Physical and mechanical properties of locally cultivated tomatoes in Sunyani, Ghana

The physical and mechanical properties of tomato fruits are very pertinent and crucial in the design of mechanised equipment for harvesting, cleaning, sorting, grading, storing and packaging for transportation from farms to processing plants or market centres. The concept of physical and mechanical properties can be applied to prevent the degradation of tomato fruits during harvesting and processing. The objective of this research is to establish the physical and mechanical properties of locally cultivated tomatoes (Eva F1 variety) in the Bono Region of Ghana. The 3-Dimensional linear characteristics of the samples obtained from linear measurement lead to the conclusion that Eva F1 is spherical and as a result it can undergo both sliding and rolling motions because of the aspect ratio which is between 77.54 to 95.18 and sphericity values above 83.00. The linear measurements also revealed that handling and sorting devices should have an aperture size between 34 and 77 mm for outlet or inlet dimension for mechanisation. An ELE compression machine was used to determine the firmness of different grades of Eva F1 tomatoes (red and yellow). An average compressive force of 16.88 N was found to cause fracture to the cell wall of a ripe (red) tomato while the yellow grade experienced an average force of 21.77 N. An inclined plane was used to determine the coefficient of friction for two different wooden surfaces (smooth and rough wawa boards). Average coefficient of friction values higher than 0.22 are recommended for mechanised material handling equipment and 0.21 or lower for packing boxes suitable for transportation. The research also showed that the best stage for the transportation of tomato is when they are at the yellow stage with low coefficient of friction and can absorb more energy before rupture.