Effect of mixed fermentation of Saccharomyces cerevisiae, Lactobacillus helveticus, Lactobacillus delbrueckii subsp. bulgaricus on physicochemical and flavor characteristics of pumpkin juice

Probiotic fermentation with a defined consortium (Saccharomyces cerevisiae, Lactobacillus helveticus, and Lactobacillus delbrueckii subsp. bulgaricus) successfully transformed pumpkin juice into a functional beverage with enhanced bioactivity and appealing aroma. The fermented product achieved a high viable count of 7.37 log CFU mL^-1, along with significant increases in vitamin C, total phenolics, flavonoids, and carotenoids compared to unfermented juice. Fermentation also imparted a distinct volatile profile enriched with esters and alcohols-such as phenylethyl alcohol, phenethyl acetate, and ethyl caprylate-which contributed intense fruity and floral notes, as confirmed by OPLS-DA and sensory evaluation. The resulting juice retained its original color (ΔE < 2) and developed desirable rheological behavior. Thus, accordingly the pumpkin juice fermented with the composite probiotics received the highest sensory evaluation. This study demonstrates that composite-culture fermentation effectively enhances the nutritional value, aroma, and sensory quality of pumpkin juice, highlighting its potential as a novel probiotic beverage.