Study of the Formation of Neuromodulatory Compounds in Fermented Products Based on Triticale, Naked Oat, and Amaranth Grains

This study investigated non-conventional crops as raw materials for plant-based fermented functional products with potential neuromodulatory properties, assessing antioxidant activity, amino acid composition, neuroactive metabolites, and aroma profile. Antioxidant activity depended not only on total phenolic content but also on the composition and extractability of other bioactive and reducing constituents released during processing. Free amino acid and γ-aminobutyric acid (GABA) profiles differed markedly from the raw grains, reflecting the effects of enzymatic hydrolysis, formulation, and microbial fermentation. The naked oat fermented product (NOFP) had the highest total, essential and branched-chain free amino acid contents and contained serotonin (811 µg/kg). The triticale fermented product (TFP) showed high phenylethylamine (440 µg/kg), proline and glutamine, and the highest diacetyl content (502 ng/g), potentially contributing to its nutritional and sensory properties. The amaranth fermented product (AFP) was distinguished by high GABA (648.9 mg/kg DW) and L-DOPA (15,272 µg/kg). Kynurenine, kynurenic acid, indole-3-lactic acid, tryptamine, and other tryptophan and tyrosine metabolites were also detected. Volatile profiles were strongly matrix-dependent; AFP was the most diverse, with high levels of aldehydes, pyrazines, furans, and sulfur-containing compounds. Overall, the grain matrix and the processing and formulation sequence strongly influence the nutritional, antioxidant, neuroactive, and aroma characteristics of the products.