In this study, the physicochemical, taste, and functional changes in low-salt Sufu paste were investigated during fermentation as enhanced by a mixed starter (Pichia fermentans, Kodamaea ohmeri, and Lactococcus lactis subsp. lactis) and α-ketoglutarate. The total free amino acids increased from 0.02 mg/g dry matter to 12.63 mg/g dry matter, and monosodium glutamate-like was the major free amino acid group (3.89 mg/g dry matter), followed by bitter according to the taste characteristics. Functional components such as γ-aminobutyric acid, riboflavin (VB₂), and puerarin significantly increased to 30.96, 4.97, and 12.03 mg/g dry matter, respectively, at the end of post-ripening (p < 0.05). Protease, lipase, peptidase, α-amylase, aromatic amino acid aminotransferase, and branched-chain amino acid aminotransferase activities increased and were significantly correlated (p < 0.05) with most physicochemical and functional components, indicating that enzymes may play an important role in the fermentation process of Sufu paste. Additionally, the color of the Sufu paste changed from pale yellow to yellowish brown, whereas the Sufu paste fermented without the mixed starter and α-ketoglutarate changed to gray, the unique color of gray Sufu. The preliminary results indicated that the mixed starter and α-ketoglutarate are beneficial for taste quality and color and that fermentation may be an effective method to enhance the functional components in Sufu paste. This information would be useful for future improvements in the manufacturing process and quality of Sufu paste.

The nutritional, functional and tasty components of three categories of Sufu, divided by strains in the culture phase, were comprehensively investigated in this study. The levels of isoflavones, γ-aminobutyric acid (GABA), phytosterols and soyasaponin were 0.58-2.20, 7.46-57.95, 0.73-2.72 and 10.89-23.35 mg/g dry matter (DM), respectively. Glu was the most abundant of the 17 detected free amino acids (FAAs), followed by Phe, Leu, Val and Asp. Additionally, potential tasty peptide profiles were typed by the segment of molecular weight (MW) < 300 Da, ranging from 79.22% ± 4.12% to 95.24% ± 2.93%. The complex taste impression based on the electronic tongue showed that the bitterness intensity was the highest, which was followed by saltiness and the umami intensity. To some extent, different Sufu categories can be distinguished according to the electronic tongue. The results provide a theoretical basis for improving the quality control and standardization of the manufacturing process.

Alzheimer’s disease (AD) is a common neurological disease with recognition ability loss symptoms and a major contributor to dementia cases worldwide. Gastrodia elata Bl. (GE), a food of medicine–food homology, has been reported to have a mitigating effect on memory and learning ability decline. However, the effect of GE fermented by Lactobacillus plantarum, Acetobacter pasteurianus, and Saccharomyces (FGE) on alleviating cognitive deficits in AD was not studied. Mice were randomly divided into six groups, control, model, donepezil, low, medium, and high doses of FGE, and D-Galactose/Aluminum chloride (D-Gal/AlCl₃) was used to establish an AD-like mouse model. The results indicated that FGE could improve the production of neurotransmitters and relieve oxidative stress damage in AD-like mice, which was evidenced by the declined levels of amyloid-β (Aβ), Tau, P-Tau, acetylcholinesterase (AchE), and malondialdehyde (MDA), and increased acetylcholine (Ach), choline acetyltransferase (ChAT), and superoxide dismutase (SOD) levels in brain tissue. Notably, FGE could enhance the richness of the gut microbiota, especially for beneficial bacteria such as Lachnospira and Lactobacillus. Non-target metabolomics results indicated that FGE could affect neurotransmitter levels by regulating amino acid metabolic pathways to improve AD symptoms. The FGE possessed an ameliorative effect on AD by regulating neurotransmitters, oxidative stress levels, and gut microbiota and could be considered a good candidate for ameliorating AD.

The fermentation of Gastrodia elata Blume (GEB) is an extremely complex process, and abundant metabolites are produced, which have a great influence on the quality and flavor. The non-targeted metabolomics method was used to analyze the comprehensive changes of differential metabolites and key metabolic pathways in the fermentation process of GEB. After fermented for 60 d, carbohydrate, organic acid, peptide, and nucleic acid metabolites were 79.77%, 12.91%, 4.39% and 2.79%, respectively. Compared with unfermented GEB, the carbohydrates decreased obviously, while organic acid, peptide and nucleic acid metabolites increased. A total of 32 metabolites were identified as the differential metabolites (VIP>1 and P < .05). Subsequently, metabolic pathways of differential metabolites were analyzed and 14 key metabolic pathways were found, among which methyl butyrate metabolic pathway, TCA cycle, alanine, aspartic acid and glutamate metabolism had greater influences on the GEB fermentation. Finally, the metabolic pathways network was constructed preliminarily. This work could be helpful to understand the differential metabolites and establish a preliminary foundation for further elucidation of the flavor formation mechanism during GEB fermentation.