| In recent years,the demand of people for high quality pork has increased,but there is a lack of effective quality evaluation methods which restric the development of the high quality pork industry.In this study,7 brands of pork were selected from the perspectives of breed and breeding mode,and the left dorsal longus muscle were selected as the research object(sample numbers were A,B,C,D,E,F and G).The pork quality was evaluated from four aspects:sensory evaluation,food quality,nutrition composition and flavor substance.At the same time,through sensory indicators such as the color,tenderness,tissue state and chewiness of meat,etc;pH,freshness,intramuscular fat,marble pattern,meat color,umami amino acids,water retention,texture and other food quality indicators;nutritional indicators such as protein,ash content,intramuscular fat,amino acids,fatty acids and key volatile flavor substances indicators to analyzed the pork quality.Finally,the quality evaluation method of high quality pork was studied and the basic database was established,which provided a new research idea for the breakthrough of the key technology for high quality pork’s quality evaluation.(1)Quality analysisThis study has obtained 7 pork brands,involving 5 varieties and 3 breeding models,including 42 sample information data in four aspects:sensory quality,edible quality,nutritional content and flavor substances,which can provide quality indicators for selection of high quality pork.①Sensory qualities.A 10-point sensory scoring method was used for sensory analysis of 7 kinds of pork.The results showed that the sensory quality indicators of the pork were different.Pork F had a higher overall sensory score,such as tenderness,elasticity,chewiness and taste,and had the highest comprehensive acceptance.②Edible quality.Use colorimeter and texture analyzer to analyze food quality.The results showed that Pork B and E had higher L*values,normal flesh color and the most obvious marble pattern,as well as small shear force value(nearly 50%lower than Pork A)(P<0.01),indicating that the meat qualities of Pork B and E were relatively tender and tasted better.Pork E,F,and G had low chewiness,low stickiness,and greater elasticity,which were significantly different from other types of pork(P<0.01).Pork E and G were about 20.30%～32.13%lower in chewiness than the other five types of pork.The cooking loss of 7 kinds of pork were in the range of 24.24%～30.20%,and the drip loss were in the range of 2.94%～4.86%.Pork E had the lowest cooking loss,pork A had the lowest drip loss,both A and E had strong water retention.Intramuscular fat contents of 7 kinds of pork were in the range of 1.02%～19.65%,pork B content was the highest,and the most tender.Umami amino acid contents were in the range of 39.48%～47.90%,pork G content was the highest,and umami taste was strong among several types of pork;inosinic acid contents were in the range of 5.11～5.76 mg/g,there was no significant difference between 7 kinds of pork.③Nutritional quality.The national standard method was used to determine the nutrients in pork.The results showed that the protein contents of 7 kinds of pork were in the range of 21.04%～24.24%,and the C content of pork was the highest.The intramuscular fat contents were in the range of 1.02%～19.65%,the vitamin B2 contents were in the range of 0.18～0.24 mg/100g,and the moisture contents were in the range of 59.02%～72.54%,pork B had the highest intramuscular fat and vitamin B2 content,and the lowest moisture content.The vitamin B1 contents were in the range of 0.55～0.77 mg/100g,and the pork E content was the highest.The ash content ranged from 0.94%to 1.32%.Pork D had the highest ash.From the perspective of fatty acids,SFA and MUFA were relatively high,close to 40%and 45%respectively.MUFA had the highest content,ranging from 42.85%to 49.79%.Among the seven types of pork,pork D’s MUFA content was the most prominent.④Analysis of volatile flavor substances.It were measured by HS-SPME-GC-MS technology.The results showed that a total of 55 volatile flavor substances were detected in 7 types of pork,mainly including alcohols,aldehydes,acids and ketones.The composition of the volatile flavor compounds of different pork was similar.Among them,the content of aldehydes was the highest(about 42.51%～59.22%).The ROAV method was used to determine the key flavor substances of pork,and the common ones are hexanal,nonanal,n-octanal and 1-octen-3-ol.Non-general flavor compounds include heptanal,trans-2-nonanal,trans-2-octenal,2-pentylfuran and trans-2-decenal.Myristaldehyde,decanal,limonene,valeraldehyde and anethole were the key flavor substances unique to A,C,D,and G respectively.Combined with the sensory evaluation,pork A,C,D,and G had lower odor scores,suggesting that the difference in volatile flavor substances was one of the reasons for the difference in the sensory acceptance of pork.(2)Establish quality evaluation methods.Based on 40 index data of sensory quality,edible quality,and nutritional composition,through PCA combined with coefficient of variation and correlation analysis,it was determined that the indexes that have a greater contribution to the quality of high-quality pork are hardness,adhesiveness,and chewiness,tenderness,TVB-N,marbling,a*,umami amino acids,drip loss and cooking loss.Using PCA to analyze the main indicators and extract 4 principal components,determine the weight coefficients according to the contribution rate of each principal component,and construct a comprehensive evaluation model for high-quality pork quality:F综=0.41 F1+0.26 F2+0.21 F3+0.12 F4.The four main components of F1～F4 were renamed as sensory factors,freshness factors,processed flavor factors and water retention factors.The cumulative contribution rate was 89.04%,which can summarize most of the information on pork quality.According to this model,the comprehensive scores of pork A～G are-0.452,0.319,0.001,0.304,-0.844,0.563,0.263.It is preliminarily determined that the comprehensive score is greater than 0 and can be judged as high quality pork.Using this evaluation method to evaluate pork has guiding significance for consumers and the breeding industry.(3)Establish a basic database of high quality pork.Microsoft Access 2016 was selected as the carrier software.Firstly established basic data tables and clarify the relationships between tables,secondly established database objects such as queries,forms,and macros,and at last combine each database object organically.Finally established a database management system.This database can realize the query and update of different pork’s brand information and quality information,and it also can provide a convenient information platform for the selection and quality analysis ofhigh quality pork breeds. |
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