A method and application of detecting volatile flavor substances in spice oil based on PCA analysis technology

Abstract

The invention relates to a method for detecting volatile flavor substances in spice oil based on PCA analysis technology, comprising: (1) preparing spice oil samples; (2) selecting a Heracles II ultrafast gas phase electronic nose to measure the volatile flavor substances in the spice oil samples; (3) using a PCA method to perform statistical analysis on the volatile flavor substance measurement data; and (4) performing discrimination index analysis. The method is applied to the preparation and processing procedures of pepper flavor oil, and the color, acid value, peroxide value, pepper amide, fatty acid and other indicators of the pepper flavor oil are analyzed around each processing procedure. The Heracles II ultrafast gas phase electronic nose is used to monitor the volatile flavor substances between each process in the pepper flavor oil processing process, and the key technical control points in the pepper flavor oil processing process are determined in close combination with the enterprise production line, so as to provide theoretical guidance for the oil quality control of pepper flavor oil production enterprises in the future, and the method has important transformation and application value.

Description

Technical Field

[0001] The invention belongs to the field of food processing and relates to oil detection technology, in particular to a spice oil volatile flavor substance detection method based on PCA analysis technology and application. Background Art

[0002] Spices are spice components contained in natural plants. They have special smells and tastes, can give products a certain flavor, and can also suppress or correct the bad smell of food. They are ideal food processing ingredients. The flavor of spice oils is crucial to their quality evaluation and consumer preference. At present, the main detection methods for volatile flavor substances in spice oils include electronic nose, gas chromatography, gas chromatography-mass spectrometry, etc.

[0003] Existing public technologies record that there is "a method for simultaneously detecting multiple volatile components in chili or chili products (CN112083100A)" and "a method for analyzing and identifying characteristic index compounds of chili oil flavor (CN106053653A)". However, these methods are all for detecting and identifying volatile flavor substances in chili seasoning oil prepared with vegetable oil as the base oil. There are few public technologies for detecting and identifying volatile flavor substances in animal fats and oils, and there is no public technology for detecting volatile flavor substances in spice oils based on PCA analysis technology. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art, provide a method for detecting volatile flavor substances in spice oil based on PCA analysis technology, apply the method to the preparation process of pepper flavor oil, and study and compare the effects of different processing steps on the quality changes of pepper flavor oil and the PCA analysis results, which is of great significance for the flavor detection of animal fat spice oil, and can also open up new research and design ideas for quality control and product upgrading of spice flavor oil.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] A method for detecting volatile flavor substances in spice oil based on PCA analysis technology, the method steps are as follows:

[0007] (1) Preparation of spice oil samples

[0008] Heat the raw oil to 180°C, pour it into the extraction tank filled with selected and crushed spices, stir it with a stirring rod, stir it every 5 minutes for 30 minutes, soak the raw oil in the extraction tank for 3-4 days to fully extract the aroma, filter the upper layer of oil sample with a plate-type closed filter after soaking, put the filtered oil sample into a storage tank for clarification, and obtain the final finished oil sample;

[0009] (2) The spice oil samples were tested for their indexes and volatile flavor substances. The HeraclesII ultrafast gas phase electronic nose was used for the volatile flavor substance testing.

[0010] The index determination for spice oil samples includes: amide compound determination, color determination, acid value determination, peroxide value determination, and fatty acid determination.

[0011] The methods for determining amide compounds include:

[0012] (1) Establishment of standard curve

[0013] Take 5 mg of hydroxy-β-sanshool standard, dilute to 5 mL with methanol to obtain hydroxy-β-sanshool standard solution, take 0, 1, 2, 3, 4, 5, 6, 7, 8 mL of standard solution respectively, prepare 0-8 μg / mL hydroxy-β-sanshool solution with methanol, measure absorbance at 267 nm, and draw a standard curve with concentration as the abscissa and absorbance as the ordinate;

[0014] (2) Determination of prickly ash amide

[0015] The content of prickly ash amide was determined according to the method in Appendix A of DBS51 / 008-2019 "Local Food Safety Standard for Pepper Oil", and the content of hydroxy-β-sanshool was calculated according to the standard curve. The regression equation was y=0.1501x-0.1288, R 2 =0.9983, where y is the absorbance value and x is the content of prickly ash amide.

[0016] The HeraclesII ultrafast gas phase electronic nose was used for the determination of volatile flavor substances. The detection method was to take 2 g of spice oil sample into a 20 mL headspace bottle, preheat it in a 55°C water bath for 24 min, and manually inject the sample. Each sample was tested in parallel three times.

[0017] (3) The PCA analysis method was used to perform statistical analysis on the volatile flavor substance determination data. The detection parameters were: injection port temperature 200°C, injection volume 5000 μL, injection speed 125 μL / s, injection time 45 s, trap initial temperature 40°C, split flow rate 10 mL / min, final temperature 200°C, initial column temperature 50°C, increased to 80°C at 1°C / s and then increased to 250°C at 3°C / s, acquisition time 110 s, and FID detector temperature 260°C.

[0018] (4) Discrimination index analysis: The discrimination index is calculated based on the relative distance between the centroids of the two sample groups in the PCA diagram. The larger the distance between the two sample groups, the smaller the difference within the groups, and the closer the discrimination index is to 100%, that is, the discrimination index is positively correlated with the difference between samples.

[0019] The above-mentioned method for detecting volatile flavor substances in spice oil based on PCA analysis technology was applied to plant pepper oil, and PCA analysis was performed on crude oil before leaching, oil samples extracted for 24 hours, oil samples extracted for 72 hours, plate and frame filtered oil samples, clarified oil samples and finished oil.

[0020] The PCA method was applied to the processing of pepper seasoning oil in plant pepper oil. The odor differences between samples in each process were obvious. Eight volatile flavor substances were detected in soybean oil, including hexanal, nonanal, heptanal, and (E,E)-2,4-heptadienal. Thirteen volatile flavor substances were detected in pepper seasoning oil, including alcohols and olefin compounds.

[0021] The PCA method analysis showed that the variance contribution rate of the first principal component was 90.083%, the variance contribution rate of the second principal component was 8.299%, and the cumulative total contribution rate was 98.382%. The recognition index between samples was 95. In the PCA analysis diagram, the distance between samples was positively correlated with the odor differences between samples.

[0022] The advantages and positive effects of the present invention are:

[0023] The invention is scientifically and reasonably designed, provides a method for detecting volatile flavor substances of spice oil based on PCA analysis technology, and applies the method to the preparation and processing procedures of pepper flavor oil. Focusing on the influence of each processing procedure on the color, acid value, peroxide value, pepper amide, fatty acid and other indicators of pepper flavor oil, the Heracles II ultra-fast gas phase electronic nose is used to monitor the volatile flavor substances between each process in the processing of pepper flavor oil, and the quality and aroma changes in the processing of pepper flavor oil are studied. The invention is closely combined with the production line of the enterprise, and the key control points in the processing of pepper flavor oil are determined, so as to provide theoretical guidance for the oil quality control of pepper flavor oil production enterprises in the future, and has important transformation and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a process flow chart of producing pepper oil;

[0025] Figure 2 The results of the acid value change during the processing of the pepper seasoning oil in the embodiment of the present invention;

[0026] Figure 3 The peroxide value change result during the processing of pepper seasoning oil in the embodiment of the present invention;

[0027] Figure 4 The results of the change of the content of prickly ash amide during the processing of the prickly ash seasoning oil in the embodiment of the present invention;

[0028] Figure 5This is a PCA analysis diagram of samples during the processing of pepper seasoning oil in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0030] The present invention provides a method for detecting volatile flavor substances in spice oil based on PCA analysis technology and application thereof, specifically provides a method for detecting volatile flavor substances in spice oil based on PCA analysis technology, applies the method to the preparation process of pepper flavor oil, and studies and compares the influence of different processing procedures on the quality change of pepper flavor oil and PCA analysis.

[0031] The experimental pepper was green pepper purchased from Sichuan Manyuanqing Trading Co., Ltd.; soybean oil was purchased from Shandong Yuwang Ecological Food Co., Ltd. The pepper oil used in this experiment was sampled on site from Tianjin Honglu Food Co., Ltd. The sampling points were pre-immersion (crude oil), 24h immersion, 72h immersion, plate and frame filtration, clarification, and finished product.

[0032] Glacial acetic acid and 95% ethanol were of analytical grade and purchased from Tianjin Tianli Chemical Reagent Company; phenolphthalein indicator and methanol potassium iodide were of analytical grade and purchased from Tianjin Damao Chemical Reagent Factory; chloroform was of analytical grade and purchased from Tianjin Chemical Reagent Supply and Marketing Company; soluble starch, 0.1 mol / L sodium hydroxide standard titration solution, and 0.01009 mol / L sodium thiosulfate standard titration solution were purchased from Tianjin Chemical Reagent Factory No. 3; hydroxy-β-sanshool was purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0033] Instruments and equipment involved: HZ-K500C electronic balance: Shanghai Youke Instrument Co., Ltd.; HeraclesII ultrafast gas phase electronic nose: Alpha MOS, France; UV-800 ultraviolet-visible spectrophotometer: Hmadzu, Japan; CM-5 colorimeter: Shenzhen Sanenchi Technology Co., Ltd.; Agilent 7890A gas chromatograph: Agilent, USA.

[0034] The specific experimental steps are as follows:

[0035] 1. Preparation of pepper flavor oil

[0036] Sichuan pepper oil production companies heat soybean oil to 180°C, pour it into an extraction tank filled with selected and crushed Sichuan peppercorns, and use a special stirring rod to stir the raw materials in the extraction tank every 5 minutes for 30 minutes. Soak the oil in the extraction tank for 3-4 days to fully extract the aroma. After soaking, use a high-efficiency plate-type closed filter to filter the upper oil sample, and the filtered oil sample is placed in a storage tank for clarification to obtain the final product. The process flow is as follows: Figure 1 shown.

[0037] 2. Determination of amide compounds

[0038] (1) Establishment of standard curve

[0039] Take 5 mg of hydroxy-β-sanshool standard, dilute to 5 mL with methanol to obtain hydroxy-β-sanshool standard solution, take 0, 1, 2, 3, 4, 5, 6, 7, 8 mL of standard solution respectively, and prepare 0-8 μg / mL hydroxy-β-sanshool solution with methanol, and measure the absorbance at 267 nm. Draw a standard curve with concentration as the horizontal axis and absorbance value as the vertical axis.

[0040] (2) Determination of prickly ash amide

[0041] The content of prickly ash amide was determined according to the method in Appendix A of DBS51 / 008-2019 "Local Food Safety Standard for Pepper Oil", and the content of hydroxy-β-sanshool was calculated according to the standard curve. The regression equation was y=0.1501x-0.1288(R 2 =0.9983), where y is the absorbance value and x is the content of prickly ash amide.

[0042] (3) Determination of volatile flavor substances

[0043] The HeraclesII ultrafast gas phase electronic nose was used to detect the volatile flavor substances in samples of pepper seasoning oil during different processing steps.

[0044] 2 g of pepper seasoning oil was weighed into a 20 mL headspace bottle at several sampling points including before leaching (crude oil), leaching (24 h), leaching (72 h), plate and frame filtration, clarification, and finished product. The oil was preheated in a 55 °C water bath for 24 min and injected manually. Each sample was replicated three times.

[0045] Detection parameters: injection port temperature 200°C, injection volume 5000μL, injection speed 125μL / s, injection time 45s. Trap initial temperature 40°C, split flow rate 10mL / min, final temperature 200°C. Initial column temperature 50°C, increased to 80°C at 1°C / s and then to 250°C at 3°C / s, acquisition time 110s, FID detector temperature 260°C.

[0046] Experimental results and data analysis

[0047] 1. Effect of processing procedures on the color of pepper seasoning oil

[0048] The color change of pepper seasoning oil during the processing is shown in Table 1. It can be seen from Table 1 that the L* value of pepper seasoning oil is low at 72h of extraction, which is considered to be caused by the residual impurities in pepper dissolved in the oil. After filtration and clarification, the L* value increased significantly to 11.88. It shows that fat oxidation is positively correlated with the formation of yellow pigment. It can be seen from Table 1 that the b* value of pepper seasoning oil during processing first rises, then falls, and then slowly rises, which is consistent with the change trend of peroxide value. During the entire extraction process, the a* value of pepper seasoning oil showed a downward trend, indicating that the pigment in pepper gradually dissolved with the increase of extraction time. There was no significant difference in a* value between 24h and 72h of extraction (P<0.05), so the longer extraction time had little effect on the color of pepper seasoning oil.

[0049] Table 1 Color changes of pepper seasoning oil during processing

[0050]

[0051] Note: L* value indicates light and dark, a* value indicates red and green, and b* value indicates yellow and blue; “+” indicates brighter, red, and yellow, and “-” indicates darker, green, and blue.

[0052] 2. The influence of processing procedures on the acid value of pepper seasoning oil

[0053] When oil and fat react with oxygen, they will produce a special, pungent smell called "rancid smell", which will reduce the quality of the oil. The content of free fatty acids in the oil determines the quality of the oil. The acid value measures the free fatty acids produced by the hydrolysis of triglycerides and is considered to be one of the main indicators for identifying oil quality. Figure 2 shown.

[0054] Depend on Figure 2 It can be seen that the acid value of Sichuan pepper seasoning oil increased significantly after 24 hours of extraction, which may be due to the fact that the moisture in the Sichuan pepper accelerated the oxidation of oil during the extraction process. The acid value of the samples fluctuated slightly and was relatively stable during the processing of 24 hours of extraction, 72 hours of extraction, filtration, clarification and finished products. It is speculated that the moisture in the Sichuan pepper has evaporated during the high-temperature extraction process. At this time, the moisture content in the oil is small, the oil stability is increased, and the acid value has increased slightly after filtration. It is considered that the residual trace moisture in the Sichuan pepper was squeezed out during the plate and frame filtration. Therefore, the moisture content of the Sichuan pepper should be strictly controlled in advance to reduce the impact of the moisture content of the Sichuan pepper on the acid value during the processing. After testing, the acid value of the finished Sichuan pepper seasoning oil was 0.3418 mg / g, which is lower than the limit of 3 mg / g specified in GB2716-2018 and meets the standard.

[0055] 3. Effect of processing steps on the peroxide value of pepper seasoning oil

[0056] After oxidation, oil affects the taste and nutrition. At the same time, its biological activity changes after oxidation, which has a certain damage effect on tissues and organs. Peroxide value is an important indicator for identifying the degree of oil deterioration. Figure 3 shown.

[0057] Depend on Figure 3 It can be seen that the peroxide value of crude oil is 0.079g / 100g, and the peroxide value shows a trend of first increasing and then decreasing during the extraction process. The increase in peroxide value after 24 hours of extraction is speculated to be due to the high temperature during the heating process of soybean oil, which catalyzed the oxidation of oil; the decrease in peroxide value after 72 hours of extraction may be due to the oxidation of peroxides into small molecules such as aldehydes, ketones, and acids, and the peroxide value decreases. The peroxide value shows an upward trend during the processing of filtration and clarification. After testing, the peroxide value of the finished pepper seasoning oil is 0.089mg / g, which is lower than the limit of 0.25g / 100g specified in GB2716-2018 and meets the national standard.

[0058] 4. Effect of processing procedures on prickly ash flavoring oil prickly ash amide

[0059] Most of the pepper amide compounds are chain unsaturated fatty acid amides, which are important flavoring substances (numbing taste) in pepper oil. Among them, the higher content includes hydroxy-α-sanshool, hydroxy-β-sanshool, hydroxy-γ-sanshool, etc. The changes of hydroxy-β-sanshool content in the processing of pepper seasoning oil are as follows: Figure 4 shown.

[0060] Depend on Figure 4 It can be seen that the highest content of hydroxy-β-sanshool in pepper seasoning oil during processing is 3.65 mg / g, and the lowest is 2.62 mg / g, both exceeding the standard of 2.0 mg / g for amide substances (hydroxy-β-sanshool) in pepper seasoning oil in Sichuan Provincial Standard. Compared with 24h of extraction, the content of sanshoamide decreased at 72h of extraction, which may be caused by the long extraction time and the loss of sanshoamide. It can be seen that the extraction time in the later stage of extraction is not proportional to the content of sanshoamide in pepper seasoning oil, so the extraction time can be appropriately shortened during processing to improve the production efficiency of the enterprise. The content of hydroxy-β-sanshool in the later stage of seasoning oil processing decreased and then stabilized, which may be the result of mutual conversion between isomers such as hydroxy-α-sanshool, hydroxy-β-sanshool, and hydroxy-γ-sanshool.

[0061] 5. Effect of processing steps on fatty acids in pepper seasoning oil

[0062] The changes in fatty acid composition during the processing of Sichuan pepper seasoning oil are shown in Table 2. As shown in Table 2, the unsaturated fatty acid content in soybean oil is relatively high at 84.6%, of which linoleic acid and α-linolenic acid, two essential fatty acids for the human body, are 55.22% and 8.42% respectively. The fatty acid composition of Sichuan pepper oil after extraction (24h), extraction (72h), filtration, clarification and finished product is very different from that of crude oil, indicating that the glyceride in Sichuan pepper is not well dissolved in soybean oil during the processing of Sichuan pepper seasoning oil, which is consistent with the research results of Li Jin [7]. This shows that fatty acid composition cannot be used as an important indicator for quality control during the processing of Sichuan pepper seasoning oil.

[0063] Table 2 Changes in fatty acid composition during the processing of pepper seasoning oil

[0064]

[0065] The main components of the volatile flavor substances of the above samples were analyzed, and the specific analysis results are as follows:

[0066] 1. PCA analysis

[0067] The principal component analysis of samples during the processing of pepper seasoning oil is shown in the figure Figure 5 As shown. Figure 5 It can be seen that the variance contribution rate of the first principal component is 90.083%, the variance contribution rate of the second principal component is 8.299%, and the cumulative total contribution rate of the two is 98.382%, indicating that the spectrum can better reflect the integrity of the odor data in the measured samples. When the recognition index is between 80-100, it indicates that the data is effectively distinguished. Figure 5 It can be seen that the identification index between samples is 95, indicating that the samples are effectively distinguished. In the figure, there is no overlap between the six groups of samples in the process of pepper seasoning oil processing, indicating that the six groups of samples can be well separated by the HeraclesII ultra-fast gas phase electronic nose. In the PCA analysis diagram, the distance between samples is positively correlated with the odor difference between samples. Figure 5 It can be seen that there is a certain distance between the samples during the processing of pepper seasoning oil, indicating that the odor differences between the samples are quite obvious. It is considered that the flavoring substances are lost during the filtering, clarifying, filling and other processes. The processing time of pepper seasoning oil can be appropriately shortened to reduce flavor loss and improve the production efficiency of enterprises.

[0068] 2. Distinction Index Analysis

[0069] The discrimination index is calculated based on the relative distance between the centroids of the two sample groups in the PCA diagram. The larger the distance between the two sample groups, the smaller the difference within the group, and the closer the discrimination index is to 100%, that is, the discrimination index is positively correlated with the difference between samples. The discrimination index between samples during the processing of pepper seasoning oil is shown in Table 3. As can be seen from Table 3, the discrimination index between each sample is large, indicating that the difference between each sample is large.

[0070] Table 3 Analysis of the difference index between samples during the processing of pepper seasoning oil

[0071]

[0072] Note: YY: crude oil; JT-24: extraction (24h); JT-72: extraction (72h); GL: filtration; CQ: clarification; CP: finished product

[0073] 3. Effect of processing steps on volatile flavor substances in pepper seasoning oil

[0074] The HeraclesII ultrafast gas phase electronic nose was used to determine the volatile flavor substances in the samples during the processing of pepper seasoning oil. Combined with the search database, the volatile flavor components that may be contained in the samples were obtained (see Table 4). As shown in Table 4, there are large differences in the flavor components between soybean oil and pepper seasoning oil, among which hexanal, nonanal, heptanal, and (E,E)-2,4-heptadienal are characteristic flavor substances in soybean oil. The types of flavor substances that may be contained in the samples of pepper seasoning oil during each processing step are basically the same, including alkanes, ketones, aldehydes, esters, olefins, alcohols, etc., among which α-pineneol has more obvious antibacterial and anti-inflammatory effects; linalool is an important flavor substance of pepper numbing, with antioxidant and hypnotic effects, and is widely used in the perfume industry. Different volatile flavor substances have different thresholds. For example, ketones and alcohol compounds have higher thresholds, while aldehydes and pyrazine compounds have lower thresholds. Therefore, a slight change in the content of volatile flavor substances may have a greater impact on the overall odor, which may also be the reason for the difference in odor between samples during the processing procedure.

[0075] Table 4 Qualitative analysis of aroma components of pepper seasoning oil during processing

[0076]

[0077] Note: YY: crude oil; JT-24: extraction (24h); JT-72: extraction (72h); GL: filtration; CQ: clarification; CP: finished product

[0078] In summary, the embodiments of the present invention experimented with the changes in various physical and chemical indicators and volatile flavor substances during the processing of pepper seasoning oil. There was no significant difference in a* value during the extraction of pepper seasoning oil. The acid value showed an overall upward trend, and the peroxide value and pepper amide showed a trend of first increasing and then decreasing. There was almost no difference in the fatty acid composition between the various processes during the processing, so the fatty acid composition cannot be used as an important indicator for quality control during the processing of pepper seasoning oil. The odor difference between samples of each process during the processing of pepper seasoning oil was quite obvious. 8 possible volatile flavor substances were detected in soybean oil, of which the main ones were hexanal, nonanal, heptanal, and (E,E)-2,4-heptadienal. 13 possible volatile flavor substances were detected in pepper seasoning oil, mainly alcohols and olefin compounds. During the processing of Sichuan pepper seasoning oil, the moisture content of the raw materials should be further controlled to reduce the impact of moisture in the Sichuan pepper on the acid value; too long extraction time has no positive effect on color and pepper amide content, and at the same time, volatile flavor substances in the Sichuan pepper seasoning oil will be lost during the processing. Therefore, companies can consider appropriately reducing the extraction time during processing, shortening the time of each processing step to reduce flavor loss, and at the same time improve the company's production efficiency. The patent application technology can provide a reference for seasoning oil manufacturers.

[0079] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for detecting volatile flavor substances in spice oil based on PCA analysis technology, characterized in that: The steps are as follows: (1) Preparation of spice oil samples Heat the raw oil to 180°C, pour it into the extraction tank filled with selected and crushed spices, stir it with a stirring rod, stir it every 5 minutes for 30 minutes, soak the raw oil in the extraction tank for 3-4 days to fully extract the aroma, filter the upper layer of oil sample with a plate-type closed filter after soaking, put the filtered oil sample into a storage tank for clarification, and obtain the final finished oil sample; (2) The spice oil samples were tested for their indexes and volatile flavor substances. The HeraclesII ultrafast gas phase electronic nose was used for the volatile flavor substance testing. (3) Statistical analysis of volatile flavor compound determination data was performed using the PCA analysis method; (4) Distinction index analysis: The discrimination index is calculated based on the relative distance between the centroids of the two sample groups in the PCA graph. The larger the distance between the two sample groups, the smaller the difference within the groups, and the closer the discrimination index is to 100%. That is, the discrimination index is positively correlated with the difference between samples. In step (2), the spice oil sample is subjected to index determination, which includes: amide compound determination, color determination, acid value determination, peroxide value determination, and fatty acid determination. The methods for determining amide compounds include: (1) Establishment of standard curve Take 5 mg of hydroxy-β-sanshool standard, dilute to 5 mL with methanol to obtain a hydroxy-β-sanshool standard solution, take 0 mL, 1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 6 mL, 7 mL, and 8 mL of the standard solution, respectively, and prepare a hydroxy-β-sanshool solution with a concentration of 0-8 μg / mL with methanol, measure the absorbance at 267 nm, and draw a standard curve with concentration as the abscissa and absorbance as the ordinate; (2) Determination of prickly ash amide The content of prickly ash amide was determined according to the method in Appendix A of DBS51 / 008-2019 "Local Food Safety Standard for Pepper Oil", and the content of hydroxy-β-sanshool was calculated according to the standard curve. The regression equation is: y =0.1501 x -0.1288, R 2 = 0.9983, where y is the absorbance value, x is the content of prickly ash amide, In step (2), the volatile flavor substances were determined using the Heracles II ultrafast gas phase electronic nose. The detection method was to take 2 g of the spice oil sample into a 20 mL headspace bottle, preheat it in a 55°C water bath for 24 min, and manually inject the sample. Each sample was run in parallel for 3 times.

2. The method for detecting volatile flavor substances in spice oils based on PCA analysis technology according to claim 1, characterized in that: Detection parameters: injection port temperature 200°C, injection volume 5000 μL, injection speed 125 μL / s, injection time 45 s, trap initial temperature 40°C, split rate 10 mL / min, final temperature 200°C, initial column temperature 50°C, increased to 80°C at 1°C / s and then increased to 250°C at 3°C / s, acquisition time 110 s, FID detector temperature 260°C.

3. A method for detecting volatile flavor substances in spice oil based on PCA analysis technology as described in claim 1 is applied to plant prickly ash oil, and PCA analysis is performed on crude oil before leaching, oil sample extracted for 24 hours, oil sample extracted for 72 hours, plate and frame filtered oil sample, clarified oil sample and finished oil.

4. The method for detecting volatile flavor substances in spice oils based on PCA analysis technology according to claim 3, characterized in that: The PCA method was applied to the processing of pepper seasoning oil in plant pepper oil. The odor differences between samples in each process were obvious. Eight volatile flavor substances were detected in soybean oil, including hexanal, nonanal, heptanal, and (E,E)-2,4-heptadienal. Thirteen volatile flavor substances were detected in pepper seasoning oil, including alcohols and olefin compounds.

5. The method for detecting volatile flavor substances in spice oils based on PCA analysis technology according to claim 3, characterized in that: The PCA method analysis showed that the variance contribution rate of the first principal component was 90.083%, the variance contribution rate of the second principal component was 8.299%, and the cumulative total contribution rate was 98.382%. The recognition index between samples was 95. In the PCA analysis diagram, the distance between samples was positively correlated with the odor differences between samples.

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