Method for calculating service life of olive oil based on thermal decomposition reaction dynamic equation

Abstract

The invention relates to the field of food science, and discloses a method for calculating the service life of olive oil based on a thermal decomposition reaction dynamic equation, and the method comprises the following steps: S1, at different heating rates, carrying out thermal analysis on an olive oil sample to obtain a thermal weight loss and differential thermal analysis curve of the olive oil sample; s2, calculating peak top temperatures at different heating rates; s3, respectively calculating the activation energy of the olive oil by using an Ozawa method and a Kissinger method; and S4, separating variable integrals from the thermal analysis kinetic equation, and calculating the oxidation life of the olive oil at different temperatures. According to the method, differential thermal-thermogravimetric analysis (TG / DTA) is combined with kinetic calculation of an Ozawa method and a Kissinger method, so that a more accurate way for predicting the oxidation stability of the olive oil is provided, and edible oil manufacturers and consumers can better understand the storage potential and the quality retention time of products.

Description

Technical Field

[0001] The invention relates to the field of food science and technology, and in particular to a method for estimating the shelf life of olive oil based on a thermal decomposition reaction kinetic equation. Background Art

[0002] When considering the storage and shelf life of olive oil, several key technical challenges are often faced. First, as a widely consumed edible oil, the maintenance of its quality and nutritional value is extremely important to consumers. However, olive oil is susceptible to oxidation during storage, which can lead to a decline in oil quality and affect taste, nutrition and safety. Traditional storage methods and standards usually rely on empirical rules and do not fully consider the actual oxidation kinetic behavior of oils under different conditions.

[0003] Secondly, although various preservation technologies and packaging methods are used in the prior art to extend the shelf life of olive oil, these methods often focus on physical and chemical protection measures, such as light protection and oxygen protection. These methods can delay the oxidation process of olive oil to a certain extent, but still fail to provide a scientific method to accurately predict its shelf life under specific storage conditions. In addition, these traditional methods cannot quantify the specific impact of different storage conditions on the oxidation rate of oil products, and therefore have limitations in providing precise usage guidance.

[0004] Finally, although thermal analysis techniques have been successfully applied to predict the stability and life of materials in other fields, applying these techniques to the evaluation of the oxidative stability of edible oils still faces challenges. In particular, the methods of combining these techniques with reaction kinetic models are not mature enough in practice and require more innovation and technological development. Therefore, it is particularly important to develop a method that can combine thermal analysis data and kinetic equations to accurately predict the shelf life of olive oil under different conditions, which will help scientifically manage the storage and use of olive oil and ultimately improve consumer satisfaction and the market competitiveness of products. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for estimating the shelf life of olive oil based on the kinetic equation of thermal decomposition reaction, which solves the problem of inaccurate prediction of the storage and shelf life of olive oil and other edible oils.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for estimating the shelf life of olive oil based on the thermal decomposition reaction kinetic equation, comprising the following steps:

[0007] Thermal analysis of olive oil samples was performed at different heating rates to obtain their thermogravimetric and differential thermal analysis curves.

[0008] Calculate the peak temperature at different heating rates;

[0009] The activation energy of olive oil was calculated using the Ozawa method and the Kissinger method respectively;

[0010] The thermal analysis kinetic equation was separated and integrated to estimate the oxidation life of olive oil at different temperatures.

[0011] Preferably, the heating rates used in the step of thermally analyzing the olive oil sample are 2, 5, 10 and 20 K / min.

[0012] Preferably, the temperature range of the thermal analysis is 25°C to 600°C.

[0013] Preferably, the step of thermally analyzing the olive oil sample is performed under static air conditions.

[0014] Preferably, the method for calculating activation energy using the Ozawa method comprises the following steps:

[0015] The peak temperature was measured at different heating rates;

[0016] Using the formula Calculate, where β is the heating rate, in K / min; A is the pre-exponential factor; E is the activation energy, in kJ / mol; R is the gas constant, 8.314 J / (K·mol); T is the absolute temperature of the peak temperature, in K, and G(α) is the conversion function;

[0017] By plotting logβ against , and perform linear fitting to calculate the activation energy E.

[0018] Preferably, the method for calculating activation energy (E) using the Kissinger method comprises the following steps:

[0019] The peak temperature was measured at different heating rates;

[0020] According to the formula Calculate, where β i is the heating rate, in K / min; T pi is the peak temperature at this heating rate, in K; A is the pre-exponential factor; E is the activation energy, in kJ / mol; R is the gas constant 8.314 J / (K·mol);

[0021] By drawing right , and perform a linear fit to obtain the activation energy E from the slope of the straight line.

[0022] Preferably, estimating the olive oil oxidation lifespan comprises the following steps:

[0023] Using the thermal analysis kinetic equation Where a is the conversion rate of the reaction; t is the reaction time; A is the pre-exponential factor; E is the activation energy, in kJ / mol; R is the gas constant 8.314 J / (K·mol); T is the reaction temperature, in K, and n is the reaction order;

[0024] The heating rate Substituting in, we get

[0025] The oxidation life of olive oil was estimated at different temperatures through integral calculation.

[0026] The present invention also provides a device for estimating the use period of olive oil based on the thermal decomposition reaction kinetic equation, comprising:

[0027] A differential thermal-thermogravimetric simultaneous determination device is used to perform thermal analysis of olive oil samples at different heating rates;

[0028] A data processing unit for receiving and processing thermal analysis data and calculating the peak temperature and activation energy of olive oil;

[0029] Analytical unit for estimating the oxidation lifetime of olive oil using the thermoanalysis kinetic equation.

[0030] The present invention also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the above method is implemented.

[0031] The present invention also provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the method described above is implemented.

[0032] The invention provides a method for estimating the service life of olive oil based on a thermal decomposition reaction kinetic equation.

[0033] It has the following beneficial effects:

[0034] 1. The method of the present invention provides a more accurate way to predict the oxidative stability of olive oil by combining differential thermal-thermogravimetric analysis (TG / DTA) with kinetic calculations of the Ozawa method and the Kissinger method. This accurate prediction helps edible oil producers and consumers better understand the storage potential and quality retention time of the product.

[0035] 2. The method of the present invention can predict the oxidation life of olive oil under different temperature conditions at an early stage, thereby providing a scientific basis for the storage, packaging and sales strategies of olive oil. This prediction helps to optimize the storage conditions of olive oil, such as recommending storage at a lower temperature and in an environment with reduced air contact, significantly extending its service life after opening. This can not only reduce the waste of edible oil, but also maintain the freshness and nutritional value of the oil.

[0036] 3. The method provided by the present invention enables food manufacturers to more accurately label the best use date and storage conditions of edible oils, which directly enhances the food safety and quality management of products. With scientific data support, consumers can get clear guidance on how to properly store and use olive oil, thereby avoiding quality degradation and potential health risks caused by improper storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0038] Figure 2 The heating rate of the embodiment of the present invention is 20K·min -1 Schematic diagram of thermal decomposition curve of olive oil;

[0039] Figure 3 The heating rate of the embodiment of the present invention is 10K·min -1 Schematic diagram of thermal decomposition curve of olive oil;

[0040] Figure 4 The heating rate of the embodiment of the present invention is 5K·min -1 Schematic diagram of thermal decomposition curve of olive oil;

[0041] Figure 5 The heating rate of the embodiment of the present invention is 2K·min -1 Schematic diagram of thermal decomposition curve of olive oil;

[0042] Figure 6 This is a combined diagram of DTA curves of thermal decomposition of olive oil at different heating rates according to an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram of numerical linear fitting of the Ozawa kinetic equation according to an embodiment of the present invention;

[0044] Figure 8 This is a schematic diagram of numerical linear fitting of the Kissiger kinetic equation according to an embodiment of the present invention;

[0045] Fig. 9 It is a schematic diagram of the structure of the device of the present invention;

[0046] Fig.10It is a schematic diagram of the computer device structure of the present invention.

[0047] Among them, 10, differential thermal-thermogravimetric simultaneous measurement device; 20, data processing unit; 30, analysis unit; 40, computer equipment; 41, processor; 42, memory; 43, storage medium. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Please see attached Figure 1 An embodiment of the present invention provides a method for estimating the shelf life of olive oil based on the kinetic equation of thermal decomposition reaction. The method uses thermal analysis technology to evaluate the physical and chemical changes of olive oil during heating, and combines kinetic equations to predict its oxidative life under different storage conditions, thereby providing a scientific basis for the storage and use of olive oil.

[0050] Specifically, the method comprises the following steps:

[0051] S1. Thermal analysis experiment

[0052] In this step, a thermal analysis of the olive oil sample is performed using a differential thermal-thermogravimetric simultaneous determination device (such as Shimadzu DTG-60). First, the olive oil sample is accurately weighed to 2 to 3 mg and placed in a ceramic crucible. The experiment was carried out in a static air environment, with the heating rates set to 2, 5, 10 and 20 K / min, and the temperature range controlled at 25°C to 600°C. Under these conditions, the thermogravimetric (TG) and differential thermal analysis (DTA) curves of the olive oil sample can be obtained. The TG curve reflects the mass loss of the sample as the temperature changes, while the DTA curve reveals the changes in energy absorption or release of the sample during heating.

[0053] S2. Calculation of peak temperature

[0054] According to the DTA curve obtained in step S1, calculate the peak temperature T at different heating rates P The peak temperature refers to the temperature at which the reaction rate reaches its maximum value in the DTA curve, which is a key parameter for evaluating the thermal stability of olive oil.

[0055] S3. Calculation of activation energy

[0056] The activation energy E of olive oil was calculated using the Ozawa method and the Kissinger method. The Ozawa method is based on the formula:

[0057]

[0058] Plotting logβ against The activation energy E is calculated from the slope of the straight line. Where β is the heating rate in K / min; A is the pre-exponential factor; E is the activation energy in kJ / mol; R is the gas constant, 8.314 J / (K·mol); T is the absolute temperature of the peak temperature in K, and G(α) is the conversion function. The Kissinger method uses the formula:

[0059]

[0060] Also by drawing right The slope of the graph is analyzed to obtain the activation energy E. i is the heating rate, in K / min; T pi is the peak temperature at this heating rate, in K; A is the pre-exponential factor; E is the activation energy, in kJ / mol; R is the gas constant, 8.314 J / (K·mol).

[0061] These activation energy data provide a quantitative assessment of the thermal stability of olive oil and aid in further analysis and prediction.

[0062] S4. Calculation of oxidation life

[0063] According to the thermal analysis kinetic equation:

[0064]

[0065] Where a is the conversion rate of the reaction; t is the reaction time; A is the pre-exponential factor; E is the activation energy, in kJ / mol; R is the gas constant 8.314 J / (K·mol); T is the reaction temperature, in K, and n is the reaction order.

[0066] Here, the activation energy E and the frequency factor A (obtained from the Kissinger method) are substituted into the equation. Assuming that the oxidation process is a first-order reaction (i.e., n=1), the expected oxidation lifetime of olive oil at different temperatures is obtained by separation and integration of variables. This calculation is based on the behavior of olive oil at the peak temperature to estimate its oxidative stability under low temperature storage conditions.

[0067] The method of the present invention can provide olive oil producers and consumers with a scientific basis for the storage conditions and shelf life of the oil. By accurately predicting the oxidation life of olive oil under different temperature conditions, it helps to formulate a more effective storage strategy, thereby extending the service life of olive oil, reducing waste, and ensuring product quality.

[0068] Example:

[0069] This embodiment provides a method for estimating the shelf life of olive oil based on the thermal decomposition reaction kinetic equation. The method predicts the oxidation life of olive oil at different temperatures by thermal analysis combined with kinetic calculation. The method utilizes differential thermal-thermogravimetric analysis (TG / DTA) technology, combined with the Ozawa method and the Kissinger method to calculate the activation energy of olive oil, and thereby derives the expected shelf life of olive oil under different temperature conditions.

[0070] Experimental Section

[0071] Sample and instrument setup

[0072] Sample: Olive oil purchased from a supermarket, 2 to 3 mg was measured into a ceramic crucible.

[0073] Instrument: Shimadzu differential thermal and thermogravimetric simultaneous measurement device DTG-60, capable of recording TG and DTA curves simultaneously.

[0074] Experimental conditions:

[0075] Sample weight: 2mg~3mg.

[0076] Atmospheric conditions: static air.

[0077] Heating rate: 2, 5, 10, 20 K / min.

[0078] Temperature range: 25~600℃.

[0079] Experimental data recording and analysis

[0080] Acquisition of TG and DTA curves: TG and DTA curves were collected at different heating rates, such as Figures 2 to 6 These graphs show the thermal decomposition curves of olive oil samples at different heating rates.

[0081] Kinetic equation processing and activation energy calculation

[0082] Ozawa method:

[0083] According to the heating rate (β) and peak temperature (T P ) data, and use the Ozawa equation to calculate the activation energy (E). The details are as follows:

[0084] According to the Ozawa formula,

[0085] Where: β——heating rate, K / min;

[0086] E——activation energy, K / min;

[0087] R——gas constant, 8.314 J / (K·mol);

[0088] T——absolute constant, K.

[0089] For different DTA curves, at the maximum reaction rate, i.e., the peak temperature T P At , the conversion rates of the samples are basically the same. A curve is obtained by plotting the slope of the straight line, and the activation energy E can be calculated.

[0090] The data used and the calculation results are summarized in Table 1.

[0091] Table 1 Data required for Ozawa formula

[0092] β(K / min) logβ <![CDATA[T P (K)]]> <![CDATA[1 / T P ]]> 20 1.30103 556.74 0.001796 10 1 526.97 0.001898 5 0.69897 508.51 0.001967 2 0.30103 475.76 0.002102

[0093] OriginPro7.0 software was used for linear fitting, and the results were as follows: Figure 7 shown.

[0094] We get: -0.4567E / R = -3318.83067, and solve for E = 60.418 kJ / mol.

[0095] Kissinger method:

[0096] Similarly, the same peak temperature data is processed using the Kissinger equation as follows:

[0097] According to the Kissiger formula,

[0098] Where: T pi ——Peak temperature, K.

[0099] and They are in a linear relationship. Plotting the two graphs gives a straight line. From the slope of the line, we can find E. k , find A from the intercept k , and its linear correlation is generally above 0.9.

[0100] The data used and the calculation results are summarized in Table 2.

[0101] Table 2 Data required for Kissiger formula

[0102]

[0103] OriginPro7.0 software was used for linear fitting, and the results were as follows: Figure 8 As shown. The formula is: ln[R·A / E]=2.248①

[0104] -E / R=-6616.187 ②

[0105] The solution is: A = 62671E = 55.006 kJ / mol

[0106] The comparison of activation energies of the two kinetic equations is shown in Table 3:

[0107] Table 3 Comparison of activation energies of two kinetic equations

[0108]

[0109] Oxidation life calculation:

[0110] The general equation for thermal analysis kinetics is:

[0111]

[0112] Where: a——rate of change

[0113] t——reaction time

[0114] A——Pre-exponential factor

[0115] n——reaction order

[0116] When n=1,

[0117] When the temperature rises linearly, β=dT / dt ③

[0118] Substituting ③ into ②, we get:

[0119] We can conduct micro-business on ④ and sort them out:

[0120] When the reaction reaches the maximum reaction rate (i.e. at the peak temperature T P At:

[0121] and

[0122] Then we get: E / (RT 2 )-(A / β)e -E / (RT) =0

[0123] Therefore, A=|(βE) / (RT P 2 )|e E / (RT) ⑥

[0124] Integrate the separated variables to get:

[0125] -ln(1-α)=A(e -E / (RT) ) ⑦

[0126] Take the logarithm of both sides of ⑦ and sort them out to get:

[0127] ln t=E / RT+ln[-ln(1-α)]-ln A ⑧

[0128] The reaction time t in ⑧ is the oxidation lifetime. ⑧ represents the relationship between the oxidation lifetime t and the activation energy E of the thermal oxidation reaction, the pre-exponential factor A and the rate of change α at temperature T.

[0129] ⑧ is derived under the assumption that the oxidation mechanism remains unchanged, and the oxidation reaction of edible olive oil reaches the maximum reaction rate (i.e., the peak temperature T P ), which can be approximately considered as a first-order reaction. Therefore, it can be assumed that h = 1, and the Ozawa method can be used to calculate the oxidation life of olive oil at different temperatures, as shown in Table 4.

[0130] Table 4 Oxidation life of olive oil at different temperatures in static air atmosphere (d-days)

[0131]

[0132] From the table above, we can see that when olive oil is opened and stored at 5°C, it will be oxidized after 264.2 days, which means the shelf life is 264.2 days. At 20°C, the shelf life is 69.2 days, at 30°C, the shelf life is 30.5 days, and at 40°C, the shelf life is only 13.8 days.

[0133] Therefore, only by keeping it at low temperatures and avoiding contact with air (in fact, isolating it from oxygen) can olive oil be preserved for a longer period of time.

[0134] This method provides a rapid and scientific evaluation method to effectively predict the oxidative stability of olive oil and other edible oils under different storage conditions, which has important economic and practical value for producers, transporters and consumers of edible oils.

[0135] The present invention provides an efficient and accurate prediction method for the oxidation life of olive oil by combining modern thermal analysis technology with kinetic theory. Through the disclosed experimental settings and data processing steps, technicians in this field can replicate this method and then evaluate the quality retention of olive oil under different conditions. This invention not only improves the scientific management level of edible oils and fats, but also provides a scientific basis for consumers to use.

[0136] Please see attached Fig. 9 The present invention also provides a device for estimating the use period of olive oil based on the thermal decomposition reaction kinetic equation, comprising:

[0137] A differential thermal-thermogravimetric simultaneous determination device 10 is used to perform thermal analysis on olive oil samples at different heating rates;

[0138] A data processing unit 20, for receiving and processing thermal analysis data, and calculating the peak temperature and activation energy of olive oil;

[0139] The analysis unit 30 is used to estimate the oxidation life of olive oil using a thermal analysis kinetic equation.

[0140] Please see attached Fig.10 The present invention further provides a computer device 40, comprising: a processor 41 and a memory 42, wherein the memory 42 stores a computer program executable by the processor, and when the computer program is executed by the processor, the above method is executed.

[0141] The present invention further provides a storage medium 43 on which a computer program is stored. When the computer program is run by the processor 41, the above method is executed.

[0142] Among them, the storage medium 43 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable red-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, disk or optical disk.

[0143] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for estimating the shelf life of olive oil based on the thermal decomposition reaction kinetic equation, characterized in that: The following steps are involved: Thermal analysis of olive oil samples was performed at different heating rates to obtain their thermogravimetric and differential thermal analysis curves. Calculate the peak temperature at different heating rates; The activation energy of olive oil was calculated using the Ozawa method and the Kissinger method respectively; The thermal analysis kinetic equation was separated and integrated to estimate the oxidation life of olive oil at different temperatures.

2. The method for estimating the use period of olive oil based on the thermal decomposition reaction kinetic equation according to claim 1, characterized in that: The heating rates used in the thermal analysis step of the olive oil samples were 2, 5, 10 and 20 K / min.

3. The method for estimating the use period of olive oil based on the thermal decomposition reaction kinetic equation according to claim 1, characterized in that: The temperature range of the thermal analysis is 25°C to 600°C.

4. The method for estimating the use period of olive oil based on the thermal decomposition reaction kinetic equation according to claim 1, characterized in that: The step of thermal analysis of the olive oil samples was performed under static air conditions.

5. The method for estimating the use period of olive oil based on the thermal decomposition reaction kinetic equation according to claim 1, characterized in that: The method for calculating activation energy using the Ozawa method comprises the following steps: The peak temperature was measured at different heating rates; Using the formula Calculate, where β is the heating rate, in K / min; A is the pre-exponential factor; E is the activation energy, in kJ / mol; R is the gas constant, 8.314 J / (K·mol); T is the absolute temperature of the peak temperature, in K, and G(α) is the conversion function; By plotting logβ against , and perform linear fitting to calculate the activation energy E.

6. The method for estimating the use period of olive oil based on the thermal decomposition reaction kinetic equation according to claim 1, characterized in that: The method for calculating activation energy (E) using the Kissinger method comprises the following steps: The peak temperature was measured at different heating rates; According to the formula Calculate, where β i is the heating rate, in K / min; T pi is the peak temperature at this heating rate, in K; A is the pre-exponential factor; E is the activation energy, in kJ / mol; R is the gas constant 8.314 J / (K·mol); By drawing right , and perform a linear fit to obtain the activation energy E from the slope of the straight line.

7. The method for estimating the shelf life of olive oil based on the thermal decomposition reaction kinetic equation according to claim 1, characterized in that: Calculating the olive oil oxidation life includes the following steps: Using the thermal analysis kinetic equation Where a is the conversion rate of the reaction; t is the reaction time; A is the pre-exponential factor; E is the activation energy, in kJ / mol; R is the gas constant 8.314 J / (K·mol); T is the reaction temperature, in K, and n is the reaction order; The heating rate Substituting in, we get The oxidation life of olive oil was estimated at different temperatures through integral calculation.

8. A device for estimating the shelf life of olive oil based on the thermal decomposition reaction kinetic equation, based on the method according to any one of claims 1 to 7, characterized in that: include: A differential thermal-thermogravimetric simultaneous determination device is used to perform thermal analysis of olive oil samples at different heating rates; A data processing unit for receiving and processing thermal analysis data and calculating the peak temperature and activation energy of olive oil; Analytical unit for estimating the oxidation lifetime of olive oil using the thermoanalysis kinetic equation.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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