Distribution and Quantification of 1,2-Propylene Glycol Enantiomers in Baijiu.

Enantiomers of 1,2-Propylene glycol (1,2-PG) were investigated in 64 commercial Chinese Baijiu including soy sauce aroma-type Baijiu (SSB), strong aroma-type Baijiu (STB), and light aroma-type Baijiu (LTB), via chiral gas chromatography (-cyclodextrin). The natural enantiomeric distribution and concentration of 1,2-PG in various baijiu were studied to evaluate whether the distribution and content of the two isomers of 1,2-PG were correlated with the aroma type and storage year. The results showed that 1,2-PG has a high enantiomeric ratio and the ()-configuration predominated in SSB. The average / enantiomeric ratio of this compound in SSB was approximately 87:13 (±3.17), with an average concentration of 52.77 (±23.70) mg/L for the ()-configuration and 8.72 (±3.63) mg/L for the ()-enantiomer. The ()-configuration was predominant in the STB, whereas neither () nor ()-form of 1,2-PG were detected in LTB. The content of the two configurations of 1,2-PG in the JSHSJ vintage of SSB showed a wave variation, with an average / enantiomeric ratio of 89:11 (±1.15). The concentration of ()-1,2-PG in XJCTJ vintage liquors showed an upward and then downward trend with aging time, with an overall downward trend, and the concentration of ()-form showed a wavy change with an overall upward trend. Except for the LZLJ-2019 vintage where both () and ()-1,2-PG were present, all other samples only existed ()-form, and a decreasing trend of ()-enantiomer with aging time was observed. The enantiomeric ratio of 1,2-PG might be one of the potential markers for adulteration control of Baijiu as industrial 1,2-PG usually presented in the racemic mixture. Sensory analysis revealed olfactory thresholds of 4.66 mg/L and 23.92 mg/L for the ()- and ()-configurations in pure water respectively. GC-O showed both enantiomers exhibited different aromatic nuances.