Mechanistic insights into quality and flavor enhancement of sour meat by ultrasound-assisted frying: the role of oxidative and Maillard reactions.

This study investigated the effects of ultrasound-assisted frying (UAF) on the quality and flavor of fermented sour meat and elucidated the underlying mechanisms using metabolomics and correlation analyses. Ultrasound treatment significantly reduced cooking loss, improved moisture retention (10.38 % in the control; +5.53 % at 400 W), and decreased hardness, chewiness, and shear force, thereby enhancing tenderness and texture. Lipid oxidation was promoted in an intensity-dependent manner. GC-IMS identified 98 volatile compounds, including 17 differential ones responding distinctly to ultrasound. At 400 W, several alcohols, ketones, and esters were enhanced, with flavor-active compounds such as 1-hydroxy-2-propanone and 2,3-butanedione reaching relatively high levels. Electronic tongue analysis revealed increased sourness and reduced bitterness and saltiness at 400 W, giving a more balanced taste. Mechanistically, ultrasonic cavitation promoted tissue disruption and release of flavor precursors, facilitating free fatty acid generation and conversion into volatile aromatics while accelerating Strecker degradation and Maillard reactions. Metabolic pathway analysis indicated that dicarbonyl compounds preferentially contributed to flavor formation under moderate ultrasound, whereas excessive intensity (800 W) enhanced oxidative stress and redirected precursors toward advanced glycation end products (AGEs), as evidenced by elevated pentosidine and 1,4-dioxane, raising safety concerns. Overall, moderate UAF improved sour meat quality through moisture retention, structural modification, lipid oxidation, amino acid degradation, and Maillard-driven aroma generation. Among tested conditions, 400 W provided the most favorable balance among texture, taste, aroma, and safety, making it an appropriate ultrasound intensity for improving fried sour meat quality.