| Summary: | 碩士 === 國立中興大學 === 動物科學系所 === 106 === Emphasis of the importance in meat qualities has been increased continuously recently. Evaluation the qualities of beef and pork has been conducted for years. Some characteristics, such as juiciness, texture and flavor of pork and beef are often determined using physicochemical analysis and sensory evaluation. In contrast, there is less an objectively assessed standard for chicken meat. In Taiwan, some pork is sold at the ambient temperature. Consumers choose and purchase meat according to the sensory characteristics of products. A multivariate statistical method namely principal component analysis (PCA) has been used to identify the most critical variables in a multivariate data matrix, thus analyze data more effectively and efficiently. Additionally, some methods including the triangle test have been applied in the sensory evaluation. Therefore, this study was intended to utilize of physicochemical analysis, sensory evaluation and statistical methods to evaluate pork and chicken meet quality. In the 1st experiment, Taiwan native chicken (TNC) breast was cooked in a 95°C water bath until the internal temperature of the meat reached 85°C for 0, 20 and 40 minutes. Cooking loss, moisture content, water holding capacity (WHC) and some descriptive sensory parameters were determined, followed by a PCA analysis, thus to determine the juiciness of meat samples. In the 2nd experiment, shear force, total collagen content, and soluble collagen content as well as some descriptive sensory parameters of breast from TNC which fed for 12 and 16 weeks were determined, followed by a PCA analysis to analyze the texture of samples. In the 3rd experiment, sensory panelists attempted to apply the triangle test to differentiate the pork loins stored at 23±2°C for 4, 6, and 8 h (M4h, M6h, and M8h) as well as at 33±2°C for 2, 4, and 6 h (H2h, H4h, and H6h) to the one stored at 7°C (COM).
The results of the 1st experiment showed that the four major principal components explained about 80.0% of the total variation. The PCA score plot showed a clear separation into the three clusters. According to the loadings, cooking loss, moisture content and WHC, as well as some sensory characteristics including moisture release, cohesiveness and oily mouthcoat were considered as the most effective variables for PC1, while WHC was most effectively to PC2. Sensory attributes including fiber texture, meat particle size, and chicken flavor intensity were effectively to PC3, while initial hardness, residual loose particles, and total acceptance were effectively to PC4. The results of the 2nd experiment showed that the four major principal components explained about 84.6% of the total variation. The PCA score plot showed a clear separation in two clusters. Base on the loadings, the soluble collagen content was effectively to PC1, while the total collagen content as well as some sensory characteristics including chew down hardness, chicken flavor intensity and total acceptance were the most effective variables to determine PC2. Three sensory attributes including moisture release, oily mouthcoat and chicken flavor intensity were effectively to PC3, while the total collagen content was effectively to PC4. The results of the 3rd experiment showed that the sensory characteristics of M8h and H6h samples significantly differed than those of COM (P < 0.05) base on the result of triangle test. According to the Fisher’s exact test, the chooses of 5 sensory characteristics including color, exudative, odor, mucus, and texture did not significantly relate to the correct answering and differentiation the samples (P > 0.05), thus more than one sensory characteristics was applied by the panelist to differentiate the samples. For M8h samples, texture was chosen by the 42.1% of the panelists who successfully differentiate samples, while texture was also chosen by the 80% of the panelist who differentiate samples fail. The results implied texture might be an appropriate judge criterion for those experienced panelists to functionally successfully while texture might be the possible cause leading to the failure for those inexperienced panelists. In summary, PCA can be applied to select a number of physicochemical and sensory parameters to determine the juiciness and texture characteristics of Taiwan native chicken breast effectively. Triangle test can be applied to evaluate the qualities of pork stored at ambient temperatures for 6 to 8 hours. In addition to the sensory characteristics that evaluated in the current study, the safety of product (i.e., the microbiological) should be also addressed. In conclusion, it is promising to apply physicochemical analysis, sensory evaluation and statistical methods appropriately to evaluate meat quality more effectively and efficiently.
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