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

To develop a nutritious and aromatic probiotic-fermented pumpkin juice, fresh pumpkin juice was utilized as the raw material. This juice was co-fermented using Saccharomyces cerevisiae, Lactobacillus helveticus, and Lactobacillus delbrueckii subsp. bulgaricus. Comparative analyses were conducted on the physicochemical properties and aroma components of the fermented pumpkin juice. The results indicate that the viable bacterial count in the fermented pumpkin juice reached 7.34 log CFU mL ^− 1 . Compared with fresh pumpkin juice, fermented pumpkin juice exhibited significant increases ( P  < 0.05) in total acid content, vitamin C, polyphenols, flavonoids, and carotenoids. Additionally, there were significant decreases ( P  < 0.05) in pH and soluble solids. The fermentation process was effective in preserving the original color of the pumpkin juice (ΔE < 2). Furthermore, the rheological properties of the pumpkin juice were altered by the composite probiotic fermentation. Notably, GC-MS analysis identified a total of 35 aroma compounds in the pumpkin juice samples, including 9 esters, 8 aldehydes, 5 ketones, 5 acids, 5 alcohols and 3 other substances. The types of esters and alcohols were higher in fermented pumpkin juice compared to fresh pumpkin juice. After OPLS-DA analysis, Prominent aroma compounds detected in the fermented pumpkin juice included phenylethyl alcohol, phenethyl acetate, and ethyl caprylate, which imparted a more intense floral and fruity aroma to the fermented pumpkin juice. And, the pumpkin juice fermented with the composite probiotics received the highest sensory evaluation.