Bigeye tuna (Thunnus obesus) is an important fish species worldwide due to its desirable flavour and rich nutrition. Cold chain logistics is one of the most common methods to store and sell bigeye tuna (Thunnus obesus). The purpose of this study was to investigate how bigeye tuna (T. obesus) deteriorate during simulated cold chain logistics with fluctuating temperatures by monitoring the quality changes and water distribution. The physical and chemical results showed that the sensory score, texture profile analysis (TPA), and water holding capacity (WHC) decreased, while total volatile basic nitrogen (TVB-N), K value, aerobic plate counts (APC), and psychrotrophic bacterial counts increased with fluctuating temperatures during 132 h. Low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) detection showed that the T₂₁ (trapped water) and proton density decreased, while T₂₂ (free water) decreased initially and then increased, indicating continuous water loss and water migration during storage. Principal component analysis (PCA) revealed that springiness, hardness, chewiness, T₂₁, and sensory score were correlated with each other (p < 0.05) and the linear combination of quality indicators and T₂transverse relaxation time was established. Besides, temperature fluctuation (batch 3) accelerated the deterioration of bigeye tuna according to the comprehensive score of PCA. Results were based on LF-NMR which can be used to monitor quality changes in a fast non-invasive manner.

大眼金枪鱼（Thunnus obesus）由于其理想的风味和丰富的营养而成为世界上重要的鱼类。冷链物流是存储和出售大眼金枪鱼（Thunnus obesus）的最常用方法之一。这项研究的目的是调查大眼金枪鱼（T. obesus）通过监视质量变化和水分布，在温度波动的模拟冷链物流过程中恶化。物理和化学结果表明，感官评分，质构分析（TPA）和持水量（WHC）降低，而总挥发性碱性氮（TVB-N），K值，需氧板数（APC）和精神营养在132小时内，细菌数量随着温度的波动而增加。低场核磁共振（LF-NMR）和核磁共振成像（MRI）检测表明，T ₂₁（被困水）和质子密度下降，而T ₂₂（游离水）先减少后增加，表明在储存过程中持续失水和水分迁移。主成分分析（PCA）显示，弹性，硬度，耐嚼性，T ₂₁和感官评分彼此相关（p  <0.05），并且建立了质量指标和T ₂横向松弛时间的线性组合。此外，温度波动（第3批）根据PCA的综合得分加速了大眼金枪鱼的退化。结果基于LF-NMR，可用于以快速，非侵入性的方式监测质量变化。