The microbiome modulating potential of superheated steam (SHS) treatment of dietary fibres

In this study, wheat and oat bran fibres were used to investigate the potential beneficial prebiotic-enhancing effects of superheated steam (SHS) treatment. Following SHS treatment of fibres, in-vitro simulated gastric and intestinal digestion followed by batch culture fermentation was performed. 16S rRNA gene sequencing and short chain fatty acid analysis were conducted, which demonstrated that SHS treatment was associated with significant differences in beta diversity and the relative abundances of several microbial taxa. Principal Coordinate Analysis (PCoA) revealed significant separation between SHS-treated oat and non-treated oat (p = 0.013), and between SHS-treated wheat and non-treated wheat following in vitro batch fermentation (p = 0.042). Abundances of Ruminococcus were found to be significantly higher by 1.09-log in SHS-treated oat when compared with non-treated oat while abundances of Escherichia_Shigella, and Alistipes were significantly lower by 1.47-log and 0.39-log, respectively in the SHS-treated oat samples than the non-treated oat samples (p = 6.85E-06, p = 0.002037, p = 0.002458; respectively). These data demonstrate that SHS treatment of dietary fibre enhanced its effectiveness to modulate the gut microbiome. Industrial Relevance: Superheated steam (SHS) treatment has emerged as an effective method to improve the shelf-life of grains by reducing lipid hydrolysis and oxidation. Our results revealed that SHS treatment of wheat and oat brans led to increased physiological and chemical properties including higher water-binding capacity, water-extractable arabinoxylan, and total phenolics as well as improvement in human gut microbiota. Our results suggest that this method could be implemented in the food industry in order to improve beneficial properties of oat and wheat brans.