We undertook this study in order to explore the effect of reduced glutathione (GSH) on the physicochemical indexes and non-volatile and volatile metabolites of Chardonnay wine during a five-month storage period after the end of alcoholic fermentation. Five different concentrations of GSH were added into the wine after the end of alcoholic fermentation. The changes of physicochemical indexes, total phenolic content and color during the storage period were measured. Widely targeted metabolomic analysis and volatile metabolomic analysis based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) were performed on wine samples with and without the addition of 20 mg/L GSH. The results showed that during the five-month storage period, the addition of different concentrations of GSH had no significant effect on the volatile acid content, total acid content and pH of white wine (P > 0.05) but significantly influenced its total phenol content, total flavonoid content, color and free SO₂ content. The total phenol content of the wine sample added with 30 mg/L GSH was highest after storage for five months, and the color index of the wine sample added with 20 mg/L GSH was lowest. The addition of GSH could delay the decrease of free SO₂ content. A total of 693 non-volatile metabolites and 816 volatile metabolites were identified. Based on variable importance in projection (VIP) greater than 1.0 and fold change (FC) equal to or greater than 1.4, a total of 33 non-volatile differential metabolites and 22 volatile differential metabolites were selected. Among the 32 non-volatile metabolites, 17 were down-regulated and the rest 16 were up-regulated. Among the 22 volatile metabolites, three were down-regulated and the other 19 were up-regulated. Some phenolic acids, fatty acids and amino acids were associated with changes in volatile metabolites.

The effects of different base wine volumes (150, 200, and 250 L) during the distillation process on the volatile compounds of distilled wine made from Merlot grapes from the Jiaodong Peninsula were investigated in order to optimize the distillation conditions of distilled Merlot wine. In this study, headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to qualitatively and quantitatively analyze the volatile compounds of the intermediate distillates from different volumes of base wine. In addition, statistical analysis of the volatile composition data was performed by principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). In total, 67, 67, and 64 aroma compounds were detected in the distillate samples from 150, 200, and 250 L of base wine, respectively. In each sample, 37 esters were found. Ester content was significantly higher in the distillate from 150 L than 200 and 250 L from base wine. PCA and OPLS-DA results consistently showed that 13, 1, and 1 aroma substances had positive effects on distilled samples from 150, 200, and 250 L of base wine, respectively. This study will lay the foundation for the production of high-quality distilled wine and thereby contribute to the development of the wine industry.