Extraction and characterisation of arabinoxylan from brewers spent grain and investigation of microbiome modulation potential

Abstract

Purpose Brewers’ spent grain (BSG) represents the largest by-product of the brewing industry. Its utilisation as an animal feed has become less practical today; however, its high fibre and protein content make it a promising untapped resource for human nutrition. BSG contains mainly insoluble fibre. This fibre, along with protein, is trapped with the complex lignocellulosic cell structure and must be solubilised to release components which may be beneficial to health through modulation of the gut microbiota. Methods In this study, the application of a simultaneous saccharification and fermentation process for the extraction and solubilisation of arabinoxylan from BSG is demonstrated. Results Processing of the BSG was varied to modulate the physicochemical and molecular characteristic of the released arabinoxylan. The maximum level of arabinoxylan solubilisation achieved was approximately 21%, compared to the unprocessed BSG which contained no soluble arabinoxylan (AX). Concentration of the solubilised material produced a sample containing 99% soluble AX. Samples were investigated for their microbiome modulating capacity in in-vitro faecal fermentation trials. Many samples promoted increased Lactobacillus levels (approx. twofold). One sample that contained the highest level of soluble AX was shown to be bifidogenic, increasing the levels of this genus approx. 3.5-fold as well as acetate (p = 0.018) and propionate (p < 0.001) production. Conclusion The findings indicate that AX extracted from BSG has prebiotic potential. The demonstration that BSG is a source of functional fibre is a promising step towards the application of this brewing side-stream as a functional food ingredient for human nutrition.

Feed your microbes to deal with stress: a psychobiotic diet impacts microbial stability and perceived stress in a healthy adult population

“…DNA extraction: DNA was extracted from 200 mg of fecal sample using the QIAamp Fast DNA Stool Mini Kit (Qiagen, Germany) combined with repeated bead beating steps, according to methods previously described [27,28]. DNA concentrations were quantified using Qubit High Sensitivity Kit (Invitrogen).…”

The Potential of Brewer’s Spent Grain in the Circular Bioeconomy: State of the Art and Future Perspectives

“…The average content of lignin is 11.41%, but it can vary from 3.35% (Castro and Colpini, 2021) to 21% (Giacobbe et al, 2019). The amount of arabinoxylans, the main components of hemicellulose, in BSG ranges from 2.67% (Bravi et al, 2021) to 21.9% (Lynch et al, 2021). β-glucans are present in an amount of 1% (Bravi et al, 2021).…”

Arabinoxylans as Functional Food Ingredients: A Review

“…In the particular case of AX, a prebiotic effect has been reported in in vitro and in vivo studies. In a recent study by Lynch et al, [ 97 ], brewer’s spent grain (BSG) was used to extract soluble AX through simultaneous saccharification and fermentation processes. The extracted solutions containing 99% soluble AX were studied for their microbiome-altering abilities through in vitro faecal fermentation trials.…”