Flavor is an essential element of food quality. Flavor can be improved by adding flavoring substances or via microbial fermentation to impart aroma. Aroma-producing yeasts are a group of microorganisms that can produce aroma compounds, providing a strong aroma to foods and thus playing a great role in the modern fermentation industry. The physiological characteristics of aroma-producing yeast, including alcohol tolerance, acid tolerance, and salt tolerance, are introduced in this article, beginning with their origins and biological properties. The main mechanism of aroma-producing yeast is then analyzed based on its physiological roles in the fermentation process. Functional enzymes such as proteases, lipases, and glycosidase are released by yeast during the fermentation process. Sugars, fats, and proteins in the environment can be degraded by these enzymes via pathways such as glycolysis, methoxylation, the Ehrlich pathway, and esterification, resulting in the production of various aromatic esters (such as ethyl acetate and ethyl caproate), alcohols (such as phenethyl alcohol), and terpenes (such as monoterpenes, sesquiterpenes, and squalene). Furthermore, yeast cells can serve as cell synthesis factories, wherein specific synthesis pathways can be introduced into cells using synthetic biology techniques to achieve high-throughput production. In addition, the applications of aroma yeast in the food, pharmaceutical, and cosmetic industries are summarized, and the future development trends of aroma yeasts are discussed to provide a theoretical basis for their application in the food fermentation industry.

Probiotics have extensive use in daily life, due to the function of the changing intestinal metabolism and material conversion processes, wherein they remodel the intestinal microbiota, regulate the intestinal function and affect the organism’s health. Limosilactobacillus reuteri (L. reuteri), originally discovered in breast milk and currently reported to be present within the gut of almost all vertebrates and mammals, is an intestinal probiotic with prebiotic efficacy. Most L. reuteri have good intestinal colonization and bacteriocin secretion abilities, which can increase the expression of the mucin (mucoprotein) genes 2 MUC2 and MUC13, which in turn promote the development and maturation of intestinal organoids, and augment mucin secretion. In enteritis patients, L. reuteri downregulates α Tumor necrosis factor-α, (TNF-α), Interleukin-6 (IL-6), IL-8, and IL-12 expression to attenuate inflammation. It also induces the host’s production of immunoglobulin A (IGA), which manipulates the intestinal microbial community, inhibiting the growth of pathogens. L. reuteri has been widely used in daily life. with in-depth studies having been conducted on the prebiotic effects of L. reuteri. However, the complexity of its application in a clinical setting is still unclear because the pathogenesis of various diseases still requires a large amount of data and theoretical support.

The probiotic role of lactic acid bacteria (LAB) in regulating intestinal microbiota to promote human health has been widely reported. However, the types and quantities of probiotics used in practice are still limited. Therefore, isolating and screening LAB with potential probiotic functions from various habitats has become a hot topic. In this study, 104 strains of LAB were isolated from and identified in traditionally fermented vegetables, fresh milk, healthy infant feces, and other environments. The antibacterial properties—resistance to acid, bile salts, and digestive enzymes—and adhesion ability of the strains were determined, and the biological safety of LAB with better performance was studied. Three LAB with good comprehensive performance were obtained. These bacteria had broad-spectrum antibacterial properties and good acid resistance and adhesion ability. They exhibited some tolerance to pig bile salt, pepsin, and trypsin and showed no hemolysis. They were sensitive to the selected antibiotics, which met the required characteristics and safety evaluation criteria for probiotics. An in vitro fermentation experiment and milk fermentation performance test of Lactobacillus rhamnosus (L. rhamnosus) M3 (1) were carried out to study its effect on the intestinal flora and fermentation performance in patients with inflammatory bowel disease (IBD). Studies have shown that this strain can effectively inhibit the growth of harmful microorganisms and produce a classic, pleasant flavor. It has probiotic potential and is expected to be used as a microecological agent to regulate intestinal flora and promote intestinal health. It can also be used as an auxiliary starter to enhance the probiotic value of fermented milk.

Canned bamboo shoots in clear water could produce a unique flavor through bacterial diversity via the fermentation process. Weissella, Streptococcus, Leuconostoc, Acinetobacter, Lactococcus and Lactobacillus were the main microorganisms. Tyrosine was the most abundant free amino acid (FAA), which had a negative correlation with Lactococcus. Ten kinds of flavor substances, such as 3-methyl-1-butanol, acetic acid, 2-phenylethyl ester, benzene acetaldehyde, benzoic acid and ethyl ester, were important influential factors in the flavor of fermented bamboo shoots. Through the verification test of tyrosine and phenylalanine decarboxylase, it was found that Lactococcus lactis TJJ2 could decompose tyrosine and phenylalanine to produce benzaldehyde and benzene acetaldehyde, which provided the fermented bamboo shoots with a grassy aroma.

Although mulberry leaf (Morus alba L., ML) and Siraitia grosvenorii (SG) individually demonstrate anti-diabetic properties, their combined efficacy against type 2 diabetes mellitus (T2DM) remains unexplored. This study systematically explored the multi-target mechanisms and synergistic potential of the MLSG combination (MLSG) for T2DM intervention. We evaluated the in vitro inhibitory activities of MLSG, ML, and SG on α-amylase and α-glucosidase, alongside antioxidant capacity assessments through DPPH/ABTS radical scavenging, reducing power, and FRAP assays. Bioactive metabolites were identified using non-targeted metabolomics, while core targets and pathways were predicted using network pharmacology and validated through molecular docking. The results reveal MLSG’s significantly enhanced inhibition of α-amylase (IC₅₀ = 14.06 mg/mL) and α-glucosidase (IC₅₀ = 0.02 mg/mL) compared to individual extracts, exhibiting 1.3–15.5-fold higher potency with synergistic effects (combination index < 1). MLSG also showed improved antioxidant capacity, outperforming SG in DPPH/ABTS⁺ scavenging and reducing power (p < 0.05), and surpassing ML in ABTS⁺ scavenging, reducing power, and FRAP values (p < 0.05). Metabolomics identified 26 MLSG-derived metabolites with anti-T2DM potential, and network analysis pinpointed 26 active components primarily targeting STAT3, AKT1, PIK3CA, EGFR, and MAPK1 to regulate T2DM pathways. Molecular docking confirmed strong binding affinities between these components and core targets. Collectively, MLSG exerts potent synergistic anti-T2DM effects through dual-enzyme inhibition, elevated antioxidant activity, and multi-target pathway regulation, providing a solid foundation for developing MLSG as functional food ingredients.

Depression is a common mood disorder, and growing evidence has revealed the critical role of gut microbiota in its onset and progression. The gut–brain axis, which connects the central nervous system and intestinal microecology, offers new strategies for depression intervention. In this study, an acute depression model was established in mice using lipopolysaccharide (LPS), and the potential antidepressant effects and mechanisms of Bifidobacterium animalis CP-9 were investigated. The results indicated that CP-9 may exert antidepressant effects through multiple pathways, including modulation of peripheral and central inflammatory responses, restoration of gut microbiota balance, enhancement of short-chain fatty acid (SCFA) production, and regulation of neurotransmitter metabolism such as γ-aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT). Notably, intervention with CP-9 at a dose of 10⁸ CFU/mL significantly alleviated depressive-like behaviors in mice, suggesting its promising potential in the prevention and treatment of mood disorders.