Modelling the odor profile of fungal Solid-State Fermentation

The sensory properties of alternative proteins are key to consumer acceptance, yet the processes shaping their odor remain unclear. Solid-state fermentation (SSF), a promising method for producing alternative proteins from agro-industrial by-products such as bagasse, brans, pomaces, husks and oil cakes, is used in this study to model odor profile development of surplus bread crusts, supplemented with perennial ryegrass protein with Rhizopus oligosporus, Aspergillus oryzae, and Neurospora intermedia at 32 °C for up to 72 h. Volatile organic compounds (VOCs) were analyzed by solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS), identifying over 150 compounds. A mechanistic model based on the Weber-Fechner law predicted odor profiles from VOC concentrations, odor descriptors and thresholds, and was validated against a quantitative descriptive analysis (QDA) performed by a trained panel using multiple factor analysis (MFA). The model reflected changes in the overall odor intensity and sweet, baked, and grass-like notes, though correlations were weaker for fungal-derived descriptors (fruity, earthy, herbal). These findings elucidate how fungal SSF alters odor profiles in alternative proteins and establish a framework for mechanistic odor prediction in food systems.