鮰鱼冷藏期间的品质变化及优势腐败菌分析

    Analysis of quality changes and specific spoilage organisms in channel catfish during cold storage

    • 摘要: 为分析鮰鱼在低温贮运期间品质变化的规律并确定其优势腐败菌,该研究将鮰鱼肉块分别置于4和10 ℃条件下冷藏,通过测定感官指标、质构特性、色度、pH值、菌落总数(total viable count, TVC)及挥发性盐基氮(total volatile basic nitrogen, TVB-N)含量等指标,系统分析其品质变化规律。同时,采用高通量测序和16S rDNA技术鉴定分析鮰鱼中的微生物组成,并对优势腐败菌的致腐能力进行评估。结果表明,冷藏期间鮰鱼的pH值呈现先下降后上升的趋势,硬度、咀嚼度及红绿值a*均呈下降趋势,且TVB-N含量与TVC呈正相关。其中4 ℃条件下鮰鱼的腐败速率较慢,感官品质保持较好,微生物分析显示,相对丰度较高的气单胞菌属(Aeromonas)(28.74%)和希瓦氏菌属(Shewanella)(6.34%)致腐能力也最强,是鮰鱼冷藏期间的优势腐败菌。综上所述,鮰鱼4 ℃条件下冷藏时的新鲜度和品质保持较好,气单胞菌属(Aeromonas)和希瓦氏菌属(Shewanella)是导致鮰鱼腐败的主要菌属。本研究为基于菌群结构演替规律的淡水鱼品质控制技术开发提供了一定的理论依据和数据支持。

       

      Abstract: Channel catfish is the most numerous catfish species in the world. This study aims to analyze the dynamics of quality and bacterial composition in channel catfish subjected to various low-temperature storage. The research also revealed the correlation between the evaluation metrics and the predominant spoilage bacteria. Specifically, the catfish was selected and then stored under refrigeration at 4 and 10 °C. Various parameters included sensory metrics, texture, color, pH value, total viable count (TVC), and the total volatile base nitrogen (TVB-N). High-throughput sequencing was employed to determine the microbial community composition of catfish. Traditional sieving was utilized to isolate and identify the microorganisms. While the spoilage capacity and growth kinetics were utilized to characterize the dominant spoilage species. The results indicated that the pH changes of catfish exhibited the initial decline and then increased, with the prolongation of low-temperature storage time. Additionally, the TVB-N, TVC, lightness (L*), yellow-blue value (b*), and Whiteness (W) demonstrated an increasing trend, whereas the hardness, chewiness, and red-green value (a*) displayed a decreasing trend. Furthermore, The TVB-N content exhibited a significant positive correlation with the TVC. There was a correlation coefficient of 0.95 (P<0.05). The decay rate of catfish was slower under the condition of 4 °C. The sensory quality was maintained, in terms of the various indicators. Microbiological analyses found that Firmicutes, Bacteroidota, and Proteobacteria were the dominant phylum associated with catfish spoilage. The corruption of catfish meat involved a total of 19 families, more than 20 genera, and more than 30 bacterial species. According to the genus level, the predominant genera with the high relative abundance of the catfish were identified as Myroides sp. (39.68%), Aeromonas sp. (28.74%), Acinetobacter sp. (16.33%) and Shewanella sp. (6.34%). A total of six bacterial strains were screened, including two strains of Pseudomonas, one strain of Shewanella, two strains of Aeromonas veronii, and one strain of Acinetobacter johnsonii. Among them, the spoiled catfish muscle was taken as the raw material. The screening data was consistent with the microbial diversity on the channel catfish. The growth kinetics was used to determine the two strains with the strongest decay at different temperatures. Furthermore, the lag phase (λ) was extended significantly, as the incubation temperature decreased. While the maximum specific growth rate (μmax) was reduced significantly. Notably, the μmax of Shewanella baltica consistently exceeded that of Aeromonas veronii. Both strains shared excellent growth at low temperatures, where Shewanella veronii was more suitable for the low-temperature adaptation. The yield factor (YTVB-N/CFU) revealed that the spoilage potential greatly varied among the six identified spoilage bacteria strains. Aeromonas veronii and Shewanella baltica exhibited the most pronounced spoilage potential, whereas Acinetobacter johnsonii had relatively limited spoilage activity. The findings can offer valuable insights for future investigations into the spoilage mechanisms of channel catfish. A theoretical foundation and data support were also provided for the quality control technologies for the freshwater fish, according to the succession patterns of microbial communities. A great contribution was also made to the low-temperature sustainable storage and transportation of freshwater fish.

       

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