Fermentation-linked conversion of dimethylpyrazines in moutai-flavor liquor: Insight from HPLC-FLD analysis

Abstract

Moutai-flavor Baijiu (MFB), is renowned worldwide for its mysterious brewing process and its sauce-like flavor. Dimethylpyrazines (DMPs) are functional flavor compounds that make significant contributions to the aroma of MFB. To investigate the variation rule of DMPs during the brewing process of MFB, and to gain insights into the link between of DMPs and Moutai-flavor, we developed a simple, rapid, and effective HPLC-FLD method. The detection limits and quantification limits of our proposed method ranged from 0.008 to 0.035 mg/L, with an RSD of precision of less than 2 %. And the average recoveries ranged from 98 % to 100.48 %. The results showed that DMPs initially increased, reaching peak in 6th round with a concentration up to 14.997±0.414 mg/L, and then decreased during fermentation. In the aging stage, DMPs displayed a gradual upward trend, peaking at 10.052±0.252 mg/L after 7 years, before experiencing a minor decline at 9 years. These conversion behaviors are closely related to microbial metabolic activity and the Maillard reaction. We found high content of DMPs from the 4th-6th rounds (A round of fermentation takes a month) and the aged 7 years Baijiu have been described with strong sauce aroma and superior quality. This study provides a technical for focusing further investigating the unique flavor of Baijiu, revealing the conversion behavior of DMPs during the brewing process and their potential causes.