Solid-state fermentation by Trichoderma viride for enhancing phenolic content, antioxidant and antimicrobial activities in ginger

The phenolic content of methanol and water extracts of ginger fermented by Trichoderma spp. using solid-state fermentation (SSF) was evaluated and was compared with unfermented ginger. The total phenolic content in fermented ginger increased several times. The highest phenolic content in ginger was detected after SSF by T. viride. The optimal physiological conditions for the maximum production of phenolic compounds and β-glucosidase activity of fermented ginger by T. viride were detected at day 7 incubation, pH 6·0, 30°C and 30% moisture. The SSF of ginger by T. viride greatly enhanced the antioxidant potency of phenolic compounds and was evaluated using DPPH and ABTS assays. A potent antibacterial activity of the phenolic compounds of fermented ginger was observed against all the tested human-pathogenic bacteria.

Significance and impact of the study: This is the first report to investigate the optimal physiological conditions of solid-state fermentation (SSF) of ginger by Trichoderma viride for enhancing its phenolic content and antioxidant capacity. In addition, the phenolic compounds of fermented ginger could be potentially used as a dietary adjunct and an antibacterial agent.