Influence of varied extraction procedures on the volatile fingerprint of liver protein products from polarity-resolved insights

Protein extraction offers a route for the valorization of livestock and poultry livers, but residual off-odors constrain their application. This study assessed the effects of ultrasound, trehalose, and propylene glycol on the volatile fingerprint of lamb liver protein products. Volatile organic compounds (VOCs) were profiled by headspace solid-phase microextraction–gas chromatography–mass spectrometry and interpreted using principal component analysis, orthogonal partial least squares–discriminant analysis, relative odor activity value (ROAV) evaluation, and molecular docking. A total of 66 VOCs were identified and classified by polarity. Compared with the control (ST), the combined ultrasound–trehalose–propylene glycol treatment (SUAP) showed the greatest reductions in class-level summed peak-area signals, particularly for acids (57.6%) and ketones (39.1%). Variable importance in projection and ROAV analyses identified 11 important contributors, including the key odorants 3-methylbutanal, 1-octen-3-ol, and 2-heptanone. Molecular docking supported plausible hydrophobic association of these odorants with a representative protein model. Overall, SUAP yielded the lowest residual VOC signals, supporting a polarity-resolved strategy for their reduction during lamb liver protein extraction.