Research on interaction regularities and mechanisms between lactic acid and aroma compounds of Baijiu.

This study investigated the interactions between lactic acid (LA) and odorants of Baijiu using headspace solid phase microextraction with gas chromatography-mass spectrometry (HS-SPME-GC-MS), ultraviolet absorption spectroscopy (UV) and nuclear magnetic resonance (NMR). The HS-SPME-GC-MS analysis results showed that LA promoted the volatilities of most of low boiling acids, esters, alcohols, aldehydes and ketones, especially short-chain branched esters were promoted by 41-49%. In contrast, LA suppressed the volatilities of most aromatic compounds. UV spectroscopy, thermodynamic analysis, and NMR combined with theoretical calculations further revealed that the interactions between LA and 4-ethyl-2-methoxyphenol (4-EP), 2-methoxy-4-methylphenol (2-MP) and 1-butanol were dominated by van der Waals forces and supplemented by electrostatic interactions, which included hydrogen bonds formed between the carboxyl group in LA and the hydroxyl and methoxy groups in 4-EP or 2-MP and π-hydrogen bonds between the hydrogen of the carboxyl group of LA and the benzene ring of 4-EP or 2-MP.