Next-generation fermented foods from non-conventional proteins: Linking fermentation dynamics, flavor chemistry, and gut microbiome modulation.

The urgent need to diversify protein sources beyond animal agriculture has propelled non-conventional proteins (e.g., insects, microalgae, single-cell organisms, novel plants) to the forefront of food innovation. However, their adoption is limited by off-flavors, anti-nutritional factors, and low digestibility. Fermentation can address these drawbacks and may impart health-relevant benefits, though human evidence remains limited. This review defines next-generation fermented foods (NGFFs) as rationally fermented non-conventional protein substrates achieving superior sensory, nutritional, and gut health outcomes and possessing the potential to replace existing food products. We synthesize the cascading effects of controlled fermentation on these matrices, connecting fermentation dynamics with flavor chemistry and gut microbiome modulation. We dissect substrate compositional peculiarities, proteolysis kinetics, metabolic fluxes, and microbial ecology under tailored conditions, showing how process parameters steer formation of desirable volatiles and elimination of off-note compounds. We explore the prebiotic and probiotic potential of the resulting ferments, with preliminary evidence for gut microbial restructuring, short-chain fatty acid enhancement, and intestinal barrier reinforcement. From these interdependencies, we propose an integrated process-property-health (PPH) nexus to rationalize NGFF design. Finally, we discuss how artificial intelligence, synthetic biology, and life-cycle assessment can accelerate translation to sustainable, consumer-accepted food systems, providing a holistic framework for harnessing fermentation to unlock alternative proteins' full potential. Critically, we identify persistent knowledge gaps, unresolved conflicts in literature, and methodological limitations that constrain current understanding, and we propose prioritized research directions to advance the field from descriptive case studies toward predictive, mechanistic design of next-generation fermented foods.