Dynamic metabolic changes and flavor modulation during co‐fermentation of blackened jujube juice by <i>Lactiplantibacillus plantarum</i> and <i>Streptococcus thermophilus</i>

BACKGROUND: Blackened jujubes demonstrate enhanced bioactive compounds, and probiotic fermentation can further improve metabolite bioavailability and flavor development. This study investigated metabolic dynamics during co-fermentation of blackened jujube juice using Lactiplantibacillus plantarum and Streptococcus thermophilus. RESULTS: ). It also induced coordinated metabolic shifts in blackened jujube juice, primarily involving glycolysis and organic acid metabolism (including malolactic conversion). Carbohydrate depletion (27.3% reduction in total sugars) coincided with pronounced acidification (pH 3.74 → 3.45; titratable acidity +23.5%) and a marked rise in lactic acid (+140%), indicating efficient carbon flux from sugars to organic acids. Meanwhile, the preferential decrease of malic acid (-36.6%) and succinic acid (-49.5%) suggests selective utilization and rebalancing within the organic acid network. Volatile analysis by gas chromatography-mass spectrometry identified 41 compounds, with microbial metabolism elevating key aroma-active constituents, including ethyl acetate, n-hexanol, and benzaldehyde. Electronic nose measurements further confirmed progressive aroma remodeling, and the sensor response patterns were consistent with the observed dynamics of organic acids and ester formation. CONCLUSION: Co-fermentation of blackened jujube juice with LP121 and ST021 enables robust probiotic growth and drives coordinated shifts in carbohydrate metabolism, organic acid composition, and volatile formation, resulting in measurable aroma enhancement. These findings provide a mechanistic and practical basis for developing high-value probiotic functional beverages derived from blackened jujube with improved sensory quality. © 2026 Society of Chemical Industry.