Comprehensive quality evaluation of ultrasound-assisted fermented Yuluxiang pear juice: Physicochemical characteristics, antioxidant activity, and multi-dimensional flavor analysis

Yuluxiang pear juice processing faces critical technical challenges: enzymatic browning, nutrient degradation during thermal processing, and flavor volatilization. Ultrasound (US)-assisted fermentation, an emerging non-thermal technology, enhances fruit juice quality. However, its regulatory mechanisms in fermented pear juice flavor formation remain unclear. This study investigated the effects of 0–500 W US power on Lactiplantibacillus plantarum -fermented Yuluxiang pear juice. An integrated electronic nose (E-nose), electronic tongue (E-tongue), and gas chromatography-ion mobility spectrometry (GC-IMS) system characterized physicochemical properties, antioxidant capacity, and flavor profiles. Results suggested significant power-dependent effects on fermentation quality. The 300 W treatment was associated with optimal comprehensive quality, including the lowest browning index, highest transmittance (52%), maximum polyphenol content (1.44 mg/100 mL), and greatest viable lactic acid bacteria count (1.3 × 10 9 CFU/mL), while 400 W treatment yielded to peak ABTS radical scavenging activity (75.6%). Enzyme activity assays indicated that 300 W significantly inhibited polyphenol oxidase (70.6%) while enhancing peroxidase (112.0%) and superoxide dismutase (269.2%) compared to the untreated fermentation group ( p < 0.05). E-nose revealed significantly elevated responses for W1S (esters) and W2S (alcohols/aldehydes) sensors with increasing US power. E-tongue implied that 400 W reduced bitterness/astringency and enhanced sourness. GC-IMS fingerprinting identified linalool, 2-methylbutyl acetate, and (Z)-4-heptenal as characteristic differential volatiles (VIP > 1). Correlation analysis pointed toward possible mechanistic pathways whereby acoustic cavitation modulates the physicochemical microenvironment, promoting lactic acid bacteria metabolism and polyphenol biotransformation, synergistically enhancing flavor and functional quality. This study provided theoretical insights and technical support for high-value processing of Yuluxiang pear.