攝入腐敗或受污染的食品可能會對公眾健康造成潛在危害，故評估食品是否腐敗對於消費者而言至關重要。魚極為容易腐敗，且在製造過程中很容易失去魚本身的形態特徵，使得消費者無法輕易透過感官方法評估其腐敗程度，構成一個潛在的食品安全問題。非標的代謝體學是探討食品安全和品質的新領域，為食品儲存過程的理解提供了新的視野。本研究的目的為利用以質譜技術為基礎之非標的代謝體分析找尋魚儲藏期間之新鮮度化學指標。為了找尋具有再現性的潛在新鮮度指標，在4℃下進行了三次將魚儲存0, 24, 48, 72小時各六重複的實驗（n = 4×6）。在三組質譜數據中交集的訊號共有115個。115個訊號已利用曼－惠特尼U檢定（the Mann Whitney U test）確認其在0小時與72小時的組別間具有顯著差異（α = 0.005）。利用精確質量與二次質譜數據進一步鑑定和闡明潛在新鮮度指標的化學結構。在115個訊號中，鑑定出8個潛在新鮮度指標，包括尿嘧啶，次黃嘌呤，肌苷，醯基肉鹼（10：0），α-次亞麻油酸，二十二碳六烯酸，花生四烯酸以及亞麻油酸。經過斯皮爾曼等級相關係數（the Spearman's rank correlation coefficient）評估後，8個潛在新鮮度指標的趨勢在72小時內保持一致，證實此方法學作為品質保證潛在工具之有效性。

The consumption of spoiled or contaminated food may pose potential harm to public health. Therefore, it is essential for consumers to assess the presence of food freshness in perishable foods. Fish is extremely perishable, and morphological characteristics of fish are easily lost during manufacturing processes, making the freshness challenging to assess via sensory methodologies and therefore posing a potential food safety issue. Untargeted metabolomics, the new frontier in food safety and quality research, has given rise to extraordinary opportunities for increasing our understanding of the process in food storage. The specific aim of this study is to discover chemical markers for fish freshness during storage using mass spectrometry-based untargeted metabolomics analysis. To discover the potential freshness markers with reproducibility, the fish storage experiments for 0, 24, 48, 72 hours in sextuplicate (n = 4 × 6) at 4 ℃ were conducted three times. A total of 115 features were intersected from 3 batches of experiments, and they showed differences between the fish samples with storage 0 and 72 hour(s) by the Mann Whitney U test (α = 0.005). Chemical structures of freshness marker candidates were further elucidated using accurate mass and MS/MS spectrum. Among 115 candidates, 8 potential freshness markers have been identified, including uracil, hypoxanthine, inosine, acylcarnitine 10:0, α-linolenic acid, docosahexaenoic acid, arachidonic acid, and linoleic acid. After the evaluation of the Spearman's rank correlation coefficient, the trends of identified potential freshness markers were consistent in 72 hours, verifying the effectiveness of the methodology as a potential tool for quality assurance.

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