 47
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Proximate Composition of the gruel samples 49
4.2 Mineral Composition of the gruel samples 52
4.3 Vitamin Composition of the gruel samples 56
4.4 Antinutrients composition 59
4.5 Sensory Evaluation 62
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 64
5.2 Recommendations 64
REFERENCES 65
LIST OF TABLES
Table 1: Proportion of Recommended Nutrient Intake from Complementary food at 9-11 Month of Age 25
Table 4.1: Proximate Composition of the gruel samples 49
Table 4.2: Mineral Composition of the gruel samples 54
Table 4.3: Vitamin Composition of the gruel samples 57
Table 4.4: Antinutrients composition 59
Table 4.5: Sensory Evaluation 63
LIST OF FIGURES
Fig 1: Flow diagram for the preparation of sieved maize gruel 31
Fig 2: Flow chart for the preparation of unsieved maize 32
CHAPTER 1
1.1 INTRODUCTION
Maize, the American Indian word for corn literally means that which sustains life. It is the most important cereal grain in the world after wheat and rice, (Fernandez et al., 2002). Maize is the third most important cereal in the world and ranked the second most important cereal crop in Nigeria (Enwere, 1998). In some countries, maize constitutes a substantial part of the diet of most of the population (FAO, 1992). In Nigeria, products from maize include maize fufu, pap (akamu or ogi) otherwise known as maize gruel. In Enugu state, maize pudding known as igba oka, is also produced from maize. It is the major ingredients used industrially to produce cornflakes, golden morn, cerelac, nutrient, etc (Enwere, 1998). Apart from being consumed by humans, it is also used to prepare animal feeds, and useful in the chemical industry. Maize can be cooked, roasted, fried, ground, pounded or crushed (Abdulraharan and Kolawole, 2006). The carbohydrate levels of maize grains are very high and the protein quality of common maize is similar to that of rice and wheat with lysine as the most limiting amino acids (FAO, 1992). Maize is reasonably fair in sulphur containing – amino acids (methionine and cystine) and vitamin A precursor, beta-carotene (Obi, 1991; Obiakor, 2001). The grains are rich in vitamin A, C and E; carbohydrates, essential minerals and protein. They are also rich in dietary fiber and calories, which means it is a good source of energy (IITA, 2009). They can further be processed into flour, starch, oil, bran, sugar syrup, moreover, they are fed to livestocks which convert them to animal protein of meat, milk, and eggs (Onimawo and Egbekun, 1998).
Maize gruel is a fermented cereal based porridge. It could be made from maize (Zea mays), millet (Pennisetum glancum) and sorghum (Sorghum bicolor). Its fermentation involves Lactic acid bacteria notably Lactobacillus sp and various yeasts including Saccharomyces cerivisiae (Sanni et al., 2001). Ogi is a popular breakfast cereal product in West Africa with high acceptability, low cost and shelf life stability characteristics. It is widely consumed by Infants, children and adults in Nigeria (Mbata et al., 2009). However, maize-ogi is still the usual first traditional complementary food given to children in Nigeria. It is called ogi, akamu, koko, pap (Enwere, 1998).
It could be prepared as liquid gruel and consumed sole or with supporting bean cakes or it could be made into stiff consistency (eko or agidi) and consumed with vegetable soups or bean cakes. Lactic acid bacteria converts the carbohydrates in the cereals during ogi production to organic acids which contribute to softness in the product and the characteristic flavor and sour taste (Oyarekua, 2001). The stages of traditional ogi production include: washing of grains, steeping for 3days at ambient temperature (28 ± 2℃), wet-milling, wet-sieving with a hand sieve or muslin cloth with about 300 µm pore size and sedimentation/ souring of the filtrate for 1–3days. Thereafter, the water is decanted and the wet, clean sediment (ogi) is collected and stored for personal use or sold to consumers in its wet form in small units packaged in leaves or polypropylene bags (Omemu and Omeike, 2010). The physical and biochemical qualities of ogi are influenced by the type of cereal grain, fermentation or souring periods and the milling method (Osungbaro, 1990; Hounhouigan et al., 1993). Many workers have reported on different aspects of ogi production. Particular attention has been given to process variations, process mechanization, and nutritional improvement (Olasupo et al., 1997). The traditional method of ogi processing is accompanied by severe nutrient losses, the magnitude of which depends on the type of grains and the processing method used (Aremu, 1993).
Hence, there have been several attempts at improving the nutritional quality of ogi. This work however, compares the nutrient content of maize gruel which contains its pomace and the one which its pomace was sieved out.
1.2 STATEMENT OF PROBLEM
Complementary food is the food given to children when breast milk alone is no longer sufficient and the transition from exclusive breast feeding to family food (Dewey, 2002). Maize gruel is popularly used as complementary food in Nigeria.
Food being very indispensable in life, infants in particular must be given serious attention as infants are at very delicate stage of life with little resistibility to diseases and are in a period of great nutritional stress (UNICEF, 2008).
Cereals, example maize have lower nutritional value than animal based ones. Plain porridges made from cereals and tuber flour, though commonly used is not sufficiently rich in energy, proteins and essential vitamins such as vitamin A and C. Also, commercial ready-to-eat complementary foods are available in the market, but they are relatively expensive and out of the reach of rural and low income group (Ijarotimi, 2008; Nnam, 2008). This has made utilisation of cereals a very important source of complementary food among low income nursing mothers (Ijarotimi and Bakare, 2008). Coupled with these problems is the problem of processing which leads to leaching or depletion of protein from the resultant gruel. Complementary feeding improvement should be of highest priority for nutrition of infant and young children because of its crucial role in preventing mortality and enhancing children development (Lutter and Dewey, 2003).
Studies have shown that corn gruel (ogi) is bulky and devoid of essential nutrients, such as protein and vital micronutrients that is needed for normal child growth and development (Levin et al., 1993; Pinstrup-Andersen et al., 1993; Millward and Jackson, 2004). Efforts have therefore been made to improve on the nutritional quality of the traditional complementary foods through the fermentation of the cereal component (Amankwah et al., 2009), however, studies on the improvement of complementary foods through processing methods are limited. However, due to the demands of family and work, mothers have little time to devote to their children. Nevertheless, it is important to provide children with complementary food that is easily prepared based on locally available products, inexpensive and acceptable to both mother and child (WHO, 1999).
Therefore, this study will evaluate the nutrient composition of maize gruels (pap); one which contains its pomace and the other without its pomace, to compare their adequacy as complementary food. This study therefore examines the effects of processing methods on the physicochemical properties of gruels prepared from maize.
1.3 OBJECTIVES OF THE STUDY
1.3.1 General objective of the study
This study was designed to compare the physicochemical and organoleptic properties of two gruels made from maize; one of the steps, sieving is skipped during processing in one and the other processed using the steps stated by Odunfa, (1985).
1.3.2 Specific objectives of the study
1. To determine the proximate composition of the maize gruels produced from different processing methods.
2. To determine the vitamin and mineral contents of the maize gruels produced from different processing methods.
3. To determine the Antinutrient and Phytochemical contents of the gruel samples
4. To evaluate the sensory qualities of the maize gruel.
1.4 SIGNIFICANCE OF THE STUDY
The main significance of the study is the improvement in the nutrient content of maize as opposed to the known method in which the pomace is sieved out.
The comparative analysis as well as the and/or facts from such comparison will help to enlighten individuals especially mothers who are involved in preparation of complementary foods for children. It will also be of benefit to dietitians/nutritionists who are involved in the counselling of mothers on appropriate complementary feeding practices.
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