Food detection method

Abstract

The invention relates to the field of detection, in particular to a food detection method which can determine heat conduction lag coefficients of a sample to be detected and a reference substance at previous moments for points corresponding to each target moment on a heat flow curve generated by a differential scanning calorimeter. The method comprises the following steps: determining the actual heat conducted to a to-be-detected sample and a reference substance at a target moment according to the heat quantity of the to-be-detected sample and the reference substance, calculating the actual heat flow to correct a heat flow curve, and judging the quality of the food by using the corrected heat flow curve, so that the hysteresis quality of the heat generated by the heater conducted to the sample and the reference substance is fully considered; the heat flow curve obtained through correction according to the method can better show the actual heat characteristics of the sample, and therefore accurate judgment on the quality of the sample can be achieved.

Description

Technical Field

[0001] This invention relates to the field of testing, and in particular to a method for testing food. Background Technology

[0002] Differential scanning calorimetry (DSC) is a technique that measures the difference in heat between a sample and a reference as a function of temperature or time. It can sensitively capture thermal events such as phase transitions, decomposition, oxidation, and solidification. In food testing, DSC is widely used for food component identification, quality evaluation, and safety assessment due to its advantages of speed, small sample volume, and quantitative analysis capabilities.

[0003] Currently, differential scanning calorimetry (DSC) is used to detect the heat in food, generating corresponding heat flow curves. These curves are then analyzed to determine the food's quality. However, the principle of DSC is to actively adjust the heating power of the heaters (each with its own heater for the sample and reference material) to maintain a consistent temperature. The heat flow of the sample is then reflected by the power difference between the two materials. However, because there is a certain heat conduction path between the heater and the sample / reference material, the heat generated by the heater lags behind the heat received at each moment. The actual heat received by the sample / reference material at each moment is the heat generated by the heater at previous moments. Therefore, the heating power collected at that moment cannot accurately represent the heat change of the sample / reference material. Consequently, the power difference calculated from the collected heat generation power cannot accurately reflect the heat flow of the sample, resulting in a deviation between the obtained heat flow curve and the actual heat flow. This makes it difficult to accurately characterize the thermal behavior of the sample and thus accurately determine its quality. Summary of the Invention

[0004] Therefore, it is necessary to provide a food testing method to address the above-mentioned problems.

[0005] The present invention is implemented as follows: a food testing method is provided, the method comprising:

[0006] S1: Take the target food of a set mass and pre-process it to obtain the sample to be tested;

[0007] S2: Place the sample to be tested in a differential scanning calorimeter for thermal detection;

[0008] S3: Retrieve the heat flow curve generated by the differential scanning calorimeter and identify the time corresponding to each point on the heat flow curve. The horizontal axis of each point on the heat flow curve is the time, and the vertical axis is the measured heat flow.

[0009] S4: For each point on the heat flow curve, take that time as the target time, determine the heat conduction hysteresis coefficient of the sample at each previous time, and determine the heat generation power of the heater corresponding to the sample at each previous time to determine the heat contribution of the sample at the target time, and obtain the first actual heat at the target time.

[0010] S5: Determine the heat conduction hysteresis coefficient corresponding to the reference at each previous moment, so as to determine the heat generation power of the heater corresponding to the reference at each previous moment to the heat contribution of the reference at the target moment, and obtain the second actual heat at the target moment.

[0011] S6: Subtract the second actual heat from the first actual heat to obtain the corrected heat flow at the target time. Replace the corresponding measured heat flow with this corrected heat flow to obtain the corrected heat flow curve.

[0012] S7: Obtain food testing results based on the corrected heat flow curve.

[0013] Preferably, determining the thermal hysteresis coefficient of the sample at previous times includes:

[0014] Obtain the temperature curve of the sample to be tested, where the horizontal axis of the temperature curve represents time and the scale is consistent with the horizontal axis scale of the heat flow curve, and the vertical axis represents the measured temperature of the sample to be tested.

[0015] The time preceding the target time is identified on the horizontal axis of the temperature curve of the sample under test;

[0016] Retrieve the time-temperature standard curve of the standard corresponding to the sample to be tested, and determine the fitting equation of the temperature of the sample to be tested versus the heat conduction hysteresis time based on the time-temperature standard curve.

[0017] For each prior time, determine the temperature of the sample to be tested corresponding to that prior time, and substitute the temperature of the sample to be tested into the fitting equation to obtain the heat conduction hysteresis time corresponding to that prior time.

[0018] Calculate the heat conduction lag coefficient at the earlier moment based on the heat conduction lag time.

[0019] Preferably, the fitting equation for determining the temperature of the sample under test versus the heat conduction hysteresis time based on the time-temperature standard curve includes:

[0020] Identify the length and corresponding temperature of each horizontal segment after the initial horizontal segment on the time-temperature standard curve, and obtain a fitted coordinate point with temperature on the horizontal axis and length on the vertical axis, where the length of the horizontal segment represents the heat conduction lag time.

[0021] Generate a coordinate system with temperature on the horizontal axis and heat conduction hysteresis on the vertical axis, and label each fitted coordinate point in this coordinate system;

[0022] Determine the temperature range within which the standard sample exhibits no thermal behavior;

[0023] Exclude coordinate points in the coordinate system that do not belong to the determined temperature range;

[0024] A fitting curve is generated based on the remaining coordinate points in the coordinate system, and the equation of the fitting curve is obtained.

[0025] Preferably, the steps for determining the time-temperature standard curve include:

[0026] Obtain the range of heat production power of the heater;

[0027] After the standard sample is placed into the differential scanning calorimeter, the corresponding heater is adjusted to operate at the minimum value of the heat production power range, and the corresponding time-temperature curve is generated in real time.

[0028] When the time-temperature curve is observed to rise and reach a horizontal range, the heat production power of the heater is increased by the set value. This step is repeated until the heat production power of the heater is increased to the upper limit of the heat production power range. The final time-temperature curve is the time-temperature standard curve.

[0029] Preferably, the heat conduction hysteresis coefficient is calculated using the following formula:

[0030]

[0031] Among them, t g For the target time, t x For the earlier time, h1(t) g , t x ) represents the sample to be tested at a prior time t x The thermal conduction hysteresis coefficient, τ1(t x ) represents the sample to be tested at a prior time t x The hysteresis time of heat conduction.

[0032] Preferably, determining the heat generation power of the heater corresponding to the sample at each previous moment as the heat contribution value of the sample at the target moment includes:

[0033] Retrieve the time-heat generation power curve of the sample under test during the detection process;

[0034] For each prior time t x Determine t on the time-heat generation power curve. x The corresponding heat generation power P1(t) of the sample under test x );

[0035] The following formula can be used to calculate the value of the sample at time t. x The heat generation power's contribution to the heat output of the sample at the target time:

[0036] C1(t g ,t x )=h1(t g ,t x )·P1(t x )

[0037] Among them, C1(t) g ,t x ) represents the sample to be tested at t x The heat generation power is the contribution of the sample to heat at the target time.

[0038] The first actual heat is calculated using the following formula:

[0039]

[0040] Where Q1(t) g ) represents the target time t g The corresponding first actual heat.

[0041] Preferably, the target time t g The corresponding second actual heat is expressed as:

[0042]

[0043] Among them, Q2(t) g ) represents the target time t g The corresponding second actual heat; C2(t) g ,t x ) as a reference at t x The heat generation power is the contribution of the sample to the heat at the target time, specifically expressed as:

[0044] C2(t g ,t x )=h2(t g ,t x )·P2(t x )

[0045] Among them, P2(t) x ) is the time-heat generation power curve determined during the reference material detection process. x The corresponding heat production power; h2(t) g ,t x (The reference is at a prior time t) x The heat conduction hysteresis coefficient is specifically expressed as:

[0046]

[0047] Wherein, τ2(t x (The reference is at a prior time t) x The hysteresis time of heat conduction.

[0048] Preferably, the corrected heat flow is calculated using the following formula:

[0049] Q cor (t g )=Q1(t g )-Q2(t g )

[0050] Among them, Q cor (t g ) for in t g Corrected heat flow.

[0051] This invention provides a food testing method. A target food sample of a predetermined weight is pre-treated to obtain a test sample. The test sample is then placed in a differential scanning calorimeter (DSC) for thermal detection. The heat flow curve generated by the DSC is retrieved, and the time corresponding to each point on the heat flow curve is identified. For each time point on the heat flow curve, this time is taken as the target time. The thermal conduction hysteresis coefficient corresponding to the test sample at previous times is determined to determine the heat contribution value of the heater corresponding to the test sample at each previous time point to the heat of the test sample at the target time, thus obtaining the first actual heat at the target time. The thermal conduction hysteresis coefficient corresponding to the reference material at previous times is determined to determine the heat contribution value of the heater corresponding to the reference material at each previous time point to the heat of the reference material at the target time, thus obtaining the second actual heat at the target time. The first actual heat is then subtracted from the second actual heat. The second actual heat is used to obtain the corrected heat flow rate at the target time. This corrected heat flow rate is then used to replace the corresponding measured heat flow rate, thereby obtaining the corrected heat flow rate curve. The food testing results are obtained based on the corrected heat flow rate curve. In this application, for each point on the heat flow rate curve generated by the differential scanning calorimeter corresponding to the target time, the heat conduction hysteresis coefficient of the sample and reference material at previous times can be determined, thereby determining the actual heat conducted to the sample and reference material at the target time. The actual heat flow rate is then calculated to correct the heat flow rate curve, and the quality of the food is then judged using the corrected heat flow rate curve. This method fully considers the hysteresis of the heat generated by the heater being conducted to the sample and reference material. The heat flow rate curve obtained by this method better reflects the actual thermal characteristics of the sample, thereby enabling accurate judgment of the sample quality. Attached Figure Description

[0052] Figure 1 This is a flowchart of a food testing method provided in one embodiment;

[0053] Figure 2This is a diagram illustrating the application environment of a food testing method provided in one embodiment.

[0054] Figure 3 This is a time-temperature standard curve of a food detection method provided in one embodiment. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0056] It is understood that the terms "first," "second," etc., used in this invention may be used to describe various elements herein, but unless specifically stated otherwise, these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this invention, a first script may be referred to as a second script, and similarly, a second script may be referred to as a first script.

[0057] like Figure 1 As shown, in one embodiment, a food testing method is proposed, the method comprising:

[0058] S1: Take the target food of a set mass and pre-process it to obtain the sample to be tested;

[0059] S2: Place the sample to be tested in a differential scanning calorimeter for thermal detection;

[0060] S3: Retrieve the heat flow curve generated by the differential scanning calorimeter and identify the time corresponding to each point on the heat flow curve. The horizontal axis of each point on the heat flow curve is the time, and the vertical axis is the measured heat flow.

[0061] S4: For each point on the heat flow curve, take that time as the target time, determine the heat conduction hysteresis coefficient of the sample at each previous time, and determine the heat generation power of the heater corresponding to the sample at each previous time to determine the heat contribution of the sample at the target time, and obtain the first actual heat at the target time.

[0062] S5: Determine the heat conduction hysteresis coefficient corresponding to the reference at each previous moment, so as to determine the heat generation power of the heater corresponding to the reference at each previous moment to the heat contribution of the reference at the target moment, and obtain the second actual heat at the target moment.

[0063] S6: Subtract the second actual heat from the first actual heat to obtain the corrected heat flow at the target time. Replace the corresponding measured heat flow with this corrected heat flow to obtain the corrected heat flow curve.

[0064] S7: Obtain food testing results based on the corrected heat flow curve.

[0065] In this embodiment, step S1 of the method is performed manually, and step S2 is performed manually by operating the differential scanning calorimeter; steps S3-S7 are performed by computer equipment, which can be an independent physical server or terminal, or a server cluster consisting of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud servers, cloud databases, cloud storage, and CDN; for example... Figure 2 As shown, the computer equipment is connected to the differential scanning calorimeter (DSC). The DSC includes a sample cell for holding the sample to be tested and a reference cell for holding the reference material. Each of the sample and reference cells has a heater underneath to heat the sample and reference material to maintain a consistent temperature. Temperature sensors are installed in both the sample and reference cells to monitor the temperature of the sample and reference material. The DSC can adjust the temperature of the two heaters according to the monitored temperature to keep the temperature of the sample and reference material consistent.

[0066] In this embodiment, the food being tested can be a solid food, such as beef or pork; or a liquid / paste-like food, such as milk, cooking oil, or jam. Different pretreatment methods are used for different forms of food. For example, for solid foods, a high-speed tissue homogenizer or cryogenic grinder (for heat-sensitive components) is used to pulverize them into uniform powder or fine particles with a particle size of <1mm. If the sample contains a large amount of fiber, it needs to be repeatedly ground and passed through an 80-100 mesh sieve to remove coarse and hard impurities. If the sample contains free water (which easily interferes with the thermal effect), it can be vacuum dried at 50-60℃ or freeze-dried to reduce the moisture content to below 5%. After drying, it is placed in a desiccator to cool and prevent moisture absorption. If a specific moisture content needs to be retained, deionized water is added according to the target content, and the sample is refrigerated at 4℃ for 24-48 hours to equilibrate. Volatile impurities (such as flavorings) can be removed by vacuum drying at room temperature for 1-2 hours. High-salt / high-sugar crystals need to be ground until dissolved or dispersed. If separate analysis is required... For certain components (such as fats and proteins), purification is first achieved through Soxhlet extraction, defatting, and enzymatic hydrolysis. Finally, 3-10 mg of the treated sample is taken (3-5 mg for strong thermal effects, 8-10 mg for weaker effects). The powder is gently compacted to ensure close contact with the bottom of the sample cell. Block samples are cut into small cubes with sides <3 mm to fit the sample cell. For liquid samples, a magnetic stirrer or ultrasonic oscillator is used for 5-10 minutes to eliminate stratification (such as separation of oils and water phases) or agglomeration of suspended particles, ensuring uniform composition. When specific moisture needs to be retained, deionized water is precisely calculated and added, and the sample is refrigerated at 4°C for 24-48 hours in a sealed container to ensure uniform moisture distribution. For samples containing low-boiling-point volatile impurities (such as alcohol and fragrances), vacuum drying at room temperature for 1-2 hours or vacuum drying at 40°C can remove them. Finally, 5-8 μL of sample is precisely injected into the DSC sample cell using a microsyringe to avoid spillage and detector contamination.

[0067] In this embodiment, the reference material needs to meet the requirements of high thermal stability and no thermal effect within the test temperature range. Alpha-alumina, magnesium oxide, zirconium oxide, etc. can be selected.

[0068] In this embodiment, the differential scanning calorimeter calculates the real-time power difference by monitoring the heat generation power of the two heaters. This power difference is the real-time measured heat flow, which generates a heat flow curve. For each target time, due to the lag in heat conduction, this heat flow curve cannot accurately represent the actual heat flow of the sample at the target time. The actual heat flow is the cumulative sum of the heat generated by the heaters at previous times that is conducted to the sample at the target time (the larger the interval between the heat generation time and the target time, the smaller this portion of heat). In this embodiment, the heat conduction lag coefficient at times before the target time can be determined for both the sample and the reference material. This allows for the determination of the heat generated by the heaters at previous times that is conducted to the sample and reference material at the target time, thus accurately determining the actual heat conducted to the sample and reference material at the target time. This allows for the determination of the accurate heat flow at the target time, and the correction of the heat flow at that time. Each time can be used as a target time, thereby enabling the correction of the entire heat flow curve.

[0069] In this embodiment, food testing results are obtained based on the corrected heat flow curve, i.e., food quality is judged based on the corrected heat flow curve. The core is to compare the corrected heat flow curve with the "standard heat flow curve" of the same type of qualified food (which is also the curve obtained by correcting using this method). By analyzing the position, shape, area, and presence of abnormal peaks of characteristic thermal effects (such as phase transition, melting, decomposition, and oxidation peaks) in the curve, the purity, freshness, processing state, or adulteration of the food's components can be inferred. For example, the heat flow curve of qualified food in a specific temperature range (such as not reaching phase transition / Before the decomposition temperature, the sample curve should show a stable baseline without abnormal fluctuations. When the temperature reaches the characteristic heat effect temperature of a specific component in the food (such as oil, starch, or protein), a corresponding peak will appear (such as the endothermic peak of starch gelatinization, the endothermic peak of oil melting, and the endothermic peak of protein denaturation). If there is a difference between the sample curve and the standard curve, it indicates a quality problem. For example, the standard curve of oily foods (such as edible oil and nuts) has a clear and sharp endothermic melting peak (such as the melting peak of pure olive oil at approximately -6 to 0°C). If the position of this peak in the sample curve shifts (such as an increase in peak temperature), it may indicate the adulteration with high-melting-point saturated fats. If the peak temperature decreases (potentially indicating adulteration with low-melting-point mineral oil), the peak shape broadens (indicating uneven composition, possibly due to adulteration with multiple oils), or the peak area decreases (indicating reduced oil content, possibly due to adulteration with water / impurities), it indicates insufficient purity or adulteration. The protein denaturation endothermic peak (approximately 55–65°C) of fresh meat should be complete. If this peak appears prematurely in the sample curve (temperature below 50°C, possibly indicating meat spoilage and premature protein degradation) or disappears (due to overheating, complete protein denaturation, and loss of fresh meat characteristics), it suggests poor freshness. The gelatinization endothermic peak of starchy foods (such as flour and steamed buns) should also be present. The temperature range of approximately 55–70℃ is crucial. If this peak weakens or splits in the sample curve (potentially due to starch aging, such as in leftover steamed buns), or shifts to the back of the curve (potentially due to the addition of excessive anti-aging agents), it indicates poor processing quality or storage conditions. In addition, if abnormal peaks not present in the standard curve appear in the curve (such as an extra endothermic peak in the low-temperature region, which may indicate water addition leading to freezing; or an abnormal exothermic peak in the high-temperature region, which may indicate food oxidation and spoilage, such as the oxidative decomposition peaks produced by rancid oils), or if the baseline shifts overall (the sample contains volatile impurities, such as small molecules produced by mold), it also directly points to quality problems.

[0070] In this application, for each point corresponding to a target time on the heat flow curve generated by the differential scanning calorimeter, the thermal conduction hysteresis coefficient of the sample and reference material at previous times can be determined, thereby determining the actual heat conducted to the sample and reference material at the target time. The actual heat flow is then calculated to correct the heat flow curve, and the corrected heat flow curve is used to judge the quality of the food. This method fully considers the hysteresis of the heat generated by the heater being conducted to the sample and reference material. The heat flow curve obtained by this method can better reflect the actual thermal characteristics of the sample, thereby enabling accurate judgment of the sample quality.

[0071] As a preferred embodiment, determining the thermal hysteresis coefficient of the sample at previous times includes:

[0072] Obtain the temperature curve of the sample to be tested, where the horizontal axis of the temperature curve represents time and the scale is consistent with the horizontal axis scale of the heat flow curve, and the vertical axis represents the measured temperature of the sample to be tested.

[0073] The time preceding the target time is identified on the horizontal axis of the temperature curve of the sample under test;

[0074] Retrieve the time-temperature standard curve of the standard corresponding to the sample to be tested, and determine the fitting equation of the temperature of the sample to be tested versus the heat conduction hysteresis time based on the time-temperature standard curve.

[0075] For each prior time, determine the temperature of the sample to be tested corresponding to that prior time, and substitute the temperature of the sample to be tested into the fitting equation to obtain the heat conduction hysteresis time corresponding to that prior time.

[0076] Calculate the heat conduction lag coefficient at the earlier moment based on the heat conduction lag time.

[0077] The fitting equations for determining the temperature and heat conduction hysteresis of the sample under test based on the time-temperature standard curve include:

[0078] Identify the length and corresponding temperature of each horizontal segment after the initial horizontal segment on the time-temperature standard curve, and obtain a fitted coordinate point with temperature on the horizontal axis and length on the vertical axis, where the length of the horizontal segment represents the heat conduction lag time.

[0079] Generate a coordinate system with temperature on the horizontal axis and heat conduction hysteresis on the vertical axis, and label each fitted coordinate point in this coordinate system;

[0080] Determine the temperature range within which the standard sample exhibits no thermal behavior;

[0081] Exclude coordinate points in the coordinate system that do not belong to the determined temperature range;

[0082] A fitting curve is generated based on the remaining coordinate points in the coordinate system, and the equation of the fitting curve is obtained.

[0083] The steps for determining the time-temperature standard curve include:

[0084] Obtain the range of heat production power of the heater;

[0085] After the standard sample is placed into the differential scanning calorimeter, the corresponding heater is adjusted to operate at the minimum value of the heat production power range, and the corresponding time-temperature curve is generated in real time.

[0086] When the time-temperature curve is observed to rise and reach a horizontal range, the heat production power of the heater is increased by the set value. This step is repeated until the heat production power of the heater is increased to the upper limit of the heat production power range. The final time-temperature curve is the time-temperature standard curve.

[0087] In this embodiment, the standard is a qualified food product of the same type as the sample to be tested;

[0088] In this embodiment, as Figure 2 As shown, the horizontal axis of the time-temperature curve represents time, and the vertical axis represents temperature. The real-time generated time-temperature curve initially has an initial horizontal segment (the heater's temperature has not yet been conducted to the sample). Once the heat generated by the heater is conducted to the sample, the time-temperature curve begins to rise. When the time-temperature curve reaches another horizontal segment, it indicates that the sample has reached the steady-state temperature corresponding to the heater's current heat generation power. At this point, increasing the heat generation power by the set value (which can be 5% of the heat generation power range) will generate additional heat. However, due to the lag in the conduction of this additional heat to the sample, the time-temperature curve will remain horizontal. At this temperature for a certain period of time, the horizontal segment will extend by a certain length. When additional heat reaches the sample, the horizontal segment bends and continues to rise. Therefore, the length of the horizontal segment can characterize the heat conduction lag time of the heat generated by the heater to the sample. Furthermore, the heat conduction lag time will change with the temperature of the sample (as the temperature of the sample increases, the heat difference between it and the heater decreases, and the heat conduction efficiency also decreases). According to the method of this embodiment, the heat conduction lag time of the standard at each temperature can be determined, thereby enabling the fitting of the relationship between the heat conduction lag time and the sample temperature, i.e., the relationship characterized by the fitting equation.

[0089] In this embodiment, the temperature range in which no thermal behavior occurs in the standard is determined. First, the heat flow curve of the standard (the curve has been corrected by this method) is retrieved, and the time periods in which thermal behavior occurs are identified on the curve (such as the time periods corresponding to the melting peak and oxidation peak in the thermal curve). Then, the time periods outside the time periods in which thermal behavior occurs are determined on the time-temperature standard curve, that is, the time periods in which no thermal behavior occurs. Thus, the temperature range in which no thermal behavior occurs can be determined. Since the temperature of the sample will not change significantly after absorbing heat during the time periods in which thermal behavior occurs, this embodiment excludes the coordinate points of the time periods in which thermal behavior occurs, so that the fitted curve can more accurately characterize the relationship between the heat conduction hysteresis time and the sample temperature.

[0090] As a preferred embodiment, the heat conduction hysteresis coefficient is calculated using the following formula:

[0091]

[0092] Among them, t g For the target time, tx For the earlier time, h1(t) g , t x ) represents the sample to be tested at a prior time t x The thermal conduction hysteresis coefficient, τ1(t x ) represents the sample to be tested at a prior time t x The hysteresis time of heat conduction.

[0093] Determining the heat generation power of the heater corresponding to the sample at each previous time step, and the heat contribution of the sample at the target time, includes:

[0094] Retrieve the time-heat generation power curve of the sample under test during the detection process;

[0095] For each prior time t x Determine t on the time-heat generation power curve. x The corresponding heat generation power P1(t) of the sample under test x );

[0096] The following formula can be used to calculate the value of the sample at time t. x The heat generation power's contribution to the heat output of the sample at the target time:

[0097] C1(t g ,t x )=h1(t g ,t x )·P1(t x )

[0098] Among them, C1(t) g ,t x ) represents the sample to be tested at t x The heat generation power is the contribution of the sample to heat at the target time.

[0099] The first actual heat is calculated using the following formula:

[0100]

[0101] Where Q1(t) g ) represents the target time t g The corresponding first actual heat.

[0102] Target time t g The corresponding second actual heat is expressed as:

[0103]

[0104] Among them, Q2(t) g ) represents the target time t g The corresponding second actual heat; C2(t) g ,tx ) as a reference at t x The heat generation power is the contribution of the sample to the heat at the target time, specifically expressed as:

[0105] C2(t g ,t x )=h2(t g ,t x )·P2(t x )

[0106] Among them, P2(t) x ) is the time-heat generation power curve determined during the reference material detection process. x The corresponding heat production power; h2(t) g ,t x (The reference is at a prior time t) x The heat conduction hysteresis coefficient is specifically expressed as:

[0107]

[0108] Wherein, τ2(t x (The reference is at a prior time t) x The hysteresis time of heat conduction.

[0109] The corrected heat flux is calculated using the following formula:

[0110] Q cor (t g )=Q1(t g )-Q2(t g )

[0111] Among them, Q cor (t g ) for in t g Corrected heat flow.

[0112] In this embodiment, the start time of the differential scanning calorimeter is taken as time 0, t x The variable can be the target time t. g any time before; t x With t g The greater the difference, that is, the longer the time interval with the target time, the less heat generated can act on the sample at the target time, and therefore the smaller the corresponding heat conduction hysteresis coefficient.

[0113] In this embodiment, the horizontal axis of the time-heat generation power curve is time, and the vertical axis is heat generation power, which can characterize the real-time heat generation power of the heater during the detection process; the heat generation power at one time is equivalent to the instantaneous heat generation at one time, and the heat contribution value is the heat transferred to the sample at the target time by the instantaneous heat generation. The first actual heat obtained by integration is the cumulative sum of the heat contribution values ​​of the previous times.

[0114] In this embodiment, the determination method for the thermal conduction hysteresis time and thermal conduction hysteresis coefficient of the reference material is the same as that for the sample to be tested, specifically:

[0115] Determining the thermal hysteresis coefficients of the reference material at previous time points includes:

[0116] Obtain the reference temperature curve, where the horizontal axis of the reference temperature curve represents time, and the scale is consistent with the horizontal axis scale of the heat flow curve; the vertical axis represents the measurement temperature of the reference.

[0117] The time preceding the target time is identified on the horizontal axis of the reference temperature curve;

[0118] Retrieve the time-temperature standard curve of the reference standard to determine the fitting equation of the temperature of the reference and the heat conduction hysteresis time based on the time-temperature standard curve;

[0119] For each prior time, determine the reference temperature corresponding to that prior time, and substitute that reference temperature into the fitting equation to obtain the heat conduction hysteresis time corresponding to that prior time;

[0120] Calculate the heat conduction lag coefficient at the earlier moment based on the heat conduction lag time.

[0121] The fitting equations for the temperature of the reference material versus the heat conduction hysteresis time, determined based on the time-temperature standard curve, include:

[0122] Identify the length and corresponding temperature of each horizontal segment after the initial horizontal segment on the time-temperature standard curve, and obtain a fitted coordinate point with temperature on the horizontal axis and length on the vertical axis, where the length of the horizontal segment represents the heat conduction lag time.

[0123] Generate a coordinate system with temperature on the horizontal axis and heat conduction hysteresis on the vertical axis, and label each fitted coordinate point in this coordinate system;

[0124] Determine the temperature range within which the standard sample exhibits no thermal behavior;

[0125] Exclude coordinate points in the coordinate system that do not belong to the determined temperature range;

[0126] A fitting curve is generated based on the remaining coordinate points in the coordinate system, and the equation of the fitting curve is obtained.

[0127] The steps for determining the time-temperature standard curve include:

[0128] Obtain the range of heat production power of the heater;

[0129] After the standard sample is placed into the differential scanning calorimeter, the corresponding heater is adjusted to operate at the minimum value of the heat production power range, and the corresponding time-temperature curve is generated in real time.

[0130] When the time-temperature curve is observed to rise and reach a horizontal range, the heat production power of the heater is increased by the set value. This step is repeated until the heat production power of the heater is increased to the upper limit of the heat production power range. The final time-temperature curve is the time-temperature standard curve.

[0131] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A food testing method, characterized in that, The method includes: S1: Take the target food of a set mass and pre-process it to obtain the sample to be tested; S2: Place the sample to be tested in a differential scanning calorimeter for thermal detection; S3: Retrieve the heat flow curve generated by the differential scanning calorimeter and identify the time corresponding to each point on the heat flow curve. The horizontal axis of each point on the heat flow curve is the time, and the vertical axis is the measured heat flow. S4: For each point on the heat flow curve, take that time as the target time, determine the heat conduction hysteresis coefficient of the sample at each previous time, and determine the heat generation power of the heater corresponding to the sample at each previous time to determine the heat contribution of the sample at the target time, and obtain the first actual heat at the target time. S5: Determine the heat conduction hysteresis coefficient corresponding to the reference at each previous moment, so as to determine the heat generation power of the heater corresponding to the reference at each previous moment to the heat contribution of the reference at the target moment, and obtain the second actual heat at the target moment. S6: Subtract the second actual heat from the first actual heat to obtain the corrected heat flow at the target time. Replace the corresponding measured heat flow with this corrected heat flow to obtain the corrected heat flow curve. S7: Obtain food testing results based on the corrected heat flow curve.

2. The method according to claim 1, characterized in that, Determining the thermal hysteresis coefficients of the sample at previous time points includes: Obtain the temperature curve of the sample to be tested, where the horizontal axis of the temperature curve represents time and the scale is consistent with the horizontal axis scale of the heat flow curve, and the vertical axis represents the measured temperature of the sample to be tested. The time preceding the target time is identified on the horizontal axis of the temperature curve of the sample under test; Retrieve the time-temperature standard curve of the standard corresponding to the sample to be tested, and determine the fitting equation of the temperature of the sample to be tested versus the heat conduction hysteresis time based on the time-temperature standard curve. For each prior time, determine the temperature of the sample to be tested corresponding to that prior time, and substitute the temperature of the sample to be tested into the fitting equation to obtain the heat conduction hysteresis time corresponding to that prior time. Calculate the heat conduction lag coefficient at the earlier moment based on the heat conduction lag time.

3. The method according to claim 2, characterized in that, The fitting equations for determining the temperature and heat conduction hysteresis of the sample under test based on the time-temperature standard curve include: Identify the length and corresponding temperature of each horizontal segment after the initial horizontal segment on the time-temperature standard curve, and obtain a fitted coordinate point with temperature on the horizontal axis and length on the vertical axis, where the length of the horizontal segment represents the heat conduction lag time. Generate a coordinate system with temperature on the horizontal axis and heat conduction hysteresis on the vertical axis, and label each fitted coordinate point in this coordinate system; Determine the temperature range within which the standard sample exhibits no thermal behavior; Exclude coordinate points in the coordinate system that do not belong to the determined temperature range; A fitting curve is generated based on the remaining coordinate points in the coordinate system, and the equation of the fitting curve is obtained.

4. The method according to claim 3, characterized in that, The steps for determining the time-temperature standard curve include: Obtain the range of heat production power of the heater; After the standard sample is placed into the differential scanning calorimeter, the corresponding heater is adjusted to operate at the minimum value of the heat production power range, and the corresponding time-temperature curve is generated in real time. When the time-temperature curve is observed to rise and reach a horizontal range, the heat production power of the heater is increased by the set value. This step is repeated until the heat production power of the heater is increased to the upper limit of the heat production power range. The final time-temperature curve is the time-temperature standard curve.

5. The method according to claim 2, characterized in that, The heat conduction hysteresis coefficient is calculated using the following formula: Among them, t g For the target time, t x For the earlier time, h1(t) g , t x ) represents the sample to be tested at a prior time t x The thermal conduction hysteresis coefficient, τ1(t x ) represents the sample to be tested at a prior time t x The hysteresis time of heat conduction.

6. The method according to claim 5, characterized in that, Determining the heat generation power of the heater corresponding to the sample at each previous time step, and the heat contribution of the sample at the target time, includes: Retrieve the time-heat generation power curve of the sample under test during the detection process; For each prior time t x Determine t on the time-heat generation power curve. x The corresponding heat generation power P1(t) of the sample under test x ); The following formula can be used to calculate the value of the sample at time t. x The heat generation power's contribution to the heat output of the sample at the target time: C1(t g ,t x )=h1(t g ,t x )·P1(t x ) Among them, C1(t) g ,t x ) represents the sample to be tested at t x The heat generation power is the contribution of the sample to heat at the target time. The first actual heat is calculated using the following formula: Where Q1(t) g ) represents the target time t g The corresponding first actual heat.

7. The method according to claim 6, characterized in that, Target time t g The corresponding second actual heat is expressed as: Among them, Q2(t) g ) represents the target time t g The corresponding second actual heat; C2(t) g ,t x ) as a reference at t x The heat generation power is the contribution of the sample to the heat at the target time, specifically expressed as: C2(t g ,t x )=h2(t g ,t x )·P2(t x ) Among them, P2(t) x ) is the time-heat generation power curve determined during the reference material detection process. x The corresponding heat production power; h2(t) g ,t x (The reference is at a prior time t) x The heat conduction hysteresis coefficient is specifically expressed as: Wherein, τ2(t x (The reference is at a prior time t) x The hysteresis time of heat conduction.

8. The method according to claim 7, characterized in that, The corrected heat flux is calculated using the following formula: Q cor (t g )=Q1(t g )-Q2(t g ) Among them, Q cor (t g ) for in t g Corrected heat flow.

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