Ultrasound-driven ternary conjugation reshapes protein-lipid interfaces and volatile profiles in high-protein egg...

Heat-induced aggregation, sulfurous off-flavors, and oxidative instability pose challenges for the use of egg white proteins (EWPs) in high-protein beverages. In this study, a ternary conjugated system comprising EWP, milk casein, and xylitol (EMX) was incorporated into skimmed milk powder (SMP) and whole-fat milk powder (WFM) beverages, which were subsequently treated with ultrasound (US; 20 kHz, 300 W). Physicochemical properties, oxidative stability, volatile compounds, in vitro digestion, and storage stability over 30 days at 4 °C were monitored. The results showed that EMX conjugated system exhibited higher solubility (91.04 % vs. 88.54 %) and a 2.4-fold reduction in turbidity compared with skimmed beverages. Ultrasound further decreased particle size and increased molecular flexibility in whole-fat formulations. Additionally, EMX showed the greatest thermal stability (Td 114.17 °C; ΔHd 179.3 J/g), while US treatment improved Td from 102.21 °C to 113.23 °C in SMP. US-treated whole-fat beverages demonstrated lower TBARS values during days 0-14 but higher values than their untreated counterparts on day 30. Protein carbonyl levels remained lowest in US-treated skimmed beverages throughout storage. Altogether, the US increased digestibility, while mitigating dipropyl disulfide and 2-furanmethanethiol sulfurous off-flavors. In conclusion, US-assisted EMX ternary conjugation offers a promising approach for developing the functionality and sensory qualities of protein-enriched dairy model systems.