Tea oil adulteration identification method based on ultrasonic detection and characteristic indicator substance determination

Abstract

The present application belongs to the technical field of tea oil adulteration identification, and discloses a tea oil adulteration identification method based on ultrasonic detection and characteristic indicator substance determination, comprising the following steps: S1, collecting pure camellia oil, other pure plant oil and adulterated camellia oil respectively; S2, performing ultrasonic detection on the collected sample oil; S3, performing liquid chromatography-mass spectrometry analysis on the sample to determine the content of trace active ingredients in the sample oil; S4, using the partial least squares method to establish a PLS model between the ultrasonic parameters and the proportion of adulterated oil, performing principal component analysis and orthogonal partial least squares discriminant analysis based on the response value obtained by the liquid chromatography-mass spectrometry analysis, establishing a camellia oil identification model, and predicting the type of adulterated oil. The PLS model can quickly distinguish the adulterated tea oil, and the discrimination accuracy is above 95%; the camellia oil identification model can identify the type of adulterated oil and determine the production process of the sample tea oil. The method is simple to operate and reliable in technology.

Description

Technical Field

[0001] This invention relates to the field of tea oil adulteration identification technology, specifically a method for tea oil adulteration identification based on ultrasonic detection and determination of characteristic indicator substances. Background Technology

[0002] Camellia oil is a unique woody edible vegetable oil native to my country and is one of the most popular high-quality edible vegetable oils on the Chinese market. Its chemical composition is very similar to olive oil, with an unsaturated fatty acid content as high as 90%, including over 75% oleic acid. Therefore, it is an ideal health-promoting and nutritious oil for patients with hypertension, hyperlipidemia, and arteriosclerosis. The polyphenols, vitamin E, squalene, and phytosterols in camellia oil are also rich in trace active nutrients that are important for human health. Due to its limited annual production and scarcity, camellia oil is more expensive than other edible vegetable oils.

[0003] Currently, many edible oil certification and testing technologies have been developed, such as gas chromatography, high-performance liquid chromatography, gas chromatography-mass spectrometry, electronic nose, near-infrared spectroscopy, Raman spectroscopy, and differential scanning calorimetry, which are widely used in food quality control and material performance measurement. Among these methods, signal and peak overlap issues in electronic nose, spectroscopy, and nuclear magnetic resonance techniques make it difficult to improve their detection accuracy. Chromatography and mass spectrometry require cumbersome sample pretreatment, and the detection process is time-consuming. The physicochemical properties of different types of oils are crucial for differentiation. In recent years, ultrasonic technology has been widely used in the quality testing of industrial oils such as petroleum oils, which can quickly and accurately assess the physical properties (density, viscosity, etc.) of liquids. Studies have found that the energy attenuation of ultrasound waves propagating in oily media is closely related to the type of oil, making it possible to reflect the type and purity of oil by measuring changes in parameters such as the speed, energy attenuation, and acoustic impedance when ultrasound waves penetrate vegetable oils. However, adulteration identification using a single detection technology can only reflect a small portion of the differences in characteristic values, resulting in poor detection accuracy and repeatability. Summary of the Invention

[0004] This invention aims to provide a method for identifying adulterated camellia oil based on ultrasonic detection and the determination of characteristic indicator substances. It utilizes non-destructive ultrasonic testing to identify whether camellia oil is adulterated, and further determines the type of adulterated oil by measuring characteristic indicator substances. By analyzing the trace active components of lipids in camellia oil and measuring its trace active nutrients, and combining mass spectrometry with ultrasonic detection technology, a multivariate method is established to analyze the oil characteristics of camellia oil. This method enables rapid detection and accurate identification of adulterated camellia oil with high precision.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for identifying adulterated tea oil based on ultrasonic detection and determination of characteristic indicator substances includes the following steps:

[0007] S1. Sample collection: Collect several pure camellia oil samples produced by pressing and leaching methods, as well as pure oil samples of other vegetable oils. Camellia oil is the oil to be adulterated, and other oils are the adulterants. Mix the adulterants and the oil to be adulterated in different mass ratios to obtain experimental samples of adulterated camellia oil.

[0008] S2. Detection of physicochemical properties of sample oil: At a preset temperature, pure camellia oil samples, pure oil samples of other vegetable oils and adulterated camellia oil were subjected to ultrasonic testing. The acoustic impedance, energy attenuation and ultrasonic velocity change when the ultrasound passed through the oil were measured. The density and viscosity of the corresponding sample oil were determined using a densitometer and a rheometer.

[0009] S3. Analysis of trace active ingredients in sample oil: Weigh pure camellia oil, pure oil of other vegetable oils and adulterated camellia oil, and after pretreatment, perform liquid chromatography-mass spectrometry analysis on the samples to determine the content of trace active ingredients in the sample oil.

[0010] S4. Identification of adulterated samples: The correlation coefficients between viscosity, density, and ultrasonic parameters were calculated to obtain the multivariate equations of viscosity and density versus ultrasonic parameters. A partial least squares model was established to establish the relationship between independent and dependent variables, where the independent variables are viscosity, density, and ultrasonic parameters, and the dependent variable is the proportion of adulterated oil. Based on the response values ​​obtained from liquid chromatography-mass spectrometry analysis, principal component analysis and orthogonal partial least squares discriminant analysis were performed to establish a camellia oil identification model and predict the types of adulterated oil.

[0011] Furthermore, in S1, the mixing ratios of the adulterant oil and the adulterated oil are 0%, 1%, and 100%, respectively, with a gradient of 5%. The mixing ratio is defined as: mass of adulterant oil / (mass of adulterated oil + mass of adulterant oil) × 100%.

[0012] Furthermore, in S1, the adulterated oil includes one or two of peanut oil, soybean oil, rapeseed oil, cottonseed oil, corn oil, sunflower oil, cottonseed oil, and palm oil.

[0013] Furthermore, in S2, the preset temperatures are 5℃, 10℃, 20℃, and 30℃.

[0014] Further, in S3, the specific pretreatment steps are as follows: Weigh 0.1 g of tea oil sample, place it in an Erlenmeyer flask, add 2 g of ascorbic acid and 10 mL of water, vortex and shake well, then add 30 mL of anhydrous ethanol and 15 mL of 50% potassium hydroxide aqueous solution, shake well, sonicate at 80 W for 30 min, and then saponify at 80 °C for 1 h; after cooling, extract three times with 40 mL of petroleum ether, combine the extracts, wash with water until neutral, transfer the petroleum ether layer to a centrifuge bottle, dry with nitrogen, dilute to volume with methanol, filter through a 0.22 μm organic filter membrane, and wait for analysis.

[0015] Furthermore, in S3, the chromatographic column for liquid chromatography-mass spectrometry analysis was a Thermo Scientific C18 reversed-phase column, with a column temperature of 30℃, an injection volume of 5 μL, a mobile phase of 0.02% formic acid in methanol and acetonitrile, gradient elution, a mobile phase flow rate of 0.50 mL / min, and a positive ion scanning mode for mass spectrometry analysis, with high-purity nitrogen as the carrier gas at a flow rate of 10 mL / min.

[0016] Furthermore, in S3, the trace active ingredients in the sample oil include sterols, squalene, carotene, and polyphenols.

[0017] The principle and beneficial effects of this technical solution are as follows:

[0018] This invention establishes a predictive model based on the specific changes in parameters such as acoustic impedance, energy attenuation, and ultrasonic velocity when ultrasound passes through different oils. The ultrasonic parameters of the sample are then substituted into the established model for analysis and judgment. Due to the very short ultrasound duration, this invention can quickly identify adulterated tea oil, typically within seconds. Furthermore, no sample preparation is required, making it a non-destructive in-situ detection method. It can achieve 1%-100% adulteration detection of tea oil with an overall accuracy exceeding 95%. Compared to traditional detection methods, this invention offers comparable detection precision but significantly higher efficiency and lower cost compared to traditional chromatography or mass spectrometry. On the other hand, this invention obtains the content of characteristic trace active ingredients in different oils through mass spectrometry analysis of pure and adulterated tea oil processed using different methods, and establishes relevant predictive models. After identifying adulteration of tea oil using ultrasound, this model can be used to further determine the type of adulterated oil, and also to determine the tea oil preparation process.

[0019] The identification method of this invention is simple, fast, accurate, and specific, providing a reliable technical guarantee for the safety of tea oil and the identification of counterfeits in the high-end food oil industry. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of a method for identifying adulterated tea oil based on ultrasonic detection and determination of characteristic indicator substances according to the present invention.

[0021] Figure 2 This is a schematic diagram of the ultrasonic testing device.

[0022] The names of the corresponding labels in the attached diagram are:

[0023] 1. Sealed container; 2. Ultrasonic sensor; 3. Fixing plate; 4. Pulse generator; 5. Miniature oscilloscope; 6. Microcomputer processor; 7. Reflector. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments:

[0025] like Figure 1 As shown, a method for identifying adulterated tea oil based on ultrasonic detection and determination of characteristic indicator substances includes the following steps:

[0026] S1. Sample Collection:

[0027] (1) Collect 20 samples of pure camellia oil produced by pressing (numbered CY1~CY20), 20 samples of pure camellia oil produced by extraction (numbered CJ1~CJ20), 30 samples of pure peanut oil (numbered HS1~HS30), 20 samples of pure corn oil (numbered YM1~YM20), and 25 samples of pure rapeseed oil (numbered CZ1~CZ25) from the market.

[0028] (2) Pure camellia oil (CY1~CY20) was used as the oil to be adulterated, and peanut oil (HS1) was used as the adulterant oil. The adulterant oil and the oil to be adulterated were mixed evenly at a mass ratio of 1%, 5%, 10%, 15%, 20%, 25%, ..., 95% to obtain experimental samples of adulterated camellia oil, which were numbered H1~H400 respectively.

[0029] (3) Camellia oil (CY1~CY20) was used as the oil to be adulterated and corn oil (YM1) was used as the adulterant oil. The adulterant oil and the oil to be adulterated were mixed evenly at a mass ratio of 1%, 5%, 10%, 15%, 20%, 25%, ..., 95% to obtain experimental samples of adulterated camellia oil, which were numbered Y1~Y400 respectively.

[0030] (4) Camellia oil (CJ1~CJ20) was used as the oil to be adulterated and rapeseed oil (CZ1) was used as the adulterant oil. The adulterant oil and the oil to be adulterated were mixed evenly at a mass ratio of 1%, 5%, 10%, 15%, 20%, 25%, ..., 95% to obtain experimental samples of adulterated camellia oil, which were numbered C1~C400 respectively.

[0031] S2. Analysis of the physicochemical properties of the sample oil:

[0032] (5) Detect the acoustic impedance, energy attenuation, and ultrasonic velocity changes of all sample oils. The detection device is as follows: Figure 2 As shown, it consists of an ultrasonic sensor 2 and a sealed container 1 containing the oil sample to be tested, which is immersed in warm water at 20°C. The device also includes a pulse generator 4, a miniature oscilloscope 5, a microcomputer processor 6, a mounting plate 3, and a reflector 7.

[0033] (6) The density and viscosity of all sample oils were measured using a densitometer and a rheometer. The normality of density, viscosity and ultrasonic parameters was evaluated by the Shapiro-Wilk test.

[0034] S3. Analysis of trace active components in sample oil:

[0035] (7) Prepare tea oil, tea oil + peanut oil, tea oil + corn oil, and tea oil + rapeseed oil blended oil samples according to the methods in (1)-(4). Pre-treat the samples for liquid chromatography-mass spectrometry (LC-MS) analysis. The pre-treatment method is as follows: Weigh 0.1 g of tea oil sample (accurate to 0.0001 g), place it in an Erlenmeyer flask, add 2 g of ascorbic acid and 10 mL of water, vortex and shake well, then add 30 mL of anhydrous ethanol and 15 mL of 50% (v / v) potassium hydroxide aqueous solution, shake well, sonicate at 80 W for 30 min, and then saponify at 80 °C for 1 h; after cooling, extract three times with 40 mL of petroleum ether, combine the extracts, wash with water until neutral, transfer the petroleum ether layer to a centrifuge bottle, dry with nitrogen, dilute to volume with methanol, filter through a 0.22 μm organic filter membrane, and wait for analysis.

[0036] (8) After sample pretreatment, liquid chromatography-mass spectrometry (LC-MS) was performed, with the LC-MS chromatographic conditions set as follows:

[0037] Thermo Scientific C18 reversed-phase column, triple quadrupole mass spectrometer detector (Triple Quad 4500), mobile phase: A = 0.02% formic acid in methanol, B = 100% acetonitrile, flow rate: 0.50 mL / min; injection volume: 5 μL; column temperature: 30℃. Gradient elution program: 0–1.0 min, 85% B–95% B; 1.0–7.0 min, 95% B; 7.0–12.5 min, 95% B–100% B; 12.5–13.0 min, 100% B–85% B.

[0038] The mass spectrometry detection method is as follows:

[0039] Ion source: Electrospray ionization source (ESI); Scan mode: Positive ion scan mode; Capillary voltage: 3 kV; Spray voltage: 3.88 kV; Nebulizing gas pressure: 270 kPa; Drying gas (N2) flow rate: 10 mL / min; Desolventizing temperature: 300℃; Conical gas flow rate: 50 L / hr; Desolventizing gas flow rate: 800 L / hr; Collision gas: Ar; Scan mode: SRM mode; Sheath gas: 30 units; Nitrogen (N2): 5 units; Evaporator temperature: 300℃.

[0040] (9) The content of trace active ingredients (sterols, squalene, carotene, polyphenols) in the sample oil was obtained by liquid chromatography-mass spectrometry.

[0041] S4. Sample adulteration identification:

[0042] (10) Based on the normality test results in (6), the correlation equation between density, viscosity and ultrasonic parameters was calculated using the XLSTAT Premium 2018 software package.

[0043] (11) Collect the experimental data obtained, use OriginPro 9.8 to perform partial least squares (PLS) calculation, find the relationship between the independent variable (ultrasonic parameters, oil sample density, viscosity) and the dependent variable (mass fraction of adulterated oil), and then replace the oil sample density and viscosity in the relationship with the ultrasonic parameters to obtain the relationship model for predicting the mass fraction of adulterated oil using ultrasonic parameters.

[0044] The model was trained using the PLS method, and the sample set information and prediction results are shown in Table 1:

[0045] Table 1 shows the training set and results of the tea oil prediction model based on the PLS method.

[0046]

[0047] It can be seen that the model has a very good predictive effect for the adulteration ratio of peanut oil in tea oil of 1% to 10%, with an overall prediction accuracy of over 95% and an error range within ±3%.

[0048] (12) Based on the response values ​​obtained by liquid chromatography-mass spectrometry analysis, principal component analysis and orthogonal partial least squares discriminant analysis were performed to establish a camellia oil identification model and predict the types of adulterated oil.

[0049] The model was trained using the OPLS-DA method, and the sample set information and prediction results are shown in Table 2.

[0050] Table 2 shows the training set and results of the tea oil prediction model based on the OPLS-DA method.

[0051]

[0052] It can be seen that the model has a very good predictive effect on the adulteration ratio of peanut oil in tea oil ranging from 1% to 20%, with a prediction accuracy of over 98% for whether it is adulterated. When the adulteration ratio reaches 5% or more, the model's prediction accuracy for the type of adulterated oil reaches over 95%.

[0053] The method of the present invention for identifying tea oil involves first using ultrasonic testing and combining it with a model to predict its purity. For adulterated tea oil, further analysis of trace active ingredients is performed and the type of adulterated oil is predicted using a model.

[0054] In summary, this invention provides a method for identifying adulterated tea oil based on ultrasonic detection and the determination of characteristic indicator substances.

[0055] Ultrasonic nondestructive testing was used to identify adulterated camellia oil. Further analysis of characteristic indicators in adulterated camellia oil revealed the specific type of adulteration. By analyzing the lipid trace active components and measuring the trace active nutrients in camellia oil, a multivariate method was established combining mass spectrometry and ultrasonic detection to analyze the oil characteristics of camellia oil. This method enables rapid detection and accurate identification of adulterated camellia oil. The model can identify an adulteration level as low as 1%, with an overall accuracy exceeding 95%. This method is highly accurate, environmentally friendly, convenient, and low-cost, expanding the methods for identifying adulteration of camellia oil compared to other edible oils.

[0056] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for identifying adulterated tea oil based on ultrasonic detection and determination of characteristic indicator substances, characterized in that, Includes the following steps: S1. Sample collection: Collect several pure camellia oil samples produced by pressing and leaching methods, as well as pure oil samples of other vegetable oils. Camellia oil is the oil to be adulterated, and other oils are the adulterants. Mix the adulterants and the oil to be adulterated in different mass ratios to obtain experimental samples of adulterated camellia oil. S2. Detection of physicochemical properties of sample oil: At a preset temperature, pure camellia oil samples, pure oil samples of other vegetable oils and adulterated camellia oil were subjected to ultrasonic testing. The acoustic impedance, energy attenuation and ultrasonic velocity change when the ultrasound passed through the oil were measured. The density and viscosity of the corresponding sample oil were determined using a densitometer and a rheometer. S3. Analysis of trace active ingredients in sample oil: Weigh pure camellia oil, pure oil of other vegetable oils and adulterated camellia oil, and after pretreatment, perform liquid chromatography-mass spectrometry analysis on the samples to determine the content of trace active ingredients in the sample oil. The trace active ingredients in the sample oil include sterols, squalene, carotene, and polyphenols; The specific pretreatment steps are as follows: Weigh 0.1 g of tea oil sample, place it in an Erlenmeyer flask, add 2 g of ascorbic acid and 10 mL of water, vortex and shake well, then add 30 mL of anhydrous ethanol and 15 mL of 50% potassium hydroxide aqueous solution, shake well, sonicate at 80 W for 30 min, and then saponify at 80 °C for 1 h; after cooling, extract three times with 40 mL of petroleum ether, combine the extracts, wash with water until neutral, transfer the petroleum ether layer to a centrifuge bottle, dry with nitrogen, dilute to volume with methanol, filter through a 0.22 μm organic filter membrane, and wait for analysis; The chromatographic column used for liquid chromatography-mass spectrometry analysis was a Thermo Scientific C18 reversed-phase column, with a column temperature of 30℃, an injection volume of 5 μL, a mobile phase of 0.02% formic acid in methanol and acetonitrile, gradient elution, and a mobile phase flow rate of 0.50 mL / min. The mass spectrometry analysis was performed in positive ion scanning mode, with high-purity nitrogen as the carrier gas and a flow rate of 10 mL / min. S4. Identification of adulterated samples: The correlation coefficients between viscosity, density, and ultrasonic parameters were calculated to obtain the multivariate equations of viscosity and density versus ultrasonic parameters. A partial least squares model was established to establish the relationship between independent and dependent variables, where the independent variables are viscosity, density, and ultrasonic parameters, and the dependent variable is the proportion of adulterated oil. Based on the response values ​​obtained from liquid chromatography-mass spectrometry analysis, principal component analysis and orthogonal partial least squares discriminant analysis were performed to establish a camellia oil identification model and predict the types of adulterated oil. The adulterated oil is one of peanut oil, rapeseed oil, or corn oil.

2. The method for identifying adulterated tea oil based on ultrasonic detection and determination of characteristic indicator substances according to claim 1, characterized in that: In S1, the mixing ratios of adulterated oil and the original oil are 0%, 1%, and 100%, respectively, with a gradient of 5%. The mixing ratio is defined as: mass of adulterated oil / (mass of original oil + mass of adulterated oil) × 100%.

3. The method for identifying adulterated tea oil based on ultrasonic detection and determination of characteristic indicator substances according to claim 1, characterized in that: In S2, the preset temperatures are 5℃, 10℃, 20℃, and 30℃.

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