This study aimed to investigate the external force required to separate maize (Zea mays L.) kernels from the cobs core without inducing mechanical damage. Therefore, the experiment employed a triad system methodology, simultaneously considering the interactive relationship between the product and the threshing apparatus. The biometric parameters of 100 corn cobs, including mass, diameter, kernel count, and kernel weight, received analysis. For seed integrity, the physical property ‘test weight’ (natur) and kernel porosity reached evaluation. Macroscopic and microscopic damage categorization, as well as the force distribution during kernel detachment, upon evaluation, used both visual and instrumental methods. The experimental tests took place across varied disc rotation speeds (1–11 m/s) to determine the threshold detachment force (P_ext) under a dynamic impact. The study proposed a well-refined model integrating impact force, frictional resistance, and seed inertia to calculate the optimal kernel removal conditions. These results will serve to enhance threshing system designs and improve corn seed quality in postharvest processing.

Keywords: Maize (Z. mays L.), maize kernels, threshing apparatus, detachment force, threshing disc speed, mechanical damage, test weight, kernel porosity

Key findings: The results showed the test weight of maize (Z. mays L.) kernels was considerably dependent on the kernel’s size, shape, and moisture content. Increasing threshing speed enhanced the separation efficiency but raised the risks of mechanical seed damage. The theoretically determined separation force of 49–59 N plays a crucial role in preserving seed quality.