刺云实胶对草鱼肌原纤维蛋白的冷冻保护作用

为探究刺云实胶对肌原纤维蛋白的冷冻保护作用，以商业抗冻剂(4%蔗糖+4%山梨醇)为对照，研究刺云实胶对草鱼肌原纤维蛋白溶液冻结曲线的影响，并通过测定0～28 d冻藏过程(-20±1℃)中肌原纤维蛋白Ca²⁺-ATPase活性、巯基含量、表面疏水性、内源性荧光光谱及解冻后水分流动性的变化来研究刺云实胶对草鱼肌原纤维蛋白冻藏稳定性的影响。结果表明，添加1.0%刺云实胶和商业抗冻剂的草鱼肌原纤维蛋白溶液的冻结点分别为-8.3℃和-7.3℃，低于空白样品的-5.5℃。与新鲜肌原纤维蛋白相比，冻藏28 d后，添加1%刺云实胶和商业抗冻剂的肌原纤维蛋白的Ca²⁺-ATPase活性、总巯基含量、活性巯基含量分别下降了45.69%和45.17%、24.49%和42.28%、25.13%和39.79%，而表面疏水性分别增加了176.00%和122.23%，变化幅度显著低于空白对照组。低场核磁共振分析研究结果表明添加1%刺云实胶和商业抗冻剂可以显著抑制肌原纤维蛋白溶液解冻后水分流动性增加。因此，1%刺云实胶可以增强冻藏过程中草鱼肌原纤维蛋白的稳定性。

Cryoprotective Effect of Tara Gum on Myofibrillar Protein from Grass Carp during Frozen Storage

To investigate the cryoprotective effect of tara gum on myofibrillar proteins, the influences of tara gum on the freezing curve of myofibrillar proteins of grass carp were studied using a commercial cryoprotectant (4% sucrose+4% sorbitol) as a control in this study. The effects of tara gum on the freezing stability of myofibrillar proteins during frozen storage (0~28 days) were investigated by assessing Ca2+-ATPase activity, sulfhydryl content, surface hydrophobicity, endogenous fluorescence spectra and water mobility. The results showed that the freezing temperature of myofibrillar proteins solution added with 1% tara gum and commercial cryoprotectant were ?8.3 ℃ and ?7.3 ℃, respectively, which were significantly lower than that of the control (?5.5 ℃). After 28 d of frozen storage, the Ca2+-ATPase activity, total sulfhydryl content, and active sulfhydryl content of myofibrillar proteins with the addition of 1% tara gum and commercial cryoprotectant decreased by 45.69% and 45.17%, 24.49% and 42.28%, 25.13% and 39.79%, and the surface hydrophobicity increased by 176.00% and 122.23%, respectively. The changes were significantly lower than those of the blank control. Additionally, the results of LF-NMR showed that the addition of 1% gum and commercial cryoprotectant significantly inhibited the increase of water mobility of myofibrillar protein solution after thawing. Therefore, the 1% tara gum could enhance the stability of myofibrillar proteins of grass carp during frozen storage.