COMPARATIVE STUDY ON THE PHYSICO-CHEMICAL,
MICROBIAL AND SENSORY PROPERTIES OF KUNUN ZAKI
PRODUCED WITH PADDY RICE, SWEET POTATOES AND
ASPARTAME.
The research was carried out to compare the nutritional benefits of kunun zaki made from 50:50 blend of millet and sorghum; 80:20 blend of millet and sorghum with paddy rice, sweet potatoes, and aspartame). Results obtained showed that for proximate composition; the moisture content of the samples ranged from 86.10-88.10%, 0.47-4.45% for ash, 0.83-4.02% for fat, 0.03-0.09% for crude fibre, 1.02-2.54% for protein and 4.32-9.38% for carbohydrate. The values obtained for viscosity ranged from 0.12-0.63pas, total soluble solids ranged from 3.10- 6.13°Brix; pH values obtained for the kunun zaki samples ranged from 4.54-5.40, values obtained for specific gravity ranged from 0.97-0.99%, 9.93-13.93% for total solids, and 0.29-0.46mg/KOH for total titrable acidity. Value obtained from the total titrable acidity showed that control sample KC1 (50:50 blend of millet and sorghum without a sweetener) was highest compared to other samples. There was no significant difference in the values obtained for specific gravity. The mineral content of the kunun zaki samples ranged from 0.122-0.481mg/100g from Iron and 11.100-29.070mg/100g. The microbial load of the samples ranged progressively from 1.15-2.37 X 105cfu/ml and 1.01-2.05 X 105cfu/ml for total bacterial count, fungal count respectively; in addition, the total coliform count of the samples had no value because no growth was observed. Sensory evaluation showed that the samples KA1 and KA2 (50:50 and 80:20 blend of millet and sorghum produced) were liked very much with the mean values of the general acceptability ranging from 7.40-7.80. The result from the analysis showed that kunun zaki produced with aspartame had the best acceptable quality and lowest microbial load when compared to its other samples. The addition of aspartame was responsible for its enhanced quality characteristics.
TABLE OF CONTENT
Cover page
Title page i
Certification ii
Approval iii
Acknowledgment iv
Dedication v
Table of content vi
List of tables xi
List of figures xii
Abstract xiii
CHAPTER ONE
- Introduction 1
1.1 Background to the study 1
1.2 Statement of the research problem 3
1.3 Aims of the research 3
1.3.1 Specific objectives of the research 3
1.4 Scopes and limitation of the study 4
CHAPTER TWO
2.0 Literature review 5
2.1 Beverages 5
2.1.1 Types of Beverages 5
2.1.1.1 Alcoholic beverages 5
2.1.1.1.1 Beer 6
2.1.1.1.2 Wine 6
2.1.1.1.3 Spirits 6
2.1.1.2 Non-alcoholic Beverages 7
2.1.1.2.1 Coffee 7
2.1.1.2.2 Tea 7
2.1.1.2.3 Juice 7
2.1.1.3 Fermented beverages 8
2.2 Nigeria Fermented Beverages 12
2.2.1 Types of Alcoholic beverages 13
2.2.1.1 Burukutu 13
2.2.1.2 Pito 13
2.2.1.3 Palm-wine 14
2.2.1.4 Oti-oka 14
2.2.1.5 Obiolor 15
2.2.1.6 Kunun-zaki 15
2.3 Benefits of Kunun-zaki 18
2.4 Sweeteners 18
2.4.1 Natural Sweeteners 20
2.4.1.1 Honey 20
2.4.1.2 Stevia 21
2.4.1.3 Paddy Rice 21
2.4.1.4 Sweet Potatoes 23
2.4.2 Artificial Sweeteners 24
2.4.2.1 Acesulfame potassium 24
2.4.2.2 Sucralose 24
2.4.2.3 Neotame 25
2.4.2.4 Aspartame 25
2.5 Cereals Used in Kunun-zaki Production 26
2.5.1 Physical Composition of Cereals 27
2.5.2 Nutritional Quality of Cereals 29
2.5.3 Types of cereals 30
2.5.3.1 Millet 30
2.5.3.1.1 Nutritive Value of Millet Grains 31
2.5.3.2 Sorghum 32
2.5.3.2.1 Nutritional composition of sorghum 33
CHAPTER THREE
3.0 Materials and Methods 35
3.1 Collection of raw materials 35
3.2 Processing Operations 35
3.2.1 Preparation of sweet potato flour 35
3.2.2 Preparation of malted paddy rice syrup 35
3.2.3 Production of Kunun-zaki 35
3.3 Method of Analysis 38
3.3.1 Proximate Analysis 38
3.3.1.1 Moisture content determination 38
3.3.1.2 Crude fat determination 38
3.3.1.3 Crude protein determination 39
3.3.1.3.1 Digestion 39
3.3.1.3.2 Distillation 39
3.3.1.3.3 Titration 40
3.3.1.4 Ash content determination 40
3.3.1.5 Crude fibre determination 41
3.3.1.6 Carbohydrate content determination 41
3.3.2 Physico-chemical Analysis 42
3.3.2.1 pH determination 42
3.3.2.2 Determination of Total Titrable Acidity 42
3.3.2.3 Determination of Total Solids 42
3.3.2.4 Determination of Total Soluble Solids (oBrix) 43
3.3.3 Microbial Analysis 43
3.3.4 Sensory Evaluation 44
3.3.5 Statistical Analysis 44
CHAPTER FOUR
4.0 Results and discussion 45
4.1 Proximate composition 45
4.2 Physico-chemical composition 49
4.3 Mineral content analysis 52
4.4 Microbial analysis 54
4.5 Sensory evaluation 56
CHAPTER FIVE
5.0 Conclusion and Recommendation 59
5.1 Conclusion 59
5.2 Recommendation 60
6.0 References 61
7.0 Appendices
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CHAPTER ONE
INTRODUCTION
1.0 Background to the study
Kunun zaki is a traditional non-alcoholic fermented beverage widely consumed in the northern part of Nigeria. Obadina et al. (2008) observed that kunun zaki is now widely consumed in the Southern parts among low and middle income workers who cannot afford industrial beverages. The beverage is characterized by sweet-sour taste, creamy, refreshing quality as well as its flowing consistency (Obadina et al., 2008). They may exist as liquid or thin gruel preparation with high water content which supplies the body with water sufficient to maintain health (Oguntimein, 1994). Kunun is the generic name for all kinds of non-alcoholic beverages that are cereal based with specifications usually attached to denote the base cereal grain (Sowonola et al., 2005, Nahemiah et al., 2014).
There are various types of kunun processed and consumed in Nigeria. These include kunun zaki, kunun-gyada, kunun-akamu, kunun-tsamiya, kunun-baule, kunun-jiko, ashamu and kunun-gzakimba. Of these, kunun zaki is the most widely produced and consumed (Inatimi et al., 2011). Kunun zaki are made from sorghum (Sorghum bicolor), millet (Pennisetum typhodium), maize (Zea mays), rice (Oryza sativa), and other cereals such as guinea corn or rice (Adebayo et al., 2010). It is normally flavoured with a combination of spices normally called “Kayan Yaji” which includes ginger (Zingiber officinale), cloves (Eugenia aromatica), and black pepper (Piper guinese (Adebayo and Idowu, 2003).
The process of cleaning, steeping, wet milling, sieving, settling, decantation and slurry recovery were -applied in the preparation (Adebayo et al., 2010). Kunun zaki is acceptable to all age groups and is being served at home and public places as a refreshing drink and complimentary food for infants. It can also be consumed in the morning as breakfast by adults and children, serve as appetizer to entertain guests in rural and urban settings (Onuorah et al., 2005). Akoma et al. (2006) reported that kunun zaki have immense social, economic and medicinal importance to its numerous consumers. It is relatively cheap and nutritious when compared to carbonated drinks (Adejuyitan et al., 2008). It contains all the essential nutrients such as carbohydrates, fat, protein, minerals and vitamins (Ugwuanyi et al., 2015). According to Elmahmood et al. (2007), kunun zaki is produced at village technology level, its production protocols, packaging and distribution are not yet standardized. Kunun zaki stored at ambient temperature (28 ± 2 °C) has a shelf life of about 24 hours (Adeyemi and Umar, 1994). Attempts have been made to improve the shelf life of kunun zaki by using pasteurization method coupled with refrigeration storage (Osuntogun and Aboada, 2004) and the use of sodium benzoate treatment followed by refrigeration method (Olasupo et al., 2000). With these methods, the keeping qualities of kunun zaki beverage were prolonged.
Sweeteners are compounds added to food substances to improve the taste. They are broadly classified into natural sweeteners and artificial sweeteners. Natural sweeteners are gotten from saps, syrups and other natural sources and include honey, molasses, maple syrup, and stevia while artificial sweeteners are synthetic sugar substitutes but can be derived from natural sources including herbs or sugar itself. These includes neotame, saccharin, aspartame, ace-k and sucralose (Stacey et al., 2002). In the production of kunun zaki, sugar (sucrose) is not the only sweetening agent that can be used. Paddy rice can be used to produce a syrup which acts as a sweetener (Shaw, 1992). Paddy rice is rich in lipids, proteins, minerals, vitamins, phytin, trypsin inhibitor, lipase, and lectin (Luh et al., 1991). Consumption of paddy rice syrup is linked to reduced risk of obesity and weight gain. (McKeown et al., 2002; Newby et al., 2003; Slavin, 2005; Rose, 2005)
Sweet potato roots are rich in starch, sugar, vitamin C, β-carotene, iron, and several other minerals (Laurie et al., 2012; Oloo et al., 2014). Despite its high carbohydrate content, sweet potato has a low glycemic index due to low digestibility of the starch making it suitable for diabetic or overweighed people (Ellong et al., 2014; Fetuga et al., 2014; Ooi and Loke, 2013)
Aspartame is a non-saccharide sweetener used as a sugar substitute in some foods and beverages. It can be found in over 6,000 products, including carbonated soft drinks, powdered soft drinks, chewing gum, tabletop sweeteners, and some pharmaceuticals such as vitamins and sugar-free cough drops (Walters, 2009).
1.2 STATEMENT OF THE RESEARCH PROBLEM
From the foregoing, kunun zaki; a locally produced beverage is mainly produced with sugar as a sweetening agent, hence, under-utilizing the potentials of other sweeteners. In view of the above, this project is designed to produce kunun zaki with different kinds of sweeteners other than sugar and these includes the use of paddy rice, sweet potato and aspartame. The goal will be to modify these sweeteners to impart some desirable characteristics to kunun zaki and hence, determine the most suitable one preferred by consumers.
1.3 AIMS OF THE RESEARCH
The overall goal of this research is to carry out a comparative study on the sweeteners used in the production of Kunun zaki (paddy rice, sweet potatoes, and aspartame).
1.3.1 Specific objectives of the research
The specific objectives of this work are to:-
- To produce kunun zaki with different kinds of sweeteners (paddy rice, sweet potatoes, and aspartame).
- To determine the proximate composition of the samples.
- To evaluate the physico-chemical properties of the samples.
- To ascertain the mineral composition of the samples.
- To determine the microbial load of the samples
- To assess the sensory attributes of the samples.
1.4 Scope and limitations of the study
The study is limited to the use of sorghum (Sorghum bicolor) and millet (Pennisetum typhodium) as cereals used in the production of kunun zaki and the use of paddy rice, sweet potatoes and aspartame as sweeteners.
Limitations to the study include lack of necessary equipments, insufficient power supply as well as time and financial constraint.
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