Number of Pages: 48

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Chapters: 1 - 5



This study was conducted to determine the physical properties of fresh and dried Tiger nut which are essential for designing engineering processes, material handling, storage, equipment design and fabrication. Samples of Tiger nut were collected from the market (Ekeonunwa), both fresh and sun dried was used as sample A and B respectively. Some selected physical properties of Tiger nut were determined at moisture content levels of wet basis only, the moisture content level for each samples are A=39.4% and B=14% . The average length, width, thickness (dimensional size), weight, geometric mean diameter, arithmetic mean diameter, sphericity index, aspect ratio, surface area, projected area, volume, true density, bulk density and porosity were determined. The dimensional size (length, width, thickness) were 10.72mm, 9.35mm, 11.13mm3 for A and 9.28mm, 8.22mm, 9.81mm for B, while the weight for the both sample was 0.88g and 0.51g. The bulk density, true density  porosity and the volume were found to be 1.60g/ml, 1.05g/ml,  42.86%, 584.15mm3  for sample A.0.63g/m/, 1.08ml, 42.50% and 396.22mm3 for sample B respectively.

KEY WORKS: Tiger nut, dimensional properties, and Gravimetric properties.


Title Page                                                                                                                    i

Approval Page                                                                                                                        ii

Dedication                                                                                                                  iii

Acknowledgment                                                                                                       iv

Table of Contents                                                                                                       v

Abstract                                                                                                                      vi


1.0 Introduction                                                                                                          1

1.1 Background of the study                                                                                      1

1.2 Statement of Problem                                                                                           1

1.3 Aim and Objectives of the study                                                                          2

1.4 The scope of the study                                                                                          2

1.5 Justification of the study                                                                                      2


2.0 Literature Review                                                                                                 3

2.1 Brief History of Tiger Nut                                                                                    3

2.2 Physical Properties of food                                                                                   3

2.3 Related works on physical properties of food                                                      4

2.4 The Physical Properties of some Agricultural Grains                                           4

2.5 Some Engineering and Chemical Properties of Cooked Bambara groundnut      5

2.6 The Physical and Thermal Properties of Baobals Fruit Pulp Powder                   6

2.7 Determination of Some Engineering Properties of Morama Bean                       6

2.8 The Physical and Engineering Properties of Tamarind Fruit                                7



3.0 Materials and Methods                                                                                         9

3.1 Sample Preparation                                                                                               9

3.2 Moisture Content

3.3 Determination Properties                                                                                      10

3.4 Gravimetric Properties                                                                                          11


4.0 Results and Discussion                                                                                         13

4.1 Results                                                                                                                  13

4.2 Discussion                                                                                                             14


5.0 Conclusion and Recommendations                                                                      16

5.1 Conclusion                                                                                                            16

5.2 Recommendations                                                                                                            16

References                                                                                                      17                    Appendix                                                                                                        21




Tiger nut (Cyperus esculentus) is an underutilized crop in the family of Cyperaceae, which produce rhizomes from the base and tubers that are somewhat spherical. Tiger nut tubers contain about 8% protein and have 20-30% tiger nut oil, which is nourishing to the epidermis (Alobo & Ogbogo, 2007). The necessary essential minerals, calcium, magnesium and iron required for bones, tissue repairs, muscles and blood stream, as well as vitamin B that assist in balancing the central nervous system is contained in tiger nut tubers (Oladele & Aine, 2007). Chevalier (1996) also reported that tiger nut tuber could be used for the treatment of flatulence, indigestion, diarrhea, dysentery and excessive thirst and contain higher essential amino acids than those proposed in the protein standard by the FAO/WHO (1985) for satisfying adult needs (Bosch et al; 2005).

Understanding the physical properties of food is important as they are used in process design, product and process optimization, product development, food quality control and food process modeling.

Information on physical properties of tiger nut needed in design, of machines used during harvesting, separating, cleaning, handling and storage of the nut and converting them into food, feed and fodder is scarce. Hence, the properties which are useful during design must be known.


Many work has be done on tiger nut, such as processing and preservation; but no work has be done on physical properties of tiger nut in order to ascertain suitable machinery for its process and production. In most of the countries, production of tiger nut into different product such as flour, beverages etc were a challenge to producers. As  a result of this, there is need to ensure that all potential sources of tiger nut are exploited effectively and utilized industrially, study on physical properties of tiger nut will form a platform for mechanization of the process. That is;

The study is to determine the physical properties of tiger nut in order.

  • To construct agricultural machinery.
  • To improve process design and food process modeling
  • To develop the product and food quality control
  • To increase its utilization as a food resources.


The project work is aimed to investigate some physical properties of tiger nut that is needed in design of machines and processes.


The current study, sought to determine some physical properties of tiger nut, which are relevant to the mechanization of its processing in order to increase its utilization as a food resource. These include size, shape, surface area, volume, density, porosity, arithmetic mean diameter, geometric diameter, weight, sphericity determination and finally the moisture content. (Wet basis).


Tiger nut is commonly underutilized in Nigeria; it is well grown and available in semi-dried form. Its tubers can be eaten unprepared, roasted with sugar etc. (Umerie, et al; 1997). This work intends to increase its utilization as a food resource by determining some physical properties that aids to mechanization of its processing such as harvesting, separating, cleaning, handling, packaging and storage.






Tiger nut (Cyperus esculentus), a non-conventional and underutilized tuber belong to the family cyperceae and is native to Mediterranean and tropical regions. Its tubers can be eaten unprepared, roasted with sugar, soaked in water or can be processed into starch (Umerie, et al; 1997) and flour (Oladele & Aina, 2007). It can be processed into a milky beverage caved “Horchate de Chuta” in Spain or “Atadwe” milk in Ghana; (Cortes et al; 2005). Tiger nut is common known as earth almond, chu-fa and zulunut’s known as in Nigeria as aya in Hausa,  ofio in Yoruba and akiausa in Igbo where three(3) varieties (black, brown, and yellow)readily available in market (okafor et al; 2003)Tiger nut can be used in conjunction with other foods to fight cardiovascular diseases (Djomdi & Ndjouenkeu, 2006). In Nigeria, tiger nut is well grown and mostly available in semi-dried form in Nigerian markets where it is sold locally and consumed uncooked, they are underutilized due to lack of information on their nutritional (Fatoki et al, 1995).


Physical properties of food such as the shape, size, weight, geometric mean diameter, arithmetic mean diameter, densities, porosity, surface area etc are used in process design, product and process optimization, product development food quality control and food process modeling. The physical properties of Tiger nut is needed in design of machines used during harvesting, separating cleaning, and storing of the nut. The ability of any grain or fruit to either roll or slide depends on the aspect ratio and as well as sphericity, moreover, the relatively high sphericity and aspect ratio will be easier in getting the seed.



The physical properties such as size, sphericity index, aspect ratio true density, bulk density and porosity of two varieties of fresh oil palm fruit (dura and tenera) were investigated by Owolarfe et al (2007a). They studied the characterization of palm fruit by determining some macro-structural (physical and mechanical) properties of palm fruit (tenera variety) at different processing conditions, such as sterilization time and duration of digestion, while The physical and acrodynamic properties, Such as the length, thickness, geometric mean diameter were investigated by Gursoy S. and Guzel E. (2010) which result to the mechanization of the grain in order to increase utilization as a food resources etc.


The purpose of determining physical and aerodynamic properties, some varieties of wheat, barley, chickpea, and lentil were used. The length, width, thickness, geometric mean diameter, equivalent sphere diameter, sphericity. Seed mass, bulk density, true density, projected area, terminal velocity, drag coefficient of each grain variety were determined. The theoretical terminal velocities of those grains were calculated by using equations corrected with the shape factor. For all the grains, theoretical terminal velocities were lower than the experimental values. The average experimental terminal velocity was found to be in the range of 7.52 to 8.14 m/s for wheat varieties, 7.04 t 7.07mls for barley varieties, 7.72 to 7.78m/s for lentil varieties and 11.15 to 12.01m/s for chickpea varieties. The drag coefficients of seeds according to projected areas in different positions and equivalent spheres were calculated. The drag coefficient in the position of the lowest projected area for all the grain varieties was higher than that in the other position. (Gursoy & Guzel, 2010)


According to Adeyanju & Abimbola (2015), the effect of cooking duration on physical, chemical and thermal properties of Bambara groundnut. The samples were analyzed for chemical composition, physical properties (length, width and thickness, arithmetic mean, geometric mean, sphericiety, surface area and sepet ratio) and thermal properties (specific heat capacity, thermal conductivity and thermal diffusivity). Data were analyzed using analysis of variance (ANOVA) and means were separated using the Duncan multiple range test at P <0.05. Times required for samples to be cooked were 1,2 and 3 hours respectively. The result of chemical composition for uncooked and cooked Bambara groundnut showed that protein (18.32-21.70% fat (4.12-5.29%); crude fibre (3.15-4.34%) ash (1.17-3.13%); moisture content (6.33-15.03%) and carbohydrate (54.27-61.34%) length, width, and thickness of uncooked to cooked Bambara groundnut at different time interval were 12.49 to 15.22mm,  11.46 to 13.67mm and 10.90 to 1254mm, respectively. The arithmetic mean diameter and geometric mean diameter of the samples were 11.62 to 13.81mm and 11.59 to 13.75mm respectively. The sphericity, surface area and aspect ratio of the samples varied from 0.89 to 0.93, 423.31 to 595.88mm and 88.22 to 92.13%, respectively. Thermal conductivity varies from 0.15 to 0.20 w/mk, specific heat capacity varies from 1.298 to 1.5898kj/kgk. Thermal diffusivity varies from 1.10 x 104 to 1.12 x 104m2/s. the chemical, physical and thermal properties of Bambara groundnut studied were significantly different (P<0.05).



According to Adekunle, et al; (2013), the physical and thermal properties of baobab (Adansonia digitata) fruit pulp powder which are essential for designing engineering processes, material handling, storage, equipment design and fabrication were determined. The physical properties, namely, mean particle size bulk density, true density, and porosity were determined. Also angle of repose and coefficient of friction were tested on mild steel, plywood and plastic which are probable engineering materials for construction of food processing equipment.


According to Pius & Phumuza (2014). The morma bean (Tylosema esculentum) is an underutilized legume native to the kalabari region of southern Africa. Some engineering properties relevant to the mechanization of its processing have been characterized namely; size, shape, surface area, projected area, volume, density, porosity, 100-gram mass, static angle of repose, static coefficient of friction and texture. At moisture content of 7.4% (wb), the average length, width and thickness of the beans were 19.25, 17.21 and 13.39mm, respectively. Geometric mean, equivalent diameter and arithmetic mean diameters were 16.4, 16.51 and 16.61mm respectively. Morama beans are spherical in shape, having average sphericity of 85.45%, aspect ratio of 0.90 and flakiness ratio of 0.78 surface area, projected area and volume of the beans were 850.43mm2, 261.95 and 2,352.82mm3, respectively. Mean true and bulk densities were, respectively 1,075.13 and 795.31 kg/m3 with bulk porosity derived as 25.76% mean 1000‑ grain mass was 2.21kg. static angle of repose were 12.980, while static coefficient of friction of Morama against plywood, galvanized iron, stainless steel, plastic, and itself, were 0.2, 0.26, 0.2, 0.18, and 0.24, respectively. Texture analysis by flat-plate compression testing showed that the beans required an average of 546.78N to break absorbed up to 470.03mj of energy before breaking with hardness computed at 120.52 N/mm.


According to karpoora; (2013), the average length, width, thickness, geometric mean diameter, spericity index, surface area, bulk density, true density, and porosity of tamarind fruit at the moisture content of 25% on dry basis were determined. Angle of repose during filling and emptying were in an average of 33.53 and 49.72, respectively. Coefficient of friction for tamarind fruits on different surfaces namely, hard steel, mild steel stainless steel, aluminum and galvanized iron sheet were found to be 0.59, 0.41, 0.48 and 0.58, respectively.

To successfully design the equipment for agricultural processing, knowledge of the physical and mechanical or engineering properties of the agricultural produce is essential (Tabatabaeefer et al., 2003; Irtwange, 2009). Also during the processing and handling of the agricultural materials, these properties are needed for setting the operational parameters of the equipment for efficient operations. Different researches report the use of characteristic dimensions to determine the size of seeds (Sinsomboon et al., 2007; Irtwange and Igbeka, 2002; Gursory and Guzel, 2010; Mirzabe et al., 2013). Size and shape are important for separation, sorting, grading and quality evaluation of agricultural produce (Sahin and Sammu, 2006). Furthermore, the characteristic dimensions allow calculation of the surface area and volume of grains, important technological considerations for instance surface area of crops and fruit is useful in respiration measurements, determination of quality and quantity, colour, and in acrodynamic computations (Sitkei, 1986; Singh and Heldman, 2009). Porosity affects the bulk density of materials which determines produce the bulk density of materials, which determines produce storage requirement and conveyor capacity. It is also a critical factor in drying and ventilation processes, while the true density is useful in materials separation processes.

The knowledge of the physical properties of Tiger Nut, the current study sought to determine strategies relevant to the mechanization of its processing in order to increase its utilization as a food resource.


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