Uni-axial Compression Loading and Cutting Behaviour of Cocoa Pods (Theobroma cacao L.) as related to Pod Breaking

Information on rupture force by uni-axial compression and cutting force of cocoa pods, is required for the design of pod breaker. These forces were determined for cocoa pods of F1 progeny varieties in a Universal Testing machine. The uni-axial compressive rupture load increased with increase in pod length. Rupture load was 0.43, 0.58 and 0.67 kN along transverse axis and 0.52, 0.65 and 1.03 kN along longitudinal axis for small (less than 120 mm), medium (120 – 140 mm) and large size pods (above 140 mm), respectively. The cutting force to cut the pods was determined with 15, 30, 45 and 60° sharp (bevel angle) knives at the stem end and apex with a straight edge one side sharp blade, and along the length (longitudinal axis) with a curved blade of 150 mm radius sharpened at both sides, with cutting speed of 10 mm min^-1 for all cutting experiments. The minimum force required to cut the pods near stem end for the pod sizes, small, medium and large, ranged from 0.11 to 0.18 kN with one side beveled 15° sharp blade. The minimum force required to cut the pods near apex for the pod sizes, small, medium and large ranged from 0.08 to 0.13 kN with one side beveled 15° sharp blade. The minimum force required with 45° double side beveled sharp curved blade ranged from 0.06 to 0.19 kN to cut along the length.