Extracting proteins from Brewers’ spent grain using emerging
technologies: Evaluating efficiency and use as emulsifier
Abstract
Brewers’ spent grain (BSG) is the main side-stream of the brewing
industry with an annual production of 40 million tons of wet weight. BSG
has a protein content of 15-30 % dry basis, which makes it an
interesting material for protein extraction. Normally, extraction is
performed under high temperatures or high alkaline conditions. In this
study, microwave-assisted extraction, pulsed electric field, ultrasound,
and ohmic heating were tested to extract proteins from BSG without pH
adjustment (pH 6) or at pH 9. The extracts were further tested for their
emulsifying activity. The results obtained showed that the use of
ultrasound at pH 9 resulted in the highest protein content and protein
recovery of 24.1 % and 58.6 %, respectively. Extracts produced from
microwave-assisted extraction and ohmic heating could produce the
smallest emulsion droplets; however, the stability of all emulsions was
low. The present study highlights the potential of emerging technologies
as an alternative to harsh solvent usage in order to extract BSG
proteins.