Impact of solid-state fermentation utilizing Saccharomyces boulardii on the chemical composition and bioactive constituents of rice husk

The objective of this study was to evaluate the effect of solid-state fermentation, utilizing Saccharomyces boulardii on brown rice husk, black rice husk, and smoked rice husk substrates in terms of the availability of different compounds. The fermentation process was carried out at 37 °C for a maximum of 12 hours, using yeast (2.5 % w/w) and water (25 %). During fermentation, black rice husks (BLRH) exhibited an increase in vitamins, protein, and fiber content, whereas brown rice husks (BRRH) showed an increase in carbohydrate and fiber, and smoked rice husks (SRH) decreased lipid and fiber content. The solid-state fermentation process also enhanced the availability and accessibility of minerals, except for smoked rice husk. The levels of phenolic compounds in fermented black, brown, and smoked rice husks were 1165, 1108, and 1051 micrograms per gram of sample, respectively. Importantly, black rice husk fermented for 8 hours demonstrated the most favorable results in terms of nutrient and bioactive compound availability. Principal Component Analysis (PCA) revealed correlations among the variables, which could be manipulated to improve the accessibility of diverse compounds.