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Evaluation of freshness quality and spoilage indicators of squid and tuna
|Authors: ||Yi-Hsiang Tseng|
|Contributors: ||NTOU:Department of Food Science|
|Issue Date: ||2011-06-22T08:53:19Z
|Abstract: ||本研究以鮮度及腐敗指標分析魷魚 (阿根廷魷魚、祕魯魷魚、赤魷) 原料與產品共8件，其中6件之揮發性鹽基態氮 (VBN)、總生菌數 (TPC)、大腸桿菌群和大腸桿菌皆合乎食品衛生標準，祕魯魷魚產品與 1 件魷魚加工製品之 VBN 超過 25 mg/100g 之標準，秘魯魷魚甚至高達 148 mg/100g，VBN 值過高與其含高活性蛋白分解酵素有關，TMAO-N 含量以秘魯魷為最高 (266 mg/100 g)，ATP 相關化合物則以 AMP 為主。魷魚於 4℃ 儲藏期間之鮮度及腐敗指標皆隨儲藏時間增長而逐漸上升，秘魯魷片之 TPC 於第 3 天超過限量值，阿根廷魷魚與赤魷產品於第 12 天不符標準；阿根廷魷魚原料貯存 3 天後VBN 即超過限量值，赤魷胴身與阿根廷魷胴身 VBN 分別於第 9 及12 天超過限量標準。魷魚儲藏期間 K 值無顯著變化，因此 K 值不適合作為魷魚鮮度指標。 檢測鮪魚生魚片產品共 10 件，其中 6 件之 VBN、TPC、大腸桿菌群和大腸桿菌皆合乎生食衛生標準，但 4 件不符標準，鮪魚生魚片處理、運輸與販售之品管問題仍須改善。大目鮪肉 4℃ 貯存至第 6 天之 VBN 值超過生食標準，但TPC、大腸桿菌群和大腸桿菌皆合乎標準，而黃鰭鮪肉則至第 12 天超過標準，鮪魚生菌數與 VBN 值具相關性。鮪魚 ATP 相關化合物以 IMP 為主，K 值隨貯存時間增加而增加，K 值與 VBN 值亦具相關性，K 值 20% 可作為鮪魚生食參考指標。|
Several freshness and spoilage indicators were used to evaluate the qualities of 8 squid products. The squid specimens included Illex argentines, Ommastrephes bartrami and Dosidicus gigas. Six samples showed the contents of volatile basic nitrogen (VBN), total plate counts (TPC), coliforms and E. coli were lower than the limited values. However, the VBN of frozen Dosidicus gigas steak and a processed product were over the limited standard of 25 mg/100 g. The high level of VBN detected in Dosidicus gigas muscle (148 mg/100g) might be associated with its high proteolytic enzyme activity. The major ATP-related compounds (ARC) were adenosine monophosphate (AMP). The levels of freshness indicators were increased with storage time of squid products during storage at 4℃. The TPC of Dosidicus gigas steak exceeded standard count at day 6, but Illex argentines and Ommastrephes bartrami products exceeded limited count at day 12. The contents of VBN in whole round of Illex argentines exceeded 25 mg/100 g at day 3, and the tubes of Illex argentines and Ommastrephes bartrami exceeded the limited value at day 12 and 9, respectively. TPC of squid products was found correlated with VBN. The K value, an indicator derived from ARC, remained unchanged during storage, and was not suitable for evaluating squid freshness. The qualities of 10 tuna products were evaluated using freshness and spoilage indicators, of which 6 samples meet the sashimi standard limits of VBN, TPC, coliforms and E. coli. The results indicated that the quality control of tuna sashimi products should be improved. The VBN of big-eye tuna meat exceeded the sanitary standard limit at day 6 during storage at 4℃, while the yellow-fin tuna meat at day 12. The major ARC of tuna products was IMP. The K value increased with storage time, and the value of 20% could be used as a sashimi standard. The TPC and K value of tuna products were found correlated with VBN.
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