A method for detecting empty-cup aroma flavor substances of liquor

Abstract

The present application relates to the field of liquor detection technology, and specifically to a method for detecting flavor substances of liquor empty cup aroma, comprising the following steps: (1) taking a liquor sample in a container, pouring the liquor sample out of the container after standing, blowing the container with nitrogen, and adding an internal standard to obtain a liquor empty cup aroma sample to be tested; (2) extracting the flavor substances of the liquor empty cup aroma sample to be tested by headspace solid phase microextraction, and then detecting the flavor substances of the liquor empty cup aroma sample to be tested by gas chromatography-mass spectrometry. The present application can reduce the interference of volatile substances on detection and improve the stability of detecting semi-volatile or non-volatile substances.

Description

Technical Field

[0001] The present application relates to the technical field of liquor flavor substance detection, and in particular to a method for detecting empty-cup aroma flavor substances of liquor. Background Art

[0002] The empty cup aroma of liquor refers to the phenomenon that the aroma of liquor remains on the wall of the cup after being filled with high-quality liquor, leaving a lingering aftertaste. There are two reasons for this phenomenon: first, there are many kinds of flavor substances in high-quality liquor, and the complex interactions between substances cause their volatilization rate to be slow; second, liquor itself contains many non-volatile flavor substances, and their aroma can remain in the empty cup for a long time. Studies have shown that the duration of the empty cup aroma is a major factor in evaluating the quality of liquor. Therefore, studying the flavor substances that cause the long-lasting empty cup aroma of liquor will provide technical and data support for the scientific understanding of the sensory characteristics of the empty cup aroma of liquor, and is also of great significance to the quality evaluation of liquor.

[0003] In the prior art, static headspace-gas chromatography-mass spectrometry is used to detect and analyze the aroma components of the empty cup aroma of Maotai-flavor liquor, and a total of 11 key compounds that contribute to the aroma are identified. However, this method has the following problems: this method is suitable for analyzing volatile alcohols and aldehydes, but is not suitable for analyzing semi-volatile or difficult-to-volatile substances with low content. It is impossible to accurately and effectively detect semi-volatile or difficult-to-volatile substances that contribute more to the empty cup aroma, and the required amount of wine sample is large. The natural volatilization pre-treatment is easily affected by environmental conditions, and the detection stability is low. Summary of the invention

[0004] In order to solve the above problems, the present application provides a method for detecting empty cup aroma flavor substances of liquor.

[0005] The present application provides a method for detecting empty-cup aroma flavor substances of liquor using the following technical solution:

[0006] A method for detecting empty-cup aroma flavor substances of liquor, comprising the following steps:

[0007] (1) putting a liquor sample in a container, letting it stand, then pouring the liquor sample out of the container, nitrogen-blowing the container, and adding an internal standard to obtain a liquor empty cup aroma sample to be tested;

[0008] (2) extracting the flavor substances of the empty cup aroma sample of the liquor to be tested by headspace solid phase microextraction, and then detecting the flavor substances of the empty cup aroma sample of the liquor to be tested by gas chromatography-mass spectrometry;

[0009] The flavor substances of the empty cup aroma sample of the liquor to be tested are semi-volatile or hardly volatile flavor substances.

[0010] Preferably, the step (1) comprises: taking 2 to 4 mL of liquor sample into a container, letting it stand for 8 to 12 minutes, then pouring the liquor sample out of the container, nitrogen-blowing the container, and then adding an internal standard to obtain a liquor empty cup aroma sample to be tested;

[0011] Preferably, the step (1) comprises: taking 2 mL of liquor sample into a container, letting it stand for 10 minutes and then pouring the liquor sample out of the container, nitrogen-blowing the container and then adding an internal standard to obtain a liquor empty cup aroma sample to be tested.

[0012] Preferably, the nitrogen blowing time for nitrogen blowing the container is determined by the empty cup aroma sensory profile, the total peak area of ​​volatile substances and the total peak area of ​​substances with greater aroma intensity detected after the nitrogen blowing treatment;

[0013] Preferably, the nitrogen blowing time for the container to be nitrogen blown is 20 minutes.

[0014] Preferably, the volume of the added internal standard is 1 to 3 μL;

[0015] Preferably, the volume of the added internal standard is 2 μL.

[0016] Preferably, the internal standard is citronellol or tert-amyl alcohol;

[0017] Preferably, the internal standard is citronellol;

[0018] More preferably, the concentration of citronellol is 238 mg / L.

[0019] Preferably, the step (2) comprises: using an extraction head to extract the flavor substances of the empty cup aroma sample of the white wine to be tested to obtain an extraction head with extracted flavor substances; inserting the extraction head with extracted flavor substances into a gas chromatography inlet, and then using a gas chromatography-mass spectrometer to detect the flavor substances of the empty cup aroma sample of the white wine to be tested.

[0020] Preferably, the extraction temperature of the flavor substances of the empty cup aroma sample of the liquor to be tested by using the extraction head is 70-80° C., and the extraction time is 40-50 min;

[0021] Preferably, the extraction temperature for extracting the flavor substances of the empty cup aroma sample of the liquor to be tested by using the extraction head is 70° C., and the extraction time is 40 min.

[0022] Preferably, in step (2), the gas chromatography parameters are set as follows: using a FFAP column, the FFAP column parameters are 30m×0.25mm×0.25μm, the carrier gas is helium, the flow rate is 0.8-1.2mL / min, and non-split injection is used;

[0023] The heating program was as follows: initial temperature 40°C, maintained for 1 min, increased to 80°C at a rate of 8-12°C / min, then increased to 140°C at a rate of 3-5°C / min, and finally increased to 220°C at a rate of 8-12°C / min and maintained for 10 min.

[0024] Preferably, the gas chromatography parameters are set as follows: using a FFAP column, the FFAP column parameters are 30m×0.25mm×0.25μm, the carrier gas is helium, the flow rate is 1mL / min, and non-split injection is used;

[0025] The heating program was as follows: initial temperature 40°C, maintained for 1 min, increased to 80°C at a rate of 10°C / min, then increased to 140°C at a rate of 3°C / min, and finally increased to 220°C at a rate of 10°C / min and maintained for 10 min.

[0026] Preferably, in step (2), the mass spectrometry parameters are set as follows: the quadrupole temperature is 140-160° C., the EI ion source temperature is 220-240° C., the ion scanning mode is adopted, and the scanning range is m / z 30-400 amu;

[0027] Preferably, the mass spectrometry parameters are set as follows: the quadrupole temperature is 150° C., the EI ion source temperature is 230° C., the ion scanning mode is adopted, and the scanning range is m / z 30-400 amu.

[0028] This application has the following beneficial technical effects:

[0029] The present application first removes volatile flavor substances through nitrogen blowing treatment, and then conducts enrichment detection through headspace solid phase microextraction; it can reduce the detection interference of volatile flavor substances on semi-volatile or difficult-volatile empty cup aroma flavor substances, and enable the semi-volatile or difficult-volatile empty cup aroma flavor substances to be detected, and the stability of nitrogen blowing treatment detection is much higher than that of natural volatilization, and the detection results are more accurate and reliable; at the same time, more semi-volatile or difficult-to-release flavor substances can be detected through headspace solid phase microextraction, and a more comprehensive detection of the empty cup aroma flavor substances of liquor can be conducted. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a comparison chart of peak areas detected at different extraction temperatures in Example 3;

[0031] Figure 2 is a comparison chart of peak areas detected at different extraction times in Example 4;

[0032] Figure 3 This is a comparison chart of peak areas detected by liquor samples of different volumes in Example 5;

[0033] Figure 4is the hollow cup aroma sensory profile diagram of Example 6;

[0034] Figure 5 is the empty cup aroma sensory profile diagram of different nitrogen blowing times in Example 6;

[0035] Figure 6 is a comparison chart of the total peak areas of volatile substances at different nitrogen blowing times in Example 6;

[0036] Figure 7 is a comparison chart of the total peak areas of substances with greater aroma intensity at different nitrogen blowing times in Example 6;

[0037] Figure 8 This is a graph showing the test results of static headspace extraction of empty cup aroma flavor substances in Comparative Example 1;

[0038] Fig. 9 This is a graph showing the test results of extracting empty cup aroma flavor substances by headspace solid phase microextraction in comparative example 1;

[0039] Fig.10 is the empty cup aroma sensory profile diagram of different natural volatilization times in comparative example 2;

[0040] Fig.11 This is a comparison chart of the total peak areas of volatile substances at different natural volatilization times in Comparative Example 2;

[0041] Fig.12 It is a comparison chart of the total peak areas of substances with greater aroma intensity at different natural volatilization times in Example 2. DETAILED DESCRIPTION

[0042] The duration of the empty cup aroma is a major factor in evaluating the quality of liquor. Therefore, studying the flavor substances that make the empty cup aroma of liquor last longer will provide technical and data support for scientifically understanding the sensory characteristics of the empty cup aroma of liquor, and is also of great significance to the quality evaluation of liquor. Since volatile liquor flavor substances will evaporate into the air in a short time, semi-volatile or difficult-volatile empty cup aroma flavor substances contribute more to the duration of the empty cup aroma of liquor. When detecting the flavor substances of the empty cup aroma of liquor, it is necessary to detect the semi-volatile or difficult-volatile empty cup aroma flavor substances.

[0043] In the prior art, static headspace-gas chromatography-mass spectrometry is used to detect and analyze the aroma components of the empty cup aroma of Maotai-flavor liquor, and a total of 11 key compounds that contribute to the aroma are identified. However, this method has the following problems: This method is suitable for analyzing volatile alcohols and aldehydes, etc., but is not suitable for analyzing semi-volatile or difficult-to-volatile substances with low content. It is impossible to accurately and effectively detect semi-volatile or difficult-to-volatile substances that contribute more to the empty cup aroma, and the required wine sample volume is large. The natural volatilization pre-treatment is easily affected by environmental conditions, and the detection stability is low. Based on this, the present application provides a method for detecting flavor substances of the empty cup aroma of liquor to solve the above problems.

[0044] The present application is further described below with reference to embodiments.

[0045] Example 1

[0046] A method for detecting empty-cup aroma flavor substances of liquor, comprising the following steps:

[0047] (1) Put a liquor sample in a container, pour the liquor sample out of the container, blow nitrogen into the container, and then add an internal standard to obtain a liquor empty cup aroma sample to be tested.

[0048] Specifically, 2 mL of the sauce-flavor liquor sample is transferred into a container. The container in this embodiment is a 20 mL screw bottle, and in other embodiments it may also be a headspace bottle. After standing for 10 minutes, the liquor sample is poured out from the screw bottle, the inside of the screw bottle is nitrogen-blown for 20 minutes, and then 2 μL of citronellol is added into the screw bottle as an internal standard. The concentration of citronellol is 238 mg / L, and the empty cup aroma sample of the liquor to be tested is obtained.

[0049] (2) The flavor substances of the empty cup aroma sample of the liquor to be tested are extracted by headspace solid phase microextraction, and then the flavor substances of the empty cup aroma sample of the liquor to be tested are detected by gas chromatography-mass spectrometry (GC-MS); the flavor substances of the empty cup aroma sample of the liquor to be tested are semi-volatile or difficult-to-volatile flavor substances.

[0050] Specifically, an extraction head (50 / 30 μm DVB / CAR / PDMS) was used to extract the flavor substances of the empty cup aroma sample of the liquor to be tested, the extraction temperature was 70°C, and the extraction time was 40 minutes, to obtain an extraction head with extracted flavor substances. The extraction head with extracted flavor substances was inserted into the gas chromatography injection port, and then the flavor substances of the empty cup aroma sample of the liquor to be tested were detected by gas chromatography-mass spectrometry.

[0051] The gas chromatography parameters were set as follows: using a FFAP column with parameters of 30 m × 0.25 mm × 0.25 μm, helium as the carrier gas, a flow rate of 1 mL / min, and splitless injection;

[0052] The heating program was as follows: initial temperature 40°C, maintained for 1 min, increased to 80°C at a rate of 10°C / min, then increased to 140°C at a rate of 3°C / min, and finally increased to 220°C at a rate of 10°C / min and maintained for 10 min.

[0053] The mass spectrometer parameters were set as follows: quadrupole temperature was 150°C, EI ion source temperature was 230°C, ion scanning mode was used, and the scanning range was m / z 30-400 amu.

[0054] GC-MS was used to detect the empty cup aroma flavor substances of Maotai-flavor liquor. The empty cup aroma flavor substances of liquor were qualitatively detected by chromatographic retention time (RT), comparison results of NIST standard spectral library and aroma substance combination method. The content of each flavor substance was semi-quantitatively analyzed using internal standard citronellol. The 17 semi-volatile or difficult-to-volatile empty cup aroma flavor substances of Maotai-flavor liquor detected are shown in Table 1.

[0055] Table 1 Flavor substances of empty cup aroma of Maotai-flavor liquor

[0056]

[0057]

[0058] Method stability evaluation:

[0059] The stability evaluation of the method is expressed as the inter-day relative standard deviation (RSD). The method for determining the inter-day relative standard deviation is as follows: After an interval of 2 days, the detection steps of Example 1 are used to detect the empty cup aroma flavor substances of white wine, and the total peak area of ​​the empty cup aroma flavor substances is calculated. Three parallel experiments are performed, and the relative standard deviation (inter-day relative standard deviation) is calculated based on the total peak area of ​​the empty cup aroma flavor substances of white wine measured three times. The calculated inter-day relative standard deviation is 2.1%.

[0060] Example 2

[0061] The difference between this embodiment and embodiment 1 is that the liquor sample in this embodiment is a light-flavor liquor sample, and the remaining detection steps are the same as those in embodiment 1. The 15 semi-volatile or difficult-volatile liquor empty-cup aroma flavor substances of the light-flavor liquor detected are shown in Table 2.

[0062] Table 2 Flavor substances of empty cup aroma of light-fragrance liquor

[0063]

[0064]

[0065] It can be seen from Example 1 and Example 2 that the empty cup aroma flavor substances of liquor samples with different aroma types are different, and the detection method of the present application is also applicable to the detection of empty cup aroma flavor substances of light-fragrance liquor.

[0066] Example 3 Investigating the effects of different extraction temperatures on the detection results of headspace solid phase microextraction

[0067] This example is to explore the effect of different extraction temperatures of headspace solid phase microextraction on the detection results. The different extraction temperatures include: 50°C, 60°C, 70°C, and 80°C. The empty cup aroma flavor substances of the liquor sample were extracted at 50°C, 60°C, 70°C, and 80°C, respectively, and then detected. The remaining detection steps are the same as those in Example 1. The total peak areas detected at different extraction temperatures are shown in FIG. Figure 1 shown.

[0068] from Figure 1 It can be seen that when the extraction temperature is 50-70°C, as the extraction temperature increases, the total peak area of ​​the empty cup aroma flavor substances of the detected liquor samples gradually increases and reaches the maximum value when the extraction temperature is 70°C. When the extraction temperature exceeds 70°C, the total peak area of ​​the empty cup aroma flavor substances of the detected liquor samples shows a downward trend. This shows that by adjusting the extraction temperature of headspace solid phase microextraction, the total peak area of ​​the empty cup aroma flavor substances of the detected liquor samples can be significantly increased, and the empty cup aroma flavor substances of the liquor samples can be detected more accurately.

[0069] Example 4 Investigating the effect of different extraction times of headspace solid phase microextraction on the detection results

[0070] This example is to explore the effect of different extraction times of headspace solid phase microextraction on the detection results. The different extraction times include: 20min, 30min, 40min, 50min, and 60min. The empty cup aroma flavor substances of the liquor sample were extracted at 20min, 30min, 40min, 50min, and 60min, respectively, and then detected. The remaining detection steps are the same as those in Example 1. The total peak area detected at different extraction times is shown in FIG. Figure 2 shown.

[0071] from Figure 2 It can be seen that when the extraction time is 20-40 minutes, as the extraction time increases, the total peak area of ​​the empty cup aroma flavor substances of the detected liquor samples gradually increases and reaches the maximum value when the extraction time is 40 minutes. When the extraction time exceeds 40 minutes, the total peak area of ​​the empty cup aroma flavor substances of the detected liquor samples shows a downward trend. This shows that by adjusting the extraction time of headspace solid phase microextraction, the total peak area of ​​the empty cup aroma flavor substances of the detected liquor samples can be significantly increased, thereby improving the accuracy of detecting the empty cup aroma flavor substances of the liquor samples.

[0072] Example 5: Influence of different volumes of liquor samples on test results

[0073] This example is to explore the effect of different volumes of liquor samples on the test results. The volumes of different liquor samples include: 0.5mL, 1mL, 1.5mL, 2mL, 2.5mL, 3mL, and 4mL. 0.5mL, 1mL, 1.5mL, 2mL, 2.5mL, 3mL, and 4mL liquor samples were placed in 20mL threaded bottles respectively, and the nitrogen blowing treatment was replaced by natural standing and volatilization for 2h. The remaining steps were the same as in Example 1 for testing. The total peak area of ​​liquor samples with different volumes is shown in Figure 1. Figure 3 shown.

[0074] from Figure 3 It can be seen that when the volume of the liquor sample is less than 2 mL, the amount remaining on the bottle wall is small due to the small volume, and the total peak area of ​​the substance response is low; when the volume of the liquor sample is 2 mL or more, the total peak area values ​​of the substance response are close, so 2 mL of liquor sample is selected as the best choice.

[0075] Example 6 Investigating the influence of different nitrogen blowing time on the test results

[0076] Pipette 2mL of sauce-flavor liquor sample into a 20mL screw-thread bottle, let it stand for 10 minutes, and then pour the liquor sample out of the screw-thread bottle. Use a 0-3 point 6-point scale to evaluate the sour, sweet, floral, nutty, dry plant, and grass aroma of the liquor in the screw-thread bottle. 0.5 points is one scale, 0.5 points means it can be smelled, and 3 points means the strongest intensity. The sensory profile of the evaluated empty cup aroma is shown in the figure below. Figure 4 As shown, the sensory characteristics of the empty cup aroma are mainly a combination of sour aroma, dry plant aroma, sweet aroma, nutty aroma and floral aroma.

[0077] The GC-O smelling method was used to find the aroma substances in each dimension of the empty cup aroma sensory radar chart, and to detect the representative substances of the aroma and the corresponding smell intensity.

[0078] The GC-0 scenting method specifically includes the following steps:

[0079] The flavor substances of the empty cup aroma sample of the liquor to be tested were extracted using an extraction head (50 / 30μm DVB / CAR / PDMS) at an extraction temperature of 70°C and an extraction time of 40 min to obtain an extraction head with extracted flavor substances. The extraction head was inserted into a gas chromatograph-mass spectrometer equipped with an aroma meter to obtain the aroma characteristics of each substance. The instrument was equipped with a sniffing port and an air humidifier, which was connected to an Rtx-5 column (30m×0.25mm×0.25μm).

[0080] Gas chromatography conditions: FFAP column with parameters of 30m×0.25mm×0.25μm, helium as carrier gas, flow rate of 1mL / min, splitless injection; temperature program: initial temperature 40°C, maintained for 1min, increased to 80°C at a rate of 10°C / min, then increased to 140°C at a rate of 3°C / min, and finally increased to 220°C at a rate of 10°C / min, maintained for 10min.

[0081] Mass spectrometry conditions: quadrupole temperature was 150°C, EI ion source temperature was 230°C, ion scanning mode was used, and the scanning range was m / z 30-400 amu.

[0082] Nitrogen was used as a carrier at a constant flow rate of 1.0 mL / min to separate the chromatographic column effluent in a 1:1 ratio between the sniffing port and the mass spectrometer. At the same time, humid air and hydrogen were injected into the sniffing port at flow rates of 40 mL / min and 30 mL / min, respectively, to quickly remove the odor from the sniffing port. The results of the GC-0 smelling method are shown in Table 3.

[0083] Table 3 Empty cup aroma GC-O smell results

[0084] substance Scent Description <![CDATA[GC-O Aroma Intensity a > 3-Methylbutyraldehyde Fruity, slightly nutty 0.5 3-Methyl-1-butanol Burnt aroma 0.5 Ethyl lactate Mushrooms, dried herbs 2.5 Trimethylpyrazine Nutty aroma 2.5 Acetic acid Sour 2.5 Tetramethylpyrazine Baked aroma, nutty aroma 2.5 Propionic acid Sour 1.5 Butyric acid Sour 2.5 Isovalerate Sour 2.5 Ethyl phenylacetate Floral scent 2 Ethyl decanoate Fruity 1.5 Phenylethyl alcohol Rose scent 3 Nonalactone Toffee, sweet 2.5

[0085] It can be seen from Table 3 that the substances with greater aroma intensity in each aroma dimension are acetic acid, ethyl lactate, nonalactone, tetramethylpyrazine, and phenylethanol, so the response changes of these substances are selected as optimization indicators.

[0086] The influence of different nitrogen blowing time on the test results was explored. Different nitrogen blowing time included nitrogen blowing for 0, 20, 40, 60, and 80 minutes. The inside of the threaded bottle was nitrogen blown for 0, 20, 40, 60, and 80 minutes respectively. The remaining test steps were the same as those in Example 1. The GC-O scenting technology was used to detect the scent intensity of the empty cup aroma. The sensory profile of the empty cup aroma is shown in the figure below. Figure 5 As shown in Figure 2, the total peak areas of volatile substances such as ethanol, n-butanol, 2-methylpropanol, n-butanol, isopentanol, and amyl alcohol are as follows: Figure 6 As shown in Figure 2, the response peak areas of substances with strong aroma intensity such as acetic acid, ethyl lactate, nonalactone, tetramethylpyrazine, and phenylethanol are as follows: Figure 7 shown.

[0087] from Figure 5 It can be seen that with the increase of nitrogen blowing time, the sensory intensity of each aroma dimension gradually decreased. When nitrogen blowing was continued for 20 minutes, the sensory intensity of each aroma dimension was still strong. Figure 6 It can be seen that after 20 minutes of nitrogen blowing, the total peak area of ​​volatile substances decreased significantly, which means that most of the volatile substances have evaporated and the interference of volatile substances has been removed. Figure 7 It can be seen that acetic acid, ethyl lactate, nonalactone, tetramethylpyrazine, and phenylethanol can still be effectively detected after nitrogen blowing for 20 minutes, but acetic acid and nonalactone can no longer be effectively detected after nitrogen blowing for 40 minutes. Figure 5 to Figure 7 In summary, nitrogen blowing for 20 minutes can not only remove most of the volatile substances and reduce detection interference, but also effectively detect empty cup aroma substances.

[0088] Comparative Example 1

[0089] 1 mL of Maotai-flavor liquor sample was placed in a 20 mL screw bottle and allowed to stand for 10 min before being poured out. After being naturally allowed to stand for 2 h, static headspace (HS) and headspace solid phase microextraction (HS-SPME) were used to extract empty cup aroma flavor substances, and then gas chromatography-mass spectrometry was used for detection. The remaining detection steps were the same as in Example 1. The HS-GC-MS detection results are shown in FIG. Figure 8 As shown, the HS-SPME-GC-MS test results are as follows Fig. 9 As shown, Figure 8 and Fig. 9 The horizontal axis is the type of substance, and the vertical axis is the specific number of substances.

[0090] from Figure 8 and Fig. 9 It can be seen that 35 empty cup aroma flavor substances can be detected by HS-GC-MS, and most of them are volatile flavor substances such as acetaldehyde and 3-methylbutanol, while more than 70 empty cup aroma substances can be detected by HS-SPME-GC-MS. Comparing the results of the two, HS-GC-MS is suitable for analyzing volatile aroma substances, while HS-SPME-GC-MS is conducive to analyzing semi-volatile and non-volatile aroma substances and has an enrichment effect on aroma substances.

[0091] Comparative Example 2: Influence of natural volatilization instead of nitrogen blowing on the test results

[0092] This comparative example is to explore the effect of natural volatilization instead of nitrogen blowing on the test results. 2mL of Maotai-flavor liquor sample is transferred into a 20mL screw bottle. After standing for 10 minutes, the liquor sample is poured out from the screw bottle and left to volatilize naturally for 0, 1, 2, 3, and 4 days (recorded as 0d, 1d, 2d, 3d, and 4d) respectively to replace nitrogen blowing. The remaining detection steps are the same as those in Example 1. The GC-O smelling technique is used to detect the smell intensity of the empty cup aroma. The sensory profile of the empty cup aroma is shown in the figure below. Fig.10 As shown in Figure 2, the total peak areas of volatile substances such as ethanol, n-butanol, 2-methylpropanol, n-butanol, isopentanol, and amyl alcohol are as follows: Fig.11 As shown in Figure 2, the response peak areas of substances with strong aroma intensity such as acetic acid, ethyl lactate, nonalactone, tetramethylpyrazine, and phenylethanol are as follows: Fig.12 shown.

[0093] Depend on Fig.10 It can be seen that after the empty cup evaporates naturally for 1 day, the intensity of each aroma changes only slightly. After the empty cup evaporates naturally for 2 days, the sensory intensity of each aroma is significantly weakened, and the flavor profile is more different than that of day 0. Fig.11 It can be seen that when the empty cup evaporates naturally for one day, the peak area of ​​volatile substances only decreases by half, and there is still a large interference in the detection of semi-volatile or non-volatile substances. When the empty cup evaporates naturally for 2 days, the peak area of ​​volatile substances shows a significant decrease, and the interference effect of volatile substances on detection will be reduced at this time. Fig.12 It can be seen that after one day of natural evaporation of the empty cup, the peak areas of acetic acid, ethyl lactate, nonanolide, tetramethylpyrazine and phenylethanol have decreased significantly, and after 2 days of natural evaporation, acetic acid, tetramethylpyrazine and phenylethanol are basically undetectable.

[0094] Combination Fig.11 and Fig.12 It can be seen that the use of natural volatilization instead of nitrogen blowing treatment can not only effectively reduce the detection interference of volatile substances on the detection of semi-volatile or non-volatile substances, but also maintain the effective detection of substances with strong aroma intensity such as acetic acid, ethyl lactate, nonanolide, tetramethylpyrazine, and phenylethanol.

[0095] The stability of the detection method using natural volatilization instead of nitrogen blowing treatment is expressed by the daily relative standard deviation (RSD). The determination method of the daily relative standard deviation is as follows: 2 mL of wine sample is transferred to a 20 mL screw bottle after an interval of 2 days, and the liquor sample is poured out from the screw bottle after standing for 10 minutes, and naturally volatilized for 1 day, 2 μL of citronellol internal standard is added, and the cap is screwed. The empty cup aroma flavor substances are detected by headspace solid phase microextraction combined with gas chromatography-mass spectrometry, and the total peak area of ​​the empty cup aroma flavor substances is calculated. Three parallel experiments were performed according to the above method, and the daily relative standard deviation (RSD) was calculated based on the total peak area of ​​the empty cup aroma flavor substances of the liquor determined by the three parallel experiments. The calculated daily relative standard deviation is 13.23%.

[0096] Combining Example 1 and Comparative Example 2, it can be seen that the daytime relative standard deviation of Example 1 is 2.1%, which is less than 5%, and is very stable, and the test results are more stable and reliable. However, the daytime relative standard deviation of Comparative Example 2 is 13.23%, and the relative standard deviation is large. The test results are greatly affected by the environment, the test results are unstable, and the accuracy is low. It can be seen that the nitrogen blowing treatment method can improve the stability of the empty cup aroma substance detection compared to natural volatilization, making the test results more reliable.

[0097] According to the detection method in Comparative Example 2, the empty cup aroma flavor substances of the liquor left to volatilize for one day and two days were detected respectively; and then the GC-0 aroma intensity of the empty cup aroma flavor substances of the liquor left to volatilize for 20 minutes in Example 1 and left to volatilize for one day and two days in Comparative Example 2 was detected according to the GC-0 aroma method in Example 6. The detection comparison results are shown in Table 4.

[0098] Table 4 Comparison results of Example 1 and Comparative Example 2

[0099]

[0100]

[0101] As can be seen from Table 4, both the 20-min nitrogen blowing and one-day standing volatilization can detect the volatile or non-volatile substances in the empty cup aroma flavor substances of white wine, but the GC-0 aroma intensity of some empty cup aroma substances in the 20-min nitrogen blowing is stronger than the aroma intensity of the one-day standing volatilization. Fig.11 It can be seen that the effect of removing volatile substances is obvious only after two days of standing and volatilization. As shown in Table 4, many substances can no longer be detected after two days of standing and volatilization, and their GC-0 aroma intensity is also significantly weaker than the aroma intensity of nitrogen blowing for 20 minutes. This shows that whether it is standing and volatilizing for one day or two days, it is not suitable for detecting the empty cup aroma flavor substances of white wine.

[0102] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for detecting empty-cup aroma flavor substances of liquor, characterized in that: The following steps are involved: (1) Put a liquor sample in a container, let it stand and then pour the liquor sample out of the container, perform nitrogen blowing on the container and then add an internal standard to obtain a liquor empty cup aroma sample to be tested, wherein the volatile substances are removed by the nitrogen blowing, and the nitrogen blowing time of the container is determined by the empty cup aroma sensory profile, the total peak area of ​​the volatile substances and the total peak area of ​​the substances with greater aroma intensity detected after the nitrogen blowing, and the empty cup aroma sensory profile detection method is: the sour aroma, sweet aroma, floral aroma, nutty aroma, dry plant aroma and grass aroma dimensions of the liquor empty cup aroma in the container are evaluated by using a 0-3 point 6-point scale method, 0.5 points is one scale, 0.5 points means that it can be smelled, and 3 points is the strongest intensity; the aroma intensity detection method is: the aroma intensity of the empty cup aroma is detected by using GC-O aroma smelling technology; (2) extracting the flavor substances of the empty cup aroma sample of the liquor to be tested by headspace solid phase microextraction, and then detecting the flavor substances of the empty cup aroma sample of the liquor to be tested by gas chromatography-mass spectrometry; The flavor substances of the empty cup aroma sample of the white wine to be tested are semi-volatile or difficult-to-volatile flavor substances, and the semi-volatile or difficult-to-volatile flavor substances are esters, aromatics and pyrazines. The esters are ethyl palmitate, ethyl oleate, ethyl linoleate, nonanolactone and ethyl lactate, the aromatics are phenylethanol and phenylacetaldehyde, and the pyrazines are tetramethylpyrazine and trimethylpyrazine.

2. The detection method according to claim 1, characterized in that: The step (1) comprises: taking 2 to 4 mL of a liquor sample into a container, leaving it to stand for 8 to 12 minutes, then pouring the liquor sample out of the container, nitrogen-blowing the container, and then adding an internal standard to obtain a liquor empty cup aroma sample to be tested.

3. The detection method according to claim 2, characterized in that: The step (1) comprises: taking 2 mL of a liquor sample into a container, leaving it to stand for 10 minutes and then pouring the liquor sample out of the container, nitrogen-blowing the container and then adding an internal standard to obtain a liquor empty cup aroma sample to be tested.

4. The detection method according to claim 3, characterized in that: The nitrogen blowing time for the container to be nitrogen blown is 20 minutes.

5. The detection method according to claim 2, characterized in that: The volume of the added internal standard is 1 to 3 μL.

6. The detection method according to claim 5, characterized in that: The volume of the added internal standard was 2 μL.

7. The detection method according to claim 5, characterized in that: The internal standard is citronellol or tert-amyl alcohol.

8. The detection method according to claim 7, characterized in that: The internal standard is citronellol.

9. The detection method according to claim 8, characterized in that: The concentration of the citronellol is 238 mg / L.

10. The detection method according to claim 1, characterized in that: The step (2) comprises: using an extraction head to extract the flavor substances of the empty cup aroma sample of the white wine to be tested to obtain an extraction head with extracted flavor substances; inserting the extraction head with extracted flavor substances into a gas chromatography injection port, and then using a gas chromatography-mass spectrometer to detect the flavor substances of the empty cup aroma sample of the white wine to be tested.

11. The detection method according to claim 10, characterized in that: The extraction temperature for extracting the flavor substances of the empty cup aroma sample of the white wine to be tested by using the extraction head is 70-80° C., and the extraction time is 40-50 minutes.

12. The detection method according to claim 11, characterized in that: The extraction temperature for extracting the flavor substances of the empty cup aroma sample of the liquor to be tested by using the extraction head is 70° C. and the extraction time is 40 minutes.

13. The detection method according to claim 1, characterized in that: In the step (2), the gas chromatography parameters are set as follows: using a FFAP column, the FFAP column parameters are 30m×0.25mm×0.25μm, the carrier gas is helium, the flow rate is 0.8-1.2mL / min, and non-split injection is used; The heating program was as follows: initial temperature 40°C, maintained for 1 min, increased to 80°C at a rate of 8-12°C / min, then increased to 140°C at a rate of 3-5°C / min, and finally increased to 220°C at a rate of 8-12°C / min and maintained for 10 min.

14. The detection method according to claim 13, characterized in that: The gas chromatography parameters are set as follows: using a FFAP column, the FFAP column parameters are 30m×0.25mm×0.25μm, the carrier gas is helium, the flow rate is 1mL / min, and non-split injection is used; The heating program was as follows: initial temperature 40°C, maintained for 1 min, increased to 80°C at a rate of 10°C / min, then increased to 140°C at a rate of 3°C / min, and finally increased to 220°C at a rate of 10°C / min and maintained for 10 min.

15. The detection method according to claim 1, characterized in that: In the step (2), the mass spectrometer parameters are set as follows: the quadrupole temperature is 140-160° C., the EI ion source temperature is 220-240° C., the ion scanning mode is adopted, and the scanning range is m / z 30-400 amu.

16. The detection method according to claim 15, characterized in that: The mass spectrometer parameters were set as follows: quadrupole temperature was 150° C., EI ion source temperature was 230° C., ion scanning mode was adopted, and the scanning range was m / z 30-400 amu.

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