CN112668142A - Construction method and application of chicken quality comprehensive evaluation model - Google Patents

Abstract

A method for constructing a comprehensive evaluation model of chicken quality comprises the following steps: s1, confirming multiple aspect evaluation indexes which change along with the change of conditions and reflect the chicken quality, and acquiring core factor indexes which are corresponding to each aspect evaluation index and influence the score of the aspect evaluation index due to the change of conditions; s2, calculating the weight of each index by using an analytic hierarchy process, constructing an aspect evaluation index model based on the core factor index and the corresponding weight of the core factor index, and constructing a chicken quality comprehensive evaluation model based on the aspect evaluation index model and the aspect evaluation index weight; the aspect evaluation index model is used for obtaining an aspect evaluation index score, and the comprehensive evaluation model is used for obtaining a chicken quality comprehensive evaluation score. The method has the advantages that the actual chicken quality is obtained by integrating multiple dimensions, the systematic qualitative evaluation of the chicken quality is realized, the determination of the optimal culture conditions and the like based on the acquisition of the chicken quality is facilitated, the quality management and quality evaluation system of the remote chicken is perfected, and the optimization development of the chicken quality is promoted.

Description

Construction method and application of chicken quality comprehensive evaluation model

Technical Field

The invention relates to the field of meat detection, in particular to a construction method and application of a chicken quality comprehensive evaluation model.

Background

The chicken quality of the edible chicken is influenced by various conditions, including age of day, feeding mode, sex and the like, and the quality of the chicken obtained based on different culture conditions is also shown to be remarkably different. Taking the Qingyuan chicken as an example, the Qingyuan chicken shows more obvious differences in flavor, sense, texture and other aspects at different growth stages, namely different ages in days, such as tender young chicken, mellow taste of old chicken and the like. On the basis, the quality of the chicken is obtained and is important for the development of the chicken market, and the farmer can further improve various conditions on the basis of obtaining the chicken quality from the breeding side, so that conditions such as culture, processing and the like which can ensure the best chicken quality are obtained, and the improvement of the chicken quality is promoted; therefore, the chicken quality is accurately and effectively obtained by considering the consumption side and the supervision side, which is beneficial to timely evaluating the quality of the chicken sold in the market, so that the chicken with excellent quality is screened, and the quality management and quality evaluation system of the chicken is perfected. Therefore, the method for obtaining the chicken quality has important significance in guiding consumption, promoting the chicken market, promoting the improvement of the chicken quality and the like. At present, a common method for acquiring chicken quality comprises personal experience judgment and physical and chemical characteristic detection, wherein the personal experience judgment is carried out according to self eating experience, the appearance of an edible chicken and the like; the physicochemical characteristic detection is to detect the quality of the chicken by detecting multiple physicochemical characteristic indexes of the chicken, although the method can realize the detection of the chicken by quantifying all substances, the method is too mechanical, the consideration on the aspects of the eating experience of a chicken eater, the nutritive value of the chicken and the like is lacked, and the comprehensive chicken quality comprehensive evaluation effect cannot be achieved; the existing physical and chemical property detection method does not form a complete system and can not accurately obtain the chicken quality; even the evaluation of chicken is carried out by referring to a physicochemical characteristic evaluation mode of non-chicken such as red meat in the prior art, so that the difference between the chicken and other meat is neglected, quality evaluation specifications are difficult to form in the field of chicken, and the accuracy of chicken quality evaluation based on physicochemical characteristic detection is difficult to guarantee. Therefore, the evaluation process of the chicken quality based on the prior art is one-sided and the accuracy is difficult to guarantee, real and reliable related information which is beneficial to improving the chicken quality is difficult to provide, the improvement of the chicken quality is not facilitated, a farmer can change breeding conditions blindly more easily, and the further improvement of the chicken quality in the breeding process is influenced. In addition to the above drawbacks, the chicken quality evaluation methods in the prior art, including physicochemical characteristic evaluation, have other drawbacks, such as: in the evaluation indexes, different indexes are single and repeated, and the information of different angles of the chicken quality cannot be independently reflected; without definite digital weight, qualitative judgment on the final chicken quality cannot be systematically made, so that the chicken quality evaluation results are uneven and the like.

The above defects directly result in that the chicken quality cannot be accurately obtained, a complete chicken evaluation system cannot be formed, and the chicken quality is difficult to improve. Therefore, a chicken quality comprehensive evaluation model which can be accurately obtained and can reflect the chicken quality by combining a plurality of aspects is urgently needed in the prior art so as to conveniently construct a complete chicken quality evaluation and quality evaluation system, conveniently cultivate edible chicken with high-quality chicken on the breeding side, and enable consumers to obtain high-quality chicken with excellent aspects such as nutritional value, edible mouthfeel and the like.

Disclosure of Invention

The invention aims to overcome at least one defect of the prior art, and provides a method for constructing a chicken quality comprehensive evaluation model and application thereof, the method for constructing the chicken quality comprehensive evaluation model can construct a comprehensive evaluation model for acquiring chicken quality based on multiple aspects and with high accuracy, can realize comprehensive and qualitative evaluation of chicken quality, and is convenient for guiding the improvement of subsequent chicken quality based on the acquisition of chicken quality; when the method, the constructed model and the process of judging the chicken quality through the model are applied to a chicken quality management and quality evaluation system, the perfection of the corresponding system can be promoted, the whole process from output to use is promoted, the chicken with excellent quality is easier to industrialize, and consumers can obtain real high-quality chicken.

The invention adopts the technical scheme that a method for constructing a chicken quality comprehensive evaluation model comprises the following steps: s1, confirming multiple aspect evaluation indexes which change along with the change of conditions and reflect the chicken quality, and acquiring core factor indexes which are corresponding to each aspect evaluation index and influence the score of the aspect evaluation index due to the change of conditions; the chicken quality is embodied in various aspects such as eating, nutritional value, processing and the like, the aspect evaluation indexes represent the aspects embodied in the chicken quality, and the aspect evaluation indexes reflecting the chicken quality can also change along with the change of conditions such as the change of the age of day, so that the change of the whole chicken quality is shown. In fact, the change of the aspect evaluation index is because the lower layer more specific core factor index changes due to the change of the condition, so in order to more accurately obtain the chicken quality, the core factor index of which the lower layer affects the score of the aspect evaluation index due to the change of the condition, corresponding to the aspect evaluation index, needs to be further obtained. S2, calculating the weight of each index by using an analytic hierarchy process, constructing an aspect evaluation index model based on the core factor index and the corresponding weight of the core factor index, and constructing a chicken quality comprehensive evaluation model based on the aspect evaluation index model and the aspect evaluation index weight; the facet evaluation index model is used for obtaining facet evaluation index scores, and the comprehensive evaluation model is used for obtaining chicken quality comprehensive evaluation scores. Therefore, the facet evaluation index is used as the lower-layer index of the whole chicken quality, the evaluation result of integrating a plurality of facet evaluation indexes can be obtained by utilizing the weight distribution and the facet evaluation index, the core factor index is used as the lower-layer index of the corresponding facet evaluation index, and the result of the facet evaluation index can be more accurately and comprehensively obtained by combining the weight of the core factor index. Therefore, comprehensive and accurate chicken quality comprehensive evaluation is finally realized through the bottom-up multilayer structure. Further, the comprehensive evaluation score of the chicken quality is equal to the weighted sum of multiple aspect evaluation index scores, and the aspect evaluation index score is equal to the weighted sum of multiple core factor index scores.

Further, the plurality of evaluation indexes include sensory evaluation indexes, physical and chemical property evaluation indexes, and fatty acid evaluation indexes. The sensory evaluation index at least reflects the eating quality of the chicken and provides consideration for the eating dimension of the chicken, so that the final chicken evaluation result also meets the sensory requirements of actual eaters, and the method is favorable for obtaining high-quality chicken with excellent culture taste based on the chicken quality; the physicochemical characteristic evaluation index at least reflects physicochemical processing quality, is an internal material basis reflecting the aspects of final comprehensive quality, processing quality and the like, and is convenient for further improving the accuracy of chicken quality evaluation on the basis of objective materials through the physicochemical characteristic evaluation index; the fatty acid evaluation index at least reflects the quality of the nutritional value, for example, part of unsaturated fatty acid in chicken is one of essential nutritional components in human body, which has important significance for promoting metabolism of human body, and part of chicken breeds also contain unsaturated fatty acid such as DHA, which has certain nutritional value for eaters; meanwhile, the prior research indicates that the nutritional value can be obtained through the proportion of saturated fatty acid and unsaturated fatty acid, and the research further indicates the representativeness of the fatty acid. Therefore, the fatty acid evaluation index can provide a consideration on the nutrition level, and high-quality chicken with good eating quality, processing quality and nutritional value and quality can be obtained by combining with other evaluation indexes.

Further, in step S1, the condition change is a day-to-day change, and the comprehensive evaluation model is such that the weight of the official evaluation index, the physicochemical characteristic evaluation index, and the fatty acid evaluation index is the same. In an embodiment of the invention, the construction method of the chicken quality comprehensive evaluation model, or the chicken quality comprehensive evaluation method, is realized by researching the changes of the chicken quality and the lower index at different ages in days. By changing the condition of the age of the day, the change of each index reflecting the quality of the chicken in the process of influencing the quality of the chicken by the age of the day can be obtained, so that the weight can be distributed based on the influence degree, and a corresponding evaluation model can be obtained. And based on the model, the condition of day age with the best chicken quality can be conveniently judged, so that the culture condition can be conveniently perfected to improve the chicken quality. The evaluation indexes of the sense, the physicochemical property and the fatty acid are indispensable part of the comprehensive quality of the chicken, wherein the physicochemical property and the fatty acid are objective substance bases, the sense is an evaluation base combined with the consumption side, and the three have the same importance degree for the comprehensive quality of the chicken; therefore, the same weight is distributed to the three evaluation indexes in the comprehensive evaluation model, and the accuracy is improved.

Further, the construction process of the sensory evaluation index model comprises the following steps: SA1, establishing multiple chicken sensory indexes and sensory index scoring systems for reflecting the sensory attributes of chicken; SA2, scoring sensory indexes of a plurality of groups of chickens with different conditions, and screening the sensory indexes which are obviously different along with the change of the conditions as main sensory indexes; SA3, performing principal component analysis on the main sensory index based on the score in the step SA2, confirming the principal component, screening indexes which basically reflect the sensory attributes represented by the whole corresponding principal component under the principal component as sensory core factor indexes, and using the sensory core factor indexes for establishing a sensory evaluation model; SA4, carrying out weight distribution on sensory core factor indexes by using an analytic hierarchy process, and obtaining a sensory evaluation model for obtaining the eating quality of chicken, wherein the sensory evaluation model is as follows: and (3) the chicken sensory comprehensive evaluation score is the weighted sum of the index scores of all the sensory core factors. Screening professional sensory personnel by a standard method, establishing a new descriptor reflecting the sensory attributes of the chicken by the professional sensory personnel in combination with the standard method, and/or adopting the existing descriptor in the prior art, giving clear definition and strength reference to the descriptor, thereby establishing a sensory index scoring system by taking the descriptor as a corresponding sensory index of the chicken. After establishing a chicken sensory index and a sensory index scoring system, professional sensory personnel are used for scoring each chicken sensory index under different conditions, and the sensory indexes which are obviously different along with the change of the conditions are screened as main sensory indexes. However, when the main sensory indexes are too many, the analysis process and the finally established model are obviously more complicated, and the method is not beneficial to being applied to chicken quality evaluation, so that sensory core factor indexes are further screened out through principal component analysis and factor load analysis, the sensory core factor indexes can cover most of information of all the main sensory indexes, analysis can be simplified through the sensory core factor indexes, and result accuracy is improved. After the sensory core factor indexes are obtained, weights are distributed according to the influence degree of the sensory core factors on the sensory evaluation indexes, and then a final sensory evaluation index model is obtained. Furthermore, because the sensory evaluation indexes are human-oriented, the importance degree of each sensory core factor index judged by the comprehensive sensory evaluator in the application in the sensory attributes of the chicken is reflected, and the comparison, the construction and the judgment matrix are carried out to calculate and obtain the weight of each sensory core factor index. Further, pearson correlation analysis is performed on the chicken sensory indicators in step SA1 or SA2 before step SA3, if no significant correlation exists between the chicken sensory indicators, the subsequent steps are continued, and if significant correlation exists between the main sensory indicators, the main sensory indicators finally used in step SA3 can be confirmed by supervised classification OPLS-DA discriminant analysis before step SA 3.

Further, the construction process of the physicochemical characteristic aspect evaluation index model comprises the following steps: SB1, detecting chicken obtained under different conditions, and screening main physical and chemical characteristic indexes with obvious difference of detection data along with the change of conditions; SB2, carrying out Pearson correlation verification on the main physical and chemical characteristic indexes obtained in the step SB1, and if no significant correlation exists between the main physical and chemical characteristic indexes, using the main physical and chemical characteristic indexes as core factor indexes of physical and chemical characteristics and constructing a chicken quality physical and chemical characteristic evaluation model; if the main physical and chemical characteristic indexes have obvious correlation, further determining the physical and chemical characteristic core factor indexes through the discrimination analysis of a supervised classification model OPLS-DA; SB3, performing weight distribution of physicochemical characteristic core factor indexes by using an analytic hierarchy process, and obtaining a physicochemical characteristic evaluation model for acquiring chicken processing quality, wherein the physicochemical characteristic evaluation model is as follows: the comprehensive evaluation score of the physicochemical characteristics is the weighted sum of the index scores of the core factors of the physicochemical characteristics. If there is significant correlation between the main physicochemical characteristic indexes, it indicates that the main physicochemical characteristic indexes have information overlapping to some extent, inevitably has the problem of co-linearity between the indexes, and cannot accurately reflect the difference information between the ages in days. By adopting the supervised classification model OPLS-DA, the main physicochemical characteristic indexes with correlation can be simplified and classified, and the purpose of enhancing the quality evaluation accuracy and efficiency is achieved. Other operations similar to the sensory indexes have corresponding effects by utilizing similar principles. The judgment matrix corresponding to the index of the core factors of the physicochemical properties is constructed based on the importance degree of each physicochemical property disclosed by the existing research in reflecting the physicochemical quality of the chicken.

Further, the construction process of the fatty acid aspect evaluation index model comprises the following steps: SC1, detecting the fatty acid composition and relative content of chicken under different conditions; SC2, performing Pearson correlation verification on the fatty acids obtained in the step SC1, and if no significant correlation exists among the fatty acids, taking the fatty acids as the fatty acid core factor indexes and using the fatty acids as the fatty acid core factor indexes to construct a chicken quality fatty acid evaluation model; if significant correlation exists among the fatty acids, further determining the index of the fatty acid core factor through the discrimination analysis of a supervised classification model OPLS-DA; SC3, performing weight distribution of the fatty acid core factor indexes by using an analytic hierarchy process, and obtaining a fatty acid evaluation model for obtaining the chicken nutrition quality, wherein the fatty acid evaluation model is as follows: the fatty acid comprehensive evaluation score is the weighted sum of index scores of various fatty acid core factors. The fatty acid composition and relative amounts are measured because it is possible that a change in conditions may also result in a change in the fatty acid type. Then, the subsequent calculation analysis is carried out on the common fatty acid under different conditions. The other operations similar to the physical and chemical property indexes have corresponding effects by utilizing similar principles. And the judgment matrix corresponding to the fatty acid core factor index is constructed based on the importance degree of each fatty acid in reflecting the nutritional value of the chicken disclosed by the existing research.

Further, when the method is applied to the research of the chicken being the Qingyuan chicken under the condition of day age, the aspect evaluation index and the core factor index form an evaluation index system, and the indexes and the system specifically comprise the following contents: the aspect evaluation index: sensory evaluation, physical and chemical properties evaluation, and fatty acid evaluation; core factor index: core factor indicators for sensory evaluation are formed by sensory terms reflecting sensory attributes, including chewiness, chicken taste, liquor clarity, oil layer thickness, liquor aroma; the core factor indexes evaluated in the aspect of physical and chemical properties comprise hardness values, intramuscular filling ratio, collagen content, crude fat content and single fiber area, and the core factor indexes evaluated in the aspect of fatty acid comprise eicosapentaenoic acid, arachidonic acid, linoleic acid, oleic acid, docosapentaenoic acid, docosatetraenoic acid, heptadecatrienoic acid, myristic acid, palmitic acid and stearic acid; the evaluation index system is as follows: the layer I is a target layer and is the comprehensive quality of the chicken to be evaluated; the layer II is a standard layer and is a plurality of evaluation indexes including sensory evaluation indexes, physical and chemical property evaluation indexes and fatty acid evaluation indexes; the layer III is an index layer and is a core factor index corresponding to each aspect evaluation index, wherein the core factor index of the sensory aspect evaluation comprises chewing strength, chicken taste, liquor color clarity, oil layer thickness and liquor aroma; the factor indexes evaluated in the aspect of physicochemical properties comprise hardness values, intramuscular filling ratio, collagen content, crude fat content and single fiber area; the core factor index evaluated in terms of fatty acid includes eicosapentaenoic acid, arachidonic acid, linoleic acid, oleic acid, docosapentaenoic acid, docosatetraenoic acid, heptadecatrienoic acid, myristic acid, palmitic acid, stearic acid; the IV layer is a scheme layer, and test objects under different conditions are Qingyuan chickens of different ages in days.

The invention also aims to provide a chicken quality comprehensive evaluation model constructed by the method for constructing the chicken quality comprehensive evaluation model. The chicken quality evaluation model obtained by the construction method can be used for evaluating the chicken quality from multiple dimensions, and a comprehensive evaluation model for qualitatively analyzing the chicken quality can be constructed by confirming the plane evaluation index and the core factor index and distributing the weights. The model can accurately reflect the actual chicken quality by combining objective substances and the actual chicken oriented object.

The invention further aims to provide a chicken quality comprehensive evaluation method, which is characterized in that a chicken quality comprehensive evaluation model is used for obtaining a chicken quality comprehensive evaluation value, and the quality of chicken is judged according to a comprehensive evaluation result.

The invention further aims to provide application of the chicken quality comprehensive evaluation model in chicken quality evaluation. Besides directly obtaining the chicken quality evaluation by using the chicken quality comprehensive evaluation model, when the evaluation indexes or other layer indexes influence the chicken quality evaluation in other aspects, the chicken quality comprehensive evaluation model can be used as the lower layer indexes of other evaluation models, so that higher-dimensionality information judgment is obtained. So as to perfect chicken quality management and chicken quality evaluation system from various aspects.

Compared with the prior art, the invention has the beneficial effects that: the chicken quality is evaluated and analyzed from multiple aspects, so that the actual chicken quality is comprehensively and accurately obtained, the whole model construction process is systematized based on the hierarchical structure, the accuracy and systematicness of real chicken quality evaluation are improved by the constructed model relative to other single-dimensional models, and the qualitative and quantitative chicken quality can be realized. According to the method, multiple evaluation indexes are selected as sensory evaluation indexes, physical and chemical property evaluation indexes and fatty acid evaluation indexes, so that the comprehensive evaluation of the chicken quality is realized on the basis of considering objective substances and the chicken oriented object, and the excellent chicken quality meeting the actual requirement is confirmed; and the analysis is carried out through the data processing process of the system including principal component analysis, factor load analysis, supervised classification model and the like, so that the analysis process can be simplified while the accuracy is ensured, and the comprehensive evaluation model constructed by the method is easier to realize practical application. When the chicken quality comprehensive evaluation model is applied to a chicken quality management and quality evaluation system, high-quality chicken which is nutritional and has good mouthfeel can be obtained, the cultivation side realizes targeted cultivation on the basis of conditions corresponding to excellent chicken quality, and development and optimization of chicken quality in the market are promoted.

Drawings

FIG. 1 is a schematic diagram of the technical scheme of the present invention.

Figure 2 is a radar plot of sensory profile at different ages of days for example 1.

FIG. 3 is a graph of sensory attributes PCA of distant chickens at different days of age in example 1.

FIG. 4 shows the S-plot of the OPLS-DA model for day-old pairwise comparison of example 2.

FIG. 5 shows the day-old pairwise comparison of the VIP contribution of the OPLS-DA model of example 2.

Figure 6 shows the fatty acid total ion flow diagram for the remote chickens of different days of age in example 3.

FIG. 7 shows the S-plot of the OPLS-DA model for day-old pairwise comparison of example 3.

FIG. 8 shows the day-old pairwise comparison of the VIP contribution of the OPLS-DA model of example 3.

FIG. 9 is a view showing a hierarchical structure of the comprehensive evaluation of different ages in days in example 4.

Detailed Description

Example 1 establishment of sensory evaluation index model for Chicken meat quality

First, preparation of test animals

The Qingyuan hens bred in accordance with the unified standard of Wenshi food group GmbH are taken as test animals, and the test period is 360 days. All groups of test chickens are uniformly bred and managed according to a broiler breeding management manual compiled by Wen's group sharps company, broiler chickens freely eat and drink water in the test process, natural illumination is adopted in the daytime, LED lamp illumination is adopted from 19:00 evening to 7:00 early morning, and the illumination intensity is 10 lx. The open chicken house is used for breeding, except that infrared lamps are adopted for heat preservation in the chick stage, no corresponding temperature control measures are adopted in the middle and large chicken stages. And (5) breeding the Qingyuan chickens to a specified daily critical point in a gradient manner, and slaughtering and cleaning the Qingyuan chickens. The daily ages are 80 days old, 100 days old, 120 days old, 140 days old, 160 days old and 200 days old in sequence, each of the 12 people in each day age group has a weight of 1.5-2.0 kg. Wherein, part of the fresh slaughtered chickens are transported to a laboratory horse for sensory evaluation, the pectoralis major muscles are taken out after the rest samples are slaughtered, the samples are filled into two layers of polyethylene film bags for numbering, and the physicochemical and other index measurement (storage at 4 ℃) in other embodiments is completed within 3 days.

Second, sensory Chicken sample preparation

The sample is divided into chicken and chicken soup for sensory evaluation of texture, flavor and taste; wherein, regarding the chicken part, the processing method of the chicken in DB46/T202-2011 Qiongcai white-cut Wenchang chicken, NY/T330-1997 broiler chicken processing technical specifications and the cooking method of classic white-cut chicken in Guangdong province are referenced to prepare the white-cut chicken, and two chicken breasts are completely removed along the keel and the part from the breast bone to the shoulder strap muscle by using a small-size handle scalpel and then used for sensory analysis of the meat quality; for the chicken portion, the samples were decapitated and chopped into 3.5 x 6.5 x 2.5cm pieces, then mixed with water: adding the meat into a cooking utensil according to the mass ratio of 1:1.5, heating for 15min in an electromagnetic oven 1200W after boiling water to prepare chicken soup, and then analyzing and evaluating the organoleptic flavor and taste characteristics. Then, each group of evaluation samples are filled into white containers marked with random codes according to the same size and quantity, including soup and meat, the containers are placed in a random sequence and are sequentially presented to sensory evaluators screened by the following process for sensory inspection.

Screening sensory evaluation personnel

More than 50 reserves of different ages and sexes are screened out through basic information questionnaire, basic information comprises eating experience, eating frequency and understanding degree of the Qingyuan chickens, then basic sensory ability examination and screening are carried out on the reserves according to the general guidance of national standard GB/T16291.1-2012 sensory analysis selecting, training and management evaluators, and the examination method is carried out according to the three-point inspection of the sensory analysis method of the national standard GB/T12311 + 2012 and the sensory analysis method sequencing method of GB/T12315 + 2008. And (4) providing real chicken samples for attribute description for the personnel obtained by secondary screening, and checking whether the evaluators can perform professional detailed description on the chicken samples. And (4) integrating the three evaluation results, screening to obtain a plurality of sensory evaluators, and forming a sensory evaluation group.

Fourth, building sense description word library

Repeated training of selected sensory evaluators with real Qingyuan chicken samples with reference to existing studies: (>150h) Familiarize it with the sample properties. According to the GB/T10221-. And statistical and computational analysis of the descriptive words to preliminarily determine the terms used for the description, the statistical and computational analysis process being described in GB/T16861-

Performing a calculation wherein F: the descriptors being actually mentionedThe number of times is a percentage of the total number of times the descriptor may be referred to; i: the intensity of a descriptor actually given by the panel and the percentage of the maximum possible intensity of the descriptor; the M value generally reflects the frequency of appearance and the intensity of perception of the sensory evaluation profile descriptors, and the larger the value, the larger the contribution to the sensory quality. In the present example, 10 sensory evaluators were used for 150h round table discussion and training, 19 descriptors were preliminarily determined to describe the sensory properties of chicken in different aspects, and M values of the descriptors were calculated, and the results are shown in table 1 below.

TABLE 1 sensory descriptors M value

The prior research shows that the M value is key data reflecting the appearance frequency and the feeling intensity of the sensory evaluation section descriptors, the larger the value is, the larger the contribution to the sensory quality of the product is, and when the M value is more than 50%, the vocabulary can be used as a key sensory analysis term. Therefore, 10 indexes of chicken taste, chewy property, liquor color clarity, liquor aroma, meat juice feeling, oil color, oil layer thickness, fresh sweet value, chicken fishy smell and peculiar smell value are superior to other descriptors in terms of use frequency and perception intensity of sensory evaluators, and can be used as an analysis term for sensory analysis of Qingyuan chicken. In order to ensure that all the sensory indexes of the chicken can independently reflect a certain sensory attribute of the Qingyuan chicken and avoid the problem of collinearity among the indexes, Pearson correlation analysis is further carried out on the 10 terms so as to consider the interaction relation among the indexes. The correlation analysis result shows that only 1 correlation exists on the level of alpha being 0.05 in 55 correlation coefficients, and no significant correlation exists among other indexes, which indicates that redundant repetition does not exist among 10 terms generated by a sensory evaluation group, and the 10 terms represent sensory properties of different aspects of Qingyuan chickens, so that the integrity and comprehensiveness of sensory analysis are ensured. And the final sensory indexes of the chicken reflect the main sensory attributes of the Qingyuan chicken from three aspects of meat quality, taste and flavor.

Then, the finally determined sensory indexes of the chicken are discussed in accordance with the consistency of all evaluators, each index is respectively given a definite definition and a grading reference, the reference is mainly simulated by adopting a real form of the chicken or other objects with similar texture to replace or is expressed in a more intuitive way, the reference grades are divided into four grades, namely high, medium, low and no, and a 9-point scale is used for quantification.

Fifth, sensory Profile analysis

1. Sensory Profile evaluation

In order to explore specific changes of sensory attributes of the Qingyuan chickens caused by the influence of the age of the day, various sensory attribute evaluation and analysis tests based on different age groups are carried out; based on the established descriptors (namely the finally determined chicken sensory indexes) and the scoring standards, the evaluation groups perform sensory scoring and variance analysis on the 6 day-old groups at the same time, and the scoring results show that the evaluation results of the chicken sensory indexes of each chicken at the same day age are basically consistent without significant difference, so that the stability of sensory data is shown, and the corresponding sensory attributes exist as the consistent sensory attributes of the young and clear chickens at the same day age. Oil color, oil layer thickness, liquor color clarity, liquor aroma degree, fresh sweet value, chewing strength, chicken taste and meat juice feeling among 6 age groups are obvious in sensory indexes of 8 chicken meat which change with age, and the fishy smell and the peculiar smell of the chicken do not change obviously with the age; therefore, the influence strength of the age in days on 8 chicken sensory indexes which have obvious difference along with the change of the age in days is presumed to be obvious, and the fishy smell and the peculiar smell of the chicken are not influenced by the change of the age in days. And in order to further visually compare the whole sensory attribute variation trend of the distant chickens under the change of the age of the day, a clear distant chicken sensory attribute profile radar chart is drawn according to the mean value scoring result of 10 evaluators (as shown in figure 2, wherein, the test level P is 0.05, and the test level P is 0.01). According to the existing data and profile radar chart, 8 chicken sensory indexes with obvious difference along with the change of the age of the day are determined as main sensory indexes.

2. Establishing a sensory evaluation index model of chicken quality

(1) Sensory core factor index screening

The sensory profile is characterized by being an important index for evaluating the eating quality of the Qingyuan chickens at different ages in days, the eating characteristics of the Qingyuan chickens can be directly reflected, and in order to enable the sensory evaluation model based on the quality of the Qingyuan chickens at different ages in days to more accurately reflect the difference between the quality of the Qingyuan chickens at different ages in days, the obtained sensory attributes are screened based on the sensory profile analysis results at different ages in days. In this embodiment, PCA clustering analysis and factor load analysis are performed on the obtained sensory profile analysis results of different ages in days, and principal components mainly contributing to changes with the ages in days and characteristic sensory factors thereof are screened out. And the screening process utilizes the following matrix transformation processing to obtain characteristic sensory factors, P^T(A^TA)P＝P^-1(A^TA) P ═ Λ; wherein, A is a sample matrix,

the row vectors in the a matrix represent samples and the column vectors represent features, so the matrix means m sample values with n features. The above matrix transformation process represents: the A matrix is subjected to linear change to obtain a characteristic vector matrix Lambda of A; and Λ is a diagonal matrix formed by characteristic values of A, P is a corresponding characteristic vector group, the characteristic vector corresponding to the characteristic values is the ideal coordinate axis to be obtained, and the characteristic values are equal to the variance of the data on the corresponding dimension on the coordinates after rotation. The information quantity contained in the direction of the corresponding feature vector is described by using the feature value, and the value obtained by dividing a certain feature value by the sum of all feature values is as follows: the variance contribution ratio of the feature vector (variance contribution ratio represents the proportion of the amount of information implied in that dimension).

Specifically, in this embodiment, based on the sensory profile analysis results of different ages in days, the main component and PCA clustering analysis is performed on 8 main sensory indicators that have significant changes at 6 ages in days by using SIMCA 14.0 (the clustering result is shown in fig. 3). As can be seen from FIG. 3, 6 distant chickens at different ages in days can be clearly distinguished by sensory analysis, and different main sensory indicators represent the difference between age changes in days. The different principal component contribution rates are analyzed according to the PCA clustering result in FIG. 3 (the result is shown in Table 2), and the result shows that the cumulative interpretation contribution rate of the PCA model to all sensory data of 6 different ages in days is increased along with the increase of the principal components, and the cumulative prediction contribution rate of the model data is increased and then decreased. And when the main component is 3, the cumulative interpretation contribution rate of the sensory data is 91.4%, and the maximum cumulative prediction contribution rate is 71.0%. In combination with the prior studies show: when the characteristic contribution is more than 70%, the principal component under the model can more comprehensively reflect most of information of the original evaluation index, and the model prediction degree is high; therefore, the characteristic sensory attributes under the first 3 main components are preliminarily selected for the establishment of a subsequent sensory evaluation model.

TABLE 2 principal Components contribution ratio

Using the extracted principal components in a PCA model in SIMICA 14.0 to extract characteristic factors through the matrix transformation processing mentioned above, aiming at enabling one variable to have higher load on fewer factors, because the magnitude of the load value reflects the importance degree of each variable in the principal components, and the processing process is helpful for obtaining representative factors representing the corresponding principal components under the principal components; the results of the treatment are shown in Table 3. The existing research shows that the larger the load coefficient p (corr), the higher the degree of partial correlation between the representative index and the age in days, the more representative factor can represent the main contribution factor under the main component, and therefore, the factor with p (corr) closer to 1 is selected as the representative factor under the main component. Therefore, after screening, the first principal component is represented by the following factors: oil layer thickness, liquor color clarity, liquor aroma, fresh and sweet value, chicken flavor. The second main component representative factor is meat juice feeling; the third principal component represents the chewing power. Meanwhile, the further screening is carried out according to the principle that a few quality indexes represent most information of all indexes and certain variation coefficients are required to be arranged among the same indexes among different influence factors. The three main components represent the variation coefficients of the thickness of an oil layer, the clarity of soup color, the taste of soup, the fresh sweet value, the chicken taste, the meat juice feeling and the chewing strength which are 0.370720, 0.320102, 0.269414, 0.169815, 0.300013, 0.260633 and 0.334308 in sequence, so that the oil layer thickness, the taste of soup color, the taste of soup, the chicken taste and the chewing strength are finally selected as sensory core factor indexes reflecting the age difference according to the screening principle.

TABLE 3 principal component factor contribution Table

(2) Weight assignment

Respectively calculating respective weights of the sensory core factor indexes by using hierarchical analysis; the specific process comprises the following steps: and comparing every two screened core indexes, and establishing a judgment matrix A by using a 1-9 scale method. Wherein, a in the judgment matrix A (orthogonal matrix)_ijRepresenting the comparison result of the ith factor relative to the jth factor;

carrying out geometric mean (square root method) on each row vector according to the judgment matrix, and then carrying out normalization to obtain index weight W of each sensory core factor_iAnd a feature vector W, and

meanwhile, in order to ensure the logic consistency of the judgment thinking, the consistency of the judgment matrix needs to be checked. Consistency check determines the maximum eigenvalue lambda of the matrix by calculation_maxThe consistency index CI, the random consistency index RI and the consistency ratio CR, in particular,

CR is CI/RI, where CR may be queried according to table 4 random consensus RI. In general, when CR < 0.1, the matrix is considered to have satisfactory consistency, otherwise, the judgment matrix needs to be adjusted. Specifically, in this embodiment, a DSP data processing system is used to perform hierarchical analysis calculation.

Table 4 random consistency RI table

Specifically, in this embodiment, from the perspective of importance of the sensory core factor index, which is judged by the evaluation group, affecting sensory quality, a hierarchical analysis judgment matrix (as shown in table 5) of 5 sensory core factor indexes is established by using a 1-9 scaling method, so as to obtain the sensory core factor index weight.

TABLE 5 sensory core factor decision matrix

The judgment matrix of table 5 is calculated, and the weights of the calculation results of the judgment matrices of the 5 core sensory indexes are shown in table 6.

TABLE 5 sensory core factor AHP judgment matrix calculation results

In order to check the reasonableness of each index weight obtained by the discrimination matrix, the obtained result is subjected to consistency check, when n is 5, RI is 1.12, and the matrix lambda is judged_max5.139 final CR 0.035<0.1, indicating that the judgment matrix has better satisfactory consistency, the weights can be assigned to be used in sensory evaluation models of chicken quality based on different days old Qingyuan chickens. The sensory evaluation index model is as follows: y0.27954 chewy +0.27954 chicken flavor +0.11834 broth clarity +0.08591 oil layer thickness +0.23668Soup flavor.

According to the obtained sensory aspect evaluation model, sensory core factor index profile analysis results at different ages in days can be substituted into the model for calculation and quality ranking (the results are shown in table 6).

TABLE 6 results of profile analysis and ranking of model calculated quality

(3) Model for verifying evaluation indexes in sensory aspects

After obtaining the model, the accuracy and the practicability of the model need to be verified, the method is proposed to be a consumer acceptance inspection scale research method with reference to the common Yumei (2013), the whole quality acceptability of the long-range chickens in the day age is actually graded by adopting 15 grades, then linear fitting with a model evaluation result is carried out, and the accuracy of the model is determined through the linear fitting result. The evaluation group performs comprehensive evaluation on the reasonable-satisfaction degree of the 6-day-old Qingyuan chickens, and scores to obtain the integral actual quality score of each day-old Qingyuan chicken (the result is shown in Table 7).

TABLE 7 quality scores of 'reasonableness-satisfaction' of Qingyuan chickens at different ages of day

Then, the quality data calculated by the model and the actual overall evaluation quality data are subjected to linear fitting (linear fitting analysis is performed by adopting Origin 9.1 Pro), and the goodness of fit (R) is determined²) The difference between the expected value of the model and the actual value obtained in reality is judged. And (4) carrying out verification by using a linear regression analysis method, wherein the sensory evaluation model is used for calculating and dividing the sensory evaluation model into a horizontal coordinate, and the reasonable-satisfaction degree evaluation model is used for dividing the sensory evaluation model into a vertical coordinate. The formula y-3.016X-8.922 (R) is obtained by fitting²0.907), which shows that the fitting coefficient is more than 0.8, the fitting degree between the two is high, all evaluation score points fall within a 95% confidence interval, the evaluation model is proved to be consistent with an actual quality result, which shows that the sensory evaluation index model accurately reflects the real quality of the Qingyuan at different ages of days, the results of the two are displayed in 6 ages of days, the quality of the Qingyuan chickens at 200 ages of days is the best, and the quality of the Qingyuan chickens at 80 days of ages is the worst.

Example 2 establishment of evaluation index model for physicochemical characteristics of chicken meat quality

In the embodiment, the basic physicochemical characteristics of the chickens at different ages in days are analyzed, the physicochemical characteristic core factor indexes reflecting the quality difference of the chickens at different ages in days are screened out, and the evaluation index model of the physicochemical characteristics of the chickens at different ages in days is established.

First, analysis of physical and chemical properties of chicken

In order to explore the change of each physicochemical characteristic along with the change of the age of the day, and further explore the influence of the physicochemical characteristic on the quality of chicken in the change process of the age of the day, a plurality of physicochemical characteristics of the chicken are detected and analyzed.

1. And (3) comparing the pH value of chicken: the change of pH is the change of hydrogen ion concentration caused by the production of orthophosphoric acid and lactic acid by muscle glycolysis in the animal body, and the produced hydrogen ions can complex iron ions and influence the formation of hydrogen bonds, thereby influencing the color and luster of muscles and the water system property, and being one of important indexes for reflecting the chicken quality; in order to stably explore the change of pH of the slaughtered Qingyuan chicken with the age of the day and further explore the influence of the slaughtered Qingyuan chicken on the quality of the slaughtered Qingyuan chicken at the age of the day, experiments are planned to carry out comparative analysis by measuring the pH value of the slaughtered Qingyuan chicken at different ages of the day after standing for 24 hours. Specifically, the pectoralis major muscle portions of chickens after slaughtering the chickens 24 hours at different ages in days were obtained, external fat and connective tissue were cut out and crushed, the homogenized meat sample was dissolved in a beaker using potassium chloride, measured using a pH meter (the average of several times was taken as a result), and subjected to comparative analysis (the results are shown in table 8).

Table 8 different day-old distant chickens pH (n ═ 9); the data in the table are mean values plus or minus standard deviations, different letters in the same column indicate that the difference is obvious (P is less than 0.05), and the expression mode is also adopted in other tables of physical and chemical property detection results in the following.

2. Comparing the water content characteristics of chicken: the water is taken as an important substance in the muscle composition to participate in the composition of a cell structure and serve as an important medium, the distribution fluidity and the binding property of water molecules in food can directly influence the eating quality and the processing stability, and the content of the bound water and the free water in meat products can directly influence the tissue structure, the eating flavor, the eating taste and the like of meat, and is particularly more remarkable in poultry; because the water content obtained by the short-time direct drying method is mainly free water which is easy to lose in intercellular spaces, the water lost in the cooking mode is mainly bound water intercepted by a network structure formed by chicken myofibrils, and the changes of the free water and the bound water in the chicken along with the influence of the age of the day can be reflected together by the direct drying method and the cooking loss rate after cooking; the results obtained for the chicken moisture profile are shown in table 9.

Table 9 different day-old moisture characteristics (n ═ 9);

3. comparing the fiber characteristics of chicken: muscle fiber characteristics of muscles are the histological basis of chicken quality, and the existing research shows that the muscle fiber characteristics influence the sensory edible experience of chicken to a certain extent, so that the acquisition of the fiber characteristics has important significance for quality evaluation. Specifically, 6 day-old, clear and distant chicken breast muscles were selected for HE staining of sections (intramuscular filling ratio (%) -white part area/all red fiber area), and their associated fiber index changes were further analyzed. And to objectively present the visual difference, myofibrillar area, density and intramuscular filling ratio were also quantitatively analyzed (results are shown in table 10).

Table 10 different day old fiber characteristics (n-9);

4. comparing the chicken texture characteristics: elasticity and hardness values of the young chickens at 6 days of age were measured by a TA-XT Puls type texture analyzer to reflect their texture characteristics (the results are shown in Table 11).

Table 11 different day-old texture property changes (n ═ 9);

5. comparing the collagen content of chicken: the hydroxyproline content in the 6 day-old distant chickens was measured to show the change in the collagen content (the results are shown in Table 12).

Table 12 hydroxyproline content changes for different days of age (n ═ 9);

6. comparison of intramuscular fat content of chicken: intrabody fat of the chickens at different ages of the day was extracted and analyzed (the results are shown in table 13). The crude fat extraction process can be seen in example 3.

Table 13 crude fat content at different ages of day (n ═ 9);

secondly, establishing a physical and chemical evaluation model of chicken

1. Screening of index of core factor of physicochemical characteristics

And (3) carrying out variance analysis on physical and chemical property indexes of the Qingyuan chickens of different ages in days, and displaying the results: 10 physical and chemical characteristic indexes (pH, fat content, single fiber area, elasticity, intramuscular filling, collagen content, water content, fiber density, hardness value and cooking loss) of the Qingyuan chickens show different degree difference changes (P is less than 0.05) along with the change of the age of days, namely the indexes can be used as physical and chemical evaluation indexes for screening the quality of the Qingyuan chickens of different ages of days and serve as main physical and chemical characteristic indexes of the application. However, since the physicochemical properties are influenced by each other and act on the quality of chicken, and the core factor indexes of the screened physicochemical properties have relative independence, pearson correlation analysis was further performed, and the results showed that among 100 physicochemical correlation coefficients, significant correlation existed at the level of α ═ 0.01. Therefore, the 10 main physical and chemical property indexes have obvious correlation, which indicates that the measured indexes have information overlapping to a certain degree, inevitably has the problem of collinearity among the indexes, and is difficult to accurately reflect the difference information among the ages. In order to simplify and classify the indexes with correlation and achieve the purpose of enhancing the accuracy and efficiency of quality evaluation, 10 main physical and chemical characteristic indexes of the Qingyuan chickens of 80, 100, 120, 140, 160 and 200 with different ages in days are subjected to discriminant analysis by adopting SIMCA 14.0 through a supervised classification model OPLS-DA discriminant analysis. FIG. 4 is an S-plot diagram generated by pairwise comparison of physicochemical data of 6-day-old distant chickens by using OPLS-DA, wherein the abscissa represents the co-correlation coefficient p (corr) between the principal component and the analysis index, the ordinate represents the correlation coefficient (p) between the principal component and the analysis index, and the larger the value of p (corr) corresponding to the analysis index is, the higher the correlation between the index and the model principal component is. Fig. 5 is a pairwise comparison variable projection importance (VIP) in an OPLS-DA model, which is used to measure the influence strength and the interpretation ability of the expression pattern of each metabolite on the discrimination of each group of sample classes, and the existing research shows that generally a VIP value >1.0 is considered to have strong influence strength and interpretation ability on each group of sample classes, and can be used as a feature index screening standard.

Therefore, according to the OPLS-DA analysis results, the indexes with VIP >1 and p (corr) >0.5 under pairwise comparison are screened (the results are shown in table 14), so as to be used for the establishment of an index model for evaluating physicochemical properties in the subsequent step. In addition, in order to ensure the uniformity of single physicochemical property index data, the in-group Student's T-test is carried out aiming at the physicochemical index of each day age group, and the screening result shows that the in-group difference between 10 physicochemical properties under 6 different day ages does not exist, and the variation between parallel samples is low, and the data is stable. In order to ensure that the variation of the physicochemical index difference between the ages in days is comprehensively reflected, the physicochemical characteristic core factor indexes of the screening results of all the age groups in pairs are merged, and finally the hardness value, the area of a single fiber, the intramuscular filling, the collagen content and the crude fat are determined as the physicochemical characteristic core factor indexes.

TABLE 14 comparison of results of screening physicochemical factors for pairwise comparisons (n ═ 9)

2. Weight assignment

Based on the difference of the influence degree of different physical and chemical characteristic indexes on the quality of the Qingyuan chickens of different ages in days, in order to enable the different indexes to reflect the quality of the Qingyuan chickens more accurately, an analytic hierarchy process is used for carrying out weight distribution on the indexes. Based on the existing research on the physicochemical properties of high-quality chickens and the degree of importance of the influence of each physicochemical property on the chicken quality, a hierarchical analysis judgment matrix of 5 physicochemical property core factor indexes is constructed by combining a 1-9 proportional scaling method (as shown in Table 15).

TABLE 15 decision matrix

The results of calculating the judgment matrix of table 15 are shown in table 16.

TABLE 16 results of AHP judgment matrix calculation

Performing consistency check, when n is 5, RI is 1.12, and judging matrix lambda_max5.094, final CR 0.021<0.1, the judgment matrix has better satisfactory consistency and can be used as model weight distribution. The evaluation index model in the aspect of the physicochemical characteristics of the quality of the Qingyuan chickens of different ages in days is as follows: y0.4965 × hardness value +0.14746 × intramuscular filling ratio +0.14746 × collagen content +0.14746 × crude fat content +0.06112 × single fiber area. The physicochemical characteristic core factor index data under different ages of days are substituted into the model according to the established physicochemical characteristic aspect evaluation index model to calculate and rank the quality (the result is shown in table 17), and the rank and the age of days are in positive correlation.

TABLE 17 results of physicochemical analyses and model calculation quality ranking

Third, verifying evaluation index model of physical and chemical properties of chicken quality

A linear fit was performed in conjunction with the actual scoring results in example 1. And (4) calculating by using a physicochemical evaluation model to obtain a horizontal coordinate, and performing verification by using a linear regression analysis method, wherein the evaluation of the reasonable-satisfaction degree is obtained by using a vertical coordinate. The formula y-0.0156-3.606 (R) is obtained by linear fitting²0.872), the fitting coefficient is higher than 0.8, the fitting degree between the two is high, and all the evaluation score points fall within a 95% confidence interval, which indicates that the evaluation model can accurately reflect the clear real quality under different ages in days based on the physical and chemical level.

Example 3 establishment of evaluation index model for fatty acid aspect of Chicken meat quality

In this embodiment, the fatty acid difference of the Qingyuan chickens of different ages in days is researched, and the main fatty acid which has obvious influence on the quality of the chicken is screened out by a multivariate analysis means, so that an evaluation index model in the aspect of fatty acid of the Qingyuan chickens of different ages in days is established.

Intramuscular fatty acid content and composition analysis

Intramuscular fat in the Qingyuan chickens of different ages in days is extracted, and the composition and the content of the intramuscular fat are determined by combining GC-MS. Specifically, fat was extracted under the conditions of chicken extraction in example 1Acid extraction and derivatization, comprising the following steps: extracting crude fat, separating chicken breast skin and meat of different ages in days, boning, removing tendon, cutting into small pieces, respectively placing into a beater, uniformly beating, respectively weighing about 8-10g of three meat samples of each age in days, placing into a 50mL centrifuge tube, firstly adding 10mL of methanol, whirling for 2min to uniformly break the samples, then adding 20mL of chloroform, and extracting for 1h at 37 ℃ in a 250r/pm shaking table; filtering the extractive solution, adding the residue into chloroform-methanol (2:1, V/V) solvent, extracting for 30min, and mixing filtrates; centrifuging at 3000r/min for 15min, discarding the upper methanol layer, washing the lower chloroform layer with 5mL saturated saline solution, collecting the lower chloroform layer, vacuum drying at 40 deg.C, and constant-weight to obtain crude fat. The crude fat content was calculated as follows:

wherein W is the lipid content (%) of the sample, and m is₀Is the sample mass (g), m₁Is the mass (g) of the container and the lipid material; m is₂Is the mass (g) of the container after constant weight. Based on the extraction of crude fat, the sample was hydrolyzed with reference to "determination of fatty acids in food Standard of safe countries" (GB 5009.168-2016). Adding 200mg of 150-one total lipid extracted from chickens at different ages of days into 8mL of 2% sodium hydroxide-methanol solution, connecting with a reflux condenser, and refluxing in a water bath at 80 +/-1 ℃ for 22-23 min. 7mL of 14% boron trifluoride methanol solution was added from the upper end of the reflux condenser, and the reflux was continued in a water bath at 80. + -. 1 ℃ for 3-4 min. The reflux condenser was flushed with a small amount of water. The heating was stopped, the flask was taken out of the water bath and rapidly cooled to room temperature. Accurately adding 10mL of n-hexane, shaking for 2min, adding saturated sodium chloride aqueous solution, and standing for layering. Sucking the upper n-hexane extractive solution from about 5mL to 25mL test tube, adding about 3g-5g anhydrous sodium sulfate, shaking for 1min, and standing for 5 min. And (5) sucking 1mL of the upper layer solution into a 10mL volumetric flask for constant volume, and taking 1mL of the upper layer solution into a sample injection vial to be measured.

Then, on the basis of the above process, fatty acid GC-MS analysis was performed, and total ion chromatogram of distant chickens at different days of age was measured, as shown in fig. 6. Deconvoluting all chromatographic peaks by a TraceFinder chromatographic analysis workstation, comparing NIST standard mass spectrum libraries,finally 14 consensus fatty acids at 6 days of age were determined. In addition, compared with other chicken breeds (yellow chicken in Pengxian county, black-bone chicken in Shaanbei, and the like), fatty acids of C22 series exist in the Qingyuan chicken, wherein the fatty acids are represented by DPA and DHA which are necessary for human bodies. In order to further perform qualitative analysis on the detected fatty acids, the area normalization method is used to calculate the relative content of 14 fatty acids (the calculation result is shown in table 18), wherein the process of determining the relative content of fatty acids by the area normalization method comprises the following steps: sampling 1 mu L of fat extract, obtaining a sample total ion flow diagram by using a GC-MS Full Scan mode (Full Scan), comparing a mass spectrogram of a fatty acid methyl ester chromatographic peak with an NIST standard mass spectrum library, determining the appearance sequence, retention time and compound information of each peak, and then performing an area normalization method on an Xcalibur workstation to determine the relative percentage content of each fatty acid component in Qingyuan chickens and the relative content of fatty acid (X)_i％)＝[A_i/(A₁+A₂+…+A_n)]×100，X_iIs the percentage content of the component i, A₁、A₂…A_nPeak areas for component 1, 2 …, n. As is clear from table 18, day-old mainly affected the content of each fatty acid in the breast muscle of the remote chickens, with no significant difference in composition.

Table 18 fatty acid composition and relative content scale of different day-old distant chickens (n ═ 9);

secondly, establishing a chicken fatty acid evaluation model

1. Fatty acid core factor index screening

Variance analysis is carried out on 14 common fatty acids of the Qing distant chickens of different ages in days (ANOVA variance analysis is carried out on data between different groups and between parallel groups by adopting an SPSS 18.0 software system, the difference significance of the average values of the Qing distant chickens of 6 ages in days is tested by Duncan multiple comparison, the test level is P (0.05), the values are sequentially arranged according to the size of the average values by adopting an a, b and c letter mark method, and the same level difference is represented if the letters are the same), and the results show that: the 14 common fatty acids of the Qingyuan chickens show different degree of difference change (P is less than 0.05) along with the change of the day age, so the fatty acid evaluation index can be used for screening the quality of the Qingyuan chickens at different day ages. In order to make the screened fatty acid evaluation indexes have relative independence, the pearson correlation analysis is carried out, and the results show that the fatty acid correlation coefficients are obviously correlated at the level of alpha-0.01, which indicates that the 14 detected fatty acid indexes are overlapped in information to some extent, and the colinearity problem is inevitable. It is difficult to accurately reflect the information of fatty acid difference between the ages of the days. Therefore, in order to simplify and classify the indexes with correlation and achieve the purpose of enhancing the accuracy and efficiency of quality evaluation, the 14 common fatty acids of the Qingyuan chickens with different age gradients of 80, 100, 120, 140, 160 and 200 are subjected to discriminant analysis through the supervised classification model clustering OPLS-DA. FIG. 7 is a S-plot diagram generated by comparing fatty acid data of 6 day-old distant chickens two by using OPLS-DA (a-o represents the OPLS-DA S-plot diagram obtained by comparing 80-100, 80-120, 80-140, 80-160, 80-200, 100-. FIG. 8 shows the variation projection importance (VIP) in the OPLS-DA model in two-by-two comparison (a-o represents the comparison of the VIP values of the OPLS-DA model in two-by-two comparison at the ages of 80-100, 80-120, 80-140, 80-160, 80-200, 100-.

According to the analysis result of OPLS-DA, screening indexes of VIP >1 and p (corr) >0.5 under pairwise comparison (the result is shown in table 19) so as to finally determine the index of the fatty acid core factor, and the index is used for establishing a fatty acid evaluation model of the quality of the chickens in the day-old Qingyuan. In addition, in order to ensure the regularity of single fatty acid index data, Student's T-test is carried out simultaneously aiming at each day-old fatty acid index, and screening results show that the fatty acid indexes under 6 different days have no obvious difference in groups, and the variation among parallel samples is low, and the data is stable. In order to ensure that the index difference change of fatty acids between the ages of days is comprehensively reflected, screening results of all pairwise comparison age groups are combined, and finally 10 fatty acids of DPA, linoleic acid, ARA, EPA, C17:3, stearic acid, myristic acid, C22:4, palmitic acid and oleic acid are determined as the indexes of the fatty acid core factors.

Table 19 compares the results of fatty acid factor screening two by two (n-9);

2. weight assignment

The influence degree of different indexes on the quality of the Qingyuan chickens at different ages in days is different, and in order to enable the different indexes to reflect the quality of the Qingyuan chickens more accurately, the weight distribution is carried out on the fatty acid core factor indexes by using an analytic hierarchy process. Based on the existing research on the fatty acids of high-quality chickens (for example, from the aspect of nutrition, monounsaturated fatty acid and essential fatty acid for providing nutrients, polyunsaturated fatty acid and saturated fatty acid are preferably considered) and the importance degree of each fatty acid on the nutritional quality, a hierarchical analysis judgment matrix (shown in a table 20) of 10 core fatty acid indexes is constructed by combining a 1-9 proportion scaling method

TABLE 20 decision matrix

The results of calculating the judgment matrix of table 20 are shown in table 21.

TABLE 21 fatty acid index decision matrix calculation results

Performing consistency check, when n is 10, RI is 1.49, and judging matrix lambda_max10.853 final CR 0.064<0.1, the judgment matrix has better satisfactory consistency and can be used as model weight distribution. The obtained Qingyuan tablets with different ages of daysThe chicken quality fatty acid evaluation model comprises the following steps: y0.15958 eicosapentaenoic acid (EPA) +0.14193 arachidonic acid (ARA) +0.14193 linoleic acid +0.13573 oleic acid +0.12649 docosapentaenoic acid (DPA) +0.11219 docosatetraenoic acid +0.10502 heptadecatrienoic acid +0.2571 myristic acid +0.2571 palmitic acid +0.2571 stearic acid. The method comprises the steps of scoring the Qingyuan chickens under 6 different days of age according to a fatty acid scoring model, substituting analysis results of relative content of important fatty acids under different days of age into the model to calculate and rank the quality (the result is shown in a table 22), wherein the ranking and the length of the days of age are in positive correlation as the table 22 shows, the score is calculated by the fatty acid evaluation model to be higher as the days of age are longer, wherein the highest ranking of 200 days of age is the best, and the ranking of 80 days of age is the lowest.

TABLE 22 day-old fatty acid analysis results and model calculated quality rankings

Third, verifying chicken fatty acid evaluation model

A linear fit was performed in conjunction with the actual scoring results of example 1. The fatty acid evaluation model is used for calculating and dividing the fatty acid evaluation model into a horizontal coordinate, the reasonable-satisfaction degree evaluation model is used for dividing the fatty acid evaluation model into a vertical coordinate, and a linear regression analysis method is used for verifying the fatty acid evaluation model. The formula y is 3.785X-16.152 (R) by verification²0.724) with a smaller fitting coefficient than the other models, which deviate from the actual quality assessment results, the degree of fitting is low, probably because the fatty acid assessment alone is not yet perfect for the actual quality assessment, based on fatty acids representing only part of the quality information. However, when the evaluation index model is combined with the above-mentioned sensory, physicochemical evaluation index model, the formed comprehensive evaluation model should still have high accuracy.

Example 4 construction of Chicken meat comprehensive evaluation model

Firstly, establishing a chicken quality comprehensive evaluation model

In order to realize comprehensive evaluation of the quality of the chickens in different days, the embodiment establishes judgment matrix distribution weights for three different-dimensional aspect evaluation indexes by using a fuzzy hierarchy method on the basis of sensory profile analysis, basic physicochemical characteristic analysis and fatty acid nutrition analysis of the chickens in different days, and finally determines a comprehensive evaluation model of the quality of the chickens in different days. Specifically, the hierarchical structure diagram is established as shown in fig. 9. In order to qualitatively evaluate the importance of various evaluation factors influencing the quality of the young chickens in the daytime, comprehensive evaluation weight coefficients of different analysis levels need to be determined so as to be beneficial to comprehensive evaluation. The physicochemical properties, the fatty acids and the sensory attributes respectively represent the processing quality, the nutritional quality and the eating quality of the Qingyuan chickens under the influence of the age of the day, and the physicochemical properties, the fatty acids and the sensory attributes are all an indispensable part of the comprehensive quality of the Qingyuan chickens, wherein the difference between the physicochemical properties and the fatty acids is an objective material basis of the quality of the Qingyuan chickens, and the sensory eating quality is based on the consideration of the object-oriented aspect of the chicken, and the physicochemical properties, the fatty acids and the sensory attributes have the same importance degree on the comprehensive quality of the Qingyuan chickens. Therefore, a comprehensive evaluation judgment matrix is established as shown in table 23.

TABLE 23 comprehensive evaluation factor judgment matrix

The results of calculating the judgment matrix of table 23 are shown in table 24.

TABLE 24 analysis results of the comprehensive evaluation factor AHP

Performing consistency check, when n is 3, RI is 0.52, and judging matrix lambda_max3, final CR 0.00<0.1, the judgment matrix has better satisfactory consistency and can be used for comprehensive model weight distribution. Combining the sensory evaluation model obtained in the example 1, the physicochemical evaluation model obtained in the example 2 and the fatty acid evaluation model obtained in the example 3, the weights obtained by the indexes in different aspects are respectively given to the sensory evaluation model, and the comprehensive quality evaluation model is obtained by: y0.333 (0.27954 chewy +0.27954 chicken flavor +0.11834 color of broth clarity +0.08591 oil layer thickness +0.23668A soup note) +0.333 (0.4965A hardness + 0.14746A intramuscular fill of + 0.14746A collagen content + 0.14746A crude fat content + 0.06112A fiber area) +0.333 (0.15958A eicosapentaenoic acid (EPA) + 0.14193A arachidonic acid (ARA) +0.14193 linoleic acid + 0.13573A oleic acid + 0.12649A docosapentaenoic acid (DPA) + 0.11219A docosatetraenoic acid + 0.10502A heptadecatrienoic acid + 0.2571A myristic acid + 0.2571A palmitic acid + 0.2571A stearic acid). Performing quality scoring on the clear and distant chickens under 6 different days according to a total comprehensive evaluation model, respectively substituting core factor index data of each evaluation index under different days into the model for calculation and performing quality ranking (Table 25); it can be known from table 25 that the rank is positively correlated with the age of day, the longer the age of day, the higher the score calculated by the comprehensive evaluation model, wherein the top rank of the distant chickens 200 days old is the best, and the bottom rank of the distant chickens 80 days old is the lowest.

TABLE 25 age of day Total index quality comprehensive evaluation model results

Second, verify the chicken quality and appraise the model synthetically

A linear fit was performed in conjunction with the actual scoring results of example 1. And (4) calculating by using a comprehensive evaluation model to obtain a horizontal coordinate, evaluating the reasonable-satisfaction degree to obtain a vertical coordinate, and verifying by using a linear regression analysis method. The formula y 0.0547 x-5.202 (R) is obtained by linear fitting²0.910), the fitting coefficient is more than 0.8, the fitting degree between the two is high, all the evaluation score points fall within a 95% confidence interval, the comprehensive evaluation model is proved to accurately reflect the clear and far real quality under different ages in days, and the evaluation results of the two are displayed to be the best quality at 200 ages in days and the worst quality at 80 ages in days.

According to the fitting results of the four models, the quality evaluation results of the long-day-old Qingyuan chickens in the four evaluation models are basically consistent, the quality of the long-day-old Qingyuan chickens is obviously superior to that of the short-day-old Qingyuan chickens, and the quality is inversely proportional to the age of the long-day chickens. Through the quality analysis of the four evaluation models, 200-day-old Qingyuan chickens are considered to be the best in quality of 6 days, meanwhile, the fitting degree of the analysis result of the full-index comprehensive evaluation model and the actual quality grade of direct sensory comprehensive evaluation is known through the calculation and analysis results of the four models, the fitting degree of the analysis result of the full-index comprehensive evaluation model and the actual quality grade is the highest, so that the quality evaluation accuracy of the day-old Qingyuan chickens is the highest by using the full index, the evaluation result of the sensory model is the next lowest, and the accuracy of the fatty acid model evaluation result is the lowest, so that the full-index comprehensive model or the sensory profile analysis model can be preferentially used in the day-old quality evaluation analysis of the Qingyuan chickens in the future, and besides, the quality grade and the day age of the Qingyuan chickens present trend changes, so that rough estimation can be made for the day-old.

Claims (10)

1. A method for constructing a comprehensive chicken quality evaluation model is characterized by comprising the following steps:

s1, confirming multiple aspect evaluation indexes which change along with the change of conditions and reflect the chicken quality, and acquiring core factor indexes which are corresponding to each aspect evaluation index and influence the score of the aspect evaluation index due to the change of conditions;

s2, calculating the weight of each index by using an analytic hierarchy process, constructing an aspect evaluation index model based on the core factor index and the corresponding weight of the core factor index, and constructing a chicken quality comprehensive evaluation model based on the aspect evaluation index model and the aspect evaluation index weight; the facet evaluation index model is used for obtaining facet evaluation index scores, and the comprehensive evaluation model is used for obtaining chicken quality comprehensive evaluation scores.

2. The method for constructing the comprehensive evaluation model of chicken meat quality as claimed in claim 1, wherein the multiple evaluation indexes include sensory evaluation indexes, physical and chemical property evaluation indexes, and fatty acid evaluation indexes.

3. The method for constructing a comprehensive evaluation model of chicken meat quality as claimed in claim 2, wherein the condition change in step S1 is a day-to-day change, and the comprehensive evaluation model is characterized in that the evaluation indexes of official aspect, physicochemical characteristic and fatty acid are the same in weight.

4. The method for constructing the comprehensive evaluation model of chicken meat quality as claimed in claim 2, wherein the process for constructing the sensory evaluation index model comprises:

SA1, establishing multiple chicken sensory indexes and sensory index scoring systems for reflecting the sensory attributes of chicken;

SA2, scoring sensory indexes of a plurality of groups of chickens with different conditions, and screening the sensory indexes which are obviously different along with the change of the conditions as main sensory indexes;

SA3, performing principal component analysis on the main sensory index based on the score in the step SA2, confirming the principal component, screening indexes which basically reflect the sensory attributes represented by the whole corresponding principal component under the principal component as sensory core factor indexes, and using the sensory core factor indexes for establishing a sensory evaluation model;

SA4, carrying out weight distribution on sensory core factor indexes by using an analytic hierarchy process, and obtaining a sensory evaluation model for obtaining the eating quality of chicken, wherein the sensory evaluation model is as follows: and (3) the chicken sensory comprehensive evaluation score is the weighted sum of the index scores of all the sensory core factors.

5. The method for constructing the comprehensive evaluation model of chicken meat quality as claimed in claim 2, wherein the process for constructing the evaluation index model in the aspect of physicochemical properties comprises:

SB1, detecting chicken obtained under different conditions, and screening main physical and chemical characteristic indexes with obvious difference of detection data along with the change of conditions;

SB2, carrying out Pearson correlation verification on the main physical and chemical characteristic indexes obtained in the step SB1, and if no significant correlation exists between the main physical and chemical characteristic indexes, using the main physical and chemical characteristic indexes as core factor indexes of physical and chemical characteristics and constructing a chicken quality physical and chemical characteristic evaluation model; if the main physical and chemical characteristic indexes have obvious correlation, further determining the physical and chemical characteristic core factor indexes through the discrimination analysis of a supervised classification model OPLS-DA;

SB3, performing weight distribution of physicochemical characteristic core factor indexes by using an analytic hierarchy process, and obtaining a physicochemical characteristic evaluation model for acquiring chicken processing quality, wherein the physicochemical characteristic evaluation model is as follows: the comprehensive evaluation score of the physicochemical characteristics is the weighted sum of the index scores of the core factors of the physicochemical characteristics.

6. The method for constructing the comprehensive evaluation model of chicken meat quality as claimed in claim 2, wherein the construction process of the fatty acid evaluation index model comprises:

SC1, detecting the fatty acid composition and relative content of chicken under different conditions, and screening main fatty acid with obvious difference along with the change of conditions;

SC2, performing Pearson correlation verification on the fatty acids obtained in the step SC1, and if no significant correlation exists among the fatty acids, taking the fatty acids as the fatty acid core factor indexes and using the fatty acids as the fatty acid core factor indexes to construct a chicken quality fatty acid evaluation model; if significant correlation exists among the fatty acids, further determining the index of the fatty acid core factor through the discrimination analysis of a supervised classification model OPLS-DA;

SC3, performing weight distribution of the fatty acid core factor indexes by using an analytic hierarchy process, and obtaining a fatty acid evaluation model for obtaining the chicken nutrition quality, wherein the fatty acid evaluation model is as follows: the fatty acid comprehensive evaluation score is the weighted sum of index scores of various fatty acid core factors.

7. The method for constructing the comprehensive evaluation model of chicken meat quality as claimed in claim 1, wherein when the condition is day age and the chicken meat is the meat of the Qingyuan chicken, the aspect evaluation index and the core factor index form an evaluation index system, and the indexes and the system specifically comprise:

the aspect evaluation index: sensory evaluation, physical and chemical properties evaluation, and fatty acid evaluation;

core factor index: core factor indexes of the sensory evaluation comprise chewing strength, chicken taste, soup color clarity, oil layer thickness and soup aroma; the core factor indexes evaluated in the aspect of physical and chemical properties comprise hardness values, intramuscular filling ratio, collagen content, crude fat content and single fiber area, and the core factor indexes evaluated in the aspect of fatty acid comprise eicosapentaenoic acid, arachidonic acid, linoleic acid, oleic acid, docosapentaenoic acid, docosatetraenoic acid, heptadecatrienoic acid, myristic acid, palmitic acid and stearic acid;

the evaluation index system is as follows:

the layer I is a target layer and is the comprehensive quality of the chicken to be evaluated;

the layer II is a standard layer and is a plurality of evaluation indexes including sensory evaluation indexes, physical and chemical property evaluation indexes and fatty acid evaluation indexes;

the layer III is an index layer and is a core factor index corresponding to each aspect evaluation index, wherein the core factor index of the sensory aspect evaluation comprises chewing strength, chicken taste, liquor color clarity, oil layer thickness and liquor aroma; the core factor indexes evaluated in the aspect of physicochemical properties comprise hardness values, intramuscular filling ratio, collagen content, crude fat content and single fiber area; the core factor index evaluated in terms of fatty acid includes eicosapentaenoic acid, arachidonic acid, linoleic acid, oleic acid, docosapentaenoic acid, docosatetraenoic acid, heptadecatrienoic acid, myristic acid, palmitic acid, stearic acid;

and the IV layer is a scheme layer and is a Qingyuan chicken with different ages in days.

8. A chicken quality comprehensive evaluation model, which is constructed by the method for constructing the chicken quality comprehensive evaluation model of any one of claims 1 to 7.

9. A chicken quality comprehensive evaluation method is characterized in that the chicken quality comprehensive evaluation model of claim 8 is adopted to score chicken quality, and the quality of the chicken is judged according to the scoring result.

10. The use of the chicken quality comprehensive evaluation model of claim 8 in chicken quality evaluation.

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