Nutritional and antioxidant changes in lentils and quinoa through fungal solid-state fermentation with Pleurotus ostreatus

Solid-state fermentation (SSF) may be a suitable bioprocess to produce protein-vegetal ingredients with increased nutritional and functional value. This study assessed changes in phenol content, antinutrient content, biomass production and protein production resulting from the metabolic activity of Pleurotus ostreatus, an edible fungus, in lentils and quinoa over 14 days of SSF. The impact of particle size on these parameters was also assessed because the process was conducted in both seeds and flours. Fungus biomass increased during fermentation, reaching 30.0 +/- 1.4 mg/g dry basis and 32 +/- 3 mg/g dry basis in lentil grain and flour and 52.01 +/- 1.08 mg/g dry basis and 45 +/- 2 mg/g dry basis in quinoa seeds and flour after 14 days of SSF. Total protein content also increased by 20% to 25% during fermentation, in all cases except lentil flour. However, the soluble protein fraction remained constant. Regarding phytic acid, SSF had a positive impact, with a progressive decrease being higher in flours than in seeds. Regarding antioxidant properties, autoclaving of the substrates promoted the release of polyphenols, together with antioxidant activity (ABTS, DPPH and FRAP), in all substrates. However, these parameters drastically decreased as fermentation progressed. These results provide scientific knowledge for producing lentil- or quinoa-based ingredients with low antinutrient content enriched with protein fungal biomass.

Automated summary

Solid-state fermentation (SSF) is a bioprocess that can produce protein-vegetal ingredients with increased nutritional and functional value. This study evaluated the changes in various parameters during the SSF process of Pleurotus ostreatus in lentils and quinoa. The results showed that fungus biomass and protein content increased during fermentation, while the soluble protein fraction remained constant. SSF also had a positive impact on reducing antinutrient content and promoting antioxidant activity. However, these parameters decreased as fermentation progressed.