Food Aroma Formation by Filamentous Fungi: Metabolic Pathways and Selected Applications, with Emphasis on Asian Fermented Foods

Volatile compounds (VOCs) are important factors affecting the quality of fermented foods, acceptance of plant-based ingredients, and development value of natural flavors. Coupled with the increasing consumer demand for natural and clean-label foods, microbial fermentation has been promoted as a sustainable aroma production pathway. Compared with yeast, which mainly shapes flavor through ethanol fermentation, higher alcohols, and ester metabolism, basidiomycetes and filamentous fungi show more prominent extracellular enzyme secretion, complex substrate degradation, lipid oxidation, phenolic acid transformation, terpenoid transformation, and aromatic precursor biotransformation ability, which can synthesize diverse volatile organic compounds. This review focuses on the research progress in the production of volatile compounds by basidiomycetes and filamentous fungi (yeasts are excluded) for improvements in fermented flavor and reviews the groups, metabolic basis, fermentation process, and application in fermented food of aroma-producing fungi with selected application examples emphasizing Asian fermented foods. The challenges of fungal fermentation and the prospect of future research are also discussed here, providing a theoretical basis for the development of sustainable flavor ingredients.