Fibre, protein and mineral fortification of wheat bread through milled and fermented brewer's spent grain enrichment

Brewer's spent grain (BSG) represents 85 % of brewing industry by-products. Currently, BSG is underutilised as low-value animal fodder. The current study aims to expose additional nutritional and economic benefits of BSG as a food ingredient in wheat breads. The raw material properties were studied revealing that BSG by-product contains (on a w/w) 22.13 % protein (including exceptionally high levels of essential amino acids), 1.13 % minerals, 131.0 mg/L polyphenols, 28.22 % total fibre and 3.6 % essential fatty acids. Additionally, BSG was fermented (BSG SD), using the lactic acid bacteria, Lactobacillus plantarum FST 1.7, to elucidate the benefits of traditional sourdough for processing crude BSG. Fermentation resulted in softer breads with increased springiness. Farinograph results revealed that wheat flour incorporating BSG had increased water absorption. Rheological measurements showed a positively correlated increase in dough resistance in line with BSG or BSG SD incorporation. Supplemented breads had sensory acceptability up to levels of 10 % BSG or BSG SD, resulting in breads comparing favourably with wholemeal breads from a nutritional, technological and textural perspective. Using BSG as a main stream food ingredient would increase the market value of this by-product, thus enhancing its economic potential, a factor that is also discussed.