Relationship between bran mechanical properties and milling behaviour of durum wheat (Triticum durum desf.). Influence of tissue thickness and cell wall structure

Abstract

Eight durum wheat samples, including four varieties grown in different environments, were employed in an investigation on the influence of mechanical properties of bran on milling behaviour. The anisotropic nature of bran due to the particular structure of the outer epidermis of the pericarp required investigation of its mechanical properties in two grain orientations. Rheological characteristics (strain and linear force to rupture, rigidity modulus and rupture energy) were determined using traction tests performed on isolated bran strips. The results revealed significant variability between samples with significant effects of wheat variety and crop site. Influences of tissue thckness on bran rigidity (E′), and the degree of arabinoxylan (AX) cross-linking in cell walls on bran strength and extensibility, respectively, were demonstrated. A strong influence of tissue extensibility on the degree of bran contamination of semolina generated during the milling process was established statistically. © 2002 Published by Elsevier Science Ltd.