Probiotic fermented Dendrobium beverages: Effect of co-probiotic strains on the flavor composition and bioactive...

Probiotic fermentation is a viable strategy for simultaneously improving the bioactive compound profile and flavor characteristics of food matrices. Dendrobium officinale and a mixed-probiotic beverage (L. plantarum: L. rhamnosus: L. reuteri = 5:1:4; 3.95% inoculum, 1:6.68 solid-liquid ratio, 37 °C, 82 h) were compared using HS-SPME-GC-MS with absolute quantification of key volatiles. Mixed-strain LAB fermentation significantly altered the volatile profile of D. officinale. This alteration was defined by an increase in pleasant aromatic compounds, such as linalool and benzyl alcohol, and fermentation-derived carbonyl compounds, concurrent with a decrease in solvent-like and alcoholic notes, including ethyl acetate and ethanol. Together, these chemical shifts form the basis for the more harmonious sensory perception reported after fermentation. It also decreased total sugars (64.00-15.16 mg/mL), phenolics (72.35-64.20 μg/mL) and flavonoids (106.85-84.57 μg/mL), accompanied by higher organic acid levels and sensory scores (58.02-68.45). Untargeted LC-MS metabolomics revealed that mixed-strain fermentation enhanced the hypoglycemic potential activity of D. officinale, as evidenced by increased α-GIR and α-AIR, along with improved protection of IR-HepG2 cells. This enhancement was associated with the depletion of readily fermentable sugars and a qualitative remodeling of the phenylpropanoid-flavonoid-isoflavonoid pathway. These changes were accompanied by coordinated shifts in starch and sucrose metabolism. The results indicate that mixed-probiotic fermentation enhances both flavor and bioactive constituents, providing a novel product format for this traditional D. officinale-based food.