To control Pseudomonas and Shewanella as important psychrotrophic spoilage bacteria in fish meat, we used ethanolic extracts of oregano (Origanum vulgare subsp. vulgare) and nettle (Urtica dioica), with phytochemical characterisation of the extracts and their bioactive compounds. Liquid chromatography coupled with photodiode array detection and electrospray ionisation–mass spectrometry was used for qualitative compositional determination of the extracts. Four main compounds were identified in the oregano extract, with rosmarinic acid the most abundant, followed by three glycosylated phenolics, one of which is reported for the first time in O. vulgare: 4′-O-β-d-glucopyranosyl-3′,4′-dihydroxybenzyl-4-hydroxybenzoate. Six main compounds were identified in the nettle extract, as caffeoylmalic acid and five flavonoid glycosides. These oregano and nettle ethanolic extracts showed in-vitro antimicrobial activities against selected Pseudomonas and Shewanella strains in broth and fish meat homogenate when evaluated at two inoculum concentrations. The antimicrobial activities were more pronounced for the nettle extract at the lower inoculum concentration, and for both the Shewanella strains. Growth inhibition in the fish meat homogenate was evaluated at 3.13 mg/mL and 1.56 mg/mL at 5 °C. Again, the nettle extract showed greater antimicrobial activity, which was seen as the lowest maximum growth rate, followed by the oregano extract, which was inhibitory only at 3.13 mg/mL. Finally, the extracts were applied to fish meat that was then stored at 5 °C for 9 days. Evaluation here was for the counts of the mesophilic, psychrotrophic, Pseudomonas and H₂S producers. These confirmed the better antimicrobial effects of the nettle extract, especially against the H₂S-producing bacteria, which included Shewanella. Both of the extracts were rich in glycosides of flavonoids and phenolic acids. The enzymatic activities of the Pseudomonas and Shewanella spoilage bacteria and their actions on the phenolic glycosides from natural sources will be further investigated.

为了控制鱼肉中重要的耐冷腐败菌假单胞菌和希瓦氏菌，我们使用了牛至 ( Origanum vulgare subsp. vulgare ) 和荨麻 ( Urtica dioica ) 的乙醇提取物，并对提取物及其生物活性化合物进行了植物化学表征。使用液相色谱法结合光电二极管阵列检测和电喷雾电离质谱法对提取物进行定性成分测定。牛至提取物中鉴定出四种主要化合物，其中迷迭香酸含量最高，其次是三种糖基化酚类物质，其中一种化合物是首次在牛至中报道：4′-O-β- d-吡喃葡萄糖基-3′ ,4'-二羟基苄基-4-羟基苯甲酸酯。荨麻提取物中鉴定出六种主要化合物，即咖啡酰苹果酸和五种黄酮苷。当在两种接种浓度下进行评估时，这些牛至和荨麻乙醇提取物对肉汤和鱼肉匀浆中的选定假单胞菌和希瓦氏菌菌株表现出体外抗菌活性。较低接种浓度的荨麻提取物以及两种希瓦氏菌菌株的抗菌活性更为明显。 5 °C 时，鱼肉匀浆中的生长抑制作用为 3.13 mg/mL 和 1.56 mg/mL。同样，荨麻提取物显示出更高的抗菌活性，其最大生长速率被视为最低，其次是牛至提取物，其仅在 3.13 mg/mL 时具有抑制作用。最后，将提取物应用于鱼肉，然后在 5°C 下保存 9 天。 这里评估的是嗜温菌、耐冷菌、假单胞菌和H ₂ S产生者的计数。这些证实了荨麻提取物具有更好的抗菌作用，特别是针对产生 H ₂ S 的细菌，其中包括希瓦氏菌。两种提取物都富含黄酮苷和酚酸。将进一步研究假单胞菌和希瓦氏菌腐败菌的酶活性及其对天然来源酚苷的作用。