Method for analyzing aroma components of fruits

Abstract

The invention discloses an analysis method of fruit aroma components, and relates to the technical field of food processing. An analysis method of fruit aroma components comprises the following steps: (1) performing low-temperature freeze drying treatment on fruits, and crushing the fruits to 20 meshes to obtain fruit powder; (2) extracting the fruit powder in a supercritical fluid at the extraction temperature of 35-45 DEG C for 25-35 minutes to obtain a fruit aroma extract; and (3) analyzing and detecting the fruit aroma extracting solution through a direct thermal desorption-gas chromatography-mass spectrometer to determine the components of the fruit aroma. According to the method, the supercritical extraction method is combined with the direct thermal desorption-gas chromatography-mass spectrometry technology, so that the extraction process of the fruit aroma is optimized, and the reliability and accuracy of LN-GC-MS analysis are further enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and in particular to a method for analyzing fruit aroma components. Background Art

[0002] In the research field of aroma analysis of fresh fruit samples, the current mainstream methods include a variety of techniques such as purge and trap method, solid-phase microextraction method, vacuum distillation extraction method, simultaneous distillation extraction method, steam distillation extraction method, and stir bar sorptive extraction method. However, most of these methods belong to heat treatment methods or are limited by the selectivity of extraction packing materials, which may cause a certain degree of distortion. Moreover, conventional injection methods such as direct injection (LS) and headspace injection (HS) often lead to sample discrimination due to uneven vaporization or cause component changes due to long-term heating incubation. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for analyzing fruit aroma components. The present invention adopts supercritical extraction combined with direct thermal desorption-gas chromatography-mass spectrometry (SFE-LN-GC-MS, hereinafter referred to as the SL method), which not only optimizes the extraction process of fruit aroma but also further enhances the reliability and accuracy of the analysis by direct thermal desorption-gas chromatography-mass spectrometry (LN-GC-MS).

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] In the first aspect, the present invention provides a method for analyzing fruit aroma components, including the following steps:

[0006] (1) Freeze-dry the fruit at low temperature, crush it to 20 mesh to obtain fruit powder;

[0007] (2) Extract the fruit powder in a supercritical fluid to obtain a fruit aroma extract, with the extraction temperature being 35-45°C and the extraction time being 25-35 min;

[0008] (3) Analyze and detect the fruit aroma extract by a gas chromatography-mass spectrometer to determine the components of the fruit aroma.

[0009] Preferably, in the step (1), the fruit includes but is not limited to perfume lemon, blueberry, strawberry, pineapple, Sydney pear, apple.

[0010] Preferably, in the step (1), the temperature of the low-temperature freeze-drying is -28 to -32°C. Preferably, it is -30°C.

[0011] Preferably, in the step (2), the extraction temperature is 35°C and the extraction time is 30 min.

[0012] Preferably, in the step (2), the supercritical fluid includes carbon dioxide.

[0013] Preferably, in the step (2), the fruit aroma extract is washed and purified with a saturated sodium sulfate - aqueous solution.

[0014] Preferably, in the step (2), the entrainer of the supercritical fluid is anhydrous ethanol. The flow rate of the entrainer is the same as that of the supercritical fluid.

[0015] Preferably, when analyzing with a gas chromatography - mass spectrometry (GC - MS) instrument in the step (3), the desorption program at the injection port adopts a programmed temperature method: first, it is heated to 80 °C and held for 5 s, then heated to 230 °C and held for 300 s, and the heating rate is 300 °C / min.

[0016] In a second aspect, the present invention also provides a fruit aroma component obtained by the above - mentioned analysis method.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The present invention adopts the direct thermal desorption method (LN). This method realizes the advantages of short heating time and complete gasification by quickly heating after low - temperature injection. Moreover, this injection method is particularly suitable for fresh fruit extracts, significantly improving the accuracy of GC - MS analysis and the precision of characterization.

[0019] (2) The present invention uses the supercritical extraction method (SFE) to extract samples, specifically using a supercritical fluid for inert extraction under low temperature and high pressure. This method has the following advantages: no new solvent needs to be introduced, it avoids the thermal denaturation of components caused by high - temperature treatment, the sample will not be oxidized due to long - term exposure to an oxygen - rich environment, and it is not restricted by the selectivity of extraction packing.

[0020] (3) The present invention combines the supercritical extraction method with the direct thermal desorption injection method, not only optimizing the extraction process of the fruit sample aroma but also further enhancing the reliability and accuracy of GC - MS analysis. Description of the Drawings

[0021] Figure 1 is the total ion chromatogram of the gas chromatography - mass spectrometry instrument at different extraction temperatures in Example 1 of the present invention.

[0022] Figure 2 is the total ion chromatogram of the gas chromatography - mass spectrometry instrument at different extraction times in Example 1 of the present invention.

[0023] Figure 3 is the total ion chromatogram of the gas chromatography - mass spectrometry instrument before and after impurity removal in Example 1 of the present invention.

[0024] Figure 4 It is the total ion chromatogram of the gas chromatography - mass spectrometer for the SL method and SA method of calamansi in Example 2 of the present invention.

[0025] Figure 5 It is the total ion chromatogram of the gas chromatography - mass spectrometer for the SL method and SA method of blueberry in Example 3 of the present invention.

[0026] Figure 6 It is the total ion chromatogram of the gas chromatography - mass spectrometer for the SL method and SA method of strawberry in Example 4 of the present invention.

[0027] Figure 7 It is the total ion chromatogram of the gas chromatography - mass spectrometer for the SL method and SA method of pineapple in Example 5 of the present invention.

[0028] Figure 8 It is the total ion chromatogram of the gas chromatography - mass spectrometer for the SL method and SA method of Chinese white pear in Example 6 of the present invention.

[0029] Figure 9 It is the total ion chromatogram of the gas chromatography - mass spectrometer for the SL method and SA method of apple in Example 7 of the present invention. Detailed implementation manners

[0030] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the protection scope and implementation manners of the present invention are not limited thereto.

[0031] The materials, reagents, etc. used in the following embodiments are commercially available reagents and materials unless otherwise specified.

[0032] The experimental equipment used in the present invention is shown in Table 1.

[0033] Table 1

[0034] Experimental equipment Model specification Autosampler G4513A Gas chromatography-mass spectrometry (GC-MS) 7890A-5975C Gas chromatography column HP-5MS Multifunctional autosampler RTC Injection port controller CTC OPTIC-4 Cold trap Chromtech e-trap Automatic fixture CTC Gripper Automatic solid-phase microextraction CTC SA tool Electronic balance RSH-1DR Supercritical fluid extractor ASI

[0035] Example 1

[0036] A method for analyzing the aroma components of fruits, comprising the following steps:

[0037] (1) Freeze - dry the calamansi at - 30 °C, and pulverize it to 20 mesh to obtain calamansi powder.

[0038] (2) 10 g of lemon perfume powder was extracted in supercritical carbon dioxide to obtain the lemon perfume aroma extract. The entrainer for supercritical extraction was absolute ethanol, and its flow rate changed with the flow rate of the supercritical fluid. The extraction pressure was 160 bar, and the flow rate of supercritical carbon dioxide was 5 L / min.

[0039] (3) The lemon perfume aroma extract was analyzed and detected by a direct thermal desorption-gas chromatography-mass spectrometry (DTD-GC-MS) instrument to determine the components of the lemon perfume aroma.

[0040] The analysis conditions of the DTD-GC-MS instrument are shown in Table 2:

[0041] Table 2

[0042]

[0043] 1. Influence of different extraction temperatures on obtaining the components of lemon perfume aroma

[0044] Under the same condition of maintaining the extraction time at 30 min, the extraction temperatures were set at 25 °C, 35 °C, and 45 °C respectively, and then the components of the lemon perfume aroma were detected by a DTD-GC-MS instrument respectively. By comparing different extraction temperatures, the optimal extraction temperature was studied. Based on the criterion of extracting the most aroma components, the optimal extraction temperature for the aroma components was determined.

[0045] As Figure 1 shown, when the extraction temperature was 25 °C, fewer components of the lemon perfume aroma were obtained. When the extraction temperature was 35 °C, more components of the lemon perfume aroma were obtained, indicating that when the extraction temperature was 35 °C, the most components of the lemon perfume aroma could be extracted. When the extraction temperature was 45 °C, the components of the lemon perfume aroma obtained were not much different from those at 35 °C, indicating that the optimal extraction temperature was 35 °C.

[0046] 2. Influence of different extraction times on obtaining the components of lemon perfume aroma

[0047] Under the same condition of maintaining the extraction temperature at 35 °C, the extraction times were set at 20 min, 30 min, and 40 min respectively, and then the components of the lemon perfume aroma were detected by a DTD-GC-MS instrument respectively. By comparing different extraction times, the optimal extraction time was studied. Based on the criterion of extracting the most aroma components, the optimal extraction time for the aroma components was determined.

[0048] As Figure 2As shown, when the extraction time is 20 min, fewer components of the aroma of lemon perfume are obtained. When the extraction time is 30 min, more components of the aroma of lemon perfume are obtained. This shows that when the extraction time is 30 min, the maximum amount of components of the aroma of lemon perfume can be extracted. When the extraction time is 40 min, the components of the aroma of lemon perfume are lost significantly, because too long a time will cause a large amount of volatile components to be vaporized and carried away by the supercritical fluid. Therefore, the optimal extraction time is 30 min.

[0049] 3. Influence of impurity removal on obtaining components of the aroma of lemon perfume

[0050] Under the same conditions of maintaining the extraction temperature at 35 °C and the extraction time at 30 min, the following were respectively set: no cleaning and impurity removal treatment was carried out on the extraction solution of the aroma of lemon perfume, and the extraction solution of the aroma of lemon perfume was cleaned and impurity removed by liquid separation with saturated sodium sulfate - aqueous solution. Then, the components of the aroma of lemon perfume were respectively detected by a direct thermal desorption - gas chromatography - mass spectrometry combined instrument. The components of the aroma of lemon perfume were extracted under the optimal conditions, and the influence caused by impurity removal was investigated to analyze its component characteristics.

[0051] As Figure 3 shown, after impurity removal was carried out on the extraction solution of the aroma of lemon perfume, the components of the aroma of lemon perfume obtained did not change significantly compared with those without impurity removal treatment, indicating that impurity removal is not a necessary step.

[0052] In summary, the optimal treatment conditions for the analysis and detection of the components of the aroma of lemon perfume are as follows: the supercritical extraction temperature is 35 °C, the extraction time is 30 min, no brine washing and impurity removal are required, and 1 μL of the sample is directly thermally desorbed.

[0053] The components of the aroma of lemon perfume obtained under the optimal treatment conditions are shown in Table 3:

[0054] Table 3

[0055]

[0056]

[0057] Note: The ratios in Table 3 refer to the peak area percentages in the mass spectrometry diagram.

[0058] Example 2

[0059] A method for analyzing the components of the aroma of fruits, comprising the following steps:

[0060] (1) Freeze - dry lemon perfume at - 30 °C, and pulverize it to 20 meshes to obtain lemon perfume powder;

[0061] (2) Then, place 10 g of lemon perfume powder in a headspace vial, and use a polyamide + graphitized carbon black + divinylbenzene (PA + Carb + DVB) three-phase arrow-shaped extraction head for headspace extraction at 35 °C for 30 min to obtain a lemon perfume aroma extract;

[0062] (3) Analyze and detect the lemon perfume aroma extract by gas chromatography-mass spectrometry to determine the components of the lemon perfume aroma. The GC-MS method is the same as that in Example 1, and the process is fully automated.

[0063] The analytical method for the fruit aroma components described in this example uses the arrow-shaped solid-phase microextraction-gas chromatography-mass spectrometry method (SPME-Arrow-GC-MS, abbreviated as the SA method).

[0064] The components of the lemon perfume aroma were detected using the direct thermal desorption-gas chromatography-mass spectrometry method (SFE-LN-GC-MS, abbreviated as the SL method) and the SA method, respectively.

[0065] As Figure 4 shown, more components of the lemon perfume aroma were obtained using the SL method, while fewer components of the lemon perfume aroma were obtained using the SA method.

[0066] Example 3

[0067] An analytical method for fruit aroma components, which is different from that in Example 2 in that an equal mass of blueberry powder is used to replace the lemon perfume powder in step (2). The components of the blueberry aroma were detected using the SL method and the SA method, respectively.

[0068] As Figure 5 shown, more components of the blueberry aroma were obtained using the SL method, while fewer components of the blueberry aroma were obtained using the SA method.

[0069] Example 4

[0070] An analytical method for fruit aroma components, which is different from that in Example 2 in that an equal mass of strawberry powder is used to replace the lemon perfume powder in step (2). The components of the strawberry aroma were detected using the SL method and the SA method, respectively.

[0071] As Figure 6 shown, more components of the strawberry aroma were obtained using the SL method, while fewer components of the strawberry aroma were obtained using the SA method.

[0072] Example 5

[0073] An analytical method for fruit aroma components, which is different from that in Example 2 in that an equal mass of pineapple powder is used to replace the lemon perfume powder in step (2). The components of the pineapple aroma were detected using the SL method and the SA method, respectively.

[0074] As Figure 7 shown, more components of pineapple aroma are obtained by the SL method, while very few components of pineapple aroma are obtained by the SA method.

[0075] Example 6

[0076] A method for analyzing fruit aroma components, which is different from that of Example 2 in that in step (2), pear powder of equal mass is used to replace perfume lemon powder. The components of pear aroma are detected by the SL method and the SA method respectively.

[0077] As Figure 8 shown, more components of pear aroma are obtained by the SL method, while very few components of pear aroma are obtained by the SA method.

[0078] Example 7

[0079] A method for analyzing fruit aroma components, which is different from that of Example 2 in that in step (2), apple powder of equal mass is used to replace perfume lemon powder. The components of apple aroma are detected by the SL method and the SA method respectively.

[0080] As Figure 9 shown, more components of apple aroma are obtained by the SL method, while very few components of apple aroma are obtained by the SA method.

[0081] In summary, the spectrograms obtained by the SL method are significantly better than those of the SA method in terms of both intensity and the number of substances. Especially for fruits with high water content such as blueberries and pears, there is a significant improvement, because the water in these fruits seriously affects the extraction efficiency of the SA method during the overall extraction process.

[0082] The method for analyzing fruit aroma components described in the present invention is applicable to many fruit essence flavors (perfume lemon flavor, blueberry flavor, strawberry flavor, pineapple flavor, pear flavor, apple flavor). The fruit aroma obtained by the analysis method described in the present invention can become the first choice for beverages, which can not only retain the natural sense, but also accurately reproduce or create new flavors, forming a closed-loop competitiveness of "sensory pleasure + health premium + efficient innovation", and becoming the core strategy for flavor design in the beverage industry, greatly enhancing the technical strength and market competitiveness.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for analyzing the aroma components of fruits, characterized in that, It includes the following steps: (1) Freeze-dry the fruit at low temperature, crush it to 20 mesh to obtain fruit powder; (2) Extract the fruit powder in a supercritical fluid to obtain a fruit aroma extract. The extraction temperature is 35 - 45 °C and the extraction time is 25 - 35 min; (3) Analyze and detect the fruit aroma extract by a direct thermal desorption-gas chromatography-mass spectrometry instrument to determine the components of the fruit aroma.

2. The analysis method of fruit aroma components according to claim 1, characterized in that In the step (1), the fruit includes at least one of calamansi, blueberry, strawberry, pineapple, Sydney pear, and apple.

3. The method for analyzing the fruit aroma components according to claim 1, characterized in that, In the step (1), the temperature of the low-temperature freeze-drying is -28 to -32 °C.

4. The analysis method of fruit aroma components according to claim 1, characterized in that In the step (2), the extraction temperature is 35 °C and the extraction time is 30 min.

5. The analysis method of fruit aroma components according to claim 1, characterized in that, In the step (2), the supercritical fluid includes carbon dioxide.

6. The method for analyzing fruit aroma components according to claim 1, characterized in that, In the step (2), the fruit aroma extract is washed and purified with a saturated sodium sulfate aqueous solution.

7. The method for analyzing fruit aroma components according to claim 1, characterized in that, In the step (2), the entrainer of the supercritical fluid is absolute ethanol.

8. The analysis method of fruit aroma components according to claim 1, characterized in that, When analyzing by the gas chromatography-mass spectrometry instrument in the step (3), the desorption program at the injection port adopts a programmed temperature rise method: first rise to 80 °C, hold for 5 s, then rise to 230 °C, hold for 300 s, and the heating rate is 300 °C / min.

9. A fruit aroma component obtained by the analysis method of the fruit aroma component according to any one of claims 1 - 8.

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