Method for measuring the bitterness complex taste intensity of a liquid food product

Abstract

The application discloses a method for determining the bitterness and astringency compound taste intensity of liquid food, and belongs to the technical field of food measurement. The method comprises the following steps: (1) determining the composition and content of bitterness and astringency compound taste simulation solution of liquid food; (2) dividing the proportion of bitterness and astringency compounds in each sample into different groups, selecting one compound from the bitterness and astringency compounds, and establishing a bitterness and astringency compound taste intensity quantitative curve under each group; (3) determining the content and proportional relationship of the bitterness and astringency compounds in the liquid food to be measured, substituting the bitterness and astringency compound taste intensity quantitative curve under the corresponding proportional relationship, and calculating the bitterness and astringency compound taste intensity value of the liquid food to be measured. The method solves the technical problem that the bitterness and astringency compound taste intensity cannot be quantitatively described in the field of liquid food at present, can overall evaluate the bitterness and astringency of food, does not need to train sensory panelists, is high in accuracy, is wider in application range, and can better provide help for product development and popularization.

Description

Technical Field

[0001] This invention relates to the field of food measurement technology, and in particular to a method for determining the intensity of bitter and astringent complex taste in liquid foods. Background Technology

[0002] The content of bitter substances can affect consumers' perception of smell, touch, taste, and aftertaste. Since each consumer has a different tolerance for bitterness, they also have different preferences for the type and quality of liquid foods. Some people like the sweet aftertaste that follows bitterness and have an extreme craving for bitterness, while others like a sweet and sour taste and have a strong aversion to bitterness. Therefore, standardizing the intensity of bitterness in liquid foods and labeling it at the time of manufacture will help consumers choose the liquid foods that suit them best, and it will also help the food industry to develop standards to regulate the cultivation and processing processes.

[0003] Currently, there are two main methods for evaluating the bitterness of food: one is sensory evaluation by experts or consumers. This type of test requires a lot of human resources, and for factories, each test costs a lot of money. Moreover, the results can change depending on the taster's choice and condition. Although it can obtain the most direct data on the bitterness of green tea, it is not cost-effective. The other method is instrumental measurement. Currently, the bitterness sensor of electronic tongues can obtain signal values ​​focused on bitterness. However, the cross-sensitivity of the sensor, its high price, and the inability to directly connect with human senses limit the application of electronic tongues.

[0004] Of course, the content of bitter and astringent substances in food can also be used to determine this, but the level of content does not directly represent the direct sensory perception. Bitter and astringent substances interact in taste, thus changing the overall bitter and astringent experience. For example, flavonol glycosides and epigallocatechin gallate in green tea have a synergistic effect on the perception of bitterness from caffeine; the coexistence of caffeine enhances the bitterness and astringency of epigallocatechin gallate. Currently, most research on sensory evaluation focuses on the evaluation of single bitter and astringent tastes. However, the human brain processes taste information in an overlapping manner, so the psychophysical intensity of the taste corresponding to bitter and astringent substances needs to be clearly defined in order to directly convert the substance content into the equivalent intensity of a complex bitter and astringent taste. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the present invention aims to provide a method for determining the intensity of bitter and astringent complex tastes in liquid foods. This method establishes a quantitative formula for the bitter and astringent complex tastes in liquid foods, so that the intensity of the bitter and astringent complex taste can be equivalently determined based on the content of bitter and astringent compounds, providing a reference for producers and consumers. This method is objective, simple, rapid, and accurate.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for determining the intensity of bitter and astringent complex tastes in liquid foods, comprising the following steps:

[0008] Step 1: Determine the types and contents of bitter compounds and the total amount of other flavor components in each sample of liquid food.

[0009] Step 2: Calculate the taste activity value of each bitter and astringent compound component, and prepare several bitter and astringent complex taste simulation solutions with the same content of bitter and astringent compounds as in each sample. The bitter and astringent complex taste simulation solutions contain one or more bitter and astringent compounds determined in Step 1. The matrix of the bitter and astringent complex taste simulation solutions is composed of the representative compound with the highest content among the other taste components, and the content of the representative compound is equal to the total amount of the corresponding taste components.

[0010] Step 3: Conduct forced-choice sensory tests on both the liquid food and the bitter complex taste simulation solution to determine the optimal composition of bitter compounds in the bitter complex taste simulation solution based on the selection probability.

[0011] Step 4: Based on the proportion of the optimal composition of bitter and astringent compounds in each sample, divide the proportion into different groups, select one compound from the optimal composition of bitter and astringent compounds, and establish a quantitative curve of the bitter and astringent complex taste intensity for each group.

[0012] y = a * ln(xb) - c

[0013] Where a, b, and c are constants, x represents the initial concentration of the selected bitter compounds under each group ratio and the theoretical concentration calculated in each round of forced selection sensory test, and y represents the value of the bitter complex taste difference intensity point;

[0014] Step 7: Determine the content and ratio of the optimal composition of bitter and astringent compounds in the liquid food to be tested, substitute them into the quantitative curve of bitter and astringent complex taste intensity under the corresponding ratio, and calculate the bitter and astringent complex taste intensity value of the liquid food to be tested.

[0015] Preferably, the liquid food mentioned in step one is any one of tea, coffee, or a bitter-tasting fruit juice.

[0016] Preferably, the bitter compound mentioned in step one includes one or more of alkaloids, bitter amino acids, and polyphenols.

[0017] Preferably, the other flavor components mentioned in step one include one or more of sugars, organic acids, and umami amino acids.

[0018] Preferably, the taste activity value in step two is the ratio of the content of bitter compounds to the bitterness threshold, and bitter compounds with a taste activity value greater than 1 are screened.

[0019] Preferably, step three includes:

[0020] (1.1) Classify bitter and astringent compounds in liquid food according to taste category, and according to the order of taste activity value of bitter and astringent compounds in liquid food from small to large; under the premise of ensuring that the taste activity value is greater than 1 and that at least one compound exists in each taste, gradually eliminate the compound with the smallest taste activity value, and prepare several bitter and astringent compound complex taste simulation solutions containing different bitter and astringent compounds.

[0021] (1.2) Each liquid food sample solution and each bitter complex taste simulation solution were randomly arranged in pairs at room temperature and labeled with random three-digit numbers; a forced selection sensory test was conducted on the paired solutions, and the probability of the bitter complex taste simulation solution being selected in each group of experiments was recorded.

[0022] (1.3) Traverse all liquid food samples and count the number m of corresponding liquid food sample solutions with a selection probability of less than 75% and greater than 25% for each bitter and astringent complex taste simulation solution. The composition of the bitter and astringent complex taste simulation solution with the largest m value is taken as the optimal composition of bitter and astringent compounds. When there are at least two bitter and astringent complex taste simulation solutions with the largest m values, the composition of the bitter and astringent complex taste simulation solution with the fewest types of bitter and astringent compounds is taken as the optimal composition of bitter and astringent compounds.

[0023] Preferably, the taste classification in step (1.1) includes bitterness, astringency, and bitter-astringent taste.

[0024] Preferably, step four includes:

[0025] (2.1) Determine the content range of each compound based on the content of the bitter compounds obtained from screening in all samples;

[0026] (2.2) Based on the proportion of the optimal composition of bitter and astringent compounds obtained from screening in each sample, the proportions are divided into different groups;

[0027] (2.3) The lowest content of any bitter compound in the sample under each ratio relationship is taken as the starting concentration, and the bitter complex taste difference intensity point of the starting concentration is defined as 1.

[0028] (2.4) Prepare several bitter and astringent complex taste recombinant solutions for each set of proportions: Based on the initial concentration of the selected bitter and astringent compound, prepare the first recombinant solution according to the set of proportions, and use the logarithmic series as the interval for content growth to prepare bitter and astringent complex taste recombinant solutions with different contents of bitter and astringent compounds under each set of proportions.

[0029] (2.5) The first group of bitter complex taste recombinant solutions and the remaining recombinant solutions are randomly arranged in pairs at room temperature according to the order of content from low to high and labeled with random three-digit numbers; the forced selection sensory test is carried out on the pairs of solutions in sequence and the probability of the first group of bitter complex taste recombinant solutions being selected in each group of experiments is recorded until the probability value recorded in the forced selection sensory test of the m group of solutions is less than or equal to 25% and the content of the selected bitter taste compound in the m group of recombinant solutions is recorded as Cm;

[0030] (2.6) Increment the bitterness complex taste difference intensity point by one, and calculate the theoretical concentration C of the selected bitterness compound corresponding to the new difference intensity point:

[0031]

[0032] Among them, C m-1 This indicates the content of the selected bitter compounds in the m-1th group of recombinant solutions;

[0033] (2.7) Take the theoretical concentration corresponding to the new bitter and astringent complex taste difference intensity point calculated in step (2.6) as the starting concentration for the next round, return to step (2.4) and determine whether the content of compounds in the first recombinant solution prepared in step (2.4) meets the content range of bitter and astringent compounds in step (2.1). If it meets the requirements, continue; otherwise, execute step (2.8).

[0034] (2.8) The initial concentration of the selected bitter and astringent compounds under each group ratio and the theoretical concentration calculated by each round of forced selection sensory test are used as the abscissa, and the value of the bitter and astringent complex taste difference intensity point is used as the ordinate. The quantitative curve of bitter and astringent complex taste intensity under each group ratio is obtained by fitting.

[0035] Preferably, in the two-stage forced sensory test, the tasting order needs to be changed between two adjacent tests.

[0036] Preferably, in step seven, based on the ratio of the optimal composition of bitter and astringent compounds in the liquid food to be tested, the quantitative curve of the bitter and astringent complex taste intensity corresponding to the ratio closest to it is selected and substituted into the calculation.

[0037] The present invention has the following beneficial effects:

[0038] (1) The method of the present invention can obtain the specific bitter and astringent complex taste intensity value based only on the content of bitter and astringent substances in the food, instead of the trend of increasing or decreasing single bitter and astringent taste intensity as in the prior art.

[0039] (2) This invention does not require training of subjects, does not require a large number of evaluators, has a short detection time for each sample, is simple and easy to operate, and the detection results are objective and reliable, thus having high application value. Attached Figure Description

[0040] Figure 1 A flowchart of a method for determining the intensity of bitter and astringent complex taste in liquid foods.

[0041] Figure 2 Quantitative curves of the bitter and astringent complex taste intensity of green tea under different caffeine concentrations (a: groups 1-4; b: groups 5-7; c: groups 8-10; d: groups 11-14).

[0042] Figure 3 The graph (a) shows the linear regression analysis of the bitterness and astringency values ​​of green tea obtained from the quantitative curve of the complex bitterness and astringency taste intensity of green tea selected based on the ratio of caffeine to epigallocatechin gallate to quercetin rutin, and the bitterness and astringency values ​​obtained from the traditional scaling method. The graph (b) shows the linear regression analysis of the bitterness and astringency values ​​of green tea obtained from the quantitative curve of the complex bitterness and astringency taste intensity of green tea selected based on the ratio of caffeine to epigallocatechin gallate to quercetin rutin. Detailed Implementation

[0043] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] The experimental procedure is as follows Figure 1 As shown.

[0046] A total of 43 green tea experimental samples were collected: 11 modeling samples and 32 validation samples. Specific sample information is shown in Table 1 and Table 2.

[0047] Table 1. Sample Information for Modeling

[0048]

[0049] Table 2 Verification Sample Information

[0050]

[0051] The green tea sample was prepared as follows: the tea leaves were crushed into particles that could pass through a 16-mesh sieve but not a 20-mesh sieve. 1 gram of tea leaves and 100 ml of 95°C ultrapure water were added to a 440 ml tea bowl. The mixture was stirred with a magnetic stirrer at 300 rpm for 1 minute and then filtered.

[0052] Theanine, sucrose, and citric acid account for more than 50% of the total free amino acids, total sugars, and organic acids. Therefore, the matrix of the green tea simulated bitterness solution is composed of theanine (fresh), sucrose (sweet), and citric acid (acid). The free amino acid content was determined by a total free amino acid kit, the sugar content by a total sugar kit, and the organic acid content by GB5009.157-2016. The free amino acid, total sugar, and organic acid contents of each green tea sample are listed in Table 3. The average values ​​are used as the matrix of the green tea simulated bitterness solution for final modeling: theanine (21.77 mg / L), sucrose (96.65 mg / L), and citric acid (475.5 mg / L).

[0053] Table 3. Content of total phenols, total free amino acids, total sugars and organic acids in green tea

[0054]

[0055] The determination of bitter and astringent compounds in green tea was performed using liquid chromatography: a C18 column (250 mm × 4.6 mm), an injection volume of 10 μL, mobile phase A of 0.1% formic acid aqueous solution, and mobile phase B of acetonitrile, with a flow rate of 1 mL / min and gradient elution: 0–2 min, 5% B; 2–8 min, 5–13% B; 8–22 min, 13–28% B; 22–25 min, 28–95% B; column temperature 35℃; UV-Vis detector; detection wavelengths of alkaloids, gallic acid, and catechins at 278 nm, and flavonol glycosides at 360 nm. The specific compound contents are listed in Table 4.

[0056] Twenty experienced sensory evaluators (nine men and eleven women, aged 18–28 years) passed a screening test and, after being informed of the purpose of the study, received two weeks of training in a forced-choice test. All sensory evaluators were not allowed to have cold symptoms, smoke, or eat for at least one hour before the test.

[0057]

[0058] Table 4. Content and threshold values ​​of bitter and astringent compounds in tea

[0059] Note: Threshold A is the astringency threshold; threshold B is the bitterness threshold.

[0060] First, determining the composition of bitter and astringent compounds in the green tea bitter and astringent complex taste simulation solution involves the following steps:

[0061] Step 1: Ensuring that each taste category contains at least one compound, compounds in green tea were progressively eliminated according to their bitterness / astringency activity values ​​from smallest to largest, preparing multiple sets of green tea bitterness / astringency complex taste simulation solutions (the matrix of which had the same content of theanine, sucrose, and citric acid as the corresponding green tea). Green tea bitterness / astringency complex taste simulation solution 1 consisted of all bitterness / astringency compounds with a taste activity value greater than 1. Subsequently, bitterness / astringency compounds were progressively eliminated, creating new green tea bitterness / astringency complex taste simulation solutions 2-8 (as shown in Table 5).

[0062] Step 2: Provide the green tea bitter and astringent complex taste simulation solution and the corresponding green tea sample to the sensory evaluators (with nose clips) in random order at room temperature. Each cup contains 20 ml of solution and is placed in a 50 ml paper cup (labeled with a random three-digit number).

[0063] Step 3: Sensory evaluators are required to take a small sip of the green tea bitter and astringent complex taste simulation solution, enough to cover the entire surface of their tongue, hold it in their mouth for 7-8 seconds, then spit it out, rinse their mouths with ultrapure water for 20 seconds, and then taste the green tea sample. The tasting requirements are the same as for the green tea bitter and astringent complex taste simulation solution.

[0064] Step 4: After tasting the two samples, the sensory evaluator is asked to write down the sample number with the stronger bitter complex taste intensity (BACI), and then eat unsalted biscuits to relieve taste bud stress for 20 minutes.

[0065] Step 5: Repeat steps 3 and 4, but change the tasting order each time. For example, the first time, taste the green tea bitter and astringent complex taste simulation solution first and then taste the green tea sample. The second time, taste the green tea sample first and then taste the green tea bitter and astringent complex taste simulation solution.

[0066] Step six: If the probability of a sensory evaluator selecting one of the samples is greater than or equal to 75%, it indicates that the sample has a high BACI. If the probability of a sensory evaluator selecting one of the samples is less than 75% but greater than 25%, it proves that there is no significant difference in BACI between the two samples.

[0067] The optimal composition for the green tea bitterness and astringency complex taste simulation solution is the one that shows no significant difference from the corresponding green tea sample and contains the fewest types of compounds. Green tea bitterness and astringency complex taste simulation solutions 7 and 6 show no significant difference in bitterness and astringency intensity values ​​compared to 82% of the green tea samples. Based on the principle that the composition with the fewest types of compounds is the optimal composition, the compound composition of green tea bitterness and astringency complex taste simulation solution 7 was determined to be the optimal composition. Table 5 lists the composition and selection rate of each green tea bitterness and astringency complex taste simulation solution.

[0068] Table 5 shows the percentage of tasters who found the simulated bitterness of the green tea complex taste solution more bitter than the green tea sample (n=20).

[0069]

[0070] Note: Green tea bitter and astringent complex taste simulation solution 1: Caffeine, EGC, EGCG, ECG, Que-gal, Que-glu, Que-rut, Kae-rut, Kae-glu

[0071] Green tea bitter and astringent complex taste simulation solution 2: Caffeine, EGC, EGCG, Que-gal, Que-glu, Que-rut, Kae-rut, Kae-glu

[0072] Green tea bitter and astringent complex taste simulation solution 3: caffeine, EGCG, Que-gal, Que-glu, Que-rut, Kae-rut, Kae-glu

[0073] Green tea bitter and astringent complex taste simulation solution 4: caffeine, EGCG, Que-gal, Que-glu, Que-rut, Kae-rut

[0074] Green tea bitter and astringent complex taste simulation solution 5: caffeine, EGCG, quercetin, quercetin, kaletin

[0075] Green tea bitter and astringent complex taste simulation solution 6: caffeine, EGCG, quercetin, quercetin

[0076] Green tea bitter and astringent complex taste simulation solution 7: caffeine, EGCG, Quervain

[0077] Green tea bitter and astringent complex taste simulation solution 8: caffeine, EGCG

[0078] The compound ratio of the BACI quantitative curve for green tea can be determined based on the compound content detected by liquid chromatography. By taking multiple ratios that are close to the concentration range, the group of the BACI quantitative curve for green tea can be determined, as shown in Table 6.

[0079] Table 6. Grouping Basis and Limitations of Quantitative Curves for Bitterness and Astringency Complex Intensity (BACI) of Green Tea

[0080]

[0081] Based on the grouping in Table 6, the determination of the difference intensity point concentration of BACI in different groups includes the following steps:

[0082] Step 1: Using the lowest concentration of bitter and astringent compounds as the starting point for the BACI difference intensity (BACI difference intensity point 1), and using lg11 as the interval for concentration increase, prepare green tea bitter and astringent complex taste simulation solutions of different concentrations. The concentrations are labeled as concentration A, concentration B, concentration C, concentration D, and concentration E in order from low to high.

[0083] Step 2: Provide the lowest concentration and concentration A solutions to the sensory evaluators in random order at room temperature, 20 ml of solution per cup, placed in 50 ml paper cups (labeled with a random three-digit number);

[0084] Step 3: Sensory evaluators are required to take a small sip of the lowest concentration solution, enough to cover the entire surface of their tongue, hold it in their mouth for 7-8 seconds, then spit it out, rinse their mouths with ultrapure water for 20 seconds, and then taste solution A. The taste requirement is the lowest concentration solution.

[0085] Step 4: After tasting the two samples, the sensory evaluator is asked to write down the sample number with the stronger BACI score, and then eat unsalted biscuits to relieve the pressure on the taste buds for 20 minutes.

[0086] Step 5: Repeat steps 3 and 4, but change the tasting order each time. For example, the first time, taste the lowest concentration solution first and then taste the concentration A solution. The second time, taste the concentration B solution first and then taste the lowest concentration solution.

[0087] Step 6: When the probability of the sensory evaluator choosing the lowest concentration solution is less than or equal to 25%, it indicates that the BACI of the sample in the forced selection between the lowest concentration solution and the lowest concentration solution is higher.

[0088] Step 7: Set the sample concentration corresponding to Step 6 as C. m Its initial concentration is set as C. m-1 Then the concentration corresponding to the difference intensity point 2 of BACI is:

[0089]

[0090] Step 8: Take the concentration corresponding to the difference intensity point 2 of BACI obtained in step 7 as the starting concentration for the next round of forced selection between the two, and repeat steps 1 to 7, and so on, until the concentration exceeds the specified range.

[0091] Using the measured caffeine concentration at the BACI difference intensity point as the x-axis and BACI as the y-axis, a curve fitting was performed:

[0092] y BAPI =a*ln(x 咖啡因 -b)-c

[0093] Where a, b, and c are constants;

[0094] Specific information about the fitted curve is as follows: Figure 2 As shown in Table 7.

[0095] Table 7. Parameters of the quantitative curve of the bitterness and astringency complex taste intensity (BACI) of green tea.

[0096]

[0097] To verify the applicability of this quantitative curve, 32 green tea samples were used as validation samples. Using the BACI sensory intensity points of the last group as a scale, all green tea samples were scored for bitterness intensity using the traditional scaling method (with a nose clip). Then, the bitterness value of green tea was obtained from the quantitative curve of the complex bitterness and astringency taste intensity of green tea selected based on the ratio of caffeine to EGCG to Que-rut. Linear regression analysis was performed on the bitterness value obtained from the quantitative curve of the complex bitterness and astringency taste intensity of green tea selected based on the ratio of caffeine to EGCG and the bitterness value obtained by the traditional scaling method (Table 8 and...). Figure 3 ).

[0098] Table 8 shows the BACI curves used for the green tea validation samples and their corresponding values.

[0099]

[0100] Note: When selecting the BACI curve based on scale n, first select the curve closest to scale n. If two or more curves match, then select the curve closest to scale m.

[0101] Through linear regression analysis Figure 3 It was found that the Pearson correlation coefficient for the quantitative curve of the bitter and astringent complex taste intensity of green tea selected based on proportion m was only 0.6691, and the goodness of fit was only 0.4477, indicating that the fitting curve selected based on proportion m was not suitable. However, the Pearson correlation coefficient for the quantitative curve of the bitter and astringent complex taste intensity of green tea selected based on proportion n was 0.9708, the adjusted goodness of fit was 0.9425, the sum of squared residuals was 4.3331, and the estimated standard error was 0.3800. This shows that selecting the BACI quantitative curve based on proportion n is the correct approach, as the bitter and astringent complex taste intensity of the corresponding green tea can be accurately assessed based solely on the content of caffeine and EGCG.

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the bitterness compound taste intensity of a liquid food product, characterized by, It includes the following steps: Step 1: Determine the types and contents of bitter compounds and the total amount of other flavor components in each sample of liquid food. Step 2: Calculate the taste activity value of each bitter and astringent compound component, and prepare several bitter and astringent complex taste simulation solutions with the same content of bitter and astringent compounds as in each sample. The bitter and astringent complex taste simulation solutions contain one or more bitter and astringent compounds determined in Step 1. The matrix of the bitter and astringent complex taste simulation solutions is composed of the representative compound with the highest content among the other taste components, and the content of the representative compound is equal to the total amount of the corresponding taste components. Step 3: Conduct forced-choice sensory tests on both the liquid food and the bitter complex taste simulation solution to determine the optimal composition of bitter compounds in the bitter complex taste simulation solution based on the selection probability. Step three includes: (3.1) Classify bitter and astringent compounds in liquid food according to taste category, and according to the order of taste activity value of bitter and astringent compounds in liquid food from small to large; under the premise of ensuring that the taste activity value is greater than 1 and that at least one compound exists in each taste, gradually eliminate the compound with the smallest taste activity value, and prepare several bitter and astringent compound complex taste simulation solutions containing different bitter and astringent compounds. (3.2) Each liquid food sample solution and each bitter complex taste simulation solution were randomly arranged in pairs at room temperature and labeled with random three-digit numbers; a forced selection sensory test was conducted on the paired solutions, and the probability of the bitter complex taste simulation solution being selected in each group of experiments was recorded. (3.3) Traverse all liquid food samples and count the number m of corresponding liquid food sample solutions with a selection probability of less than 75% and greater than 25% for each bitter and astringent complex taste simulation solution. The composition of the bitter and astringent complex taste simulation solution with the largest m value is taken as the optimal composition of bitter and astringent compounds. When there are at least two bitter and astringent complex taste simulation solutions with the largest m values, the composition of the bitter and astringent complex taste simulation solution with the fewest types of bitter and astringent compounds is taken as the optimal composition of bitter and astringent compounds. Step 4: Based on the proportion of the optimal composition of bitter and astringent compounds in each sample, divide the proportion into different groups, select one compound from the optimal composition of bitter and astringent compounds, and establish a quantitative curve of the bitter and astringent complex taste intensity for each group. ； where a, b and c are constants, represents the initial concentration of the selected bitter compound and the theoretical concentration calculated from each round of forced choice sensory test under the proportion of each group, represents the value of the bitter complex taste difference intensity point; Step four includes: (4.1) Determine the content range of each compound based on the content of the bitter compounds obtained from screening in all samples; (4.2) Based on the proportion of the optimal composition of bitter and astringent compounds obtained from screening in each sample, the proportions are divided into different groups; (4.3) The lowest content of any bitter compound in the sample under each ratio relationship is taken as the starting concentration, and the bitter complex taste difference intensity point of the starting concentration is defined as 1. (4.4) Prepare several bitter and astringent complex taste recombinant solutions for each set of proportions: Based on the initial concentration of the selected bitter and astringent compound, prepare the first recombinant solution according to the set of proportions, and use the logarithmic series as the interval for content growth to prepare bitter and astringent complex taste recombinant solutions with different contents of bitter and astringent compounds under each set of proportions. (4.5) The first group of bitter complex taste recombinant solutions and the remaining recombinant solutions are randomly arranged in pairs at room temperature according to the order of content from low to high and labeled with random three-digit numbers; the two pairs of solutions are subjected to forced selection sensory test in sequence and the probability of the first group of bitter complex taste recombinant solutions being selected in each group of experiments is recorded until the probability value recorded in the forced selection sensory test of the m group of two is less than or equal to 25%, and the content of the selected bitter taste compound in the m group of recombinant solutions is recorded as Cm; (4.6) Increment the intensity of the bitter and astringent complex taste difference by one, and calculate the theoretical concentration of the selected bitter and astringent compound corresponding to the new intensity of the difference. : ； in, This indicates the content of the selected bitter compounds in the m-1th group of recombinant solutions; (4.7) Take the theoretical concentration corresponding to the new bitter and astringent complex taste difference intensity point calculated in step (4.6) as the starting concentration for the next round, return to step (4.4) and determine whether the content of compounds in the first recombinant solution prepared in step (4.4) meets the content range of bitter and astringent compounds in step (4.1). If it meets the requirements, continue; otherwise, execute step (4.8). (4.8) The initial concentration of the selected bitter and astringent compounds under each group ratio and the theoretical concentration calculated in each round of forced selection sensory test are used as the abscissa, and the value of the bitter and astringent complex taste difference intensity point is used as the ordinate. The quantitative curve of bitter and astringent complex taste intensity under each group ratio is obtained by fitting. Step 5: Determine the content and ratio of the optimal composition of bitter and astringent compounds in the liquid food to be tested, substitute them into the quantitative curve of bitter and astringent complex taste intensity under the corresponding ratio, and calculate the bitter and astringent complex taste intensity value of the liquid food to be tested.

2. The method for determining the intensity of bitter and astringent complex taste in liquid food according to claim 1, characterized in that, The liquid food mentioned in step one is any one of tea, coffee, or bitter fruit juice.

3. The method for determining the intensity of bitter and astringent complex taste in liquid food according to claim 1, characterized in that, The bitter compounds mentioned in step one include one or more of alkaloids, bitter amino acids, and polyphenols.

4. The method for determining the intensity of bitter and astringent complex taste in liquid food according to claim 1, characterized in that, Other flavor components mentioned in step one include one or more of sugars, organic acids, and umami amino acids.

5. The method for determining the intensity of bitter and astringent complex taste in liquid food according to claim 1, characterized in that, The taste activity value mentioned in step two is the ratio of the content of bitter and astringent compounds to the bitter and astringent threshold. Bitter and astringent compounds with a taste activity value greater than 1 are screened.

6. The method for determining the intensity of bitter and astringent complex taste in liquid food according to claim 1, characterized in that, The steps (3.1) described above are classified according to taste categories, including bitterness, astringency, and bitter-astringent taste.

7. The method for determining the intensity of bitter and astringent complex taste in liquid food according to claim 1, characterized in that, In the aforementioned forced sensory test, the tasting order needs to be changed between two adjacent tests.

8. The method for determining the intensity of bitter and astringent complex taste in liquid food according to claim 1, characterized in that, In step five, based on the ratio of the optimal composition of bitter and astringent compounds in the liquid food to be tested, the quantitative curve of the bitter and astringent complex taste intensity corresponding to the closest ratio is selected and substituted into the calculation.

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