Flax and wattle seed powders enhance volume and softness of gluten-free bread.

Gluten-free bread is generally associated with several quality defects such as reduced volume, dry texture and poor mouthfeel. Flaxseed gum has been shown to increase viscosity of bread dough. The aim of this study was to evaluate the effect of 1% (total base) addition of seed powders from flax ( Linum usitatissimum) and four acacia cultivars ( Acacia dealbata, A. decurrens, A. terminalis and A. verniciflua) on pasting properties, texture and volume of gluten-free bread. The incorporation of all seed powders reduced crumb hardness by 30-65% and increased specific loaf volume by 50%. Water absorption capacity and emulsifying ability contributed to these textural improvements and were attributed to water-soluble carbohydrates and insoluble fibre, while no foaming ability was detected. Darker crumb was observed upon flax addition, while dark particles were visible upon acacia addition. Scanning electron microscopy depicted absence of holes in the pore surface and viscoelastic starch-protein network in the seed powder containing bread.