A method for detecting and analyzing aroma components in pomegranate

Abstract

The application discloses a detection and analysis method of aroma components in pomegranate, and belongs to the technical field of chemical analysis. The analysis method comprises the following steps: S1, placing a pomegranate sample in a headspace bottle and incubating the pomegranate sample; S2, using a MonoTrapTD adsorption sub to collect volatile substances of the pomegranate sample in a static headspace mode; and S3, after the collection is completed, using a direct thermal desorption method to desorb and sample the collected substances, and introducing the desorbed substances into a gas chromatograph-mass spectrometer for qualitative and quantitative analysis. The MonoTrapTD method is used to enrich aroma components of the pomegranate, and meanwhile, a direct thermal desorption-gas chromatograph-mass spectrometer (LN-GC-MS) technology is combined, so that the types and contents of the aroma components in the pomegranate can be accurately analyzed and detected, and certain theoretical reference is established for blending and producing related fragrance of the same type.

Description

Technical Field

[0001] This invention belongs to the field of chemical analysis technology, and specifically relates to a method for detecting and analyzing aroma components in pomegranates. Background Technology

[0002] Pomegranate is a berry rich in nutrients, with vitamin C levels 1-2 times higher than apples and pears. Originally from the Western Regions of China, it was introduced to the Central Plains during the Han Dynasty. After ripening, the entire pomegranate plant is usable; the peel can be used medicinally, and the fruit can be eaten or juiced. It has high nutritional value for the health of the elderly, so seniors should eat pomegranates regularly. The pomegranate is a rare and precious berry with high nutritional value.

[0003] In analyzing fruit aromas, the main methods used for enrichment include purge-and-trap, solid-phase microextraction (SPME), vacuum distillation extraction, simultaneous distillation extraction, headspace vapor distillation extraction, and stir bar adsorption extraction. These methods all have significant drawbacks, such as low concentration, time-consuming and labor-intensive processes, susceptibility to distortion, and significant influence from the saturated vapor pressure of water.

[0004] With the development of materials science, new forms of adsorption materials are constantly being researched, developed, and applied to the analysis of volatile components, including the MonoTrap solid-phase extraction monolithic trap. Developed by Shimadzu GL Sciences, Japan, the MonoTrapTD adsorption-desorption method is a novel and state-of-the-art adsorption medium based on the high specific surface area technology of silica monolithic columns. Its three-dimensional silica monomer pores and mesoporous network are end-capped with C18 or PDMS, and simultaneously embedded with high-temperature processed graphite carbon black. The pore and mesoporous (carbon black pore) surface of the material can provide more than 150 μm of surface area. 2 With a large specific surface area of ​​ / g, MonoTrapTD, a small mixed adsorbent, possesses high adsorption and desorption capacities. It is designed for simple and rapid concentration of fragrances, aromas, and aromatic substances, and can be readily used for the analysis of volatile and semi-volatile compounds in quality control, environmental, and forensic applications. After adsorbing volatile substances, MonoTrapTD can be desorbed by solvent elution or directly thermally desorbed at the injection port, making it highly versatile.

[0005] Currently, no researchers have applied MonoTrapTD to the study of pomegranate aroma components. Summary of the Invention

[0006] In view of this, the present invention provides a method for detecting and analyzing the aroma components in pomegranate. This method uses MonoTrapTD technology to detect and analyze the aroma substances in pomegranate, study the composition and content levels of the aroma components in pomegranate, and provide valuable data reference for the research and formulation of pomegranate flavorings.

[0007] This invention is achieved through the following technical solutions:

[0008] A method for detecting and analyzing aroma components in pomegranates, comprising the following steps:

[0009] S1: Place the pomegranate sample in a headspace vial and incubate the pomegranate sample;

[0010] S2: Static headspace capture of volatile substances from pomegranate samples using MonoTrapTD adsorbents;

[0011] S3: After collection is complete, the collected substances are desorbed and injected using the direct thermal desorption method. The desorbed substances are then introduced into a gas chromatograph-mass spectrometer for qualitative and quantitative analysis.

[0012] Compared to existing technologies, this invention utilizes the MonoTrapTD method to enrich the aroma components of pomegranates, and combines it with direct thermal desorption-gas chromatography-mass spectrometry (LN-GC-MS) technology. This eliminates the need for high-temperature heating of pomegranate samples, allowing for accurate analysis and detection of the types and contents of aroma components in pomegranates, thus providing a theoretical reference for the formulation and production of related fragrances and flavorings.

[0013] Furthermore, in step S1, the edible portion of the pomegranate sample is selected and pulverized using a food grinder.

[0014] Furthermore, in step S1, the incubation temperature is 45°C.

[0015] Furthermore, in step S1, the incubation time is 120 minutes.

[0016] Furthermore, in step S2, the MonoTrapTD adsorbent is a two-phase adsorbent, and the two-phase adsorbent is a PDMS / Carb type adsorbent.

[0017] Further, in step S3, the analytical conditions for the direct thermal desorption method are as follows: programmed temperature rise vaporization injection at the injection port; splitless injection; initial temperature 80℃, increased to 250℃ at 300℃ / min, desorption temperature 250℃, and desorption time 5min.

[0018] Further, in step S3, the GC conditions of the gas chromatography-mass spectrometry (GC-MS) instrument are as follows: 60m×0.25mm×0.25μm HP-5MS capillary column, high-purity He as carrier gas, flow rate 1.5mL / min, and programmed temperature rise: initial temperature 50℃, increase to 100℃ at 5℃ / min and hold for 5min; increase to 140℃ at 4℃ / min and hold for 10min; then increase to 180℃ at 4℃ / min and hold for 10min; then increase to 250℃ at 5℃ / min and hold for 10min; finally, run at 300℃ and hold for 3min.

[0019] Further, in step S3, the MS conditions in the gas chromatography-mass spectrometry instrument are: transfer line temperature 260℃, ion source temperature 230℃, quadrupole temperature 150℃, and mass scan range m / z of 25~500.

[0020] This invention employs the MonoTrapTD method to capture and adsorb aroma compounds in pomegranate samples, combined with direct thermal desorption-gas chromatography-mass spectrometry (GC-MS) to accurately analyze and detect the types and contents of aroma compounds in pomegranates. Under optimal experimental conditions, this method yields a rich variety of aroma compounds with high reduction rates, identifying a total of 84 aroma compounds, representing a significant improvement over existing aroma compound analysis methods. Attached Figure Description

[0021] Figure 1 The graph shows a comparison of the experimental results of Example 1 and Comparative Example 1.

[0022] Figure 2 The graph shows a comparison of the experimental results of the PDMS / Carb type adsorbent and the C18 / Carb type adsorbent in Example 2.

[0023] Figure 3 The graph shows a comparison of the experimental results at incubation temperatures of 25°C, 45°C, and 65°C in Example 3.

[0024] Figure 4 The graph shows a comparison of the experimental results for incubation times of 60 min, 120 min, and 180 min in Example 4.

[0025] Figure 5 The graph shows a comparison of the experimental results at desorption temperatures of 200℃, 230℃, and 250℃ in Example 5. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below.

[0027] It should be noted that the equipment and reagents used in the following embodiments and comparative examples are shown in Table 1 below:

[0028] Table 1. The equipment involved in this invention.

[0029]

[0030] Adsorbents are generally of three types: PDMS, Carb, and C18. Shimadzu GL Sciences pioneered the use of composite porous activated carbon technology to combine two types of fillers into the same adsorbent to form a two-phase adsorbent, thus avoiding the limitations of a single filler.

[0031] Example 1

[0032] This embodiment provides a method for detecting and analyzing aroma components in pomegranates, including the following steps:

[0033] S1: Take the edible part of the pomegranate sample, crush it using a food grinder, place it in a headspace bottle, and incubate the pomegranate sample at a temperature of 45℃ for 120 minutes.

[0034] S2: Volatile substances from pomegranate samples were adsorbed in the headspace at 45℃ using PDMS / Carb MonoTrapTD adsorbents for 120 min.

[0035] S3: After collection is complete, the collected substances are desorbed and injected using the direct thermal desorption method at a temperature of 250℃. The desorbed substances are then introduced into a gas chromatograph-mass spectrometer for qualitative and quantitative analysis.

[0036] For specific GC-MS analysis conditions, please refer to Table 2 below:

[0037] Table 2 GC-MS Analysis Conditions

[0038]

[0039]

[0040] This embodiment is the best embodiment. Embodiments with other process parameters are not listed one by one. For details, please refer to the experimental example parameter condition optimization section below.

[0041] Comparative Example 1

[0042] This comparative example uses the existing SPME extraction method to detect the aroma of pomegranate. The specific method is based on the study of aroma substances in pomegranate fruit, Yuan Zhaohe, Yin Yanlei, Li Zifeng, Zhang Kequn, Zhu Liqin, Li Yun. 2008. Forestry Science, 4(1): 65-69. (hereinafter referred to as "the replicated method"). The method in the above journal was replicated to detect the aroma of pomegranate.

[0043] The specific sampling and injection process for the replication method is as follows:

[0044] Before the test, the fruit was washed and the pomegranate fruit was divided into whole pomegranate fruit, pomegranate peel, and pomegranate seed juice. The juice was evenly sampled and juiced at room temperature. The juice was placed in a headspace vial. The aged extraction head was inserted into the headspace of the sample vial and adsorbed at 40℃ for 35 min. After that, it was pulled out and inserted into the gas chromatography-mass spectrometry (GC-MS) inlet. The sample was analyzed at 250℃ for 3 min and the data was collected.

[0045] GC-MS conditions: Finnigan Trace MS gas chromatography-mass spectrometry system (Finnigan, USA), OV-1701 capillary column, column length 30m, inner diameter 0.25mm, liquid film thickness 0.25μm.

[0046] Gas chromatography: Inlet temperature 250℃, initial temperature 33℃, hold for 3 min; then at 12℃ for 1 min. -1 Raise to 60℃, then at 6℃ for 1 minute -1 Raise to 140℃ and then reduce to 20℃ for 1 minute. -1 Rise to 250°C and hold for 5 minutes; use He as carrier gas.

[0047] Mass spectrometry: temperature 200℃; ionization mode EI, ionization energy 70eV, connecting rod temperature 280℃.

[0048] The data from Example 1 and Comparative Example 1 are compared; please refer to the comparison results. Figure 1 .

[0049] like Figure 1 As shown in the comparison results, it is clear that the results of the replication method in Comparative Example 1 and the detection method established in Example 1 are significantly different. Specifically, the number of substances is less than that in the analytical method of Example 1, with only 43 substances, and the peak area of ​​the substances is significantly lower than that in the analytical method of Example 1. It is speculated that the main reason for this is that the capacity of the SPME extraction head is smaller than that of the MonoTrap, and it cannot remain stable under long incubation periods of more than 60 minutes, thus failing to obtain excellent spectra for samples with weak aromas (such as pomegranate).

[0050] Optimization Experiment Example 1: Selection Experiment of Adsorbent Subfiller

[0051] Under the same experimental conditions as in Example 1, this example uses a C18 / Carb type adsorbent for the MonoTrapTD to detect and analyze pomegranate samples. Please refer to the experimental results. Figure 2 .

[0052] like Figure 2As shown in the overlay diagram, the experimental results show that the PDMS / Carb type is significantly better than the C18 / Carb type adsorbent. This is likely because the aroma composition of the sample contains a higher proportion of highly polar substances. It also indicates that the PDMS packing material is more suitable for samples with this composition.

[0053] Optimization Experiment Example 2: Optimization Experiment of Incubation Temperature

[0054] Temperature is closely related to the release of aroma components. In principle, the higher the temperature, the more fully the aroma components are released. However, excessively high temperatures can cause thermal decomposition and spoilage of the matrix, releasing non-target aroma components that are adsorbed by adsorbents, resulting in distorted aroma component results. The extraction temperature for conventional fruits is generally room temperature to 70°C. The experimental incubation temperatures were designed at 25°C, 45°C, and 65°C, with other experimental conditions set the same as in Example 1. Please refer to the experimental results. Figure 3 .

[0055] like Figure 3 As shown in the overlay graph, the experimental results reveal that less substance was extracted at 25℃ and 65℃. At 25℃, the temperature was too low, resulting in insufficient release of the sample's aroma. At 65℃, a large amount of water vapor began to evaporate, severely impacting the adsorption efficiency of the PDMS packing material. 45℃ is the optimal incubation temperature. Therefore, the incubation temperature for Example 1 is 45℃.

[0056] Optimization Experiment Example 3: Experiment on the Selection of Incubation Time

[0057] Incubation time is also a parameter closely related to the release of aroma components. In principle, the longer the incubation time, the more aroma components the extraction head adsorbs. However, excessively long incubation times lead to the generation of large amounts of water vapor, affecting the adsorption efficiency of the adsorbents. Furthermore, excessively long adsorption times result in prolonged pretreatment time, causing spoilage of fresh fruit samples and leading to aroma distortion. The conventional incubation time is generally 60-180 minutes. The experimental design used adsorbent adsorption times of 60 minutes, 120 minutes, and 180 minutes. Other experimental conditions were the same as in Example 1. Please refer to the experimental results. Figure 4 .

[0058] like Figure 4 As shown in the overlay, the experimental results show that the highest amount of material was obtained when the incubation time was 120 minutes.

[0059] Optimization Experiment Example 4: Desorption Temperature Selection Experiment

[0060] Desorption temperature is also a parameter closely related to the release of aroma components. In principle, the higher the desorption temperature, the faster the adsorbents release aroma components. However, excessively high desorption temperatures can lead to the decomposition of the adsorbent packing material, resulting in numerous peaks indicating adsorbent loss in the spectrum. The conventional desorption temperature is generally 200℃-250℃. This experiment was designed with temperatures of 200℃, 230℃, and 250℃. Other experimental conditions were the same as in Example 1. Please refer to the experimental results. Figure 5 .

[0061] like Figure 5 As shown in the figure, the experimental results, as seen in the overlay, indicate that at the desorption temperature of 250℃, the number of peaks in the latter half of the spectrum increases significantly and all of them are effective peaks. Therefore, the desorption temperature of 250℃ was selected.

[0062] In summary, the optimal pretreatment conditions for pomegranate aroma component analysis are: using a PDMS / Carb adsorbent, headspace adsorption at 45°C for 120 min, and desorption at 250°C (i.e., the parameters of Example 1). Under these conditions, the most diverse and reduced aroma compounds were obtained, totaling 84, as detailed in Table 3 below.

[0063] Table 3: Pomegranate aroma components obtained by extraction in Example 1 (under optimal pretreatment conditions)

[0064]

[0065]

[0066]

[0067]

[0068] This invention conducted multiple optimization experiments from various perspectives, including different types of adsorbents, different incubation temperatures, different incubation times, and different desorption temperatures, to determine the optimal pretreatment conditions for pomegranate aroma components. The aim was to identify the most abundant and comprehensive aroma compounds, providing fundamental data support for the formulation of pomegranate flavorings. Through multiple experimental studies, the optimal pretreatment conditions for pomegranate aroma component analysis were determined to be: using PDMS / Carb type adsorbents, headspace adsorption at 45℃ for 120 min, and desorption at 250℃. Under these pretreatment conditions, a rich variety of aroma compounds were obtained with high reduction rates, and a total of 84 aroma compounds were identified, representing a significant improvement over existing SPME methods.

[0069] The above description is only a part of the embodiments of the present invention, and is not intended to limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the content of the present invention specification should be included within the protection scope of the present invention.

Claims

1. A method for detecting and analyzing aroma components in pomegranates, characterized in that, Includes the following steps: S1: Place the pomegranate sample in a headspace vial and incubate it at 45℃ for 120 minutes. S2: The volatile substances of pomegranate samples were statically captured by MonoTrapTD adsorbents in the headspace; the MonoTrapTD adsorbents are two-phase adsorbents, and the two-phase adsorbents are PDMS / Carb type adsorbents; S3: After collection, the collected substances were desorbed and injected using a direct thermal desorption method. The desorbed substances were then introduced into a gas chromatography-mass spectrometry (GC-MS) system for qualitative and quantitative analysis. The analytical conditions for the direct thermal desorption method were as follows: programmed temperature vaporization injection at the injection port; splitless injection; initial temperature 80℃, increased to 250℃ at 300℃ / min, desorption temperature 250℃, desorption time 5min; the GC conditions for the gas chromatography-mass spectrometry system were: 60m×0.25mm×0.25μm HP-5MS capillary column, high-purity He as carrier gas, flow rate 1.5mL / min, programmed temperature: initial temperature 50℃, increased to 100℃ at 5℃ / min, maintained for 5min; then at 4... The temperature was increased to 140℃ at ℃ / min and held for 10 min; then increased to 180℃ at 4℃ / min and held for 10 min; then increased to 250℃ at 5℃ / min and held for 10 min; the operating temperature was 300℃ and held for 3 min; the MS conditions were: transfer line temperature 260℃, ion source temperature 230℃, quadrupole temperature 150℃, and mass scan range m / z of 25~500.

2. The method for detecting and analyzing aroma components in pomegranate according to claim 1, characterized in that, In step S1, the edible portion of the pomegranate sample is selected and pulverized using a food grinder.

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