Possibility of brewer’s spent grain application in production of modified wheat flours by extrusion process

Brewer’s spent grain (BSG) is the major by-product of the brewing industry, which contains about 17% cellulose, 28% non-cellulosic polysaccharides. It is available in large quantities throughout the year, but its main application has been limited to animal feeding. Nevertheless, due to its high content of protein and fibre (around 20 and 70% dry basis, respectively), it can also serve as an attractive adjunct in human nutrition. The aim of this research was to investigate the potential of BSG application in production of modified wheat flours by extrusion process [1-2]. Mixture ratios (wheat flour : BSG) investigated in this study were: 85 : 15, 70 : 30 and 55 : 45. Mixtures with 30 % moisture content were extruded in the laboratory single screw extruder at temperature profile 70/90/110 °C, using a screw with compression ratio 1:1 and die with 5 mm diameter. The research included determination of physical and rheological properties of non-extruded and extruded samples. The obtained results showed that the addition of BSG in wheat flour and extrusion process decreased all viscosity parameters. Furthermore, extrusion caused the reduction of falling number and sedimentation values, but the increment of water absorption index and dough development time. Dough stability for all extruded sample was 0, probably due to gluten “dilution” and degradation during the extrusion.