Non-prolamin fraction from brewer’s spent grain: a novel plant-based emulsifier

Brewer’s spent grain (BSG) is a major by-product generated in brewing process, but has received little attention and needs to be subjected to value addition. The present study is aimed at fractionation of non-prolamin and prolamin proteins from wheat beer BSG, and to explore their emulsification potential. Preliminary studies showed emulsions made using non-prolamin fraction of BSG were stable, while there was a rapid fall observed in emulsion stability for prolamin fraction as measured at 30–150 min. Further studies using non-prolamin fraction showed emulsification activity index and emulsion stability of 245.6 m² g⁻¹ and 9.8% at pH 4, which increased with a rise in pH to 560 m² g⁻¹ and 90% at pH 9 respectively. Polyacrylamide gel electrophoresis (PAGE) of the non-prolamin fraction revealed a distinct band between 40–205 kD attributed to globulins, and bands with molecular weight <30 kD from albumins of wheat and barley. On estimation of zeta-potential it was seen that minimum surface charge was obtained at more than one pH value. Multiple pI values between 4 and 4.2 and 4–6.7 highlight the presence of multiple proteins and subunits as affirmed from PAGE. The obtained results enabled fractionation of non-prolamin and prolamin fractions of wheat beer BSG. The non-prolamin protein fraction isolated from beer industry waste could serve as a novel plant-based emulsifier with high value application in food industry.