碩士 / 國立海洋大學 / 食品科學系 / 87 / Abstract
Seasonal variations in the extractive nitrogenous components and proximate composition of puffer Takifugu rubripes cultured in Ilan and Taipei Prefecture were investigated from November 1996 to September 1997. It was found that the levels of proximate composition in the puffer were as follows: moisture 79.32-80.64%, protein 17.45-18.91%, ash 1.09-1.40%, fat 0.19-0.39%. There were no seasonal and regional variations in proximate composition of puffer. The amount of total free amino acids (FAA) of puffer cultured in Ilan Prefecture collected from November to January was significantly higher than that in other seasons. However seasonal variation of total FAA was not found in Taipei Prefecture. Among FAA in the puffer, the predominant one was taurine, followed by glycine, lysine and alanine. Inosine monophosphate (IMP) and guanosine monophosphate (GMP) were the predominate compounds of nucleotides and related compounds (NRC) in the muscle of puffer. The amount of total NRC in the muscle of puffer was significantly higher in July and November than that in other seasons. The levels of FAA, NRC and taste-active components including glutamic acid, proline, glycine, alanine, arginine, GMP, IMP and AMP in the muscle of puffer were more abundant in the autumn and winter seasons. Therefore, the puffer was probably more tasty at these periods.
The level of total FAA in the muscle of puffer increased significantly at initial 4 days and then decreased during storage at 4℃. Among FAA and NRC, taurine, glycine, alanine, lysine, IMP, inosine (HxR) and hypoxanthine (Hx) fluctuated significantly during storage at 4℃. Of them, IMP reached the maximum level at the second day and then gradually decreased, while HxR and Hx increased with the time of storage. With regard to the freshness indicators, most of them revealed good correlation between the levels and storage period with the exception of HxR and trimethylamine (TMA). The K value and P value were the best suitable freshness indicators for puffer. Judging from the levels of taste-active components and K value, the puffer might be the best tasty at the second day storage. During 8-days storage, the levels of K value, volatile basic nitrogen (VBN) and TMA separately reached 34.9%, 35.5mg/100g and 8mol/g，which indicated the muscle of puffer had reached initial stage of decomposition. According to these results, the shelf-life of puffer stored at 4℃ was recommended as 6 days.
The extractabilities of sarcoplasmic and myofibrillar proteins in the muscle of puffer showed little change at the 10-day storage at 4℃ and 30-day storage at -20℃. However, the extractability of myofibrillar protein decreased after 30 days storage when the muscle of puffer was stored at -20℃. There was no change in major bands of sarcoplasmic protein during iced and frozen storage. Among them, the densities of 35K, 40K and 43K proteins seemed to be stable. Of these three proteins, the density of 40K protein was higher than that of the others. Hence, the densities of these protein could be useful for identifying fish species. On the other hand, there was little change in major bands of myofibrillar protein during frozen storage but the densities of myosin and actin decreased after 60 days when the muscle of puffer stored at -20℃. However, the components of light chains (23K, 22K and 21K protein) of myofibrillar protein showed no change during storage, which indicated that these three light chains were also useful for fish species identification.
| Identifer | oai:union.ndltd.org:TW/087NTOU0253005 |
| Date | January 1999 |
| Creators | Chen Tai Yuan, 陳泰源 |
| Contributors | Hwang Deng Fwu, Shiau Chyuan Yuan, 黃登福, 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 | 102 |
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