<div>Background: The development of post-harvest equipment or machinery is vital for agricultural productivity. Bixin, a natural colourant derived from annatto seeds, is still separated manually, which may result in pigment loss. The engineering properties of annatto fruits and seeds must be analyzed in this note for the development of a mechanical seed separator. 
 
Methods: The fruits were collected from Forest College and Research Institute, TNAU, Mettupalayam, Tamil Nadu. Engineering properties such as physical, gravimetric and frictional properties, colour and bixin content were determined for two dried annatto fruit and seed varieties (A1 and A2). The Z-test and t-test (p&lt;0.05) were used to statistically analyze the data. 
 
Result: The morphological characteristics of annatto fruits A1 and A2 differed noticeably and significantly. The surface area and volume of the A1 fruit were higher. The fruit and seed were merely spherical and conical. The lowest static friction was observed for stainless steel in both fruit and seeds. The mean bixin content of the A1 and A2 seeds was 1.5&plusmn;0.4% and 1.84&plusmn;0.57%, respectively. These engineering properties will be used to design a mechanical separator without much loss of pigment.</div>

Morphological Assessment of Annatto (Bixa orellana L.) Fruit and Seed for the Development of Mechanical Seed Separator