Hydro-mechanical processing of brewer's spent grain as a novel route for separation of protein products with differentiated techno-functional properties

Hydro-mechanical processing using a colloid mill with a large gap setting leads to the preferential breakup of the residual aleurone and endosperm tissues of brewer's spent grain, forming a protein rich fines material with small particle size around 1–10 μm. This fraction can be separated from the coarser husk fraction by centrifugation, giving a protein product with enhanced techno-functional properties. The fines have good stability in aqueous suspensions, with potential for stabilising other particulate materials in food or drink formulations. The fines particles can stabilise oil-water emulsions, possibly through a Pickering mechanism, which may also support use in food applications. Fines suspensions have strong shear-thinning behaviour, which may be beneficial from a textural or transport perspective. Spray drying of fines suspensions is shown to avoid particle coalescence, which is important for effective resuspension on rehydration. The high surface area of the fines also leads to more efficient digestion by proteases.