预干燥对油炸外裹糊鱼块油脂渗透和质构特性的影响

Effect of Pre-drying on Oil Penetration and Textural Characteristics of Deep-Fried Battered and Breaded Fish Nuggets

本研究将外裹糊鱼块置于鼓风干燥箱中,40℃干燥3~9 h(3、4.5、6、7.5、9 h)后180℃油炸60 s,分析油炸前后外裹糊鱼块的水分状态、油炸外裹糊鱼块的油脂含量与分布、微观结构及质构特性,模拟油炸过程中油脂的吸收,探讨预干燥对油炸外裹糊鱼块油脂渗透和质构特性的影响。结果显示,油炸后外壳的深层结合水(T21)、弱结合水(T22)和自由水(T23)以及鱼块的结合水(T21)、肌纤维中(T22)和外部(T23)的水分含量均减小。随着干燥时间的延长,油炸后外壳T22峰的起始时间逐渐减小,水分的自由度降低,且T21和T22峰的信号强度减小,结合水向自由水转化;鱼块的T22峰只有干燥9h的发生明显左移;油炸外裹糊鱼块的表面油脂含量和总油脂含量呈减小趋势,表面渗透油脂含量逐渐增加;外壳结构先紧密后粗糙,鱼块表面先光滑后出现裂缝和孔洞;外壳中荧光强度逐渐减弱,苏丹红染色幅度逐渐减小,外壳与鱼块交界处的染色幅度逐渐增大;外壳的硬度和酥性先减小后增大,而鱼块的弹性和咀嚼性呈现相反趋势。这些结果表明,预干燥降低了外裹糊鱼块水分的自由度,改变了油炸外裹糊鱼块的微观结构,从而影响了油脂的渗透和质构特性。本研究可为低脂油炸外裹糊鱼制品的规模化生产提供科学指导和技术支撑。

This purpose of this study was to evaluate the effect of pre-drying on the oil penetration and texture characteristics of deep-fried battered and breaded fish nuggets.Battered breaded fish nuggets(BBFNs)were dried in a drying oven and dried at 40℃for 3,4.5,6,7.5 and 9 h and deep fried at 180℃for 60 s.Moisture state in dried BBFNs and deep-fried BBFNs was measured,and the oil content and distribution,microstructure and texture characteristics of deep-fried BBFNs were analyzed.The absorption of oil during deep-fat frying was simulated.The results showed that after deep-fat frying,the contents of strongly bound water(T21),weakly bound water(T22)and free water(T23)in the crust,the content of strongly bound water in the fish nuggets,the content of weakly bound water inside muscle fibers,and the content of free content outside muscle fibers were reduced.As the drying time increased,the starting time of peak T22 for the deep-fried crust gradually decreased,indicating declined freedom degree of water,and the signal intensity of peaks T21 and T22 decreased,suggesting that the bound water was converted to free water.In addition,only fish nuggets with 9 h drying showed a left shift in peak T22.The surface oil(SO)and total oil(TO)contents of deep-fried BBFNs decreased while the penetrated surface oil(PSO)content increased.The crust structure was first tight and then became rough,and the surface of the fish was smooth first and then exhibited cracks and holes.The fluorescence intensity of the crust became weaker gradually.The Sudan red-dyed region in the crust decreased while that of the junction between the crust and the fish nuggets increased gradually.The hardness and crispiness of the crust first decreased and then increased,while the elasticity and chewiness of the fish nuggets presented the opposite trend.These results indicated that pre-drying alleviated the freedom degree of moisture in BBFNs,and changed the microscopic structure of deep-fried BBFNs,thereby affecting the oil penetration and texture characteristics.The study may provide a theoretical basis and scientific guidance for the large-scale production of low-fat deep-fried BBFNs.