The relationship between bread physical texture and its structure determined by digital image analysis

Abstract

The visual (cellular structure) and physical (mechanical properties) texture of bread crumb are quality attributes that were anticipated to be interrelated. This study was undertaken to evaluate the influence of bread crumb cellular structure on its mechanical properties. Crumb structural properties were characterised by density and six crumb grain features measured using a digital image analysis (DIA) system. These grain features included crumb brightness, mean cell wall thickness (CWT), void fraction (VF), mean cell-area (MCA), crumb fineness (number of cells/cm2), and a measure of crumb uniformity--SLCC (small-to-large cell count ratio). The mechanical properties were determined by tensile testing of bone-shaped specimens cut from the same bread samples used for DIA. Tensile parameters included Young's modulus, fracture stress, fracture strain, and fracture energy. Variation in bread formulation and processing conditions are known to have a great impact on the quality of bread. The effects of flour type,water absorption (WA), sheeting passes (SP) and proof time (PT) on density, grain features, and mechanical properties of bread crumb were assessed. (Abstract shortened by UMI.)