DEVELOPMENT OF ENVIRONMENTAL FRIENDLY MULTI-CROP SLICING MACHINE TO ERADICATE UNHYGIENIC MANUAL PROCESSING FOR HEALTH SAFETY

Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo Advances in Environmental Health Sciences and Toxicology (AEHST) A publication of the University of Medical Sciences, Ondo City, Ondo State, Nigeria Background: Human health safety is very important and considered as the number one criterion in the design and fabrication of any food processing machine. Manual slicing methods are unhygienic, risky, stressful and inefficient while the use of an internal combustion engine as prime mover in the food processing machine is not environmental friendly due to the emission of gases. Objectives: The aim of this study was to design, fabricate and evaluate for performance an environmental friendly and hygienic multi-crop slicing machine. Methods: The major components of the machine include the hopper, mainframe, driving pulley, belt, driven pulley, shaft, main bearings, crank plate, connecting rod, slicing unit, groove bearings, spacers, electric motor and outlet. The machine is powered by a variable speed, three-phase 0.75 kW electric motor with rotational speed ranging between 284 and 800 rpm. The performance of the machine was evaluated in slicing six different crops namely yam, carrot, sweet potato, onion, plantain and cucumber at three machine speeds of 190, 362 and 533 rpm while the slice thickness was also varied as 3, 5 and 8 mm. The parameters that were investigated include functional efficiency (FE), slicing efficiency (SE), percentage mechanical damage (MD), percentage materials lost (ML), percentage materials retained (MR), throughput (TP), slicing capacity (SC) and quality performance efficiency (QPE). Results: Major performance criteria obtained for yam were 90.4% FE, 93.7% SE, 156.7 kg/h TP, 84.8% QPE and 11899 slices per hour. 88% FE, 93.7% SE, 120.7 kg/h TP, 82.4% QPE and 9365 slices per hour were obtained for sweet potato. 85% FE, 95.8% SE, 138.5 kg/h TP, 81.5% QPE and 31300 slices per hour were obtained for the carrot. 78% FE, 98.3% SE, 68.4 kg/h TP and 77% QPE were obtained for onion. 89% FE, 92.5% SE, 83.5 kg/h TP, 82.5% QPE and 15876 slices per hour were obtained for plantain. 93.5% FE, 94% SE, 128 kg/h TP, 88% QPE and 13790 slices per hour were obtained for cucumber. The result of the study shows that the machine can slice any fruit as well as root and tuber crops satisfactorily. Conclusion: The performance evaluation revealed that any of the speed and thickness range can be used without a significant side effect. Keywords: multi-crop; functional efficiency; percentage materials retained; throughput; quality performance efficiency INTRODUCTION A machine is a mechanical or electromechanical device or contrivance having two or more relatively constrained component parts which are actuated by a power source to transmit or modify force and motion required to accomplish some tasks or get some work done. The multipurpose crop slicing machine is a machine designed purposely for slicing different types of crops irrespective of the mechanical properties of such crops. Some of the crops in this category include plantains, bananas, cucumbers, carrots, okra, cocoyam, cassava, yams, etc. In designing such a machine knowledge of the mechanical properties of various crops which have been established by various DEVELOPMENT OF ENVIRONMENTAL FRIENDLY MULTI-CROP SLICING MACHINE TO ERADICATE UNHYGIENIC MANUAL PROCESSING FOR HEALTH SAFETY Ojolo G.T. Department of Food Science and Technology, University of Medical Science, Ondo, Nigeria *Corresponding author: E-mail: gojo- [email protected]u.ng Submitted 18 August, 2024 Accepted 17 September, 2024 ABSTRACT Vol. 1 No 1, September 2024, Pp. 62 - 76 62 URL: https://journals.unimed.edu.ng/index.php/JEMT/index Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo researchers is very paramount (Kolawole et al., 2007; ASAE, 2003; Schott, 2003; Altuntas et al., 2005). Plantain, bananas, cocoyam and yams are popular staples in Africa and in many other countries of the world. They contain ash, protein and the vitamins and are used in the human diet. It was also reported by Kachru et al. (1995) that unripe plantain is a major source of iron. This set of crops can be taken in fried, boiled, roasted and baked form. They can also be processed into chips. Through slicing, drying and grinding operation, they can be transformed to flour which is also consumed when baked. The flour can be reconstituted in boiled water to form dough which is taken with different kinds of delicious soup in many African countries. Various travellers, office workers and school children demand for banana, plantain and yam slices in form of fried chips greatly. In an effort to make these readily available, several means have been devised in cutting them into slices before being processed into chips and flour. Cucumbers, carrots and okra are very good source of vitamin and minerals in human diet. They can be eaten raw or processed into salad which is taken as part of daily meal. Cucumbers are best harvested when they are about 2 inches long up to any size before they begin to turn yellow. Okra has remained a very popular soup in many countries of the world til date. Processing of this set of crop is very advantageous because it makes storage easier due to the reduction in bulkiness and increase in their shelf life. This can be achieved through the process of slicing, drying and grinding. The kitchen knife method remains a primitive way of slicing crops in large quantities in small, medium and the large scale industries. In this case, a sharp knife is used to slice the crops on a wooden cutting board. The problems associated with this method are fatigue, a low speed which leads to poor output and low income generation, too many staff, hand injury, poor uniformity of chip thickness, high productive time and much energy consumption. The manually operated wooden platform crop slicer is another slow method employed in small scale industries. The crop is pressed and moved against the sharp blades of the machine. The major risk is that when it misses a cut, the machine operator gets his/her finger cut by the exposed sharp blades. It is also time consuming since the operator will be operating in a slow rate to avoid injury. Manually operated cutting knives are also another method in which the crops to be sliced are placed on top of a sharp blade on the base frame of the machine, and the upper handle on which sharp blades are contained is pressed down thereby crops into slices. The major problem here is that when off-loading, one gets his hands injured because of the slices stocked in-between the sharp blades. Due to the slow nature of off-loading, this method has also been considered to be time consuming. Therefore there is the need to design and develop a more efficient multipurpose crop slicing machine fit for the current commercial challenge. It is an indisputable fact that the disadvantages associated with the aforementioned methods limit the farmers’ output with little or no profit margin. However, various researchers across the world have developed machines to cater for each of the crops of concern in this project. In addition to improving the efficiency of these existing machines, there is a need to combine two or more functions in a single machine for better efficiency and productivity. Therefore, the design and development of multipurpose crop-slicing machine is the solution that crop processing industries across the world need to embrace. 2. MATERIALS AND METHOD 2.1 Conception of the Machine Conception of this machine began from the consideration of the stress, difficulty and hazard involved in the conventional slicing method and the fact that many small and medium scale chips producers are unable to afford the expensive foreign slicing machines. Moreover, the capacity in term of feed per unit operation and the efficiency of those few available locally made slicing machines are not enough. Also, a lot of cost will be saved by employing a single slicing machine for many crops instead of buying different machines to handle various individual crops differently. 2.2 Design Considerations The following are the considerations employed in the course of carrying out the design (i) The cost of the multipurpose slicer should be affordable; 63 Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo (ii) Minimum labour requirements; (iii) The design should be simple, easy to maintain and should be able to eliminate the limitations of other methods; and (iv) The materials required to fabricate the machine should be locally available. 2.3 Description and Operation of the Slicing Machine As shown in the annotated diagram of the multipurpose crop slicing machine contained in Figure 2.1, it is made up of cutting device, support frame, hopper assembly, shaft, bearings, covering guards and electric motor as a source of power. The cutting mechanism consists of the stainless steel blade, blade frame, groove, groove bearings, pulleys, two connecting rods and crank mechanism meant to convert rotary motion of shaft to reciprocating motion of the cutting unit. The blade is orientated such that it is parallel to the hopper assembly and perpendicular to the crops meant to be sliced. Moreover, the cutting mechanism of the machine is provided with adjustable spacers separating the cutting blade from the base plate with which various uniform slicing thicknesses can be achieved. The hopper assembly is made of stainless steel so as to avoid contamination of processed crops by corrosion. Power is transmitted from electric motor to input shaft via belt and pulley drive system. The crank plates hinged by the shaft on both ends transmit the motion of the shaft to the cutting unit through the connecting rods. Concurrently, the rotary motion of the shaft is converted to the reciprocating motion of the blade by the action of the crank mechanism. The crops loaded vertically in the hopper are fed automatically into the cutting chamber by gravity. As they drop on the base plate by gravity against the motion of the blade, uniform slices as predetermined are picked up by the blade at each reciprocating horizontal stroke of the blade. The operation continues by feeding the hopper with more crops continuously as its content is being exploited. The sliced crops drop inside the collector positioned at the discharge end of the machine. The facts that no stress is involved and no expertise is required in feeding the machine with crops are parts of the major advantages of this design. 2.4 Materials Selection Materials of fabrication were carefully selected to ensure high quality standard. The following were carefully considered in selecting the materials of construction. i. Physical and mechanical properties of the material ii. Chemical property of the materials iii. Reliability of the material iv. Availability v. Maintainability, and vi. Cost effectiveness Stainless steel was chosen as the appropriate material for those components that are having direct contact with the crops to avoid contamination by corrosion. Those components that were made of stainless steel include hopper, cutting blades, discharging tray and pressure plate. Spacers were made of aluminum while the remaining components were made of mild steel and galvanized metal sheet. 2.5 Design Calculations 2.5.1 Calculation of shaft and pulley speed Let the diameter of driving or motor pulley be = d = 8 cm The rotational speed of driving pulley = n = 284 rpm The diameter of driven pulley = D = 12 cm The rotational speed of driven pulley = N The speed of the driving pulley was measured as 284 rpm using digital Tachometer. 64 Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo Figure 2.1: Annotated diagram of the multipurpose crop slicing machine 65 Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo 66 Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo Figure 2.2: Belt design Figure 2.3: Angle of wrap (Ө) 67 Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo 2.5.7Determination of loads on the shaft The masses of the two cranks together with the attached connecting rod and the mass of pulley were determined using weighing balance. Their values were recorded as 1.245 kg, 1.245 kg and 1.173 kg respectively. Their weights were calculated in Newton (N) as shown below by multiplying their masses with acceleration due to gravity which is 9.81 m/s2. Moreover, the tension T1 and T2 exerted by the belt on the shaft were also calculated as shown below in order to calculate the total force acting at point (C) on the shaft. Vertical load acting on the shaft at (A) = 1.245 kg = 1.245 x 9.81 = 12.2 N Weight of pulley (Wp) = 1.173 kg = 1.173 x 9.81 = 11.5 N Vertical load acting on the shaft at (E) = 1.245 kg = 1.245 x 9.81 = 12.2 N Total vertical load acting on the shaft at (C) TVLC = Wp + T1 + T2 (2.13) TVLC = 11.5 + 160 + 837 TVLC = 1008.5 N 68 Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo Figure 2.4 Determination of belt tension (T1 and T2) on the shaft Figure 2.5 Shaft loading Figure 2.6: Free body diagram of the loaded shaft 2.5.8 Determination of bending moment (M) of the shaft Having determined the loads acting on the shaft, it became easy to calculate the reactions on bolt bearings by summing up the forces. 69 Advances in Environmental Health Sciences and Toxicology , Volume 1 Issue 1 Ojolo Figure 2.7: Bending moment diagram 70