碩士 / 國立海洋大學 / 食品科學系 / 90 / The cobia (Rachycentron canadum), an important cage-cultured fish in Taiwan, is often used as sashimi at present. The fat content in different tissues of cobia was significantly different, and that in ventral meat was the highest. There was a negative correlation between fat and moisture content. The major free amino acids (FAA) in cobia meat were taurine, glycine, glutamic acid, alanine and lysine. In addition, ornithine was also present. A dipeptide, anserine, was detected in the meat of cobia. Among 32 sashimi samples, the coliforms in 7 samples were higher than 10 MPN/g of the limited value. In addition, a sample was also found positive in the detection of E. coli. The 6 of 7 sample not qualified were ventral meat.
The pH value of vacuum package ventral meat of cobia was decreased from 6.4 to 5.8 during storage at 4℃. The value increased after storage of 14 days. The VBN was increased gradually during storage, and the value was not higher than 15 mg/100g of the limited value after storage of 28 days. However, the total plate count exceeded 105 CFU/g and did not meet the requirement of sashimi product after storage of 21 days. The FAA content was increased by 42% at the 28th day. IMP decreased significantly at the 21th day; however, HxR and Hx increased. The K value was 25.5% and a perceptible decomposed odor was observed at that time. The shelf-life of vacuum package ventral meat was 14 days during storage at 4℃.
The moisture of hot-smoked cobia was higher than cold-smoked product, but the lipid in the former was higher. The composition of FAA and dipeptide in smoked cobia was similar to that of sashimi product, and the quantity in cold-smoked cobia was more than hot-smoked cobia. Among 22 smoked samples, the coliforms in 2 samples were 10 MPN/g. The pH value in cold-smoked cobia was higher than hot-smoked cobia, but the VBN value was not significantly different. The total plate count in the former was higher than the latter. The appearance in both cold- smoked and hot-smoked cobia was not significantly different, but the flavor, texture and acceptability in the former was better than the latter.
The moisture level in tail meat was decreased after curing and smoking processing, but the protein and lipid was increased. The FAA level was higher than that of raw meat. The pH value was decreased gradually during processing, but the VBN value and total plate count was increased significantly after curing processing.
The pH and VBN values in vacuum package cold-smoked and hot-smoked cobia were increased gradually during storage at 4℃. After 35 days of storage, the VBN value was higher than the limited value. The total plate count was increased to 4.92 log CFU/g at the 21th day. The samples was not qualified after storage for 28 days. The total FAA content was increased one-fold in cold-smoked cobia at the 21th day, and the hot-smoked cobia was increased by 42%. IMP was the dominant compound of ATP-related compounds during the initial storage, and the quantity of HxR and Hx were also rather high. The K value of the cold- smoked and hot-smoked product was increased by 55.5% and 50.5%, respectively after storage of 21 days. At that time a perceptible decomposed odor was found. In conclusion, the shelf-life in both vacuum package hot-smoked and cold-smoked cobia was 14 days during storage at 4℃.
| Identifer | oai:union.ndltd.org:TW/090NTOU0253031 |
| Date | January 2002 |
| Creators | 陳宏成 |
| Contributors | 蕭 泉 源 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 0 |
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