Method for identifying peculiar smell substances in red dates
Through GC-IMS technology, red dates are detected, fingerprint maps are established, and characteristic volatile components are identified, which solves the problem that the existing technology is difficult to distinguish odorous red dates, and realizes the accurate identification of odorous substances of red dates and guarantees food safety.
Patent Information
- Application Number
- CN202411908535.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-03-28
AI Technical Summary
The prior art is difficult to effectively distinguish the apparent color and odor of red dates with little difference from normal red dates, resulting in the consumption of spoiled red dates, which may cause gastrointestinal discomfort or food poisoning.
GC-IMS was used to detect red dates. Through three-dimensional qualitative analysis, spectral mapping and data preprocessing, fingerprint maps of normal red dates and odorous red dates were established to identify characteristic volatile components, and the identification of odorous substances of red dates were achieved.
The accurate distinction between odorous red dates and normal red dates is achieved, and the theoretical basis for identifying odorous substances of red dates is provided, ensuring food safety.
Smart Images
Figure CN119715855A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of food detection, and particularly relates to a method for identifying odorous substances in red dates. Background Art
[0002] Red dates are rich in nutrients such as sugars, fats, organic acids, vitamins, flavonoids and various trace elements. They are a kind of dried fruit that combines edible, medicinal and health-care functions and is deeply loved by people.
[0003] Red dates have a long shelf life. Generally speaking, dried red dates can be stored for 1 to 2 years. However, since red dates are rich in various bioactive ingredients, they are prone to odor or even mold and spoilage if not stored properly. Once spoiled red dates are consumed, they may cause gastrointestinal discomfort such as abdominal pain, diarrhea, vomiting and other symptoms. In severe cases, they may also cause food poisoning.
[0004] Consumers can usually distinguish whether red dates are moldy or have a strong odor through physical methods, such as smelling the odor of red dates, observing the appearance and color of red dates, and pinching the flesh of red dates with hands. However, for odorous red dates whose appearance color and odor are not much different from normal red dates, traditional physical methods are no longer applicable. Summary of the invention
[0005] In order to solve the above technical problems, the present invention provides a method for identifying odorous substances in red dates.
[0006] The invention detects red dates by adopting gas chromatography-ion mobility spectrometry (GC-IMS), that is, respectively detecting normal red dates and peculiar red dates by GC-IMS, performing three-dimensional qualitative analysis according to migration rate, retention time and relative ion peak intensity, drawing corresponding spectra, establishing respective fingerprint spectra, and visually comparing the differences between normal red dates and peculiar red dates; at the same time, according to the information of volatile compounds of normal red dates and peculiar red dates, selecting characteristic regions in the spectra, qualitatively identifying characteristic volatile components, further using data preprocessing methods and chemometric means to realize the identification of peculiar smell substances in red dates, thereby providing a theoretical basis for identifying normal red dates and peculiar red dates.
[0007] The first aspect of the present invention is to provide a method for identifying odorous substances in red dates, wherein the method is to detect red dates using gas chromatography-ion mobility spectrometry GC-IMS, and the method specifically comprises the following steps:
[0008] S1: taking a red date sample to be tested and a known normal red date sample, crushing them, and placing them in headspace bottles for testing; the red date sample to be tested and the known normal red date sample are red dates of the same origin and the same variety;
[0009] S2 uses headspace GC-IMS to collect characteristic volatile compounds of the red date sample to be tested and the known normal red date sample in S1, and then performs qualitative and / or relative quantitative detection, and performs principal component analysis on the detection results;
[0010] When the test results show that the red date sample to be tested can be significantly distinguished from the known normal red date sample, the red date sample to be tested is a red date sample with an abnormal smell;
[0011] When the test results show that the red dates sample to be tested cannot be significantly distinguished from a known normal red dates sample, the red dates sample to be tested is a normal red dates sample.
[0012] In the above identification method, preferably, the sampling amount of the red date sample to be tested and the known normal red date sample described in S1 is 1.5-5.0 g, the sample is first incubated in a headspace bottle at 30-50°C and 300-600rpm / min for 10-20min, and then 500uL is sampled with a 80-90°C headspace injection needle and injected into a gas ion mobility chromatograph.
[0013] As a further preferred embodiment, the sampling amount of the red date sample to be tested and the known normal red date sample described in S1 is 1.5-2.0 g. The sample is first incubated in a headspace bottle at 40-50°C and 500-600rpm / min for 10-15 min, and then 500uL is sampled with a 80-85°C headspace injection needle and injected into a gas phase ion mobility chromatograph.
[0014] More preferably, the sampling amount of the red date sample to be tested and the known normal red date sample described in S1 is 2.0 g. The sample is first incubated in a headspace bottle at 40°C and 500 rpm / min for 15 min, and then 500 uL is sampled with an 85°C headspace injection needle and injected into a gas phase ion mobility chromatograph.
[0015] Preferably, in the GC-IMS described in S2, the detection conditions of the ion mobility chromatography are: the drift tube length is 9.8 cm, the linear voltage in the tube is 400 V / cm, the drift tube temperature is 45° C., the drift gas is high-purity nitrogen with a purity of ≥99.999%, and the drift gas flow rate is 150 mL / min.
[0016] Preferably, in the GC-IMS described in S2, the detection conditions of gas chromatography are: chromatographic column WAX column, column length 15m, inner diameter 0.53mm, particle size 1μm; column temperature 60°C, analysis time 45min; carrier gas is high-purity nitrogen, purity ≥99.999%; column flow rate is initially 2mL / min, maintained for 2min, column flow rate linearly increases to 10mL / min from 2-10min, and column flow rate linearly increases to 100mL / min from 10-20min.
[0017] Preferably, the qualitative analysis described in S2 specifically involves collecting and identifying the volatile compounds in the red date sample to be tested and the known normal red date sample using the VOCal analysis software provided by the GC-IMS device to obtain the GC-IMS fingerprint of each volatile substance; using C4 to C9 normal ketone as an external standard, and applying the built-in NIST database and IMS database of the software to perform qualitative analysis on the volatile substances.
[0018] The relative quantification is specifically to use the Gallery Plot plug-in to obtain a comparative difference spectrum of the GC-IMS fingerprint spectrum of the red date sample to be tested and the known normal red date sample, and obtain the relative content of the substance.
[0019] Through qualitative and relative quantitative processing, the plug-in Dynamic PCA was used to perform principal component analysis of the samples to determine whether the characteristic volatile compounds in the red date samples to be tested can be significantly distinguished from known normal red date samples.
[0020] Preferably, the characteristic volatile compounds described in S2 include: one or more of hydroxyacetone, 2-hexenal, 4-methyl-2-pentanone, isovaleraldehyde, isobutyraldehyde, n-hexanal, methyl caproate, dipropyl disulfide, diallyl sulfide, n-propanol, isopropyl butyrate, and propionic acid.
[0021] As further preferred, the characteristic volatile compounds of the known normal red date sample include: hydroxyacetone, 2-hexenal, 4-methyl-2-pentanone, isovaleraldehyde, isobutylaldehyde, n-hexanal, methyl hexanoate;
[0022] The characteristic volatile compounds of the peculiar-smelling red date sample include: dipropyl disulfide, diallyl sulfide, n-propanol, isopropyl butyrate, and propionic acid.
[0023] The second aspect of the present invention is to provide the use of a combination of characteristic volatile compounds as a marker in detecting red dates with peculiar smell, wherein the combination of characteristic volatile compounds includes at least one of hydroxyacetone, 2-hexenal, 4-methyl-2-pentanone, isovaleraldehyde, isobutyraldehyde, n-hexanal, methyl caproate, dipropyl disulfide, diallyl sulfide, n-propanol, isopropyl butyrate and propionic acid.
[0024] The beneficial effects of the present invention are:
[0025] The method for identifying odorous substances in red dates provided by the present invention does not require a complicated pre-treatment process for the sample, has the advantages of simple operation, visualization of characteristic areas, and the ability to quickly identify in batches, and has broad application prospects in accurately and efficiently identifying odorous substances in red dates. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1This is a direct comparison of volatile substances in normal red dates and peculiar red dates in Example 2 of the present invention.
[0027] Figure 2 This is a comparative diagram of the differences in volatile substances between normal red dates and peculiar-smelling red dates according to Example 2 of the present invention;
[0028] Figure 3 The fingerprints of volatile substances in normal red dates and peculiar red dates according to Example 2 of the present invention are as follows;
[0029] Figure 4 This is a principal component analysis diagram of normal red dates and red dates with an unusual smell according to Example 2 of the present invention. DETAILED DESCRIPTION
[0030] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in conjunction with specific implementation methods.
[0031] Example 1
[0032] A method for identifying odorous substances in red dates comprises the following steps:
[0033] S1 Sample Preparation
[0034] Take the sample of red dates with strange smell to be tested and the sample of red dates with known normal smell, crush them and place them in headspace bottles for testing respectively; among them, the sample of red dates with known normal smell and the sample of red dates with strange smell to be tested are both gray dates produced in Aral, Xinjiang.
[0035] S2 uses gas phase ion mobility spectrometry (Flavour Spec1H1-00053 GC-IMS coupling instrument, GAS, Germany) to collect and analyze the volatile components in the odorous red dates and normal red dates samples in S1, respectively, and then conducts qualitative and / or relative quantitative detection, and performs principal component analysis on the test results.
[0036] The specific operations are as follows:
[0037] Weigh 2.0 g of known normal red dates sample and 2.0 g of the odorous red dates sample to be tested respectively, place them in a 20 mL headspace bottle, seal it, and incubate it at 40 °C and shaking speed of 500 rpm / min for 15 min. Sampling 500 uL was performed with a headspace injection needle at 85 °C and injected into a gas ion mobility chromatograph.
[0038] The detection conditions of ion mobility spectrometry are as follows: drift tube length 9.8 cm, linear voltage in the tube 400 V / cm, drift tube temperature 45° C., drift gas is high-purity nitrogen with a purity ≥99.999%; and the flow rate of drift gas is 150 mL / min.
[0039] The detection conditions of gas chromatography are as follows: the chromatographic column is a WAX column with a column length of 15m, an inner diameter of 0.53mm, and a particle size of 1μm; the column temperature is 60°C and the analysis time is 45min; the carrier gas is high-purity nitrogen with a purity of ≥99.999%; the column flow rate is initially 2mL / min, maintained for 2min, and the column flow rate is linearly increased to 10mL / min from 2 to 10min, and the column flow rate is linearly increased to 100mL / min from 10 to 20min.
[0040] Example 2
[0041] Processing and analysis of the data obtained in Example 1
[0042] The retention time (RT) and migration time (DT) of the volatile components of the tested odorous red date samples and known normal red date samples were collected respectively, and the normal ketones of C4 to C9 were used as external standards for calibration. The retention index of each volatile substance was calculated, and the volatile components were qualitatively analyzed and the spectral differences were analyzed.
[0043] Qualitative analysis was performed using the VOCa1 software that comes with the GC-IMS device and the NIST database and IMS database built into the application software to conduct qualitative analysis of volatile components; spectral difference analysis was performed using the Reporter plug-in.
[0044] The relative ion peak intensity signals of the volatile components were collected, and the GC-IMS fingerprints of the red date samples to be tested were obtained using the Gallery Plot plug-in.
[0045] The Ga1lery Plot plug-in is used for fingerprint comparison, which can intuitively and quantitatively compare the differences in volatile organic compounds between different samples.
[0046] According to the relative ion peak intensity of the volatile components obtained, dynamic principal component analysis is performed, and the DynamicPCA plug-in is used to perform principal component analysis of the samples to determine whether the characteristic volatile compounds in the odorous red date samples to be tested can be significantly distinguished from the known normal red date samples;
[0047] When the test results show that the red date sample to be tested can be significantly distinguished from the known normal red date sample, the red date sample to be tested is a red date with an abnormal smell;
[0048] When the test results show that the red dates sample to be tested cannot be significantly distinguished from a known normal red dates sample, the red dates sample to be tested is a normal red dates sample.
[0049] A total of 49 volatile flavor substances were identified in the red date samples using the above method, mainly including those shown in Table 1 below.
[0050] Table 1 Composition of volatile flavor substances in red dates samples
[0051]
[0052]
[0053] 2.1 Spectral difference analysis
[0054] The GC-IMS fingerprint comparison of volatile substances in normal red dates and odorous red dates is shown in the attached figure. Figure 1-2 As shown, Figure 1 Represents the direct comparative fingerprint of volatile substances in normal red dates and red dates with strange smell. Figure 2 Represents the difference comparison spectrum of volatile substances in normal red dates and red dates with strange smell.
[0055] Figure 1 In the figure, the background of the whole figure is blue, the red vertical line at the horizontal axis is the reactive ion peak (RIP peak), the vertical axis represents the RT of the gas chromatogram, and the horizontal axis represents the DT. From left to right, they are normal red dates and red dates with peculiar smell;
[0056] Each point on both sides of the RIP peak represents a volatile organic compound;
[0057] The colors in the picture represent the concentration of the substance, white indicates a lower concentration, red indicates a higher concentration, and the darker the color, the greater the concentration.
[0058] Depend on Figure 2 It can be seen that there are differences in volatile organic compounds between samples. In order to contrast the differences more clearly, the difference comparison mode can be adopted, that is, the spectrum of the normal red dates sample is selected as the reference, and the spectrum of the red dates sample to be tested is subtracted from the reference. If the volatile organic compounds of the two are consistent, the background after subtraction is white, and red represents that the concentration of the substance is higher than the reference, and blue represents that the concentration of the substance is lower than the reference.
[0059] 2.2 Fingerprint analysis
[0060] In order to clarify which specific substances are different between the odorous red dates samples and the known normal red dates samples, all peaks were selected for fingerprint comparison in the present invention.
[0061] like Figure 3 As shown, from top to bottom right are normal red dates and red dates to be tested. Figure 3 Each row represents all the signal peaks selected from a sample, and each column represents the signal peaks of the same volatile organic compound in different samples. From the figure, we can see the complete volatile organic compound information of each sample and the differences in volatile organic compounds between samples.
[0062] Figure 3In the figure, the substances represented by area A are those contained in both normal red dates and smelly red dates, mainly including acetic acid, 3-hydroxy-2-butanone, n-hexanal, 2-butanone, 2,3-butanedione, 2-pentanone, methyl hexanoate and other substances, which mainly present sweet, fruity and green aromas.
[0063] The substances represented by area B in the figure have high contents in normal red dates and low contents in red dates with strange smells. They mainly include hydroxyacetone, 2-hexenal, 4-methyl-2-pentanone, isovaleraldehyde, isobutyraldehyde, n-hexanal, methyl caproate and other substances. These volatile substances are the main components of normal red dates and mainly present sweet, fruity and other aromas.
[0064] The compounds in region C are present in higher concentrations in peculiar-smelling red dates, mainly acids and alcohols, such as dipropyl disulfide, 2-ethylbutyraldehyde, isopropyl alcohol, diallyl sulfide, n-valeraldehyde, n-propanol, 2-ethyl-3,5-dimethylpyrazine, propionic acid, furfural, isopropyl butyrate, etc. Most of them have pungent sour and unpleasant tastes.
[0065] 2.3 Principal Component Analysis
[0066] The sample PCA analysis was performed using the Dynamic plugin. The analysis results are shown in Figure 4 , which can visually show the differences between different samples.
[0067] Figure 4 It can be seen that the normal red dates samples and the red dates samples with peculiar smell can be clustered into one category each, and can be well separated in the PCA diagram.
[0068] 2.4 Identification of odorous substances in red dates
[0069] The volatile substances in representative samples of normal red dates and red dates with peculiar smell were tested by GC-IMS to obtain control data, and finally the peculiar smell markers in red dates were identified as follows: dipropyl disulfide (with a pungent sulfur-like smell), diallyl sulfide (garlic smell), n-propanol (musty; slightly bitter), isopropyl butyrate (butyric acid-like smell), and propionic acid (sour taste).
[0070] It can be seen from the above experiments that the method of the present invention can achieve good distinction between red dates with strange smell and normal red dates. Furthermore, the method of the present invention also provides certain theoretical support for accurately and efficiently identifying the strange smell substances in red dates.
[0071] Although an embodiment of the present invention has been shown and described, the specific embodiment is merely an explanation of the present invention rather than a limitation of the invention. The specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions and variations to the embodiments without creative contribution as needed without departing from the principles and purpose of the present invention, and all such modifications, substitutions and variations shall fall within the scope of protection of the present invention.
Claims
1. A method for identifying odorous substances in red dates, characterized in that: The method described is to use gas chromatography-ion mobility spectrometry GC-IMS to detect red dates.
2. The method for identifying odorous substances in red dates according to claim 1, characterized in that: The method comprises the following steps: S1: taking a red date sample to be tested and a known normal red date sample, crushing them, and placing them in headspace bottles for testing; the red date sample to be tested and the known normal red date sample are red dates of the same origin and the same variety; S2 uses headspace GC-IMS to collect characteristic volatile compounds of the red date sample to be tested and the known normal red date sample in S1, and then performs qualitative and / or relative quantitative detection, and performs principal component analysis on the detection results; When the test results show that the red date sample to be tested can be significantly distinguished from the known normal red date sample, the red date sample to be tested is a red date sample with an abnormal smell; When the test results show that the red dates sample to be tested cannot be significantly distinguished from a known normal red dates sample, the red dates sample to be tested is a normal red dates sample.
3. The method for identifying odorous substances in red dates according to claim 2, characterized in that: The sampling amount of the red date samples to be tested and the known normal red date samples described in S1 is 1.5~5.0 g. The samples are first incubated in a headspace bottle at 30~50℃ and 300~600 rpm / min for 10~20 min, and then 500 uL is sampled with an 80~90℃ headspace injection needle and injected into the gas phase ion mobility chromatograph.
4. The method for identifying odorous substances in red dates according to claim 3, characterized in that: The sampling amount of the red date samples to be tested and the known normal red date samples described in S1 is 1.5~2.0 g. The samples are first incubated in a headspace bottle at 40~50℃ and 500~600 rpm / min for 10~15 min, and then 500 uL is sampled with an 80~85℃ headspace injection needle and injected into the gas phase ion mobility chromatography.
5. The method for identifying odorous substances in red dates according to claim 2, characterized in that: In the GC-IMS described in S2, the detection conditions of the ion mobility chromatography are as follows: the drift tube length is 9.8 cm, the linear voltage in the tube is 400 V / cm, the drift tube temperature is 45°C, the drift gas is high-purity nitrogen with a purity of ≥99.999%, and the flow rate of the drift gas is 150 mL / min.
6. The method for identifying odorous substances in red dates according to claim 2, characterized in that: In the GC-IMS described in S2, the detection conditions of gas chromatography are as follows: the chromatographic column is a WAX column with a column length of 15 m, an inner diameter of 0.53 mm, and a particle size of 1 µm; the column temperature is 60 °C and the analysis time is 45 min; the carrier gas is high-purity nitrogen with a purity of ≥99.999%; the column flow rate is initially 2 mL / min and maintained for 2 min, and the column flow rate is linearly increased to 10 mL / min from 2 to 10 min, and the column flow rate is linearly increased to 100 mL / min from 10 to 20 min.
7. The method for identifying odorous substances in red dates according to claim 2, characterized in that: The qualitative analysis described in S2 specifically involves using the VOCal analysis software provided by the GC-IMS device to collect and identify the volatile compounds in the red date sample to be tested and the known normal red date sample, and obtaining the GC-IMS fingerprints of the respective volatile substances; using C4~C9 normal ketones as external standards, and applying the built-in NIST database and IMS database of the software to conduct qualitative analysis on the volatile substances; The relative quantification is specifically to use the Gallery Plot plug-in to obtain a comparative difference spectrum of the GC-IMS fingerprint spectrum of the red date sample to be tested and the known normal red date sample, and obtain the relative content of the substance; Through qualitative and relative quantitative processing, the plug-in Dynamic PCA was used to perform principal component analysis of the samples to determine whether the characteristic volatile compounds in the red date samples to be tested can be significantly distinguished from known normal red date samples.
8. The method for identifying odorous substances in red dates according to claim 2, characterized in that: The characteristic volatile compounds described in S2 include: one or more of hydroxyacetone, 2-hexenal, 4-methyl-2-pentanone, isovaleraldehyde, isobutyraldehyde, n-hexanal, methyl caproate, dipropyl disulfide, diallyl sulfide, n-propanol, isopropyl butyrate, and propionic acid.
9. The method for identifying odorous substances in red dates according to claim 8, characterized in that: The characteristic volatile compounds of the known normal red date sample include: hydroxyacetone, 2-hexenal, 4-methyl-2-pentanone, isovaleraldehyde, isobutylaldehyde, n-hexanal, methyl hexanoate; The characteristic volatile compounds of the peculiar-smelling red date sample include: dipropyl disulfide, diallyl sulfide, n-propanol, isopropyl butyrate, and propionic acid.
10. The use of a combination of characteristic volatile compounds as a marker in detecting odorous red dates, characterized in that: The combination of characteristic volatile compounds includes: at least one of hydroxyacetone, 2-hexenal, 4-methyl-2-pentanone, isovaleraldehyde, isobutyraldehyde, n-hexanal, methyl caproate, dipropyl disulfide, diallyl sulfide, n-propanol, isopropyl butyrate, and propionic acid.