Metabolites comparison in post-fermentation stage of manual (mechanized) Chinese Huangjiu (yellow rice wine) based on GC-MS metabolomics

Abstract

In order to understand the differences of metabolites and their key metabolic pathways between traditional manual and mechanized Huangjiu, gas chromatography-mass spectrometry (GC-MS) combined with non targeted metabolomics was used to track and monitor Huangjiu in the whole post-fermentation stage. The results showed that 25 metabolites and 14 metabolites were identified as differential metabolites in manual and mechanized Huangjiu, respectively (VIP > 1, P < 0.05); three metabolic pathways had significant effects on differential metabolites (-log (P) > 1, impact > 0.01). Compared with the two kinds of Huangjiu, 21 kinds of metabolites were identified as differential metabolites (VIP > 1, P < 0.05); four metabolic pathways had significant effects on differential metabolites (-log (P) > 1, impact > 0.01). This study is helpful to gain insight into the underlying mechanism of flavor formation during the post-fermentation process of Huangjiu and provide a theoretical basis for the industrial development.

Keywords: Aroma compounds; Differential metabolites; Huangjiu; Metabolomics; Post-fermentation.

Graphical abstract

Fig. 1

a. Changes of physical and chemical indicators in each stage of manual Huangjiu fermentation; b. Changes of physical and chemical indexes in each stage of mechanized Huangjiu fermentation; c. Content difference of Alcohols in two kinds of Huangjiu (1-manual Huangjiu 2d; 2-manual Huangjiu 4d; 3-manual Huangjiu 16d; 4-manual Huangjiu 16d; 5-mechanized Huangjiu 2d; 6-mechanized Huangjiu 4d; 7-mechanized Huangjiu 14d; 8-mechanized Huangjiu 24d).

Fig. 2

a. Changes of organic acid content in each stage of manual Huangjiu fermentation; b. Changes of organic acid content in each stage of mechanized Huangjiu fermentation; c. Changes of citric acid content in each stage of all Huangjiu fermentation. d. Content difference of tartaric acid in two kinds of Huangjiu (1-manual Huangjiu 2d; 2-mechanized Huangjiu 2d; 3-manual Huangjiu 4d; 4-mechanized Huangjiu 4d; 5-manual Huangjiu 72d; 6-mechanized Huangjiu 24d).

Fig. 3

a. PCA-X diagrams of different stages of fermentation of manual Huangjiu (h) samples; b. PCA-X diagrams of different stages of fermentation of mechanized Huangjiu (m) samples; c. PCA-X diagram of Huangjiu samples taken from the initial and end stages of post-fermentation.

Fig. 4

. Heat map of different metabolites in Huangjiu at the end of fermentation. The mechanized Huangjiu is in the lower-adjusted interval on the left, and manual Huangjiu is in the upper-adjusted interval on the right. The horizontal axis corresponds to the sample number, and the vertical axis corresponds to the substance number (refer to the supplementary materials for the substance type corresponding to the number).

Fig. 5

a. Enrichment analysis of differential metabolite pathways after fermentation of manual Huangjiu; b. Metabolic pathway analysis of different metabolites after fermentation of manual Huangjiu.

Fig. 6

a. Enrichment analysis of differential metabolite pathways after fermentation of All Huangjiu; b. Metabolic pathway analysis of different metabolites after fermentation of All Huangjiu.