Lactic acid bacteria fermentation of prebiotic-supplemented apple juice: Viable counts and flavor evolution revealed by HS-SPME-GC-MS coupled with electronic sensory and chemometrics.

Lactic acid fermentation of apple juice faces microbial density deficiency and quality deterioration. This study explored probiotic-prebiotic synergy to enhance microbial density and juice quality, focusing on prebiotic selectivity for lactic acid bacteria (LAB) and their impacts on viable counts and flavor profiles in sequentially fermented apple juice. Results indicated that inulin, fructooligosaccharides, galactooligosaccharides (GOS), lactulose, and raffinose significantly enhanced LAB growth. In sequential fermentation, GOS achieved the highest viable counts (2.64 × 108 CFU/mL), total acid (4.68 ± 0.08 g/L), sugar consumption (3.48 ± 0.04 g/100 mL), lactic acid (2625.95 ± 12.78 mg/L), and DPPH scavenging activity (77.75 %). Electronic sensory and volatile compounds revealed distinct flavor profiles, with GOS showing the highest electronic nose response and richest volatile compounds. Correlation analysis indicated that prebiotics notably reduced bitterness and astringency, linked to elevated 1-Heptanol and (R,R)-2,3-Butanediol. Additionally, GOS excelled in acceptability, taste, aroma, acidity and sweetness. This research provides novel strategies for developing high-density, multi-flavor LAB fermented apple juice.