A method for identifying strong-flavor, light-flavor and sauce-flavor liquors

Abstract

The present invention discloses a method for distinguishing strong-flavor, light-flavor, and sauce-flavor liquors. Chiral gas chromatography was used to qualitatively and quantitatively analyze the two isomers of 1,2-propylene glycol in strong-flavor, light-flavor, and sauce-flavor liquors. Enantiomer separation was achieved using β-cyclodextrin as the chiral stationary phase, and the natural concentrations and ratios of the 1,2-propylene glycol enantiomers in the three liquors were determined. The concentrations and ratios of the 1,2-propylene glycol enantiomers in strong-flavor, light-flavor, and sauce-flavor liquors vary significantly and exhibit regular patterns. Therefore, strong-flavor, light-flavor, and sauce-flavor liquors can be distinguished based on the concentrations and ratios of the 1,2-propylene glycol enantiomers in the liquors. A method for detecting 1,2-propylene glycol enantiomers is also provided. The present invention has the excellent effect of distinguishing strong-flavor, light-flavor, and sauce-flavor liquors by determining the natural concentrations and ratios of the 1,2-propylene glycol enantiomers in the three liquor types, providing a new basis for distinguishing authentic liquors.

Description

Technical Field

[0001] The invention relates to the technical field of liquor flavor quality identification, and in particular to a method for identifying strong-flavor, light-flavor and sauce-flavor liquors. Background Art

[0002] Baijiu is one of the six major distilled spirits in the world.

[0003] Baijiu (Chinese liquor) contains numerous trace flavor compounds. These trace components determine the aroma and style of the liquor. To date, research has identified over 2,400 flavor compounds from various baijiu samples, a number of which are chiral. The study of chiral flavor compounds in baijiu can provide a reference for distinguishing the quality and authenticity of baijiu. Chiral enantiomers exhibit significant differences in certain physical and chemical properties, such as optical rotation and odor. These differences have been extensively studied in fields such as food and spices. Understanding the enantiomeric composition of chiral compounds in food plays a crucial role in determining food quality and authenticity. For example, analysis of the enantiomeric composition of α-ionone in wine has shown that the R / S ratio is no less than 70 / 30. Adding the racemic α-ionone will alter the enantiomeric ratio, which can be considered a sign of adulteration. Currently, over 40 chiral compounds have been reported in alcoholic beverages, including five alcoholic chiral compounds. 1,2-Propanediol is a food flavoring specified in food additive standards. Adding 1,2-propylene glycol to foods can help retain moisture by moisturizing. It does not increase water activity and is often used as a lubricant to improve the sensory quality of foods. 1,2-Propanediol is present in alcoholic beverages such as liquor, beer, and wine. Studies have reported high levels of (R)-1,2-propylene glycol in fermented beverages such as beer, wine, and sparkling wine. The chiral compound 1,2-propylene glycol is used as a potential marker for authenticity verification of alcoholic beverages such as wine and beer, as industrial 1,2-propylene glycol typically exists in a racemic form.

[0004] 1,2-Propanediol (PD) has an asymmetric chiral carbon atom in its molecular structure, resulting in two distinct isomers: (S)- and (R)-1,2-PD. Separating and determining the two isomers in Maotai-flavor, Luzhou-flavor, and Light-flavor liquors, and determining their natural concentrations and distributions within these three flavor types, is crucial for distinguishing between Luzhou-flavor, Light-flavor, and Maotai-flavor liquors. This provides a new basis for identifying genuine liquors. Summary of the Invention

[0005] The present invention aims to provide a method for identifying strong-flavor, light-flavor and sauce-flavor liquors, mainly comprising determining the natural concentrations and ratios of 1,2-propylene glycol enantiomers, namely (S)-1,2-propylene glycol and (R)-1,2-propylene glycol, in strong-flavor, light-flavor and sauce-flavor liquors, thereby achieving the purpose of identifying these three types of liquors and providing a new basis for distinguishing genuine liquors.

[0006] At the same time, the present invention also provides a method for detecting 1,2-propylene glycol enantiomers.

[0007] The present invention is achieved through the following technical solution, a method for identifying strong-flavor, light-flavor and sauce-flavor liquors, comprising the following steps:

[0008] (1) taking a certain amount of liquor sample and drying it;

[0009] (2) Separation of 1,2-propylene glycol enantiomers in liquor by chiral gas chromatography;

[0010] (3) Compare the 1,2-propylene glycol enantiomer standard with the liquor sample by chiral gas chromatography to characterize its peak order and configuration in the liquor;

[0011] (4) Determination of the concentration and enantiomeric ratio of 1,2-propylene glycol enantiomers in liquor by chiral gas chromatography standard curve method;

[0012] (5) The concentration and enantiomeric ratio of 1,2-propylene glycol in the liquor were measured to identify the strong-aroma, light-aroma and sauce-aroma liquors.

[0013] Preferably, the liquor sample processing method in step (1) is as follows: directly aspirate 5 mL of liquor sample into a centrifuge tube, add 1.86 g of anhydrous sodium sulfate, dry for 12-16 hours, and then filter with a 0.22 μm organic filter membrane for use;

[0014] Sample spike treatment: Take 10 μL of internal standard diluent 2-octanol with a concentration of 3.6975 mg / L, add 990 μL of dried wine sample to keep the internal standard mass concentration unchanged, filter with a 0.22 μm organic filter membrane into a 1.5 mL injection bottle, and wait for chiral gas phase analysis.

[0015] Preferably, the chiral gas chromatography conditions in step (2) and step (3) are:

[0016] A Thermo Fisher gas chromatograph TRACE 1300 was used, and the chiral chromatographic column was CYCLOSIL-B with a specification of 30m×0.25 mm×0.25μm. The treated wine samples were injected into the inlet in split mode with an inlet temperature of 250℃ and a split ratio of 20:1. The chiral gas chromatography programmed temperature method was: 50℃ for 1min, then increased to 80℃ at 3℃ / min, and finally increased to 170℃ at 8℃ / min and held for 5min. The detection port temperature was 250℃, the carrier gas was high-purity nitrogen, and the column head pressure was 50kPa.

[0017] Preferably, the standard curve establishment method of step (4) is as follows: accurately weigh a certain amount of (S)-1,2-propylene glycol and (R)-1,2-propylene glycol standard respectively, dissolve them in chromatographically pure anhydrous ethanol and make up to volume in a 10 mL volumetric flask to prepare (S)-1,2-propylene glycol and (R)-1,2-propylene glycol standard solutions, and then dilute them to prepare 1024 mg / L, 256 mg / L, 64 mg / L, 16 mg / L, 4 mg / L, 1 mg / L, and 0.25 mg / L standard solutions of (S)-1,2-propylene glycol, respectively;

[0018] (R)-1,2-propylene glycol was prepared into standard solutions of 128 mg / L, 64 mg / L, 32 mg / L, 16 mg / L, 8 mg / L, 4 mg / L, 1 mg / L, and 0.25 mg / L, respectively. 990 μL of the standard solution was placed in a 2 mL gas phase vial, and 10 μL of the internal standard diluent 2-octanol with a concentration of 5 mg / L was added. The standard curve was drawn with the ratio of the peak area corresponding to the standard to the peak area of ​​the internal standard as the ordinate, and the ratio of the mass concentration of the compound corresponding to the standard to the mass concentration of the internal standard as the abscissa.

[0019] A method for detecting 1,2-propylene glycol enantiomers comprises the following steps:

[0020] A gas chromatograph was used with a chiral chromatographic column of CYCLOSIL-B (30m×0.25mm×0.25μm). The 1,2-propylene glycol racemate with a concentration of 519.05 mg / L was injected into the inlet in split mode with an injection volume of 1μL, an inlet temperature of 250°C, and a split ratio of 20:1. The chiral gas chromatography programmed temperature method was as follows: maintain at 50°C for 1 min, increase to 80°C at 3°C / min, and finally increase to 170°C at 8°C / min and maintain for 5 min. The detection port temperature was 250°C, the carrier gas was high-purity nitrogen, and the column head pressure was 50kPa. This method was used to successfully separate the 1,2-propylene glycol enantiomers with a resolution of 2.31.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. According to the existing liquor market situation, many consumers and quality inspection agencies still find it difficult to distinguish the true and false flavors of liquor, and the present invention provides a new perspective for the identification of true and false liquor flavors.

[0023] 2. The present invention successfully separated and qualitatively and quantitatively determined the enantiomers of 1,2-propylene glycol in liquor by direct injection combined with chiral gas chromatography. This method can clarify which isomer is dominant in liquor or whether the two isomers are equally important, which has important guiding significance for regulating the liquor production process.

[0024] 3. The present invention utilizes chiral gas chromatography to identify the differences in the natural concentrations and ratios of 1,2-propylene glycol enantiomers in liquor to differentiate between strong-flavor, light-flavor, and sauce-flavor liquors, providing a new and feasible method for identifying strong-flavor, light-flavor, and sauce-flavor liquors. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a chromatogram showing the separation of 1,2-propylene glycol enantiomers in a typical liquor sample in Example 1 of the present invention: Maotai-flavor liquor sample 1;

[0026] Figure 2 This is a chromatogram showing the separation of 1,2-propylene glycol enantiomers in a typical liquor sample in Example 1 of the present invention: Luzhou-flavor liquor sample 2;

[0027] Figure 3 This is a chromatogram showing the separation of 1,2-propylene glycol enantiomers in a typical liquor sample in Example 1 of the present invention: Light-flavor liquor sample 3;

[0028] Figure 4 This is a chromatogram showing the separation of 1,2-propylene glycol enantiomers. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below with reference to embodiments.

[0030] Example 1

[0031] (1) Preparation of a certain sauce / strong / light-flavor liquor sample: directly pipette 5 mL of liquor sample into a centrifuge tube, add 1.86 g of anhydrous sodium sulfate, dry for 12-16 hours, and then filter with a 0.22 μm organic filter membrane for use;

[0032] Sample spike treatment: Take 10 μL of the internal standard diluent 2-octanol, with a concentration of 3.6975 mg / L, and add 990 μL of the dried wine sample to keep the internal standard concentration constant. Filter through a 0.22 μm organic filter membrane into a 1.5 mL injection vial and wait for chiral gas phase analysis.

[0033] (2) Separation of 1,2-propylene glycol enantiomers in liquor by chiral gas chromatography: A Thermo Fisher Scientific gas chromatograph TRACE 1300 was used, with a CYCLOSIL-B chiral column of 30 m × 0.25 mm × 0.25 μm. The treated liquor sample was injected into the injection port in split mode, with an injection port temperature of 250 °C and a split ratio of 20:1.

[0034] Chiral gas chromatography temperature program method: 50 °C for 1 min, then increase to 80 °C at 3 °C / min, and finally increase to 170 °C at 8 °C / min and hold for 5 min. The detection port temperature was 250 °C, the carrier gas was high-purity nitrogen, and the column head pressure was 50 kPa.

[0035] (3) Qualitative analysis of the two isomers of 1,2-propylene glycol in liquor: The 1,2-propylene glycol enantiomer standard was compared with the liquor sample by chiral gas chromatography to qualitatively analyze its peak order and configuration in the liquor. The liquor sample was preliminarily determined to have the two configurations of peak order as (S)-1,2-propylene glycol eluting first and (R)-1,2-propylene glycol eluting later by comparing the retention time with the standard. Then, by adding the corresponding configuration standard to the liquor to see whether the peak area corresponding to the corresponding retention time increases, it was further confirmed that the elution order of the two configurations on the chromatography is as follows: (S)-1,2-propylene glycol eluting first and (R)-1,2-propylene glycol eluting later.

[0036] (4) Quantification of the two isomers of 1,2-propylene glycol in liquor: The concentration and enantiomeric ratio of 1,2-propylene glycol in liquor were determined by chiral gas chromatography standard curve method:

[0037] Accurately weigh a certain amount of (S)-1,2-propylene glycol and (R)-1,2-propylene glycol standard respectively, dissolve them in chromatographically pure anhydrous ethanol and make up to volume in a 10 mL volumetric flask to prepare (S)-1,2-propylene glycol and (R)-1,2-propylene glycol standard solutions. Then dilute them to prepare 1024 mg / L, 256 mg / L, 64 mg / L, 16 mg / L, 4 mg / L, 1 mg / L, and 0.25 mg / L (S)-1,2-propylene glycol standard solutions, respectively.

[0038] (R)-1,2-propylene glycol was prepared into standard solutions of 128 mg / L, 64 mg / L, 32 mg / L, 16 mg / L, 8 mg / L, 4 mg / L, 1 mg / L, and 0.25 mg / L, respectively;

[0039] Take 990 μL of the standard solution in a 2 mL gas phase vial, add 10 μL of 2-octanol, an internal standard diluent with a concentration of 5 mg / L, and plot the standard curve with the ratio of the peak area of ​​the standard to the peak area of ​​the internal standard as the ordinate and the ratio of the mass concentration of the standard compound to the mass concentration of the internal standard as the abscissa.

[0040] (5) The concentration and enantiomeric ratio of 1,2-propylene glycol in the liquor were measured to identify the strong-aroma, light-aroma and sauce-aroma liquors.

[0041] The data of typical representative wine samples are shown in Table 1. The corresponding wine samples are: Figure 1 、 Figure 2 、 Figure 3 The chromatogram in:

[0042] Table 1. Concentrations and enantiomeric ratios of 1,2-propylene glycol enantiomers in different flavor liquors

[0043]

[0044] The present invention tested a total of 64 types of liquor, including 38 Maotai-flavor liquors, 16 Luzhou-flavor liquors, and 10 Fen-flavor liquors. The results showed that the content of 1,2-propylene glycol in Maotai-flavor liquors was higher than that in Luzhou-flavor liquors, with the average S / R ratio of this compound in Maotai-flavor liquors being 87:13±3.17. Among the liquor samples studied, (S)-1,2-propylene glycol was predominant in Maotai-flavor liquors, (R)-1,2-propylene glycol was predominant in Luzhou-flavor liquors, and no isomers of 1,2-propylene glycol were detected in Fen-flavor liquors. Therefore, the concentration and enantiomeric ratio of 1,2-propylene glycol enantiomers in the liquors can be used to distinguish between Luzhou-flavor, Fen-flavor, and Maotai-flavor liquors.

[0045] Reference Attachment Figure 4 A method for detecting 1,2-propylene glycol enantiomers comprises the following steps:

[0046] A gas chromatograph was used with a chiral chromatographic column of CYCLOSIL-B (30m×0.25mm×0.25μm). The 1,2-propylene glycol racemate with a concentration of 519.05 mg / L was injected into the inlet in split mode with an injection volume of 1μL, an inlet temperature of 250°C, and a split ratio of 20:1. The chiral gas chromatography programmed temperature method was as follows: maintain at 50°C for 1 min, increase to 80°C at 3°C / min, and finally increase to 170°C at 8°C / min and maintain for 5 min. The detection port temperature was 250°C, the carrier gas was high-purity nitrogen, and the column head pressure was 50kPa. This method was used to successfully separate the 1,2-propylene glycol enantiomers with a resolution of 2.31.

Claims

1. A method for identifying Luzhou-flavor, Light-flavor, and Maotai-flavor liquors, characterized by: The natural concentration and ratio of 1,2-propylene glycol enantiomers in three types of liquor are determined to achieve the purpose of distinguishing strong-flavor, light-flavor, and sauce-flavor liquors, including the following steps: 1) Take 5 mL of the liquor sample and add it to a centrifuge tube. Then add 1.86 g of anhydrous sodium sulfate. Dry for 12-16 hours, then filter through a 0.22 µm organic filter membrane. Sample spike treatment: Take 10 µL of the internal standard diluent 2-octanol, with a concentration of 3.6975 mg / L, and add it to 990 µL of the dried wine sample to keep the internal standard concentration constant. Filter the solution through a 0.22 µm organic filter membrane into a 1.5 mL injection vial and wait for chiral gas chromatography analysis. 2) Separation of 1,2-propylene glycol enantiomers in liquor by chiral gas chromatography. The chiral gas chromatography temperature program was as follows: 50°C for 1 min, then increased to 80°C at 3°C / min, and finally increased to 170°C at 8°C / min and held for 5 min. The gas chromatography conditions were as follows: injection port temperature of 250°C, split ratio of 20:1, detection port temperature of 250°C, and high-purity nitrogen as carrier gas; 3) Chiral gas chromatography was used to compare the peak order and configuration of 1,2-propylene glycol enantiomers with liquor samples. The chiral gas chromatography column was CYCLOSIL-B, 30 m × 0.25 mm × 0.25 µm. 4) Determination of the concentration and enantiomeric ratio of 1,2-propylene glycol in liquor using chiral gas chromatography standard curve method; 5) Identify strong-aroma, light-aroma, and sauce-aroma baijiu based on the measured 1,2-propylene glycol enantiomer concentration and enantiomeric ratio data.

2. The method for identifying Luzhou-flavor, Qing-flavor and Maotai-flavor liquors according to claim 1, wherein: The gas chromatograph was a Thermo Fisher TRACE 1300.

3. The method for identifying Luzhou-flavor, Qing-flavor and Maotai-flavor liquors according to claim 1, wherein: Accurately weigh a certain amount of (S)-1,2-propylene glycol and (R)-1,2-propylene glycol standard, dissolve them in chromatographically pure anhydrous ethanol and dilute to volume in a 10 mL volumetric flask to prepare (S)-1,2-propylene glycol and (R)-1,2-propylene glycol standard solutions. Then dilute them to prepare 1024 mg / L, 256 mg / L, 64 mg / L, 16 mg / L, 4 mg / L, 1 mg / L, and 0.25 mg / L standard solutions of (S)-1,2-propylene glycol, respectively; prepare 128 mg / L, 64 mg / L, 32 mg / L, 16 mg / L, 8 mg / L, 4 mg / L, 1 mg / L, and 0.25 mg / L standard solutions of (R)-1,2-propylene glycol, respectively. Take 990 μL of the standard solution in a 2 mL gas phase vial and add 10 μL of ethanol at a concentration of 5 mg / L. The standard curve was drawn with the ratio of the peak area of ​​the standard sample to the peak area of ​​the internal standard as the ordinate and the ratio of the mass concentration of the compound corresponding to the standard sample to the mass concentration of the internal standard as the abscissa.

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