Evaluation of food potential of tigernuts and it's products ( coffee,wine and milk )

ABSTRACT 12 The  food  potentials  of  tigernut  tubers  (Cyperus  esculentus)  locally  know  as  “aki  awusa”  in Igbo,  ”aya”  in  Hausa  and  “ofio”  in  Yoruba  were  evaluated.  The  proximate  composition  of 100g  of  raw  and  processed  tigernuts  showed  that  moisture  content  of  tigernuts  ranged  from 4.19  –  51.93  %,  crude  protein  2.61  –  10.12  %,  ash  0.70  –  1.77  %,  crude  fibre  7.48  –  13.97  %, crude  fat  10.79  –  32.06  %,  and  carbohydrate  22.73  –  56.85  %.  Energy  values  ranged  from 232.31-  487.15  Kcal.  Tigernuts  contain  significant  amounts  of  Mg  (95.32  -140.96  mg),  K (106.44  –  427.92  mg),  P  (121.78  –  195.95  mg),  Fe  (1.60  –  4.03  mg),  Cu  (0.08  –  0.99  mg),  Zn (0.32  -  2.46mg),  vitamin  C  (30.90  –  84.66  mg),  vitamin  E  (2.22  –  5.26  mg),  moderate  Ca (24.42  –  62.29  mg)  and  low  Na  (15.77  –  18.27  mg)  content.  Processing  of  tigernuts  generally increased  carbohydrate  but  decreased  magnesium  and  sodium  values.  Malting  significantly increased  calcium  content  (85  %)  and  drying  and  roasting  increased  Zn  and  Cu  by  100  %. Physico-chemical  and  functional  properties    showed  that  tigernuts  and  its  products  are  acidic while  viscosity  of  the  products  per  100  ml  was  between  88  –  90  cP,  specific  gravity  1.01  – 1.07,  reducing  sugar  0.30  –  0.44  g  ,  foaming  capacity  18  %.  Foaming  stability  5.35  %, emulsion  capacity  21.88  %,  and  emulsion  stability  49.38  %.  Alcohol  content  of  tigernut  wine was  between  3.17  –  7.13  %.  Fresh  tigernuts  were  utilized  in  the  development  of  tigernut products  (milk,  coffee  and  wine)  using  household  methods  such  as  soaking,  drying,  roasting, malting,  fermentation  and  freezing.    Organoleptic  and  acceptability  assessment  of  the developed  tigernut  products  showed  that  there  was  no  significant  difference  (P  >  0.05) between  tiegrnut  products  and  their  controls  in  most  of  the  parameters  tested.  All  then products  were  highly  acceptable.  Tigernuts  products  (milk  extract  and  wine)  evaluation  per 100  ml  showed  high  ascorbic  acid  (6.18  –  7.8  mg),  thiamin  (0.80  –  1.25  mg),  riboflavin  (0.35 –  0.59  mg),  vitamin  E  (0.22  –  0.75  mg)  and  cyanocobalamin  (0.03  –  0.05  ug)  content.  The result  of  the  microbial  count  of  tigernut  products  (milk  and  wine)  showed  values  between  3.0 x 102 – 8.0 x 102 cfu / ml and keeping quality ranged from 6 hours to 10 months.    

Table of contents                        Page Title page - - - - - - - - - - i         Approval page - - - - - - - - - ii Certification -` - - - - - - - - - iii  Dedication - - - - - - - - - - iv Acknowledgement - - - - - - - - - v Table of contents - - - - - - - - - vi Abstract - - - - - - - - - - ix Table of contents - - - - - - - - - vi List of tables and figures - - - - - - - - ix Chapter one: Introduction  1.1 Background study - - - - - - - - 1 1.2 Statement of problems - - - - - - - - 2 1.3 Objectives of study - - - - - - - - 3 1.4 Significance of study  - - - - - - - - 3 Chapter two: Literature review 2.1 History of tigernuts  - - - - - - - - 4 2.2 Botany of tigernuts - - - - - - - - 4 2.3 Ecology of tigernuts - - - - - - - - 6 2.4 Nutritional composition of tigernuts - - - - - - 7 2.5 Importance of tigernuts and its products - - - - - - 9 2.5.1 Nutritional and health importance - - - - - - 9 2.5.2 Economic importance - - - - - - - - 12 2.6 Antinutrient factor and toxicity of tigernuts  - - - - - 14 2.7 Some properties of tigernuts and its products - - - - - 15 2.8 Handling and keeping quality of tigernuts - - - - - 16 2.9 Utilization of tigernuts - - - - - - - - 17 2.10 Processing techniques - - - - - - - - 19 Chapter three: Materials and methods 3.1 Collection of samples - - - - - -  9 3.2 Sample preparation and analyses - - - - - - - 22 3.2.1 Sample preparation - - - - - - - - 22 3.2.1.1 Fresh tigernuts  - - - - - - - - 22 3.2.1.2 Tigernut milky juice extract - - - - - - - 22 3.2.1.3 Fermented tigernut milky juice - - - - - - 23 3.2.1.4 Malted tigernut - - - - - - - - 23 3.2.1.5 Dried tigernut  - - - - - - - - - 24 3.2.1.6 Roasted tigernuts  - - - - - - - - 24 3.2.2. Proximate composition analyses - - - - - - 24 3.2.2.1 Moisture content   - - - - - - - - 25 3.2.2.2 Crude protein content  - - - - - - - - 25 3.2.2.3 Mineral ash content  - - - - - - - - 25 3.2.2.4 Crude fat content - - - - - - - - 26 3.2.2.5 Crude fiber content - - - - - - - - 26 3.2.2.6 Carbohydrate content - - - - - - - - 27 3.2.3.7 Energy value - - - - - - - - - 27 3.2.3 Mineral and vitamin content analyses of tigernuts(treaated and untreated) - 27 3.2.3.1 Mineral content analyses (Mg, K, P, Ca, Fe, Cu & Zn) - - - 27 3.2.3.2 Vitamin content (vitamin C & E) - - - - - - 30 3.2.4 Physico-chemical and functional properties analyses - - - - 31 3.2.4.1 pH  - - - - - - - - - - 31 3.2.4.2 Specific gravity  - - - - - - - - 32 3.2.4.3 Viscosity - - - - - - - - - 32 3.2.4.4 Foaming capacity and stability - - - - - - 33 3.2.4.5 Emulsion capacity and stability - - - - - - 33 3.2.4.6 Ethanol content of fermented tigernut milky juice     - - - - 34 3.2.4.7 Total available reducing sugar of tigernut milk and wine - - - 34 3.2.5 Development of tigernut products (milk, coffee and wine)  - - - 34 3.2.5.1 Tigernut milk (unfermented tigernut beverages) - - - - 35 3.2.5.2 Tigernut coffee (coffee and cocoa substitute) - - - - - 36 3.2.5.3 Tigernut wine (fermented tigernut beverages) - - - - 37 3.2.7 Vitamin and zinc content of tigernut milk and wine - - - - 38 3.2.8 Organoleptic properties and general acceptability assessment - - - 41 3.2.9 Microbial count and keeping quality assessment - - - - 4 10 3.3 Statistical analyses - - - - - - - - 42 Chapter four: Results  4.1 Proximate composition and energy value of tigernuts - - - - 43 4.2 Effect of processing on the proximate composition and energy value - - 45 4.3 Percentage changes on the proximate composition and energy value of tigernuts due to processing effects - - - - - - - - - 47 4.4 Mineral and vitamin content of tigernuts - - - - - - 49 4.5 Effect of processing on the mineral content of tigernuts - - - - 51 4.6 Percentages on the mineral content of tigernuts due to processing effects - 53 4.7 Physico-chemical and functional properties and its products - - - 55 4.8 Vitamin and zinc content of tigernut milk and wine - - - - 57 4.9 Organoleptic evaluation of tigernut milk (unfermented beverages) - - 59 4.10 Organoleptic evaluation of tigernut coffee (coffee and cocoa substitute) - 61 4.11 Organoleptic evaluation of tigernut wine (fermented beverages) - - 63 4.12 Microbial count of tigernut products (milk and wine) - - - - 65 4.13 Keeping quality of tigernut products (milk, coffee and wine) - - - 65 Chapter five: Discussion 5.1 Nutritional value of tigernuts as widely consumed raw - - - - 67 5.2 Effect of processing on the nutritional composition of tigernuts - - - 69 5.3 Physico-chemical and functional properties and its products - - - 73 5.4 Organoleptic properties of tigernut products (milk, coffee and wine) - - 75 5.5 Vitamin and zinc content of tigernut milk and wine - - - - 77 5.6 Microbial count and keeping quality of tigernut products  - - - 78 5.7 Conclusion - - - - - - - - - 80 5.8 Recommendations and suggestions - - - - - - 81 References  - - - - - - - - - 83 Appendices - - - - - - - - - 89 Appendix 1 Tables 2.1 - 2.4 - - - - - - - - 89 Appendix 2 Flow diagram 3.1 – 3.3 - - - - - - - 91 Appendix 3 Sensory evaluation / General acceptability form A – C - - - 94 Appendix 4 Recipe for soya bean milk and instant coffee product samples - - 98    11  List of tables and figures                                                                                       Page Table 2.1: Energy and nutrient content of tigernuts - - - - - 89 Table 2.2: Amino acid composition of tigernut and its extract - - - 89 Table 2.3: Nutrient content of some milk beverages - - - - - 90 Table 2.4: Mineral and vitamin content of some milk beverage - - - 90 Table 4.1: Energy and proximate composition of tigernuts - - - - 44 Table 4.2a: Effect of processing on the proximate composition and energy value of  tigernuts per 100g - - - - - - - 46 Table 4.2b: Percentage increases / decreases on the proximate composition and  energy content of tigernuts due to processing effects - - - 48 Table 4.3 Mineral and vitamin content of tigernuts - - - - - 50 Table 4.4a: Effect of processing on the mineral content of tigernuts - - - 52 Table 4.4b: Percentage increases / decreases on the mineral and vitamin content of  tigernuts due to processing effects - - - - - 54 Table 4.5: Physico-chemical and functional properties and its products - - 56 Table 4.6: Vitamin and zinc content of tigernut products (milk and wine) per 100ml 58 Table 4.7: Organoleptic evaluation of tigernut milk beverages (unfermented) - 60 Table 4.8: Organoleptic evaluation of tigernut coffee (coffee and cocoa substitute) - 62 Table 4.9: Organoleptic evaluation of tigernut wine (fermented) - - - 64 Table 4.10 Microbial count of tigernut products (milk and wine) - - - 66 Table 4.11 Keeping quality of tigernut products (milk, coffee and wine) - - 66 Figure3.1: Flow diagram for the production of milky beverage - - - 91 Figure3.2: Flow diagram for the production of tigernut coffee powder - - 92 Figure3.3: Flow diagram for the production of tigernut wine - - - 93    11  List of tables and figures                                                                                       Page Table 2.1: Energy and nutrient content of tigernuts - - - - - 89 Table 2.2: Amino acid composition of tigernut and its extract - - - 89 Table 2.3: Nutrient content of some milk beverages - - - - - 90 Table 2.4: Mineral and vitamin content of some milk beverage - - - 90 Table 4.1: Energy and proximate composition of tigernuts - - - - 44 Table 4.2a: Effect of processing on the proximate composition and energy value of  tigernuts per 100g - - - - - - - 46 Table 4.2b: Percentage increases / decreases on the proximate composition and  energy content of tigernuts due to processing effects - - - 48 Table 4.3 Mineral and vitamin content of tigernuts - - - - - 50 Table 4.4a: Effect of processing on the mineral content of tigernuts - - - 52 Table 4.4b: Percentage increases / decreases on the mineral and vitamin content of  tigernuts due to processing effects - - - - - 54 Table 4.5: Physico-chemical and functional properties and its products - - 56 Table 4.6: Vitamin and zinc content of tigernut products (milk and wine) per 100ml 58 Table 4.7: Organoleptic evaluation of tigernut milk beverages (unfermented) - 60 Table 4.8: Organoleptic evaluation of tigernut coffee (coffee and cocoa substitute) - 62 Table 4.9: Organoleptic evaluation of tigernut wine (fermented) - - - 64 Table 4.10 Microbial count of tigernut products (milk and wine) - - - 66 Table 4.11 Keeping quality of tigernut products (milk, coffee and wine) - - 66 Figure3.1: Flow diagram for the production of milky beverage - - - 91 Figure3.2: Flow diagram for the production of tigernut coffee powder - - 92 Figure3.3: Flow diagram for the production of tigernut wine - - - 93 11  List of tables and figures                                                                                       Page Table 2.1: Energy and nutrient content of tigernuts - - - - - 89 Table 2.2: Amino acid composition of tigernut and its extract - - - 89 Table 2.3: Nutrient content of some milk beverages - - - - - 90 Table 2.4: Mineral and vitamin content of some milk beverage - - - 90 Table 4.1: Energy and proximate composition of tigernuts - - - - 44 Table 4.2a: Effect of processing on the proximate composition and energy value of  tigernuts per 100g - - - - - - - 46 Table 4.2b: Percentage increases / decreases on the proximate composition and  energy content of tigernuts due to processing effects - - - 48 Table 4.3 Mineral and vitamin content of tigernuts - - - - - 50 Table 4.4a: Effect of processing on the mineral content of tigernuts - - - 52 Table 4.4b: Percentage increases / decreases on the mineral and vitamin content of  tigernuts due to processing effects - - - - - 54 Table 4.5: Physico-chemical and functional properties and its products - - 56 Table 4.6: Vitamin and zinc content of tigernut products (milk and wine) per 100ml 58 Table 4.7: Organoleptic evaluation of tigernut milk beverages (unfermented) - 60 Table 4.8: Organoleptic evaluation of tigernut coffee (coffee and cocoa substitute) - 62 Table 4.9: Organoleptic evaluation of tigernut wine (fermented) - - - 64 Table 4.10 Microbial count of tigernut products (milk and wine) - - - 66 Table 4.11 Keeping quality of tigernut products (milk, coffee and wine) - - 66 Figure3.1: Flow diagram for the production of milky beverage - - - 91 Figure3.2: Flow diagram for the production of tigernut coffee powder - - 92 Figure3.3: Flow diagram for the production of tigernut wine - - - 93