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

Abstract

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. Graphical Abstract

Exploring fermentation with lactic acid bacteria as a pretreatment for enhancing antioxidant potential in broccoli stem powders

“…Regarding the intensity of the prior disruption of the plant material, it did not have a significant impact on the growth of any of the three strains tested, despite the expectation that the smaller particle size could enhance microorganisms' access to nutrients due to both nutrient release and increase of specific surface [46] , [47] . Nonetheless, grinding could also have promoted a greater release of phenolic compounds and isothiocyanates with antimicrobial properties and, therefore, with a negative impact on microbial growth.…”

The Role of Fungi in Food Production and Processing

“…The advantages that edible fungi have in comparison to general fungi are making them a possible source of food substitutes [170]. Furthermore, the substrates include various crops such as legumes and cereals, extracts such as plant proteins and starches, and concentrates like flour [171][172][173]. Moreover, it is noteworthy that the majority of end products derived from SSF, particularly filamentous fungi, Saccharomycetes and edible fungi, are devoid of toxins and considered safe for both animal and human consumption [174].…”

Comparison of antioxidant activities expressed as equivalents of standard antioxidant

“…As a standard for ABTS radical scavenging activity, Trolox > ascorbic acid > catechin > gallic acid was appropriate. Indeed, many researchers have frequently used Trolox and catechins as standards for quantitative indications of DPPH and ABTS radical scavenging activity (Saini et al, 2014;Liu et al, 2009;Sánchez-García et al, 2022;Pinto et al, 2021).…”