A model and method for rapid evaluation of the quality of long-shelf-life yogurt

Abstract

The present invention belongs to the technical field of dairy product detection and analysis, and specifically relates to a model and method for quickly evaluating the quality of long-shelf-life yogurt. The model for quickly evaluating the quality of long-shelf-life yogurt described in the present invention collects sensory smoothness and instrument rheological parameter data of yogurt samples, and performs three-dimensional modeling of the smoothness sensory score Z, consistency coefficient K, and flow behavior index n, and performs surface fitting to obtain a model for quickly evaluating the quality of long-shelf-life yogurt. The evaluation model and evaluation method described in the present invention are applicable to room temperature yogurt, have the advantage of fast detection speed, can greatly improve the efficiency of product quality evaluation, and contribute to the development and promotion of new products.

Description

Technical Field

[0001] The invention belongs to the technical field of dairy product detection and analysis, and particularly relates to a model and method for quickly evaluating the quality of yogurt with a long shelf life. Background Art

[0002] Yogurt is gradually becoming the main snack food for consumers of different age groups due to its rich nutritional value. Surveys show that with the improvement of people's living standards, especially the rise of health awareness, the per capita demand for yogurt among urban residents in China is in a stage of rapid growth. Surveys show that sensory experience is one of the main driving factors that influence consumers to buy products, second only to health claims. Among them, long-shelf-life yogurt products are very friendly to people who are intolerant of low-temperature products because of their long storage time and the advantages of being edible at room temperature. However, since the two-bar process will affect the system stability of yogurt, in order to ensure that yogurt tolerates processing interference and ensures excellent shelf life stability, a thickening system is often introduced into the yogurt formula to protect the protein gel network structure. However, the addition of different stabilizers often easily causes the product to have poor sensory experiences such as stickiness and unevenness, affecting consumers' purchasing confidence.

[0003] At present, in the process of yogurt product development, the evaluation method for the smoothness of yogurt products mainly relies on consumer sensory descriptive testing, that is, judging the ease of the product flowing over the tongue, which is usually related to the product's consistency, delicate feeling and other properties. In the case of a small sample size (≤50 people), this method often has individual differences and subjective bias, and cannot accurately and objectively evaluate product attributes; in the case of a large sample size (≥100 people), although there is consistency in data trends, it has the defects of being time-consuming and labor-intensive, which not only prolongs the product development cycle, but also increases product development costs.

[0004] For example, Wang Liang et al., in "The Effect of Fat on the Smoothness of Salad Dressing in Simulated Oral Environment", used commercial salad dressings with different fat contents as the research objects, analyzed their particle size and texture profiles, and used the constructed simulated oral environment to explore the effect of fat content on the smoothness and friction properties of salad dressings. Another example is Guo Qihui et al., in "Research on the Correlation between Sensory Evaluation and Instrumental Measurement of Stirred Yogurt", selected 8 commercially available stirred yogurts, conducted comprehensive measurements of their volatile substances, non-volatile substances and textures, and simultaneously conducted sensory evaluations (mouth consistency, swallowing strength, stringy feeling and powdery feeling) to analyze the correlation between each test index and sensory index, and established a stepwise regression model between the test index and the sensory index. For example, Wu Xueyan et al. used a texture analyzer to measure the texture indexes (gel rupture strength, hardness, elasticity, viscosity, consistency, and string length) and sensory indexes (gel feel, hardness, elasticity, swallowing force, granularity, and string feel) of five different brands of yogurt in the study of "Research on the Correlation between Sensory Evaluation and Texture of Yogurt"; analyzed the correlation between texture and sensory indexes, and established a stepwise regression model for texture and sensory indexes. In addition, He Junfei et al. selected two commonly used methods, texture testing and sensory evaluation, in the study of "Establishing a Prediction Model of Sensory Properties of Texture Parameters of Set-Type Yogurt", optimized them and combined them using the partial least squares regression method to establish a prediction model for sensory evaluation indexes of set-type yogurt, achieving the purpose of rapid and accurate analysis.

[0005] Therefore, the art expects to develop a method for quickly and accurately evaluating yogurt quality, which has positive significance for the development and promotion of yogurt products. Summary of the invention

[0006] To this end, the first object of the present invention is to provide a model for quickly evaluating the quality of long-shelf-life yogurt, wherein the model converts sensory evaluation indicators into quantifiable detection indicators, so as to evaluate the quality of yogurt more objectively and scientifically;

[0007] The second object of the present invention is to provide a method for quickly evaluating the quality of long-shelf-life yogurt, which has the advantages of fast detection speed and high product quality evaluation efficiency, and helps to shorten the product development cycle.

[0008] In order to solve the above technical problems, the present invention provides a model for quickly evaluating the quality of long-shelf-life yogurt, wherein: Z=1 / (0.009×K+0.416×n); wherein:

[0009] Z is the sensory quality score of the tested yogurt product based on the definition of yogurt smoothness;

[0010] K is the consistency coefficient of the yogurt product to be tested;

[0011] n is the flow behavior index of the yogurt product to be tested.

[0012] Specifically, in the model for quickly evaluating the quality of long-shelf-life yogurt, the consistency coefficient K and the flow behavior index n conform to the power law equation τ=Kγ n ;in,

[0013] τ is the shear stress of the yogurt product under the rheometer test;

[0014] γ is the shear rate of the yogurt product under the rheometer test.

[0015] The present invention also discloses a method for constructing the model capable of quickly evaluating the quality of long-shelf-life yogurt, comprising the following steps:

[0016] (1) Take the yogurt samples to be tested for sensory evaluation of smoothness and record the sensory score Z respectively;

[0017] (2) The shear stress τ of each yogurt sample at different shear rate γ values ​​was tested using a rheometer, and the power law equation τ = Kγ was used to calculate the shear stress τ of each yogurt sample at different shear rate γ values. n Fitting was performed to calculate the consistency coefficient K and flow behavior index n of each yogurt sample;

[0018] (3) The sensory score Z, consistency coefficient K, and flow behavior index n are three-dimensionally modeled and surface fitted to obtain the required evaluation model.

[0019] Specifically, in the method for constructing a model capable of quickly evaluating the quality of long-shelf-life yogurt, in the step (1), the smoothness sensory evaluation step comprises: placing the yogurt sample on the front of the tongue and away from the palate, allowing the yogurt sample to flow back and forth on the tongue surface, and using QDA quantitative descriptive testing to evaluate the characteristics and differences between products.

[0020] Specifically, in the method for constructing a model capable of quickly evaluating the quality of long-shelf-life yogurt, in step (1), the sensory scoring includes:

[0021] 1-3 points: The yogurt sample cannot flow back and forth on the tongue, and the tongue and palate need to squeeze hard to push the sample away;

[0022] 3-5 points: The yogurt sample can flow naturally on the tongue in a small amount, and the tongue and palate need to be slightly squeezed to push the sample away;

[0023] 5-7 points: The yogurt sample can flow naturally on the tongue, and the sample can be pushed and spread on the tongue without the need to squeeze the tongue and palate;

[0024] 7-10 points: The yogurt sample can flow back and forth naturally on the tongue and spread evenly on the tongue, giving a silky feeling.

[0025] Specifically, in the method for constructing a model capable of quickly evaluating the quality of long-shelf-life yogurt, in the step (2), the rheometer test procedure includes: using a steady-state shear sweep (Flow Sweep), the fixture is a conical plate with a diameter of 40-50 mm, an angle of 0.999°-2.015°, a test temperature of 25±2°C, a waiting time setting of 110-130s, and a shear rate range of 0.1-1000s -1 , the acquisition time of each data point is 25-45s.

[0026] Specifically, the method for constructing a model capable of quickly evaluating the quality of long-shelf-life yogurt, in the step (3), further includes a step of performing regression verification on the evaluation model.

[0027] The invention also discloses a method for quickly evaluating the quality of yogurt with a long shelf life, comprising the step of predicting the smoothness of a yogurt sample by using the model for quickly evaluating the quality of yogurt with a long shelf life.

[0028] Specifically, the method for quickly evaluating the quality of long-shelf-life yogurt includes the steps of using a rheometer to test the consistency coefficient K value and the flow behavior index n value of the yogurt sample, and using the model for quickly evaluating the quality of long-shelf-life yogurt to predict the smoothness of the yogurt sample.

[0029] The invention also discloses the application of the model capable of rapidly evaluating the quality of yogurt with a long shelf life in the field of yogurt quality control and quality analysis.

[0030] The model for quickly evaluating the quality of long-shelf-life yogurt described in the present invention collects sensory smoothness and instrument rheological parameter data of yogurt samples, and performs three-dimensional modeling of the smoothness sensory score Z, consistency coefficient K, and flow behavior index n, and performs surface fitting to obtain a model for quickly evaluating the quality of long-shelf-life yogurt. Compared with the traditional yogurt sensory smoothness evaluation, the evaluation model described in the present invention adopts instrument parameter characterization, and by establishing correlation and prediction model with sensory scores, the consumer sensory language is converted into quantifiable instrument indicators, so as to evaluate the yogurt quality more objectively and scientifically. This method is applicable to room temperature yogurt, has the advantage of fast detection speed, can greatly improve the efficiency of product quality evaluation, and is conducive to the development and promotion of new products.

[0031] The model for quickly evaluating the quality of long-shelf-life yogurt described in the present invention is based on instrument measurement on the basis of descriptive tests on a large sample size of the population, converts the sensory language of the smoothness of the product into instrument parameters, and forms a systematic and stable measurement method, so as to achieve the purpose of online, real-time, and rapid and accurate prediction of the smoothness of yogurt, effectively solves the problems of individual subjective differences, long time consumption and high development cost when relying solely on sensory descriptive tests on the population, and overcomes the defect of low accuracy of a single test method.

[0032] The method for quickly evaluating the quality of long-shelf-life yogurt of the present invention uses a fitted evaluation model to predict and evaluate the quality of yogurt. The method converts consumer sensory language into quantifiable instrument indicators to evaluate the quality of yogurt more objectively and scientifically. The method has wide applicability and is suitable for room-temperature yogurt products with different viscosities. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0034] Figure 1 The figure is a schematic diagram of the construction process of the evaluation model of the present invention. DETAILED DESCRIPTION

[0035] Example 1

[0036] like Figure 1 As shown in the flow chart, in this embodiment, room temperature yogurt samples 1-30 with different viscosities were collected for smoothness sensory testing and evaluation.

[0037] Screened consumers: 100 consumers; 20-40 years old (20-30:31-40=45%:55%); male: female = 3:7; drank room temperature yogurt in the past month.

[0038] Test sampling: A complete block balanced design was adopted (each consumer tasted all samples), and samples were randomly sampled in six groups (6 times, 5 samples each time); room temperature samples were stored at 25±2℃ in advance.

[0039] Description of sensory characteristics: QDA quantitative descriptive testing is used to characterize the characteristics and differences between products. A spoonful of yogurt is placed on the front of the tongue, away from the palate, allowing the product to flow back and forth on the tongue.

[0040] Consumers performed sensory evaluation based on the definition of yogurt smoothness in Table 1 below, and scored the test samples and recorded them in Table 2 below.

[0041] Table 1 Definition of yogurt smoothness score

[0042]

[0043] Table 2 Smoothness rating of samples

[0044]

[0045] In this embodiment, the yogurt smoothness instrument test is performed on the above samples 1-30, that is, the shear stress values ​​(τ) at different shear rates (γ) are tested on the above samples.

[0046] In this embodiment, the instrument test of the smoothness of yogurt adopts the Discovery HR-2 American TA advanced rotational rheometer.

[0047] Sample preparation: The room temperature yogurt samples to be tested are placed in a sample pool at 25±2℃ and allowed to stand.

[0048] Program settings: Steady-state shear scanning (Flow Sweep) is used, the fixture is a conical plate (diameter 40mm, angle 2.015°), the test temperature is 25±2℃, the waiting time is set to 120s, and the shear rate range is 0.1-500 s -1 , the acquisition time of each data point is 35s. Rate distribution: Generally logarithmic, the acquisition frequency is 5, that is, 5 points are taken between one order of magnitude, and the test is conducted three times in parallel to take the average value.

[0049] In this embodiment, the shear stress of the yogurt sample is measured with the set rheological parameters as a function of the shear rate. Generally speaking, the shear stress increases with the increase of the shear rate. Since yogurt is a typical shear-thinning non-Newtonian fluid, its steady-state shear scan curve can be obtained by the power law equation τ=Kγ n The consistency coefficient K and flow behavior index n are obtained by fitting to characterize the characteristics of the sample.

[0050] This example analyzes the data based on the above measured data, and converts the measured shear stress value and shear rate into the power law equation τ=Kγ n , and fitting was performed to obtain the consistency coefficient K and flow behavior index n value of the sample, which are recorded in Table 3 below.

[0051] Table 3 Calculation results of K value and n value

[0052]

[0053] In this embodiment, the sensory model is established based on the calculation results of the above K value and n to . The smoothness sensory score, consistency coefficient K and flow behavior index n are three-dimensionally modeled using R studio software, and surface fitting is performed to obtain the size of the model's adjustment coefficient (x, y) and establish a smoothness prediction model Z=1 / (0.009 *K+ 0.416 *n).

[0054] Example 2

[0055] In this embodiment, a fixed yogurt sample is selected, and the fitting effect under different detection parameters is verified by referring to the method in Embodiment 1. The specific parameter control information is as follows:

[0056] Test Example 1: Waiting time 110s, shear rate range 0.1-300 s -1, the data point collection time is 25s;

[0057] Test Example 2: Waiting time 120s, shear rate range 0.1-300 s -1 , the data point collection time is 25s;

[0058] Test Example 3: Waiting time 130s, shear rate range 0.1-300 s -1 , the data point collection time is 25s;

[0059] Test Example 4: Waiting time 120s, shear rate range 0.1-500 s -1 , the data point collection time is 25s;

[0060] Test Example 5: Waiting time 120s, shear rate range 0.1-500 s -1 , the data point collection time is 35s;

[0061] Test Example 6: Waiting time 120s, shear rate range 0.1-500 s -1 , the data point collection time is 45s;

[0062] Comparative test example 1: waiting time 90s, shear rate range 0.1-500 s -1 , the data point collection time is 35s;

[0063] Comparative test example 2: waiting time 120s, shear rate range 0.01-600 s -1 , the data point collection time is 35s;

[0064] Comparative test example 3: waiting time 120s, shear rate range 0.1-500 s -1 , the data point collection time is 50s;

[0065] Comparative test example 4: waiting time 90s, shear rate range 0.01-600 s -1 , the data point collection time is 50s.

[0066] In this embodiment, under the above parameters, the prediction models obtained by fitting according to the method in Example 1 are shown in Table 4 below.

[0067] Table 4 Fitting model

[0068]

[0069] It can be seen that when the control waiting time is 120s and the shear rate range is 0.1-500 s -1, the data point collection time is 35 s, which is the best test condition. The stress-rate curve obtained under the best test conditions is fitted by the power law equation to obtain the consistency coefficient K and flow behavior index n. The model adjustment coefficients fitted by Rstudio are 0.009 and 0.416 respectively, and the prediction equation is Z=1 / (0.009×K+0.416×n), P<0.05.

[0070] Example 3

[0071] This example is verified based on the prediction model constructed in the above-mentioned Example 1.

[0072] Fifteen non-modeled commercial room temperature yogurt samples (referred to as MP1-MP15) were collected for sensory smoothness Sz and instrument rheological parameter data collection. The experimentally obtained model was used to predict the smoothness Sm, and the SPSS data processing software was used to perform linear regression analysis on Sz and Sm to obtain the multiple correlation coefficient R 2 The verification results are shown in Table 5 below.

[0073] Table 5 Verification data

[0074]

[0075] It can be seen that the above data results show that the goodness of fit of the prediction model of the present invention can reach 0.944, indicating that the fitting accuracy of the evaluation model of the present application is relatively high and can replace the sensory method to evaluate the sensory smoothness characteristics of yogurt products.

[0076] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A model for quickly evaluating the quality of long-shelf-life yogurt, characterized in that: The model is: Z=1 / (0.009×K+0.416×n); where, Z is the sensory quality score of the tested yogurt product based on the definition of yogurt smoothness; K is the consistency coefficient of the yogurt product to be tested; n is the flow behavior index of the yogurt product to be tested.

2. The model for quickly evaluating the quality of long-shelf-life yogurt according to claim 1, characterized in that: The consistency coefficient K and the flow behavior index n conform to the power law equation τ=Kγ n ;in, τ is the shear stress of the yogurt product under the rheometer test; γ is the shear rate of the yogurt product under the rheometer test.

3. A method for constructing a model capable of quickly evaluating the quality of long-shelf-life yogurt as claimed in claim 1 or 2, characterized in that: The steps include: (1) Take the yogurt samples to be tested for sensory evaluation of smoothness and record the sensory score Z respectively; (2) The shear stress τ of each yogurt sample at different shear rate γ values ​​was tested using a rheometer, and the power law equation τ = Kγ was used to calculate the shear stress τ of each yogurt sample at different shear rate γ values. n Fitting was performed to calculate the consistency coefficient K and flow behavior index n of each yogurt sample; (3) The sensory score Z, consistency coefficient K, and flow behavior index n are three-dimensionally modeled and surface fitted to obtain the required evaluation model.

4. The method for constructing a model capable of quickly evaluating the quality of long-shelf-life yogurt according to claim 3, characterized in that: In the step (1), the smoothness sensory evaluation step includes: placing the yogurt sample on the front of the tongue and away from the palate, allowing the yogurt sample to flow back and forth on the tongue surface, and using QDA quantitative descriptive testing to evaluate the characteristics and differences between products.

5. The method for constructing a model capable of quickly evaluating the quality of long-shelf-life yogurt according to claim 3 or 4, characterized in that: In step (2), the rheometer test procedure includes: using steady-state shear scanning, the fixture is a conical plate with a diameter of 40-50 mm, an angle of 0.999°-2.015°, a test temperature of 25±2°C, a waiting time setting of 110-130s, and a shear rate range of 0.1-1000s -1 , the acquisition time of each data point is 25-45s.

6. The method for constructing a model capable of quickly evaluating the quality of long-shelf-life yogurt according to claim 3 or 4, characterized in that: The step (3) also includes a step of performing regression verification on the evaluation model.

7. A method for quickly evaluating the quality of long-shelf-life yogurt, characterized in that: The method comprises the step of predicting the smoothness of the yogurt sample by using the model capable of quickly evaluating the quality of yogurt with a long shelf life as described in claim 1 or 2.

8. Application of the model capable of quickly evaluating the quality of long-shelf-life yogurt as claimed in claim 1 or 2 in the field of yogurt quality control and quality analysis.

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