Tan Mingtang, Xie Jing
College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China.
Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, Shanghai 201306, China.
Foods. 2021 Apr 6;10(4):784. doi: 10.3390/foods10040784.
This study aimed to explore the effect of dehydration on the water migrating property and protein changes of large yellow croaker during frozen storage. A freeze-dryer was used to accelerate experiments, which was isolated from oxygen and excluded the effects of protein oxidation. After dehydration time (3, 9, 18, and 30 h) for both fast- and slow-freezing samples, the results showed that the ice sublimation of samples containing small ice crystals was faster than that of samples containing large ice crystals in the early stages of dehydration, but in the latest stage, there was an opposite trend. The results indicated that dehydration reduced the water freedom degrees and water-protein interaction. At the same time, dehydration had a significant effect on protein secondary and tertiary structures. The significant increase in surface hydrophobicity and particle size indicated that dehydration exacerbated myofibrillar protein aggregation. The ΔH1 values (from 1.275 to 0.834 J/g for slow-freezing group and from 1.129 to 0.855 J/g for fast-freezing group) decreased gradually as the dehydration time extended, indicating the decrease in protein thermal stability. Additionally, significant protein degradation occurred when the water content of the sample decreased to a certain level. This study showed that ice crystal size had an important effect on the rate of ice sublimation, and the occurrence of dehydration during frozen storage accelerated the water loss and the decrease in protein stability.
本研究旨在探讨脱水对大黄鱼在冻藏期间水分迁移特性及蛋白质变化的影响。采用冷冻干燥机加速实验，该冷冻干燥机隔绝氧气，排除蛋白质氧化的影响。对快速冷冻和慢速冷冻样品进行脱水时间（3、9、18和30小时）处理后，结果表明，在脱水初期，含有小冰晶的样品的冰升华速度比含有大冰晶的样品快，但在最后阶段，趋势相反。结果表明，脱水降低了水分自由度和水 - 蛋白质相互作用。同时，脱水对蛋白质的二级和三级结构有显著影响。表面疏水性和粒径的显著增加表明脱水加剧了肌原纤维蛋白的聚集。随着脱水时间延长，ΔH1值（慢速冷冻组从1.275 J/g降至0.834 J/g，快速冷冻组从1.129 J/g降至0.855 J/g）逐渐降低，表明蛋白质热稳定性下降。此外，当样品含水量降至一定水平时，发生了显著的蛋白质降解。本研究表明，冰晶大小对冰升华速率有重要影响，冻藏期间脱水的发生加速了水分损失和蛋白质稳定性的降低。
