CaCl2对低盐罗非鱼肌球蛋白凝胶持水性和微观结构的影响

Effect of CaCl2 on water holding capacity and microstructure of tilapia myosin gel under the low salt condition

以罗非鱼(Oreochromis niloticus)肌球蛋白为研究对象,在不同盐浓度(1,50,150,600 mmol/L NaCl)下,考察适量添加CaCl2对肌球蛋白热诱导凝胶持水性、微观结构及化学作用力的影响。结果表明,低盐浓度(1~150 mmol/L NaCl)下,热诱导肌球蛋白纤丝迅速聚集,体系呈弱的不透明凝胶,链状交联的凝胶网络结构粗糙、孔隙极大,持水性低,疏水相互作用是维持凝胶的主要化学作用力。当CaCl2添加量为10 mmol/L时,有利于凝胶化过程中肌球蛋白分子结构部分展开,氢键相互作用减弱,α-螺旋部分转化成β-折叠,分子间二硫交联作用增强(P<0.05),形成致密有序的三维网状结构,持水性显著提高(P<0.05),且1 mmol/L NaCl浓度下的改善效果更明显。因此,添加适量的CaCl2可有效改善低盐条件下肌球蛋白的凝胶性能。

Myosin was extracted from tilapia(Oreochromis niloticus)and the heat-induced gel was prepared,and the effect of CaCl2 addition on the water holding capacity,microstructure and chemical interactions of myosin gel was investigated under different salt conditions(1,50,150,600 mmol/L NaCl).The effects and mechanisms of Ca^2+ on thermal gel properties of myosin were determined under the low salt conditions.Experimental results showed that under the conditions of low salt concentration(1~150 mmol/L NaCl),there were weak opaque gels due to a rapid aggregation of myosin filaments during heating.These myosin gels exhibited a cross-linked network with coarse cross-linked strands and large cavities,and the water holding capacity of gels was low.Hydrophobic interactions were responsible for the heat-induced gel formation of myosin.During the gelation process,the addition of 10 mmol/L CaCl2 promoted the unfolding of myosin and causedα-helices to partially turn intoβ-sheets with the reduced hydrogen bond interactions,thus resulted in stronger disulfide linkages between myosin molecules(P<0.05),which contributed to the ordered and dense three-dimensional network with significantly improved water holding capacity of myosin gel(P<0.05).Moreover,this improvement was more obvious at 1 mmol/L NaCl.Therefore,an appropriate amount of CaCl2 can effectively improve the gel properties of myosin under low salt conditions.