基于射频均匀解冻技术的不同解冻速率下深冷金枪鱼微观结构及品质变化研究

Tempering rate influences the water permeation into muscle fiber, and further influences final product quality of tuna. Inappropriate tempering methods will cause high drip loss content and severely influence the final product quality, especially sensory property. However, the relationship between tempering rate and tuna product quality is still unclear due to the limitation of uncontrollable thawing conditions in traditional tempering methods. Radio frequency tempering is is fast, volumetric and power controllable in adjusting tempering rate, which has the potential of wide application in aquatic product tempering industry. In this study, strategies of further improving the temperature uniformity of radio frequency for tuna tempering will be developed based on the electromagnetic field distribution theory by exploring suitable surrounding medium. Then tempering protocol with several tempering speed will be developed and the according tempering quality of tuna will be studied. The relationship among the tempering speed, microstructure of the muscle, and the tempered product quality including drip loss, texture, color, Total Volatile Base Nitrogen (TVB-N) will be built up and the in-depth mechanism will be explored. The findings in this study will set up the foundation for fully understanding the mechanism of interaction among tempering rate, food microstructure, and food quality. It will further help developing theories of aquatic product tempering/thawing.

深冷金枪鱼在生食前，如解冻不当将导致汁液流失、颜色暗沉、肉质失去弹性等问题，影响其食用品质。解冻速率影响细胞间隙中水分恢复，进而影响解冻品质，但尚未有研究能够以均匀可调控解冻工艺为基础，阐明金枪鱼解冻速率与解冻品质之间的关联性。射频解冻具有快速整体解冻、输入功率可调等优点，在水产品解冻领域具有工业化应用潜力。本研究将以射频解冻技术为基础，通过从电磁场分布原理均匀化出发，以选择匹配环绕介质介电特性为原则，运用有限元模拟结合实验验证，开发可调控速率的快速均匀解冻方法，以此为基础研究射频解冻过程中不同解冻速率在对金枪鱼内部冰晶融化过程及冻品微观结构变化的影响。研究结论将明确环绕介质特性对解冻均匀性提升效果，建立解冻速率-肉质微观结构-解冻品质指标之间的联系，为水产品解冻机理研究起到推动作用。

本研究以金枪鱼为研究对象，针对高品质深海鱼类在冷冻及解冻过程中冻结及解冻速率对产品品质的影响机理不明确的问题，以射频解冻技术为基础开发了可调速率的均匀解冻工艺，对不同冷冻及解冻速率处理下的金枪鱼品质进行了研究。具体工作为：建立了深冷金枪鱼射频解冻过程的有限元模型并实验验证，探索数值模拟方法在深冷金枪鱼解冻过程中的有效性；深入探究了环绕介质介电特性匹配对射频解冻均匀性提升的原理，结合数值模拟方法研究射频解冻水产品均匀性及品质的普适性提升方法；通过调控解冻速率，阐明了射频解冻过程中解冻速率、水产品微观结构与水产品解冻品质之间的关联变化规律。. 研究结果表明，射频解冻技术能够满足可调速率的快速整体解冻需求，基于COMSOL Multiphysics软件所开发的有限元仿真模型能够用于优化射频解冻工艺。在解冻均匀性的提升方法开发中，从冻结点、介电特性及加热特性方面选择适宜环绕介质并进行实验对照，丙三醇以其安全性、有效性、经济性成为环绕介质的首选。随后进行了环绕介质法在肉类、鱼类、虾类等特定食品解冻中的应用探索，为技术后续的工业化运用打下了基础。最后，以可调的射频解冻工艺为基础，证明了冷冻及解冻速率对金枪鱼肉品品质存在显著影响，在解冻均匀性优化的前提下，快速冷冻与均匀慢速解冻的结合形式能提供最优的产品品质。而快速解冻往往与解冻不均匀相关联，因此在冷冻食品解冻的过程中，解冻均匀性应作为首要关注目标。