A device and method for identifying tea oil quality by online electronic tongue during supercritical extraction

Abstract

The present invention belongs to the field of oil detection, and specifically discloses a device and method for online electronic tongue identification of tea oil quality during supercritical extraction. A mixed solution of particle liquid and surfactant is added to an autoclave; the potential signal of the electronic tongue sensor arranged in the autoclave is read, and then converted by the Weber-Fechner law on the PC side, and finally a taste information file is obtained; then the taste information is substituted into the model through the preset tea oil acid value, peroxide value, total tocopherol, sterol, and squalene model on the PC side, and the corresponding physical property parameters and substance content are obtained to comprehensively evaluate the quality of tea oil; this method can complete the determination of a sample in a relatively short time, based on the mode of online electronic tongue identification during supercritical extraction, and realizes online evaluation of tea oil quality. It is simple, fast, low-cost, environmentally friendly, and has great advantages over traditional chemical methods.

Description

Technical Field

[0001] The invention belongs to the field of oil detection, and in particular relates to a device and method for identifying the quality of tea oil by online electronic tongue in a supercritical extraction process. Background Art

[0002] The traditional preparation processes of tea oil include pressing, water-enzyme method, solvent extraction, etc. Compared with these, supercritical CO2 extraction has received more extensive attention in recent years. Supercritical CO2 extraction is non-toxic, fast, and efficient, and the critical conditions are mild (T c =304.2K, P c =7.38MPa), the extracted tea oil not only has high content of biologically active ingredients such as squalene and sterols, but also has light color, strong aroma, low acidity and peroxide value, can avoid over-refining, and is very suitable for the preparation of high-end tea oil.

[0003] The composition of tea seeds is complex. In addition to oil, it also contains water, free fatty acids, peroxides and other components. Previous studies have found that the acid value, peroxide value, water content and other parameters of tea oil are greatly affected by the supercritical CO2 extraction process conditions. Due to the volatility of tea seed materials themselves, it is difficult to form the most economical process conditions in actual production, and the quality of tea oil will fluctuate.

[0004] Traditional offline analysis has hysteresis, such as HPCL, GC-MS and FTIR, and has some disadvantages, such as expensive instruments, complex sample pretreatment, and long time consumption.

[0005] In recent years, electronic tongue technology has been widely used in the food, cosmetics and pharmaceutical industries due to its simple, fast and accurate characteristics. Zhang Caiwa (2013) used a three-electrode voltammetric electronic tongue to distinguish soybean oil, corn oil, peanut oil, sesame oil and sunflower oil. Peng Xingxing (2015) used electronic tongue to study walnut oil adulteration; Zhang Hang (2013) used electronic tongue technology to identify palm oil adulteration in olive oil. Existing research is mainly aimed at offline analysis of different edible oils. There is no report on the use of online electronic tongue to identify the quality of tea oil in the supercritical extraction process in China. Therefore, it is urgent to study new devices and methods for online quality detection of tea oil supercritical extraction process to improve the control level.

[0006] In view of this, the present invention provides a device and method for online electronic tongue identification of tea oil quality during supercritical extraction, which can predict the quality of tea seed oil in real time online. The method is simple, fast, low-cost, and environmentally friendly, and has great advantages over traditional chemical methods. Summary of the invention

[0007] The present invention provides a device and method for online electronic tongue identification of tea oil quality during supercritical extraction, which is simple, fast, low-cost, and environmentally friendly, and has great advantages over traditional chemical methods.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] A method for identifying the quality of tea oil by online electronic tongue during supercritical extraction, comprising the following steps:

[0010] After the conditions of the supercritical CO2 extraction of tea oil in the autoclave are stabilized, a mixed solution of ionic liquid and surfactant is added; after sufficient stirring, the potential signal of the screen-printed electrode array electronic tongue sensor set in the autoclave is read, and then converted through the Weber-Fechner law on the PC side to finally obtain a taste information file; then, through the tea oil acid value, peroxide value, total tocopherol, sterol, and squalene model preset on the PC side, the taste information is substituted into the model to obtain the corresponding physical property parameters and substance content, and the quality of tea oil is comprehensively evaluated;

[0011] The preset models are:

[0012] Acid value: y = 19.496-2.124x1+17.469x2-6.975x3+10.457x4-2.008x5-8.815x6+1.512x7-1.808x8+3.224x9+6.554x 10 -8.874x 11 -9.323x 12 +7.674x 13 –5.214x 14 +4.895x 15 +2.008x 16

[0013] Peroxide value: y = -0.829-0.409x1-2.198x2+2.98x3+3.087x4-2.270x5-1.113x6+0.114x7+0.328x8+4.354x9+2.224x 10 -10.872x 11 -5.673x 12 +4.212x 13 –3.774x 14 +6.355x 15 +1.322x 16

[0014] Total tocopherol: y = 0.234-0.023x1+0.422x2-0.005x3+0.257x4-0.047x5-0.235x6+0.021x7-0.612x8+0.414x9+0.004x 10 -0.237x 11-0.083x 12 +0.375x 13 –0.054x 14 +0.085x 15 +0.227x 16

[0015] Sterol: y = 13.985-10.384x1+7.252x2-6.370x3+5.762x4-8.904x5-7.682x6+12.371x7-6.339x8+5.761x9+2.407x 10 -5366x 11 -4.284x 12 +7.398x 13 –6.714x 14 +4.535x 15 +6.293x 16

[0016] Squalene: y = 0.134-0.034x1+0.142x2-0.021x3+0.073x4-0.027x5-0.095x6+0.033x7-0.173x8+0.214x9+0.356x 10 -0.148x 11 -0.033x 12 +0.279x 13 –0.106x 14 +0.127x 15 +0.013x 16

[0017] Among them, x1-x 16 The taste information file is obtained by converting the potential signal fed back by the screen-printed electrode array through the Weber-Fechner law.

[0018] The ionic liquid can be an imidazole or pyridine amino acid ionic liquid; preferably at least one of lysine, arginine, asparagine and glutamine ionic liquids; the surfactant can be at least one of methyl oleate, ethyl oleate, propyl oleate and butyl oleate.

[0019] The ratio of the amount of the ionic liquid to the surfactant is 1:0.1-10, and the ratio of the mixed solution of the ionic liquid and the surfactant to the volume of the autoclave is 0.005-0.01:1.

[0020] A device for realizing online electronic tongue identification of tea oil quality during supercritical extraction, comprising:

[0021] Electronic tongue sensors with screen-printed electrode arrays are installed in the three autoclave bodies, and the electronic tongue sensors are externally connected to a PC processor; the three autoclave bodies are commonly connected to a high-pressure pump, and the ionic liquid and surfactant are pumped into the autoclave body by the high-pressure pump after passing through the liquid inlet valve. At the same time, the three autoclave bodies are respectively connected to the supercritical extraction autoclave and two separation autoclaves through valves, and are equipped with vent valves.

[0022] Furthermore, the structure of the screen-printed electrode array electronic tongue sensor is as follows: 16 carbon working electrodes, 1 auxiliary electrode, and 1 Ag / AgCl reference electrode are printed in sequence on a PET substrate, and the substrate layer is arranged with wires corresponding to the working electrode, reference electrode, and auxiliary electrode, which are covered with an insulating layer.

[0023] Furthermore, the valve is an air inlet valve and an air outlet valve.

[0024] Furthermore, the autoclave body has a stirring device, a temperature control device, and is equipped with a pressure gauge.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The present invention provides a device and method for online electronic tongue identification of tea oil quality during supercritical extraction. The method is simple, fast, low-cost, and environmentally friendly, and has great advantages over traditional chemical methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the device for online electronic tongue identification of tea oil quality during supercritical extraction.

[0028] In the figure, 1 is the autoclave body; 2 is the screen-printed electrode array electronic tongue sensor; 3 is the PC-side processor; 4 is the high-pressure pump; 5 is the air inlet valve; 6 is the air outlet valve; 7 is the liquid inlet valve; and 8 is the vent valve.

[0029] Figure 2 Schematic diagram of the screen-printed electrode array electronic tongue sensor.

[0030] In the figure, 9 is a PET substrate; 10 is a working electrode; 11 is an auxiliary electrode; 12 is a reference electrode; 13 is a wire; 14 is an insulating layer; and 15 is an electrode contact. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with examples and drawings, but the embodiments of the present invention are not limited thereto.

[0032] The three autoclave bodies 1 are equipped with electronic tongue sensors 2 with screen-printed electrode arrays and an external PC processor 3. The autoclave body is connected to a high-pressure pump 4, and a certain proportion of ionic liquid and surfactant are pumped in through an inlet valve 7. At the same time, the autoclave body is connected to a supercritical extraction kettle and a separation kettle through an inlet valve 5 and an outlet valve 6, and a vent valve 8 is installed.

[0033] Furthermore, the screen-printed electrode array electronic tongue sensor prints 16 carbon working electrodes 10, 1 auxiliary electrode 11, and 1 Ag / AgCl reference electrode 12 in sequence on a PET substrate 9, and the substrate layer is arranged with wires 13 corresponding to the working electrode, reference electrode, and auxiliary electrode, which are covered with an insulating layer 14, and the ends of the wires are connected to electrode contacts 15.

[0034] The autoclave body is equipped with a stirring device, a temperature control device, and a pressure gauge.

[0035] A method for identifying the quality of tea oil by online electronic tongue during supercritical extraction, comprising the following steps:

[0036] 1) Keep all valves closed, adjust the temperature of the autoclave body 1 equipped with the screen-printed electrode array electronic tongue sensor 2 to be consistent with that of the connected supercritical extraction kettle or separation kettle, and after the supercritical CO2 extraction conditions of tea oil in the extraction kettle reach the set conditions, open the air inlet valve 5 and the air outlet valve 6 of the autoclave body, and after the temperature and pressure in the autoclave body 1 are consistent with those of the extraction kettle or separation kettle, close the air inlet valve 5 and the air outlet valve 6;

[0037] 2) The mixed solution of the ionic liquid and the surfactant is pumped into the autoclave body 1 through the high-pressure pump 4, and after being fully stirred, the potential signal of the screen-printed electrode array electronic tongue sensor 2 is read, and the signal is converted by the Weber-Fechner law of the PC-side processor 3 to finally obtain the taste information file;

[0038] 3) The taste information is substituted into the tea oil acid value, peroxide value, total tocopherol, sterol, squalene and other models preset by the PC processor 3 to obtain the corresponding physical property parameters and substance content, and comprehensively evaluate the quality of tea oil.

[0039] The ionic liquid in step 2) can be an imidazole or pyridine amino acid particle liquid; preferably one or a combination of lysine, arginine, asparagine and glutamine ionic liquids; the surfactant can be one or a combination of methyl oleate, ethyl oleate, propyl oleate and butyl oleate.

[0040] The ratio of the amount of the ionic liquid to the surfactant is 1:0.1-10, and the ratio of the mixed solution of the ionic liquid and the surfactant to the volume of the autoclave is 0.005-0.01:1.

[0041] In step 3), the preset model is

[0042] Acid value: y = 19.496-2.124x1+17.469x2-6.975x3+10.457x4-2.008x5-8.815x6+1.512x7-1.808x8+3.224x9+6.554x 10 -8.874x 11 -9.323x 12 +7.674x 13 –5.214x 14 +4.895x 15 +2.008x 16

[0043] Peroxide value: y = -0.829-0.409x1-2.198x2+2.98x3+3.087x4-2.270x5-1.113x6+0.114x7+0.328x8+4.354x9+2.224x 10 -10.872x 11 -5.673x 12 +4.212x 13 –3.774x 14 +6.355x 15 +1.322x 16

[0044] Total tocopherol: y = 0.234-0.023x1+0.422x2-0.005x3+0.257x4-0.047x5-0.235x6+0.021x7-0.612x8+0.414x9+0.004x 10 -0.237x 11 -0.083x 12 +0.375x 13 –0.054x 14 +0.085x 15 +0.227x 16

[0045] Sterol: y = 13.985-10.384x1+7.252x2-6.370x3+5.762x4-8.904x5-7.682x6+12.371x7-6.339x8+5.761x9+2.407x 10 -5366x 11 -4.284x 12 +7.398x 13 –6.714x 14 +4.535x 15+6.293x 16

[0046] Squalene: y = 0.134-0.034x1+0.142x2-0.021x3+0.073x4-0.027x5-0.095x6+0.033x7-0.173x8+0.214x9+0.356x 10 -0.148x 11 -0.033x 12 +0.279x 13 –0.106x 14 +0.127x 15 +0.013x 16

[0047] Among them, x1-x 16 The taste information file is obtained by converting the potential signal fed back by the screen-printed electrode array through the Weber-Fechner law.

[0048] Example 1

[0049] The extraction conditions of supercritical CO2 extraction of tea oil are as follows: extraction kettle temperature 40℃, 25MPa, separation kettle temperature 1-40℃, 12MPa, separation kettle 2-40℃, 8MPa, and the following operations are performed during extraction for 2h.

[0050] Keep all valves closed, adjust the temperature of the autoclave to 40°C, open the air inlet valve and air outlet valve of the autoclave, and close the air inlet valve and air outlet valve after the temperature and pressure of the autoclave are consistent with those of the extraction kettle or separation kettle;

[0051] Lysine imidazolium ionic liquid and methyl oleate were mixed in a ratio of 1:0.5, and pumped into the autoclave body at a ratio of 0.005:1 of the volume of the mixed liquid to the volume of the autoclave body. After sufficient stirring, the potential signal of the screen-printed electrode array electronic tongue sensor was read and processed by the PC to finally obtain the taste information file. The quality parameters of tea oil were calculated by the prefabricated model as shown in the following table:

[0052]

[0053] Example 2

[0054] The extraction conditions of supercritical CO2 extraction of tea oil are as follows: extraction kettle temperature 50℃, 30MPa, separation kettle temperature 1-50℃, 10MPa, separation kettle 2-50℃, 6MPa, and the following operations are performed during extraction for 1h.

[0055] Keep all valves closed, adjust the temperature of the autoclave to 50°C, open the air inlet valve and air outlet valve of the autoclave, and close the air inlet valve and air outlet valve after the temperature and pressure of the autoclave are consistent with those of the extraction kettle or separation kettle;

[0056] Arginine imidazolium ionic liquid and ethyl oleate were mixed in a ratio of 1:1, and pumped into the autoclave body at a ratio of 0.007:1 of the volume of the mixed liquid to the volume of the autoclave body. After sufficient stirring, the potential signal of the screen-printed electrode array electronic tongue sensor was read and processed by the PC to finally obtain the taste information file. The quality parameters of tea oil were calculated by the prefabricated model as shown in the following table:

[0057]

[0058] Example 3

[0059] The extraction conditions of supercritical CO2 extraction of tea oil are as follows: extraction kettle temperature 40℃, 25MPa, separation kettle temperature 1-50℃, 10MPa, separation kettle temperature 2-60℃, 9MPa, and the following operations are performed during extraction for 4h.

[0060] Keep all valves closed, adjust the temperature of the autoclave to 40℃, 50℃, and 60℃ respectively, open the air inlet valve and air outlet valve of the autoclave, and close the air inlet valve and air outlet valve after the temperature and pressure in the autoclave are consistent with those of the extraction kettle or separation kettle;

[0061] Asparagine pyridinium ionic liquid and propyl oleate were mixed in a ratio of 1:3, and pumped into the autoclave body at a ratio of 0.008:1 of the mixed liquid to the volume of the autoclave body. After sufficient stirring, the potential signal of the screen-printed electrode array electronic tongue sensor was read, and the taste information file was finally obtained after processing by the PC end. The quality parameters of tea oil were calculated by the prefabricated model as shown in the following table:

[0062]

[0063] Example 4

[0064] The extraction conditions of supercritical CO2 extraction of tea oil are as follows: extraction kettle temperature 40℃, 25MPa, separation kettle temperature 1-50℃, 10MPa, separation kettle temperature 2-60℃, 6MPa, and the following operations are performed during extraction for 6h.

[0065] Keep all valves closed, adjust the temperature of the autoclave to 40℃, 50℃, and 60℃ respectively, open the air inlet valve and air outlet valve of the autoclave, and close the air inlet valve and air outlet valve after the temperature and pressure in the autoclave are consistent with those of the extraction kettle or separation kettle;

[0066] Glutamine pyridinium ionic liquid and butyl oleate were mixed in a ratio of 1:10, and pumped into the autoclave body at a ratio of 0.01:1 of the volume of the mixed liquid to the autoclave body. After sufficient stirring, the potential signal of the screen-printed electrode array electronic tongue sensor was read, and the taste information file was finally obtained after processing by the PC end. The quality parameters of tea oil were calculated by the prefabricated model as shown in the following table:

[0067]

[0068]

[0069] The present invention can complete the determination of a sample in a relatively short time, is based on the mode of online electronic tongue recognition during supercritical extraction, and realizes online evaluation of tea oil quality.

[0070] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for identifying the quality of tea oil by online electronic tongue during supercritical extraction, characterized in that The steps include: After the conditions of the supercritical CO2 tea oil extraction method in the autoclave are stabilized, a mixed solution of ionic liquid and surfactant is added; after sufficient stirring, the potential signal of the screen-printed electrode array electronic tongue sensor set in the autoclave is read, and then converted through the Weber-Fechner law on the PC side to finally obtain a taste information file; then, through the tea oil acid value, peroxide value, total tocopherol, sterol, and squalene model preset on the PC side, the taste information is substituted into the model to obtain the corresponding physical property parameters and substance content, and the quality of tea oil is comprehensively evaluated; The preset models are: Acid value: y = 19.496 - 2.124x1 + 17.469x2 - 6.975x3 + 10.457x4 - 2.008x5 -8.815x6 + 1.512x7 - 1.808x8 + 3.224x9 + 6.554x 10 -8.874x 11 - 9.323x 12 +7.674x 13 –5.214x 14 +4.895x 15 +2.008x 16 Peroxide value: y = -0.829 - 0.409x1 - 2.198x2 + 2.98x3 + 3.087x4 - 2.270x5 -1.113x6 + 0.114x7 + 0.328x8 + 4.354x9 + 2.224x 10 -10.872x 11 - 5.673x 12 +4.212x 13 – 3.774x 14 +6.355x 15 +1.322x 16 Total tocopherols: y = 0.234 - 0.023x1 + 0.422x2 - 0.005x3 + 0.257x4 - 0.047x5 -0.235x6 + 0.021x7 - 0.612x8 + 0.414x9 + 0.004x 10 -0.237x 11 - 0.083x 12 +0.375x 13 – 0.054x 14 +0.085x 15 +0.227x 16 Sterols: y = 13.985 - 10.384x1 + 7.252x2 - 6.370x3 + 5.762x4 - 8.904x5 -7.682x6+ 12.371x7 - 6.339x8 + 5.761x9 + 2.407x 10 -5366x 11 - 4.284x 12 +7.398x 13 –6.714x 14 +4.535x 15 +6.293x 16 Squalene: y = 0.134 - 0.034x1 + 0.142x2 - 0.021x3 + 0.073x4 - 0.027x5 -0.095x6 + 0.033x7 - 0.173x8 + 0.214x9 + 0.356x 10 -0.148x 11 - 0.033x 12 +0.279x 13 –0.106x 14 +0.127x 15 + 0.013x 16 Among them, x 1- x 16 The taste information file is obtained by converting the potential signal fed back by the screen-printed electrode array through the Weber-Fechner law; The ionic liquid is at least one of lysine, arginine, asparagine and glutamine ionic liquids; the surfactant is at least one of methyl oleate, ethyl oleate, propyl oleate and butyl oleate; The method for online electronic tongue identification of tea oil quality during supercritical extraction is achieved by the following device, including: three high-pressure autoclave bodies are equipped with screen-printed electrode array electronic tongue sensors, and the electronic tongue sensors are externally connected to a PC processor; the three high-pressure autoclave bodies are commonly externally connected to a high-pressure pump, and the ionic liquid and the surfactant are pumped into the high-pressure autoclave body by the high-pressure pump after passing through a liquid inlet valve, and at the same time, the high-pressure autoclave body is connected to the supercritical extraction autoclave and the separation autoclave through a valve, and is equipped with a vent valve.

2. The method for online electronic tongue identification of tea oil quality during supercritical extraction according to claim 1, characterized in that: The molar ratio of the ionic liquid to the surfactant is 1:0.1-10.

3. The method for online electronic tongue identification of tea oil quality during supercritical extraction according to claim 1, characterized in that: The volume ratio of the mixed solution of ionic liquid and surfactant to the autoclave body is 0.005~0.01:

1.

4. The method for online electronic tongue identification of tea oil quality during supercritical extraction according to claim 1, characterized in that: The structure of the screen-printed electrode array electronic tongue sensor is as follows: 16 carbon working electrodes, 1 auxiliary electrode, and 1 Ag / AgCl reference electrode are printed in sequence on a PET substrate, and the substrate layer is arranged with wires corresponding to the working electrode, reference electrode, and auxiliary electrode, which are covered with an insulating layer.

5. The method for online electronic tongue identification of tea oil quality during supercritical extraction according to claim 1, characterized in that: The valves are an air inlet valve and an air outlet valve; the autoclave body has a stirring device, a temperature control device, and is equipped with a pressure gauge.

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