PDF(Pubmed)
Abstract：
Superficial discolored spots on Atlantic salmon (Salmo salar) fillets are a serious quality problem for commercial seafood farming. Previous reports have proposed that the black spots (called melanized focal changes (MFCs)) may be melanin, but no convincing evidence has been reported. In this study, we performed chemical characterization of MFCs and of red pigment (called red focal changes (RFCs)) from salmon fillets using alkaline hydrogen peroxide oxidation and hydroiodic acid hydrolysis. This revealed that the MFCs contain 3,4-dihydroxyphenylalanine (DOPA)-derived eumelanin, whereas the RFCs contain only trace amounts of eumelanin. Therefore, it is probable that the black color of the MFCs can be explained by the presence of eumelanin from accumulated melanomacrophages. For the red pigment, we could not find a significant signature of either eumelanin or pheomelanin; the red color is probably predominantly hemorrhagic in nature. However, we found that the level of pigmentation in RFCs increased together with some melanogenic metabolites. Comparison with a \"mimicking experiment\", in which a mixture of a salmon homogenate + DOPA was oxidized with tyrosinase, suggested that the RFCs include conjugations of DOPAquinone and/or DOPAchrome with salmon muscle tissue proteins. In short, the results suggest that melanogenic metabolites in MFCs and RFCs derive from different chemical pathways, which would agree with the two different colorations deriving from distinct cellular origins, namely melanomacrophages and red blood cells, respectively.
摘要：
大西洋鲑鱼（Salmosalar）鱼片上的浅层变色斑点是商业海鲜养殖的严重质量问题。以前的报道提出，黑斑（称为黑色素局灶性变化（MFCs））可能是黑色素，但是没有令人信服的证据报告。在这项研究中,我们使用碱性过氧化氢氧化和氢碘酸水解对鲑鱼片的MFC和红色色素（称为红色焦点变化（RFC））进行了化学表征。这表明MFC含有3,4-二羟基苯丙氨酸（DOPA）衍生的真黑素，而RFC仅含有痕量的真黑素。因此,MFC的黑色很可能可以通过积累的黑色素中存在的真黑素来解释。对于红色颜料，我们没有发现明显的真黑素或pheomelanin特征;红色可能主要是出血性。然而,我们发现，RFC的色素沉着水平与一些黑色素代谢产物一起增加。与“模仿实验”的比较其中鲑鱼匀浆+DOPA的混合物被酪氨酸酶氧化，建议RFC包括DOPA醌和/或DOPA色素与鲑鱼肌肉组织蛋白的缀合。总之,结果表明，MFC和RFC中的黑色素代谢产物来自不同的化学途径，这与来自不同细胞起源的两种不同颜色一致，即黑色素和红细胞，分别。
