基于罗非鱼肌肉微结构分形维数表征的冻融过程品质变化分析

Quality Change of Tilapia Fillets during Freeze-Thaw Cycles Characterized Based on Fractal Dimension of Microstructure

为研究罗非鱼片经冻融过程后品质变化规律及机理,选用规格为(130±10)g的新鲜罗非鱼片为样品,分别在-4、-18、-30℃条件下进行不同次数的反复冻融处理,拟将样品品质指标与微结构分形维数建立关联,采用分形维数表征冷冻鱼肉中由因冰晶而形成的多孔微结构,并测定相应的品质参数。结果表明:分形维数随冻融次数的增加而呈下降趋势。在-4、-18℃和-30℃下冻融4次后,鱼片的分形维数从初始的1.925分别下降到1.815、1.843和1.853,且伴随着总峰面积、弹性、硬度的降低以及电导率、总挥发性盐基氮含量和总色差ΔE的升高,这些参数的变化量总体随着冷冻温度的降低而降低。相关性分析结果表明,不同温度下分形维数与这些传统品质指标存在显著相关性(P<0.05,P<0.01)。综上,本研究证明了分形维数是一种评价冻融过程中罗非鱼片品质的新颖、可行的方法。

In order to explore the pattern of changes in the quality of tilapia fillets during freeze-thaw cycles and to elucidate the underlying mechanism,fresh fillet samples weighing approximately(130±10)g were repeatedly frozen at−4,−18 or−30℃and thawed for up to four times and analyzed at each cycle.The correlation between quality parameters and the fractal dimension of the microstructure was analyzed.The porous microstructure formed by ice crystals in frozen fillets was characterized based on the fractal dimension and the quality parameters were measured.The results showed that the fractal dimension decreased with increaing number of freeze-thaw cycles.After four freeze-thaw cycles at−4,−18 and−30℃,the fractal dimension decreased from an initial value of 1.925 to 1.815,1.843 and 1.853,respectively,accompanied by a decrease in the elasticity and hardness as well as total peak area and an increase in the conductivity,total volatile basic nitrogen(TVB-N)content and total color differenceΔE.Overall,these parameters showed less changes with the decrease in freezing temperature.In addition,significant correlations were found between the fractal dimension and these quality indicators(P<0.05,P<0.01).Therefore,the fractal dimension has proved to be a novel and feasible method for evaluating the quality of tilapia fillets during freeze-thaw cycles.