Chemical characteristics of sturgeon (Acipenser baerii #westeur024# A. schrenckii) and their changes during storage

• Main Authors: Lu, Ting-Yi, 呂庭宜
• Other Authors: Shiau, Chyuan-Yuan
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/11098741500876116154

碩士 === 國立臺灣海洋大學 === 食品科學系 === 103 === Sturgeon is an important cultured fish with high economic value in Taiwan. However, few reports have been studied on its chemical properties. Therefore, this study was to investigate the chemical compositions in the muscle of sturgeon and their changes during storage. The moisture content in the muscle of sturgeon was 73%, followed by protein 20%, fat 6.5% and ash 1.7%, which was known as medium-fat and high-protein fish. The pH value was between 6.50-6.74, with no presence of urea and low content of ammonia. The total amount of free amino acids (FAA) was 78.85 mg/100 g, and β-alanine, taurine, glycine and alanine were the major FAA. Carnosine (Car) was the main dipeptide and the level reached 204 mg/100 g. Inosine monophosphate (IMP), an important source of umami, was the dominant nucleotide related compounds (NRC) accumulated in the muscle. Hypoxanthine (Hx) became the predominant NRC at the ending storage period. The main fatty acids were C16:0, C18:1 and C18:2, with monounsaturated fatty acids about 46.42%, followed by 27.57% of saturated fatty acids and 26.01% of polyunsaturated fatty acids. Besides, there were high contents of EPA and DHA in the muscle of sturgeon. The pH value of the muscle decreased and then increased during storage at 5℃ and 25℃. The initial total plate count (TPC) was 3.89 log CFU/g, and increased with storage time. TPC increased to 7.72 CFU/g during storage at 5℃ for 6 days, and 8.03 CFU/g at 25℃ for 24 hours. Both were exceeded the limit value of 3 #westeur024# 106 CFU/g. The volatile basic nitrogen (VBN) increased with storage time, and exceeded the limit value of 25 mg/100 g at 5℃ storage for 12 days and 25℃ for 32 hours, respectively. In addition, ammonia, trimethylamine nitrogen (TMA-N) and K value increased with time during storage. VBN, ammonia, TMA-N, Hx and K value could be suitable as freshness indicators of sturgeon. The degradation of Car to β-alanine and histidine at 25℃ storage was faster than that at 5℃. According to organoleptic evaluation, TPC and VBN value, the shelf-life of sturgeon was 4 days and 20 hours at 5℃ and 25℃ storage, respectively.