Fibre, protein and mineral fortification of wheat bread through incorporation of both milled and fermented malt rootlet and brewer's spent grain

Barley ranks fourth amongst all cereals in total world production and cultivation area with its primary use in malting and brewing applications. The two major bulky by-products of beer production are brewer’s spent grain (BSG) and rootlets. Currently, these barley derivatives are predominantly used as animal fodder. The aim of our research was to exploit these nutrient-rich raw materials as functional ingredients in wheat bread, up to a level of 20%, thus offering consumers a high nutrition alternative to wholemeal breads with improved technological attributes. BSG and rootlets were milled and then incorporated into bread formulations. Additionally, they were processed by traditional lactic acid bacteria (LAB) fermentation, using Lactobacillus plantarum FST 1.7, before use as ingredients. The four materials (BSG, rootlets, BSG sourdough (SD) and rootlet SD) were characterised from a nutritional perspective to ascertain their potential benefits as functional food ingredients. BSG contained (% w/w); 22.13 % protein including an exceptionally high levels of essential amino acids, 1.13 % minerals, 131 mg/L polyphenols, 50.2 % dietary fibre and 51.1 % (total fats) essential fatty acids. Analyses showed that rootlets contributed natural nutrients and bioactive compounds such as (% w/w); 36.75 % protein, 2.88 % minerals, 102 mg/L polyphenols, 43.0 % dietary fibre and 67.2 % (total fat) essential fatty acids. Rootlets are particularly rich in essential amino acids, particularly lysine (6.6 %, total protein). Additionally, BSG and rootlet sourdough addition to the bread, at certain levels, resulted in significantly softer breads with increased springiness. Rheological measurements showed a positively correlated increase in resistance of the dough in line with by-product and SD incorporation. Additionally, supplemented breads were acceptable up to levels of 10 % for each ingredient resulting in products which compared favourably with wholemeal breads from a nutrient, technological and textural perspective. Furthermore they were well accepted by sensory panellists. Using these by-products/ SD as a mainstream food ingredient would have the additional benefit of increasing the market value of these brewing by-products.