Decoding Long-Chain\nFatty Acid Ethyl Esters during\nthe Distillation of Strong Aroma-Type Baijiu and Exploring the Adsorption\nMechanism with Magnetic Nanoparticles

Simultaneous detection of the dynamic distribution of\nlong-chain\nfatty acid ethyl esters (LCFAEEs) during Baijiu distillation is crucial\nfor optimizing its flavor and health attributes. In this study, we\nsynthesized a simple, cost-effective Fe<sub>3</sub>O<sub>4</sub>@NH<sub>2</sub> adsorbent to simultaneously extract eight LCFAEEs from Baijiu.\nThrough density functional theory and adsorption experiments, we elucidated\n1,6-hexanediamine as a surface modifier, with the −NH<sub>2</sub> groups providing adsorption sites for the LCFAEEs via hydrogen-bonding\ninteractions and van der Waals forces. Additionally, we established\nthe magnetic solid-phase extraction–GC–MS extraction\ntechnique combined with stable isotope dilution analysis to analyze\nLCFAEEs. This method revealed the dynamic distribution patterns of\nLCFAEEs during strong aroma-type Baijiu (SAB) distillation. We observed\nthat the concentrations of the eight LCFAEEs gradually decreased with\nprolonged distillation and were significantly correlated with ethanol\nconcentration. To ensure optimal flavor and clarity in SAB, it is\nrecommended to select the heart-stage base Baijiu with an alcohol\ncontent of 58%–63%.