MECHANICAL BEHAVIOR AND PHYSICAL PROPERTIES OF CHICKEN EGG AS AFFECTED BY DIFFERENT EGG WEIGHTS EBUBEKIR ALTUNTAS 1,3 and AHMET SEKEROGLU 2 1 Department of Agricultural Machinery 2 Department of Animal Science Agricultural Faculty Gaziosmanpasa University 60240 Tokat, Turkey Accepted for Publication February 19, 2008 ABSTRACT This study was carried out to determine the effect of egg weight on physical properties and mechanical behavior under compression of chicken eggs. Four different weights – including medium, large, extra large and jumbo – were used. Physical properties of chicken egg – such as size, geometric mean diameter, sphericity, volume, surface area, packaging coefficient of eggs, shape index, shell thickness and static coefficient of friction on various surfaces – were determined. The mechanical properties of chicken egg to compression as effected by egg weight were determined in terms of average rupture force, specific deformation and rupture energy along x- and z-axes at different compression speeds. The length, width, geometric mean diameter, unit mass, surface area, egg volume and packaging coefficient increased as the egg weight increased. The average shape index and shell thickness values ranged from 78.37 to 79.56, and 0.400 to 0.387 mm for the eggs tested, respectively. The static coefficients of friction on various surfaces, namely, glass, plywood, galvanized metal, rubber and chipboard, increased linearly with increasing egg weight tested. The rubber surface presented the maximum friction followed by plywood, chipboard, galvanized metal and glass. The force required to initiate egg rupture on the z-axis decreased as egg weight increased from medium to jumbo. The specific deformation and rupture energy values observed for chicken eggs compressed along the z-axis were higher than the values obtained when testing eggs in the x-back and x-front orienta- tions. The results indicated that the rupture force along all three axes is highly dependent on the egg weight over the compression speed ranges investigated. 3 Corresponding author. TEL: +90-356-2521616; FAX: +90-356-2521488; EMAIL: ealtuntas@ gop.edu.tr Journal of Food Process Engineering 33 (2010) 115–127. All Rights Reserved. © Copyright the Authors Journal Compilation © 2008 Wiley Periodicals, Inc. DOI: 10.1111/j.1745-4530.2008.00263.x 115