Comparative study of solid-state fermentation with different microbial strains on the bioactive compounds and microstructure of brown rice

The effects of solid-state fermentation (SSF) with Lactiplantibacillus plantarum, Saccharomyces cerevisiae, Rhizopus oryzae, Aspergillus oryzae, and Neurospora sitophila were determined on the bioactive compound content and grain microstructure of brown rice (BR). After SSF, the β-glucan, arabinoxylans, γ-oryzanol, thiamine, riboflavin, phenolic, and flavonoid contents increased by 147, 11.2, 30.5, 16.9, 21.1, 76%, and 49.6%, respectively, indicating a marked increase in bioactive compound content. In addition, the water-soluble dietary fiber and arabinoxylan contents, and free phenolic and flavonoid contents significantly increased (p < 0.05). These changes were consistent with the microstructural changes observed after SSF, i.e., the outer cortex was rough, cracked, porous and separated from the starch endosperm, which was also cracked and porous; this should increase the dietary bioavailability of the bioactive compounds. SSF, especially with A. oryzae and Lb. plantarum, greatly enhanced the bioactive compound content in BR and has great potential in BR processing.