Evaluation of saponin and phenolic profile of quinoa seeds after fungal fermentation

Abstract

Solid-state fermentation can be an effective method of modelling the bioactive potential of plant materials, but the result is substrate and strain dependent. In this study, edible fungi traditionally used in Asian food fermentations (tempe moulds – Rhizopus oligosporus, R. oryzae and R. chinensis, koji mould – Aspergillus oryzae, oncom mould – Neurospora intermedia, and Mucor indicus) were grown on high-saponin quinoa seeds for 4 days at 30 °C. The sapogenin profile in the substrate was not changed after the fermentation. Whereas, the level and profile of phenolic compounds, as well as the antioxidant activity of the seeds, were diversified. The fermentation with R. chinensis, R. oryzae and A. oryzae caused an increase in soluble quercetin derivatives. Moreover, the concentration of bound phenolics was higher in the quinoa seeds fermented with most Rhizopus strains. The majority of the moulds were also efficient in the decomposition of phytate. Among the strains tested, the most promising results were obtained in the case of R. chinensis and R. oryzae. Further research is required to study their potential for the purpose of the fermentation of cereal and pseudocereal substrates.