Agave bagasse, a lignocellulosic byproduct of mezcal production, remains underutilized due to its structural recalcitrance and environmental burden. This study explored the use of nejayote, an alkaline effluent from tortilla production, as a pretreatment to enhance delignification and improve the bagasse's suitability for solid-state fermentation (SSF) with edible fungi. Two nejayote samples from tortilla factories in Querétaro, Mexico, were physicochemically characterized, and a 3³ factorial design was employed to optimize pretreatment conditions. The nejayote maintained a high alkaline pH (~13), reduced furfural content by up to 98 %, and increased sugar availability. Pretreated bagasse was fermented with Pleurotus ostreatus and Lentinula edodes, enhancing its nutritional profile¿soluble dietary fiber increased by 30¿50 %, and antinutritional compounds like gallic acid and lignin were reduced by 96 % and 49 %, respectively. Scanning electron microscopy showed increased porosity and lignin degradation, particularly with L. edodes. Volatile compound profiles also improved, rising from 8 to 13 compounds post-fermentation. This bioprocess valorizes two agroindustrial residues¿nejayote and agave bagasse¿into a nutrient-rich substrate for edible mushroom cultivation. The fermented biomass offers dietary fiber and bioactives, contributing to circular economy models and sustainable protein and functional ingredient development in food systems.
