革胡子鲶鱼鱼糜冻藏时间对鱼豆腐品质特性的影响

为研究革胡子鲶鱼（Clarias gariepinus，CG）鱼糜冻藏时间对鱼豆腐品质特性的影响，选用宰杀后的鲶鱼肉块，不经传统冷冻鱼糜生产的采肉、漂洗、脱水工艺，立即冰浴降温处理，添加冷冻防护剂直接斩拌得到鱼糜，将鱼糜速冻后在－18 ℃条件下冻藏，分别选取冻藏0、30、60、90 d的冷冻鱼糜缓慢解冻后制成4 组鱼豆腐（catfish tofu，CT），分别记为CT0、CT30、CT60、CT90组。对4 组鱼豆腐的感官品质、水分含量、白度、持水力、凝胶特性、水分迁移情况、微观结构等进行测定。结果表明：随着CG鱼糜冻藏时间的延长（0～90 d），鱼豆腐感官综合评分呈明显下降趋势，水分含量、白度、持水力、凝胶强度等指标显著下降（P＜0.05），横向弛豫时间T22增加，不易流动水向自由水方向迁移，P22降低；CT30组鱼豆腐感官评分、P22显著低于CT0组（P＜0.05），但水分含量、白度、持水力、凝胶强度与CT0组差异不显著，说明冻藏30 d的CG鱼糜仍保持着较高品质；CT60和CT90组鱼豆腐的各项指标均显著低于CT0组，尤其是CT90组的持水力和P22；扫描电子显微镜结果显示，CT0和CT30组鱼豆腐的三维空间网络结构结合紧密、孔洞小，CT60组鱼豆腐的微观结构出现疏松现象，CT90组鱼豆腐的三维空间结构空隙明显变大。因此，CT0和CT30组鱼豆腐品质良好，CT60组鱼豆腐品质在可接受范围内，CT90组鱼豆腐的综合指标显著降低。

Effect of Frozen Storage Time of Clarias gariepinus Surimi on the Quality Characteristics of Fish Tofu

To study the effects of the frozen storage time of Clarias gariepinus surimi on the quality characteristics of fish tofu, in this experiment, surimi was prepared by ice bath cooling immediately after slaughter and directly chopping the fish meat after adding a cryoprotectant instead of the traditional production process, involving rinsing and dehydration and was stored at ?18 ℃ after being quick frozen. After 0, 30, 60 and 90 d of storage samples were taken and slowly thawed for preparation of catfish tofu (CT0, CT30, CT60 and CT90, respectively). The sensory quality, moisture content, whiteness value, water-holding capacity, gel characteristics, moisture migration and microstructure of fish tofu were measured. The results showed that the overall sensory score of fish tofu decreased with prolonged storage time, as reflected by a significant decline in moisture content, whiteness value, water-holding capacity, gel characteristics, and other indicators (P < 0.05), as well as an increase in T22, transformation of immobilized water to free water and a consequent decrease in P22. Although the sensory score and P22 of CT30 were significantly lower than those of CT0, there was no significant difference in moisture content, whiteness value, water-holding capacity or gel strength, which indicates that the quality of surimi stored for 30 days remained good. All quality indexes of CT60 and CT90 were significantly lower than those of CT0, especially for the waterholding capacity and P22 of CT90. The results of scanning electron microscopy (SEM) showed that the three-dimensional spatial network structure of CT0 and CT30 was dense with tiny holes, the microstructure of CT60 appeared to be porous, and the three-dimensional spatial structure of CT90 exhibited obviously enlarged voids. The results showed that the quality of CT0 and CT30 was excellent, the quality of CT60 was acceptable, while the comprehensive quality of CT90 was significantly reduced.