The determination of the physical and mechanical properties of NERICA paddy (FARO's 44(SIPI), 51(Isadane), 52(WITA 40) and 57(TOX4004-43-1-2-1)) at different moisture contents were carried out. The paddy rice was studied under un-parboiled and parboiled states. The results indicate that the size ranges were 3.88mm to 5.14mm for FARO 51; 3.91mm to 4.98mm for FARO 57; 3.62mm to 4.61mm for FARO 52 and 3.10mm to 4.82mm for FARO 44. This explains that no single sample of NERICA paddy can effectively represent the size of the other samples. In mechanical properties, results indicate that FARO 51 had highest values of rupture force, 42.00N at 13% moisture content in longitudinal loading position and FARO 52 had lowest values of rupture force, 23.10N at 13% moisture content for un-parboiled samples in lateral loading position. FARO 51 had highest values of rupture force, 39.50N at 13% moisture content in longitudinal loading position and FARO 52 recorded lowest rupture force, 15.80N at15% moisture content for parboiled samples in lateral loading position. It implies that force beyond these points at this moisture contents may cause damage to the NERICA paddy.
1.1 Background to the study
After harvest, agro raw materials are normally handled, transported, dried, stored and further processed into food, feed and fiber.
In some basic post harvest activities, separation processes such as sorting, grading and cleaning are involved.
In mechanized operations, these post harvest processes are supposed to be carried out with machines and equipment. The engineering design and efficient operation of the post harvest processing machines and equipment require adequate knowledge of engineering properties of the bio-materials. Knowledge of engineering properties such as physical and mechanical properties constitute important and essential engineering data in the design of machines; storage structures; processes and controls as well as in the analysis and determination of the efficiency of machines, development of new consumer products of plants and animal origin and in the evaluation of the quality of food products. (Mohsenin,1986; Oluka, 1991; Oluka and Nwuba, 2001).
1.2 Statement Of Problem
NERICA, also known as New Rice for Africa (NERICA) is a hybrid of the local African rice variety with high disease resistant traits and the high yielding variety of Asia. The rice is quite new to Africa and is currently being adopted and tried across the continent.
As a new product, there are on-going research studies on NERICA rice varieties. Studies on the engineering properties of the new rice variety are one of them.
Physical and Mechanical handling of the post harvest processing operation of NERICA require adequate knowledge of the physical and mechanical properties. This is the challenge of this study.
Knowledge of these properties will be valuable to Engineers, Food Scientists and Processors in designing of machines, storage structures, processes and controls as well as in the development of new products and quality assessment of food products.
1.3 Research Objectives:
The overall goal is to study the physical and mechanical properties of NERICA Paddy. The specific objectives include:
(i) To determine the physical properties of NERICA paddy such as shape, size, volume, density, specific gravity, sphericity and surface area.
(ii) To determine the mechanical properties of NERICA paddy such as rupture point, deformation, compressive strength, modulus of deformability, toughness, stiffness and the force at bio-yield point relevant to its milling and processing.
1.4 Significance Of The Study
The information obtained are essential in the processing of rice paddy (NERICA) and prevention of mechanical damages during handling, processing and storage of the paddy. Equally, the knowledge of these properties will serve as a guide to designers of processing, storage and general handling equipments.
1.5 Scope Of The study
The scope of this study is limited to physical and mechanical properties of NERICA relevant to its milling and design of machines for its handling and further processing operations. Only laboratory experimentation and measurements will be used as research procedures.