基于物性参量关联的冻罗非鱼鱼片中冰晶含量检测方法及机理研究

Ice crystal content is one of the most significant indexes for characterizing the quality of frozen tilapia fillets.This research put forward a hypothesis that when there is a phase equilibrium among ice crystal and unfrozen water as well as solids within a fillet caused by temperature reduction,the physical property parameters will be certain to change correspondingly and should have fixed quantitative relations among these parameters and ice crystal content.This research will elucidate the mechanism of the physical property parameters are correlated with ice crystal content and establish a new method to detect the ice crystal content in frozen tilapia fillets.In order to substantiate this hypothesis,based on our previous research work foundation，we will detect the freezing conditions,the initial freezing point and the physical property parameters of frozen tilapia fillets,by the use of numerical analysis,regression analysis,microscopic　image　analysis methods;(1)Compare the variation and differences of the physical property parameters related to the initial freezing point,observe the decreased progressively process of apparent water activity, analyse the corresponding characteristic changes during ice crystal emergence and its mechanism, and establish relational models between the initial freezing point and physical property parameters;(2)Investigate the patterns of physical property parameters change within temperature interval of the initial freezing point to the eutectic point and their differences,Screen out the physical property parameters related to the ice crystal content,analyse the mechanism of producing differences among these physical property parameters under the different frozen conditions,and fit models to characterize the correlations between these parameters and ice crystal content;(3)Compare and analyse the difference of relational degree between the physical property parameters and ice crystal content and its influencing factors,examine the obtained results by methods of analogy analysis and cross-comparison,and test and verify the correctness and accuracy of the correlation models.

冰晶含量是表征冻罗非鱼片品质最重要的指标之一。本研究提出当降温使鱼片冰晶、未冻水和固形物达到相平衡时，物性参量必然会发生相应改变且相互间应存在固定数量关系的假设，将阐明冻罗非鱼片中冰晶含量与物性参量关联的机理并建立冰晶含量检测的新方法。为证实此假设，基于前期已有研究工作的基础，对罗非鱼片的冻结状态、初始冻结点、物性参量数据进行测定；用数值分析、回归分析、显微图像分析的方法；⑴比较与初始冻结点关联的物性参量变化和差异，观测表观水分活度的递减过程，分析冰晶产生时的特征变化及原理，构建初始冻结温度与物性参量的关联模型；⑵研究初始冻结点至低共熔点区间各物性参量变化的规律及差异，筛选与冰晶含量相关的物性参量，分析不同冻结状态下各物性参量间产生差异的机理，拟合表征冰晶含量关联的模型；⑶比较和分析物性参量与冰晶含量关联度的差异及影响因素，对获得的结果进行类比分析和交叉比较，验证关联模型的正确性和精确度。

冰晶含量是表征冻罗非鱼片品质最重要的指标之一，是鱼片细胞状态、水分分布、质构特性、物性变化及热量消耗和贮藏性能的基础数据，对掌握物料冻结状态、控制冻结质构品质、科学设计冻结过程具有重要意义。鉴于同类研究存在测定难度大、精度不够高、测定成本高等不足，通过对鱼片进行分区研究，认为鱼片不同部位品质差异明显；对鱼片冻结状态、初始冻结点、物性参量进行测定并筛选，确定硬度、胶着性、咀嚼性与冰晶含量呈显著相关，其中胶着性相关系数达0.9920，且与冻结速度有关；通过观测电导率、表观水分活度递减过程，分析了冰晶产生时变化特征及原理，构建了初始冻结温度与物性参量的关联模型；已从冰点到质构仪量程内各物性数据中筛选出与冰晶含量高度相关的物性参量，分析产生差异的机理，拟合表征冰晶含量关联的模型及比较关联度差异，并通过DSC法验证了关联模型的准确性和精确度；在冻鱼片冰晶与未冻水及固形物间的关系研究中，首次采用TDR法对未冻水含量变化进行了在线检测，阐明了冰晶含量实验监测方法与理论推算原理，并建立了冰晶含量检测的新方法。研究证明，鱼片温度下降至其冻结点后，物性参量会发生相应改变，且相互间可以通过温度的关联确定冰晶含量的测算模型，并依据关联模型及冻结速度来控制其保持适宜的水分冻结量，从而达到对鱼片产品保鲜贮藏和冷链物流的目的，可节约制冷能耗15%左右；确认了质构参量是表征冻罗非鱼片冰晶含量的数量指标，已得出当冻结达到相平衡时，物性参量必发生有规律的改变，且与质构品质间存在固定的数量关系。用质构仪和时域反射仪(TDR)法测定水分冻结率和部分物性参量，建立的相关模型决定系数达0.9950。本课题组在项目执行期间已发表标注论文8篇，直接相关研究（会议）论文8篇，指导了9名先后参与本项目工作的硕士研究生并获得毕业学位；有2项发明专利获授权，1项实用新型专利被受理；其中一项发明专利已转让给海南勤富食品有限公司，转让费3万元；资助了1篇相关内容的ISTP论文。