Multiscale mechanistic insights into sonochemical energy coupling and flavor evolution in Pu‑erh tea

Abstract

Pu’erh tea (Camellia sinensis var. assamica) represents a highly complex multiphase fermentation system in which flavor formation spans chemical transformation, energy transfer and microecological succession. To elucidate the mechanistic basis by which sonochemical energy input accelerates flavor evolution, we developed an integrated multiscale model combining flavoromics, molecular dynamics simulations and microbial ecological analysis. The model captures molecular reactions and metabolic regulation under ultrasonic cavitation.Increasing acoustic power density (0.3–0.8  W mL⁻¹) substantially enhanced cavitation intensity and energy absorption, accompanied by elevated concentrations of reactive radicals (•OH 40–96  µM) and an increased mass-transfer coefficient, generating high-energy heterogeneous microdomains. Sonochemical coupling reduced the reaction barrier of ester-type catechins (ΔG ≈ –25  kJ mol⁻¹) and accelerated their conversion into free acid polyphenols. Concurrently, high shear forces induced partial depolymerization of proteins and peptides, leading to 1.5–3-fold increases in taste-active amino acids and soluble sugars, thus reinforcing the “mellow” and “sweet” mouthfeel of the infusion.Microecological (meta-omics) profiling revealed that elevated acoustic energy favored the enrichment of functional microbial consortia dominated by Lactobacillus plantarum and Aspergillus niger. Pathways related to aroma synthesis—including phenylalanine metabolism and monoterpene biosynthesis—exhibited approximately twofold enrichment, driving the accumulation of aromatic esters and terpenes. Multivariate modeling (PLSR and RDA, R² > 0.90, Q² > 0.70) confirmed that acoustic power and cavitation indices quantitatively predict flavor outputs. However, rigorous techno-economic analysis and acoustic propagation modeling in solid-state media reveal that industrial scaling faces challenges regarding energy consumption, reactor design for solid–liquid mixtures, and downstream dewatering costs. While the optimal window of 0.6–0.75 W·mL⁻¹ reproducibly generated complex aromatic profiles comparable to aged tea, these engineering constraints necessitate further optimization for commercial viability. Collectively, these findings elucidate the cross-scale mechanism by which coupled sonochemical energy drives flavor evolution and define the application boundaries for green, energy-precise processing of fermented beverages.