冷冻环境对湿面筋蛋白中可冻结水的影响

Effects of Freezing Conditions on Freezable Water in Wet Gluten

用差示扫描量热仪测定了不同冷冻环境下湿面筋蛋白中可冻结水的含量,探讨了超声辅助食品冷冻过程中冰结晶的热力学机制;用扫描电镜间接观察和分析了冷冻湿面筋蛋白中冰晶的形状和粒度分布.结果表明:360W、440W超声辅助冷冻和液氮浸渍冷冻的湿面筋蛋白中可冻结水占总水含量的比例分别为67.3%、70.8%和77.0%,均比传统冷冻过程的(56.9%)高;不同环境下冷冻的样品其热力学特征各不不同;适宜功率的超声能加速湿面筋蛋白的冷冻过程,削弱面筋蛋白和水分子之间的相互作用力;超声辅助和液氮浸渍冷冻的湿面筋蛋白中冰晶细小,直径在4μm以内且分布均匀,可减少对面筋蛋白网络结构的破坏;与高能耗的液氮浸渍冷冻法相比,超声辅助冷冻是一种更实用的改善食品品质的技术.

The content of freezable water in frozen wet gluten was determined by means of differential scanning calorimetry （DSC） to reveal the thermodynamic mechanism of ice crystallization during the ultrasonic-assisted food freezing. The shape and size distribution of ice crystals in the frozen wet gluten were also studied by means of scan- ning electron microscopy. It is found that （1） the freezable water contents （relative to the total water content） of wet gluten frozen respectively with an ultrasonic-assisted process respectively at 360 W, 440 W and a liquid nitrogen freezing process, namely 67.3% , 70.8% and 77.0% , are higher than that with the traditional freezing process （56. 9% ） ; （2） the samples frozen in different conditions are of different thermodynamic characteristics; （3） ultrasonic with suitable power accelerates the freezing of wet gluten and weakens the interaction between gluten and water molecules; （4） both the ultrasound-assisted and the liquid nitrogen freezing processes result in well-distributed ice crystals with a small size less than 4 μm, thus reducing the deterioration of gluten network ; and （5） as compared with the liquid nitrogen freezing process with high energy consumption, the ultrasound-assisted freezing process is more practical for food quality improvement.