| Summary: | 碩士 === 國立中興大學 === 動物科學系所 === 107 === Frozen is a popular and effective storage method in meat industry. It is used to extend the shelf-life of meat product. However, the process of long-term frozen storage may lead to protein decomposition and lipid oxidation, thus resulting into the occurring of acid flavor or lipid oxidation flavor. Occasionally, chilled meats are transferred to be frozen storage probably due to some business reasons. The purpose of this study was to investigate the influences of frozen storage duration and chilling-then-frozen process on the quality characteristics and sensory evaluation of chicken meat.
In experiment 1, the parameters including proximate composition, pH values, thaw loss, drip loss, cooking loss, water holding capacity, color, VBN, TBARS, shear values and sensory characteristics of broiler chicken thigh meat which had been conventionally frozen (CF) or rapidly frozen (RF) were evaluated during frozen storage of 0, 3, 6, 9, 12, 15 and 18 months. The results showed that thaw loss increased significantly at the 9th month, whereas no significant difference was observed for the pH values. Sensory characteristic of CF samples degraded which evaluated by the panelists. TBARS values and VBN values increased with storage time. After storage for 18 months, CF had significantly higher TBARS values than RF. Sensorial off-odors of the thawed samples increased with storage time. After storage for 18 months, the results show that chicken thigh meat which has been frozen conventionally had higher TBARS values; off-odors increased with extended storage time.
In experiment 2, the parameters including moisture content, pH values, thaw loss, drip loss, cooking loss, VBN, TBARS, TPC and sensory characteristics of the samples which have been chilled for 1, 3, and 5 days (C1, C3, and C5, respectively) then frozen for 0, 1.5, and 3 months were determined in order to evaluate the effect of chilling-then-frozen on chicken meat quality. The results showed that C5 had significantly higher drip loss and cooking loss than C1 and C3 did. VBN values increased significantly with storage time, whereas VBN values of C1 were significantly lower than those of C3 and C5. The TPC significantly increased after frozen storage for 3 months, whereas the TPC was in the orders of C1＜C3＜C5 after storage for 3 months. Sensorial off-odor of chicken skin of C5 was higher than those of C1
and C3.
In conclusion, chicken thigh meat which has been frozen conventionally for 18 months become rancid and off-odor increased, thus diminishing the quality of meat. Chicken meat with longer chilling storage then frozen could result in the deterioration of quality and sensory characteristics.
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